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7.09.2010

Roofing Questions and Answers

Roof Stains, Roof Mold, and Roof Cleaning

Scotts Contracting St Louis Renewable Energy

The following article will attempt to explain a few issues you may have with your Roof. The Roof of your Home is one of the most important parts of your home- it keeps everything Dry and Comfortable.

  • If you are having a Roofing Issue and you are unable to Repair it yourself.

  • Scotts Contracting is available to assist in you.

  • We offer roofing solutions for any and every budget.

  • If a new roof is not in your Budget we offer Roof Repairs.

  • We even have Eco and Green Roofing Options available for Energy Star Rated Roofs.

  • There are also Lifetime Guarantees Available for the Roof on your Home.

  1. Click Here-For Additional Information on the Services Scotts Contracting Offers feel free to check out our web pages full of Green and Eco Friendly Products and Information-Click Here.

  2. Click Here-To Schedule a Free Estimate / Free Green Site Evaluation for your next project Click Here—Scotty will Respond ASAP.

Scotts Contracting St Louis Renewable Energy
These article that I found at : www.merchantcircle.com- they are provided in whole and Point out some very interesting points of view and solutions

Though those ugly black streaks and stains on your shingles might appear to be some sort of roof mold, a more accurate description would be to call it roof algae. This is a hardy species of algae called Gloeocapsa Magma, and if you aren't using the right chemicals or methods it can be extremely difficult to remove. Call it roof mold, roof algae, roof mildew, or whatever else you want, but just be sure to clean it off in a timely and safe manner.

Just to be thorough, there are other types of organic growth that can form on a roof other than roof algae (or mold). There's also the possibility of lichen or moss growth. Lichen is usually a whitish color, but it can also have tones of green, yellow, and brown. It often forms in patches of individual circles, each averaging about the size of a dime. It's also noticeably raised from the surface, unlike the black algae stains.

Moss, on the other hand, almost always has a green color and if left untreated for several years will become so thick as to be noticeable from the ground. I've seen some situations where it's been ignored for so long that it literally looks like a roof is covered with green carpet. Honestly I don't know what people are thinking when they allow this to happen to their home.

So how does one go about treating a roof with lichen and/or moss? Well, in most cases it should be handled in the same manner as the black algae roof stains (or "roof mold"), which has already been described in length on this site. In a nutshell, a bleach or chlorine-based solution applied with non-pressure methods will kill lichen and moderate moss growth almost instantly. It should turn a whitish color within minutes, which tells you that it's dead. Unlike black algae stains which come off immediately with the rinse phase of the cleaning, dead lichen and moss will require a few heavy rains to finish rinsing off the roof. It could take awhile but rest assured that lichen and most moss situations, once dead, will eventually dislodge and rinse off the roof thanks to mother nature.

If you are the impatient type and want the lichen and moss removed immediately, you'll have to use a pressure washer, but as you should know by now I highly discourage the use of high pressure on a roof. In those rare cases where the moss is extremely thick and out of control (this is more common in the northwest) your only choice might be to use a pressure washer, but even in these extreme scenarios you should dial down the pressure and use extreme caution.

In summation, black roof "mold" stains (algae) should come off immediately if using the proper methods. Roof mold removal doesn't have to be rocket science, people. White or green lichen and moss, on the other hand, will be killed with the same chemicals but will need a few heavy rains to finish rinsing away. If this all just sounds like too much of a hassle and you'd rather keep your feet safely on the ground (good idea) then do take a look at our directory of non-pressure roof cleaning services. There's more than likely a company in your area that knows how to remove your roof algae in a professional and safe manner.

There's a lot of false information about roof algae cleaning floating around right now, and I guess this is to be expected because it's still a relatively new industry and most homeowners still aren't that familiar with it. But I'm tired of seeing all the confusion and decided that it's time to set the record straight. It's time to blast some common roof cleaning myths out of the water once and for all. So, without further ado, I give you the top ten myths about roof stain removal. Myth #1: Black roof stains are caused by tar, acid, dirt, or jet fuel. Roof stains are caused by a hardy type of blue-green algae called Gloeocapsa Magma. All it takes is for one algae spore to land on your shingles and take hold and then it's off to the races. The algae will continue to multiply and spread, its growth fed by the limestone filler in the shingles and moisture.

Myth #2: Algae on roof shingles is really a signal that it's time for a new roof. Simply the presence of algae stains does not necessarily equate with needing a new roof. In many cases all a roof needs is a good professional cleaning to restore its original look and health. You might notice that roofers don't like roof cleaners very much, and this is because we keep them honest. If a roofer tells you that you need a whole new roof just because of some algae staining tell him to take a walk and look up your local non-pressure roof cleaning company instead. You'll save a huge amount of money.

Myth #3: Roof algae removal will have no real impact on a home's curb appeal. Most people are shocked when they see how much better their home looks after a roof cleaning. I think this is because most homeowners have gotten so used to seeing the stains on their roof that they've completely forgotten how good it once looked. I've lost count of how many times I've cleaned the roof of a house that had been on the market for months with virtually no activity and within days of the cleaning it finally started getting serious offers. I've said it before and I'll say it again that no matter how beautiful your landscaping, no matter how clean your windows, no matter how precise the painted trim, if your roof is covered in filthy algae stains then it will still ruin your curb appeal, if not in your eyes then in the eyes of your family, friends, neighbors, and potential buyers.

Myth #4: Roof algae is only a cosmetic issue so it can be ignored for now. If not cleaned off and kept at bay roof algae has the ability to shave years off the life of your shingles. It's important to remember that roof algae is a living organism that needs food to continue to grow. Guess what the favorite food of roof algae is? That's right – your shingles! Shingle makers now use limestone filler in the manufacturing process which the algae just loves to chew on. This will result in premature loss of shingle granules and general deterioration. Shingle granules are vital to the health of your roof and home because they work to deflect UV rays and heat away from your roof surface. If they are gone or covered with algae then you will have a hotter attic and higher AC bills. You'll also have to replace the roof a lot sooner, and with the average new roof these days topping $10,000 it's just a no-brainer to keep your shingles clean and functional for a fraction of the cost. Myth #5: The best way to go about removing roof algae is with high pressure. I've beaten this one to death on this site but it bears repeating that, next to positioning your home in the path of a tornado, power washing your roof to remove algae stains is the worst thing you could possibly do to it. Just because your concrete, deck, and brick siding were pressure cleaned doesn't mean you should do it to your shingles. Don't you have any idea how flimsy and fragile your shingles are? Don't you realize how many thousand or tens of thousands of shingle granules will pop right off with the use of a power washing wand? It just always blows my mind that people think this is a good idea. Yes, blasting your roof with 2000 PSI will remove some of the stains, but if it removes some of your actual roof in the process then what the heck is the point? If you bought a roof algae remover and somewhere in the instructions it says that you should walk up on your roof with a power washing wand in hand and unleash hell on your shingles then it's safe to say that you purchased the wrong product. Myth #6: Chemical roof cleaning will damage shingles, gutters, and landscaping. If you're using the right chemicals with the proper procedures and rinsing techniques then you have nothing to fear. I've cleaned hundreds of roofs with non-pressure chemical methods and have never once seen a situation where we caused damage to someone's home. I also only clean roofs with a helper present who's sole responsibility is to rinse the heck out of the grass, bushes, and perimeter landscaping so that there's absolutely no chance of plant damage. We usually do such a good job of rinsing that homeowners notice that their landscaping actually looks especially healthy and vibrant in the days following the cleaning. ARMA (the Asphalt Roofing Manufacturers Association) and GAF (North America's largest shingle maker) both recommend that shingles be cleaned with non-pressure, chemical methods, and any home inspector worth his salt would also concur. Myth #7: It's only necessary to clean the sections of the roof that have visible stains. Just because you can't see algae stains on certain parts of the roof doesn't mean that it's not already there and beginning to develop. Keep in mind that in its early stages roof algae is completely invisible to the naked eye. It's not until the more advanced stages that it actually turns black and becomes visible. So if you can see algae on even one section of your roof that means that it's probably already taking hold on your entire roof. I always try to explain this to my customers but occasionally I still get people who don't believe it and demand that I only do a spot-clean to remove visible stains. I reluctantly oblige their demands but am never surprised when I drive by a year later to see the untreated areas now completely covered in black algae! Then they usually call me back with the standard, "You were right. Can you please come back and clean the whole roof as you originally recommended?" Myth #8: Ambient temperature has no effect on the effectiveness of a roof algae cleaner. If you're using the correct chemical mixture then it will be most effective when the temperature is above 50 degrees. Below 50 and the power of the solution drops off rapidly. If you absolutely must have the roof cleaned on a day when it's right around 50 or a little bit lower just keep in mind that the chemicals will need to sit for a little bit longer on the roof to be effective. So instead of giving it five minutes to kill the algae give it 15. Then reapply if necessary. On the flip side, if it's an extremely hot day you may find that your chemical is evaporating before it even has a chance to kill the algae. In this situation you can simply soak the roof with water to cool it down before applying the chemicals. Myth #9: Roof cleaning is an easy DIY project that any homeowner can do in an afternoon. There's nothing easy or quick about roof cleaning. In fact, if you approach it with a cavalier attitude you run a good chance of injuring yourself. If you want to have any chance of cleaning your roof safely and effectively then you need to set out a clear plan of attack, have safety procedures in place, and, above all, take your time. Rushing through a roof cleaning only leads to trouble. Unless you're one of these guys that absolutely has to do every home improvement job on his own I would highly recommend that you just find a qualified, non-pressure roof cleaning company in your area. Either you can hire somebody who has the equipment and experience to clean your roof in a few hours or you can spend an entire weekend doing it yourself and risking your life. Your choice. Myth #10: Roof cleaning companies tend to overprice their work and take advantage of consumers. I guess I'm always a little disappointed when I tell someone that it will cost $300-$500 to clean their roof and they give me attitude and insinuate that I'm somehow ripping them off. I think people hear that word "cleaning" and they think it should be cheap like carpet cleaning or house cleaning. Think about it. Does a carpet cleaner spend three hours at your house sweating his butt off and getting sunburned? No. Does a carpet cleaner run the possibility of paralysis or death by simply doing his job? No. Does a carpet cleaner spend $100 on chemicals for every single job? No. Can a carpet cleaner offer you a guarantee that the treated surface will stay clean for years to come? No. There's so much more that goes into a professional roof cleaning than for any other kind of residential cleaning service that it's really not even fair to lump them into the same category. As a matter of fact, I actually think that most roof cleaning companies come in too low with their prices when you consider all the variables involved. I also challenge you to name me one other home improvement service that can instantly transform a home's curb appeal in a single afternoon for under $500. Can't be done. And when you consider that it not only makes your home more beautiful but also extends the life of your expensive roof by a matter of years I think that having a roof cleaned is one of the smartest and most cost-effective things that a homeowner could possibly do to protect their biggest investment. So now that I've cleared the air and educated you about the myths that surround the roof cleaning industry I hope you'll take these words of advice to heart because they represent the straightest talk about this topic that you're going to find. I'm not here to serve up a load of BS just because I'm trying to sell a product. I'm telling you like it is because there are too many lies flying around. Either you can buy into one of the myths and be disappointed with the results or you can clean your shingles the right way and be satisfied with your new-looking, beautiful home that is free of roof algae.

Contrary to popular belief, roof cleaning is about more than just having a nice-looking house. It's also about attending to the overall health of your roof and home. The black streaks that you're seeing on your roof consist of Gloeocapsa Magma, which is a hardy type of blue-green algae that if left to its own devices will eventually start to compromise the integrity of your shingles.

Usually the process begins when an algae spore lands on and attaches to your roof. It then begins to consume the limestone filler in your shingles' granules. The limestone acts as a food source for the algae and allows it to grow and eventually cover larger and larger portions of your roof's surface. So as the algae grows across your roof it is literally eating the shingles! If the growth goes unchecked it will eventually cause loss of roof granules, which are vital to the reflective properties of your roof. When these granules are lost it leads to greater heat build-up which leads to higher energy costs for you, especially on those hot summer days when the AC is blasting!

Loss of granules and the further deterioration of your shingles could very well shave years off the life of your roof, and with new roofs running between $5,000 and $15,000 these days for average homes, why wouldn't you do everything in your power to max out its lifespan? Take my advice to have your roof cleaned as needed and you'll not only enjoy a nicer-looking home but you'll be protecting probably your biggest investment: your home! To learn more about what qualities to look for in a service provider please read this post about roof cleaners.

For Assistance with your Next Roofing Project Let the Guys at Scotts Contracting Protect the Roof over your Head.

Scott's Contracting scottscontracting@gmail.com http://www.stlouisrenewableenergy.blogspot.com http://www.stlouisrenewableenergy.com scotty@stlouisrenewableenergy.com

8.02.2011

Roof Venting and Its Importance for your Home


A Crash Course in Roof Venting

Understand when to vent your roof, when not to, and how to execute each approach successfully

Article Re-Posted from: http://www.finehomebuilding.com/how-to/articles/a-crash-course-in-roof-venting

Click to enlarge image
So much information has been devoted to the subject of roof venting that it's easy to become confused and to lose focus. So I'll start by saying something that might sound controversial, but really isn't: A vented attic, where insulation is placed on an air-sealed attic floor, is one of the most underappreciated building assemblies that we have in the history of building science. It's hard to screw up this approach. A vented attic works in hot climates, mixed climates, and cold climates. It works in the Arctic and in the Amazon. It works absolutely everywhere—when executed properly.

Unfortunately, we manage to screw it up again and again, and a poorly constructed attic or roof assembly can lead to excessive energy losses, ice dams, mold, rot, and lots of unnecessary homeowner angst.

Here, I'll explain how to construct a vented attic properly. I'll also explain when it makes sense to move the thermal, moisture, and air-control layers to the roof plane, and how to detail vented and unvented roofs correctly.

Theory behind venting
The intent of roof venting varies depending on climate, but it is the same if you're venting the entire attic or if you're venting only the roof deck.

In a cold climate, the primary purpose of ventilation is to maintain a cold roof temperature to avoid ice dams created by melting snow and to vent any moisture that moves from the conditioned living space to the attic. (See Added  1/5/13- http://stlouisrenewableenergy.blogspot.com/2013/01/ice-dam-prevention.html)

In a hot climate, the primary purpose of ventilation is to expel solar-heated hot air from the attic or roof to reduce the building's cooling load and to relieve the strain on air-conditioning systems. In mixed climates, ventilation serves either role, depending on the season.

Vent the attic

A key benefit of venting the attic is that the approach is the same regardless of how creative your architect got with the roof. Because the roof isn't in play here, it doesn't matter how  many hips, valleys, dormers, or gables there are. It's also easier and often less expensive to pile on fiberglass or cellulose insulation at the attic floor to hit target R-values than it is  to achieve a comparable R-value in the roof plane.

The success of this approach hinges on the ceiling of the top level of the house being absolutely airtight before any insulation is installed. (See "Attic-Insulation Upgrade" in FHB #200.) It's also important to ensure that there isn't anything in the attic except lots of  insulation and air—not the Christmas decorations, not the tuxedo you wore on your wedding day, nothing. Attic space can be used for storage, but only if you build an elevated platform above  the insulation. Otherwise, the insulation gets compressed or kicked around, which diminishes its Rvalue. Also, attic-access hatches are notoriously leaky. You can build an airtight entry  attic, but you should know that the more it is used, the leakier it gets.

How do people get this simple approach wrong? They don't follow the rules. They punch a bunch of holes in the ceiling, they fill the holes with recessed lights that leak air, and they stuff mechanical systems with air handlers and a serpentine array of ductwork in the attic. The air leakage from these holes and systems is a major cause of ice dams in cold climates and a major cause of humidity problems in hot climates. It's also an unbelievable energy waste no matter where you live.

Don't think you can get away with putting ductwork in an unconditioned attic just because you sealed and insulated it. Ductsealing is faith-based work. You can only hope you're doing a good-enough job. Even when you're really diligent about airsealing, you can take a system with 20% leakage and bring it down to maybe 5% leakage, and that's still not good enough. With regard to recessed lights and other ceiling penetrations, it would be great if we could  rely on the builder to air-seal all these areas. Unfortunately, we can't be sure the builder  will air-seal well or even air-seal at all. So we have to take some of the responsibility out of the builder's hands and think of other options.

In a situation where mechanical systems or ductwork has to be in the attic space or when there are lots of penetrations in the ceiling below the attic, it's best to bring the entire attic area inside the thermal envelope. This way, it's not as big a deal if the ceiling leaks air or if the ducts are leaky and uninsulated.

Vent the roof deck

If the attic space is going to be conditioned, either for living or mechanical purposes, or if a home design calls for a vaulted ceiling, provision R806.3 in the International Residential Code calls for the roof deck above the space to be vented continuously from the eave to the ridge. This is easy to accomplish in simply constructed roofs and difficult, if not impossible, to accomplish in roofs that have hips, valleys, dormers, or  skylights that interrupt the rafter bays.

If you choose to vent the roof deck, then be serious about it and really vent it. The code calls for a minimum of 1 in. of airspace between the top of the insulation and the back of the roof sheathing. That's not enough. For best performance, the airspace in the vent chute should be a minimum of 2 in. deep. Unless you're bulk-filling rafter bays between 2x10 or 2x8 rafters with closed-cell spray foam, this approach will likely require you to fur out the rafters to accommodate additional insulation to achieve desired R-values. That can be a pain, but you won't run into the problems associated with having too little air circulating under the roof. To be sure your roof is getting enough ventilation, there are simple calculations that you can follow.

Beyond the decreased capacity for insulation when venting the roof deck, venting the roof deck or the attic has some other drawbacks worth considering. In cold climates, snow can enter the soffit and ridge vents, melt, and potentially cause rot. Similarly, in coastal environments or in regions with lots of rain and wind, moisture can be forced into the vents and into the roof assembly. In hurricane-prone zones with frequent high-wind events, vented-soffit collapse can pressurize a building, which can cause windows to blow out and the roof to be blown off. Finally, in wildfire zones, floating embers can enter the vents and cause roof fires. If any of these issues are of concern, there is another option.
Click to enlarge image

Create an unvented roof

Through provision R806.4, the IRC also allows you to build an unvented roof assembly. Unvented assemblies work particularly well on complex roofs that would be difficult or impossible to vent properly or on roofs where it would be difficult to insulate properly if the roof were vented.

It should be noted, however, that in high-snow-load areas, you still need a vented over-roof to deal with ice damming. In essence, you're creating a hybrid vented/unvented roof system.The goal in an unvented roof is to keep the roof deck—the principal condensing surface in roof assemblies—sufficiently warm through the year to prevent condensation from occurring. In most climates, builders have to insulate the roof sheathing to prevent condensation from occurring within the assembly. The exception is hot-dry climates such as in Phoenix, where condensation isn't as big an issue.

Condensation control is most often accomplished by installing rigid foam above the roof deck or by installing air-impermeable spray-foam insulation directly against the underside of the roof deck. The code also allows for air-permeable insulation, such as fiberglass or cellulose, to be used under the roof deck as long as rigid foam is used above the roof sheathing. Flash-andbatt (or flash-fill) assemblies are also allowed. Any of these approaches can adequately prevent condensation from occurring within the roof when the rigid foam or spray foam is installed at the appropriate thickness.

If you're spraying foam on the underside of the roof deck, be sure you're using the right product. Closed-cell spray foam works in all climates, but especially well in climate zones 5 through 8, where high R-values are desired and where airimpermeable insulation also must be a vapor retarder. Lowdensity, open-cell foam is permissible, but in climate zones 5 and above, it has to be covered with a vapor-retarder coating, like rigid foam or painted drywall.

Also pay attention to roofing materials. Asphalt shingles require special attention when installed on unvented roof assemblies in hot-humid, mixedhumid, and marine climates due to inward vapor drive. To keep moisture out of the roof assembly, a roofing underlayment with 1 perm or less (class-II vapor retarder) must be installed under the shingles. Also, check to be sure that you are in compliance with the manufacturer warranties when installing shingles over an unvented roof in all climates. Some manufacturers don't warranty or offer only a limited warranty when their products are used over an unvented roof assembly.

Shingles that are installed on unvented roof assemblies operate at slightly higher temperatures, roughly 2°F to 3°F warmer than shingles on vented assemblies. This can reduce  their service life by roughly 10%. You can vent the roof cladding, which will increase its  longevity, but the expense of fastening battens over the roof sheathing, then adding another layer of plywood over the battens as a nail base for the shingles, may not be worth the expense. After all, the shingle color and the roof orientation are much more significant concerns when it comes to shingle life.
Unvented roofs
Unvented roofs aren't nearly as common as vented assemblies, and builders may not be familiar with detailing them correctly. While there are certainly a variety of ways to build an unvented roof assembly that performs well, here are three examples worth considering


Option 1: Insulate below the roof The most conventional approach to insulating a roof is to put all the insulation below the roof deck. This approach is especially prevalent in retrofits when the existing roof is in good  shape but the attic is being conditioned

Prevent condensation with the right amount of insulation

Click to enlarge image
An unvented roof assembly is possible only if you keep the roof sheathing warm enough to prevent conditioned air from condensing against it. The map at right, which is based on table R806.4 of the IRC, lists the minimum R-values required to prevent condensation in unvented assemblies in various climate zones. The thickness of the insulation will vary depending on the type. These R-value requirements are intended only to prevent condensation and don't supersede the code-required R-values for energy efficiency, which are also listed.
The success of a vented attic or roof deck relies on its airtightness. The space above the top plate of exterior walls—at the bottom of each rafter bay—is especially important. Baffles placed in this area channel intake air into either the attic space or vent chutes, and also prevent insulation from falling into the soffit and blocking airflow.
Click to enlarge image
Site-built: 2-in. chutes and baffles Cut 1-in.-thick rigid polyiso insulation into 2-in.- wide spacer strips, and glue them to the inside face of each rafter with a spray-foam adhesive like Pur Stick (www.todol.com). Cut the polyiso insulation to fit snugly in each rafter bay, and foam it in place against the spacer to create a 2-in. chute or baffle.

Size: Custom-cut polyiso foam
Cost: $23 per sheet
Source: Dow
www.dow.com
Click to enlarge image
Prefab: fast and functional The AccuVent soffit insulation baffle is made of rigid recycled plastic. It's more durable than other foam-based products and installs quickly with staples. These baffles should still be air-sealed with spray foam, but they're a good option if you're looking for a stock product.

Size: 41 in. by 22 in.
Cost: $1.68 each
Source: Berger Building Products
www.bergerbuildingproducts.com
Drawings: John Hartman
From Fine Homebuilding212, pp. 68-72
July 14, 2011

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8.21.2010

White Roofs Bring Cool Savings

No matter where you live, you can save energy and money by switching to a white, or "cool," roof, for about the same cost as a conventional roof.
White roof
White or light-colored roofs can reduce energy use and lower utility bills.
NREL/CRAIG MILLER PRODUCTIONS/DOE

White roofs, aka cool roofs, are a "hot" topic these days as a means to help stem global warming. Most of us know better than to wear black on a hot day, but when it comes to the roofs on our houses, temperature often takes a back seat to aesthetics . Dark roofs mean higher air conditioning bills, and higher carbon dioxide emissions as a result. The good news is you can save money and help protect the planet by lightening the color (and therefore the temperature) of your roof, or by switching to a white roof the next time your house needs a new hat.

The Benefits of a White Roof

Switching to a white roof can actually reduce energy use by about 20 percent in hot, sunny weather, according to the Lawrence Berkeley National Laboratory Heat Island Group in Berkeley, Calif. Hashem Akbari, the Heat Island Group's lead scientist and a professor of Building, Civil and Environmental Engineering at Concordia University in Montreal, says that transitioning to reflective roofing and pavements in the world's urban areas would offset the equivalent of emissions from the planet's 600 million cars for the next 18 years. A 1,000-square-foot cool roof saves air conditioning use that otherwise would emit about half a ton of carbon dioxide per year. (The average total square footage of a home in the United States is more than 2,000.)
In urban areas, white roofs also help lower smog levels by lowering local temperatures, which tend to be higher due to the large proportion of paved surfaces.
Critics have suggested white roofs do more harm than good in colder climates. But research shows that the heating benefits of a dark roof in the winter are negligible because days are shorter, skies are cloudier, the angle of the sun is low, and sometimes roofs are covered in snow. "The amount of heat savings you may lose in the winter would be, at the maximum, 30 percent of the summertime savings," Akbari says. "If you need cooling in the summer and heating in the winter, no matter where you are, a white roof will most likely save you money."

Cool New Roof Options

"Cool" is the buzzword that encompasses a range of roofing materials that can reduce carbon footprints. And cool roofs come in a variety of light colors.  The best time to install a cool roof is when a new roof is needed or major roof maintenance is in order. According to researchers, there's little difference between the cost of roof colors.

Not ready for a new roof but still want to cool down? Install a white roof coating instead. There are a number of coatings that will substantially improve an existing roof's reflectance/emittance. Plus, coatings protect and seal, potentially extending the life of your roof. The installed cost of coating a roof is about $0.50 to $1 per square foot, according to Akbari, which will be paid back by lower energy bills and the extended life of your roof.

Roof Resources

A cool roof is measured by two properties: reflectance (the ability of the product to reflect energy away from the roof) and thermal emittance (the roof's ability to radiate absorbed heat). Ideally, you want your roof to be high in both.
The Heat Island Group has developed a Solar Reflectance Index (SRI) to rate cool roofs. You can browse the Lawrence Berkeley National Laboratory's Cool Roofing Materials Database for information about a product you're considering. The Heat Island Group says an SRI rating of 30 percent or higher for sloped roofs (70 percent or higher for flat roofs) can reduce utility bills.  The Cool Roof Rating Council also offers a product directory; just click on "Rated Products Directory."
Federal and state rebates are available; check the Database of State Incentives for Renewables & Efficiency for details specific to your project. Also call your utility company to check for local programs. "This will not be the silver bullet that solves the global warming problem," Akbari says. "But it cools your home, cools your community and helps cool the globe while putting money in your pocket."
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Scott's Contracting
scottscontracting@gmail.com
https://stlouisrenewableenergy.blogspot.com/search?q=roof

6.23.2010

Cool Roofs-Materials, Options, Insulation, Photos

Cool Roofs for Hot Climates

Lighten the loads on home air conditioners with reflective roofing, radiant barriers, or better insulation and ventilation



Steven Spencer, FSEC

Even in hot, sunny climates, it's common to see dark shingle roofs. That heat-absorbing choice carries a significant energy penalty: In sunny climates, heat gain through the roof makes up a major share of a house's cooling load.

People try different strategies to limit heat gain through the roof. Extra ceiling insulation, extra ventilation, under-roof radiant barriers, and sealed attics with insulated roof decks can all help in certain circumstances. But research shows that the single most effective way to cut the cooling loads from a hot-climate roof is to make the roof reflective. There's a reason all those quaint little cottages in Bermuda have white roofs -- they work.

Reflective roofs work because they stop the rooftop heat before it ever gets going. The sun's rays hit the roof at the speed of light, and at the speed of light they bounce back into space. White or light-colored materials work best, but some new dark pigments reflect enough invisible infrared radiation to reject a lot of solar energy. And whether you're applying tile, metal, membranes, or even asphalt shingles, choosing a more reflective version seldom adds cost.

Let's look first at reflective roofs, then consider some of the other options for cutting heat gain through the roof.


Reflective Roofing
It's well established that reflective roofing materials can lighten the load on home air conditioners. When researchers at the Florida Solar Energy Center (FSEC), where I am a principal scientist, whitened the roofs of nine occupied homes in the summer of 1994, air-conditioning savings averaged 19%. We got even better information by comparing seven otherwise identical new homes with various roof types in a study sponsored by Florida Power & Light (FPL) during the summer of 2000 (see Figure 1). All these homes had R-19 ceiling insulation, but each had a different roof covering. Clearly, reflective roofing made a huge difference.


Reflective Roof Savings
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Figure 1. Florida Solar Energy Center researchers compared the air-conditioning power use of seven identically built houses with different roof coverings. Reflective roofing dramatically reduced total power use (bottom chart) and had an even greater effect on peak A/C power demand (middle chart). Insulating the roof deck and sealing the attic, without using a reflective roof, cut total energy use somewhat but did not reduce peak cooling loads noticeably.

One house of the seven had an insulated roof deck, to keep the ductwork within the sealed, conditioned attic. That modification did save energy on average, but not as much as the reflective roofs -- and it had little effect on peak loads.

Cool colors. Until recently, a roof had to be white to have high solar reflectance -- something not every customer wants. But we now have tile and metal roofing systems made with "spectrally selective" paints, which absorb some colors of light in the visible range but reflect rays in the infrared and ultraviolet spectra that account for much of the sun's heat. These colors give designers more choices, while still saving considerable energy (Figure 2).

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Figure 2. Kynar roof coatings using spectrally selective pigments from Ferro Corporation allow Classic Roofs to produce aluminum and steel shingles in several dark colors that meet Energy Star minimums with solar reflectances better than white asphalt shingles. Tests indicate that the colors will sharply reduce solar heat gain through the roof.

BASF Corporation's ULTRA-Cool metal-roof coatings (800/669-2273, www.basf.com), which use spectrally selective pigments from Ferro Corporation (216/641-8580, www.ferro.com), have a 38% reflectivity in colors that achieve only 25% reflectivity when made with standard pigments. And at least two companies, Classic Products (800/543-8938, www.classicroof.com) and MCA Tile (800/736-6221, www.mca-tile.com) now supply metal or clay tile in a range of colors with solar reflectance around 30%. Classic's "Musket Brown," for instance, reflects 31% -- quite a bit better than a white shingle -- while the same color in traditional paint would reflect only 8%.

Bare metal roofs. Unfinished galvanized or "tin" roofs are still fairly common in the hot Southeast. Galvanized steel is highly reflective when new, but its reflectivity soon drops as the zinc oxidizes; and the material also has low infrared emittance. The high absorptance and low emittance can combine to keep the roof blazing hot.

When FSEC researchers put a white coating on the ten-year-old galvanized steel roof of a retail strip mall, the roof's reflectance went from 30% to 77%. The average air-conditioning reduction in seven monitored shops was more than 24% (Figure 3).

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Figure 3. Unfinished galvanized steel roofs may look shiny when new, but they age quickly to become very nonreflective. The infrared thermal scan (top) shows the drop ceiling (middle) at a radiant temperature of almost 90°F under the metal roof of a strip mall building, despite insulation below the roofing. When FSEC researchers applied a reflective coating (bottom), the building's air-conditioning power use dropped 16%, and tenants reported improved comfort. One tenant even called to thank the landlord for fixing the air conditioner. (He hadn't.)

If you want unfinished metal roofing, Galvalume (an alloy of aluminum and zinc) is a much better cool-roof choice than galvanized steel, especially in mixed heating and cooling climates. Galvalume maintains its reflectance as it ages, and its low emissivity means it holds heat well in winter even though it reflects well in summer.

Tile Roofing
It's conventional wisdom that tile roofs are cooler than shingle roofs. To a small extent, that's true: S-tiles permit cooling airflow between the tile and the roof deck, and their thermal mass stores energy during the day and re-radiates it at night, instead of passing it all through to the attic.

But the color of the tile matters. For instance, we painted some dark gray tiles bright white at midsummer in central Florida in 1996, and we measured an 18% drop in space-cooling energy.

Shape appears to be far less important than color. In the seven-home side-by-side study for Florida Power & Light, one of the homes had flat white tile, and another had white S-tile. We didn't see much difference -- both roofs did about 20% better than the asphalt shingle roof. An S-shaped red tile roof in the same study was only 3% better than dark asphalt shingles.

In general, light-colored metal roofs will outperform tile in a hot climate like Florida's. At night, they actually radiate attic heat upward into the night sky, cooling the attic to below the ambient air temperature. The thermal mass of tile will not let attic heat escape so readily.

Radiant Barrier Systems
When a house has a dark, sun-absorbing roof, radiant barriers in the attic can cut heat gain and save energy. But they don't necessarily work in every case, and they're not always the best solution.

The basic radiant barrier is a layer of aluminum foil placed with its shiny side facing a clear air space. Placed under the rafters, aluminum's low emissivity prevents heat from radiating off the shiny surface onto the insulation below (Figure 4). If the surface gets dirty, it won't work as well; that's why radiant barriers placed shiny side down, so dust can't collect, work better than radiant reflective material placed facing up.

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FI-Foil Corp.
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Figure 4. Radiant barrier foil under the rafters stops heat from radiating into the attic, because the foil will not emit heat radiation even when it's hot (top and middle, before and after). Lo/Mit low-emissivity silicone coating spray-applied to the roof underside (bottom) is a cost-effective alternative method.

There's now a range of material choices for attic radiant barriers, including radiant-barrier sheathing, spray-applied low-emissivity coatings, and a wide variety of foil products. Homes with complex attic geometry and poor access to the space are not great candidates for a foil application, but a radiant barrier sheathing is easy to apply to any new house, and a spray-applied low-e coating such as Lo/Mit from Solec, Inc. (www.solec.org) makes a practical retrofit.

Energy savings. Radiant barriers are effective. Our research indicates that under-roof foil barriers reduce heat flow through the ceiling by 30% to 50% and can bring annual cooling electricity savings of 7% to 10% in the Southeast climate.

Radiant barriers also have a strong effect on peak loads for the air conditioner. A nine-home retrofit study we conducted for Florida Power Corporation found that radiant barriers reduced air-conditioning power use by 9% and cut afternoon air-conditioning peak loads by 16%. In a six-ton system, that's a ton of cooling. Attic temperature peaks dropped by about 8°F. Perhaps most important, indoor temperatures fell by an average 2°F -- a boost for homeowner comfort.

But that was in the South. In colder climates, radiant barriers may create a risk of wintertime condensation, because some foil products also act as vapor barriers. For cool-climate homes, it's wise to search out a product that has high permeability as well as low emissivity (manufacturers can supply data sheets with perm ratings, emissivity ratings, and other useful information).

And be aware that if you have a reflective roof to begin with, a radiant barrier is overkill -- and may even be counterproductive. Since the underside of a reflective roof does not get hot, a radiant barrier under the roof adds little benefit. On the other hand, by reflecting heat inward, the radiant barrier will impede the ability of the attic to radiate excess heat to the night sky.

Another word of caution: We installed our test radiant barriers in midsummer, so we could immediately measure the benefit. But the attics we worked in were dangerously hot -- one of our people actually had to stop and get medical attention. It's much safer to install attic radiant barriers in the cool season, or at least during the early morning before the attic is baking hot.

Boosting Attic Ventilation
If the attic is too hot, is more ventilation a good idea? Maybe, but maybe not. Increasing the roof's passive air vents can reduce the cooling load, but it is usually one of the least effective options. The incoming ventilation air is hottest just when you need the cooling.

In retrofit work, we have seen increased ventilation bring a 5% reduction in building cooling loads. But in humid or coastal locations, it can also create problems: At night, the vents bring in moist outside air that may condense on duct systems.

Since passive vents work inconsistently, some people recommend powered ventilation fans. But the electric power used to operate the fan usually outweighs the air-conditioning savings. And there's another drawback: Power attic ventilation can depressurize the house and cause gas water heaters to backdraft. It may also draw conditioned air out of the house into the attic, creating a further energy penalty.

We've conducted tests of photovoltaic solar-powered attic fans in Florida. They run whenever the sun is shining, and we found savings of about 6% on electric bills. But at around $600 for the solar panels plus the fan, the savings don't really justify the cost in simple financial terms.

Added Insulation
Added insulation is another option for cutting heat gain through the roof. It certainly works: One of our studies for a Florida utility showed that boosting ceiling insulation from R-19 to R-30 cut space cooling by about 9% in summer.

But your mileage may vary. Duct systems in many homes run through the hot attic and may be insulated to only R-4 or R-6. So the air conditioner is sending 55°F air into the duct in a space that can reach 130°F on a hot day. That's a temperature difference of 75°F, across just an R-6 insulated duct wall -- much greater than the 20°F difference you might see from indoors to outdoors across an R-11 or R-19 building wall. And duct surface area is much greater than you might think -- often as much as 25% of the house floor area. During the hottest hours, as much as 30% of the cooling system's capacity can be lost to heat gains in the duct system. Besides the wasted energy, this means it takes longer to cool down the house when the air conditioner kicks in.

Unlike a reflective roof or attic radiant barrier, ceiling insulation does little to address duct system losses. So if your design relies on ceiling insulation to limit roof-related cooling loads, try to locate the duct system within the thermal envelope, below the insulated ceiling. Even running the ducts through the crawlspace, though they might be exposed to outdoor air temperatures, will add less to the load than running them through the solar-heated attic.

Insulated Roof Deck With Sealed Attic
Sealing the attic and insulating the roof deck is another way to get the duct system into a more friendly environment. Some code officials may not like this roof design, and researchers don't recommend it in colder climates, but it does save energy. It also creates semi-conditioned storage space in the attic, reduces interior moisture loads in hot climates, and avoids the risk of condensation on air handlers and ducts.

In our seven-home side-by-side comparison, the house with a sealed and insulated attic used 9% less energy than the base case house, even though both had dark shingles. Some of us were expecting a greater savings, but several factors limit the benefit of this method.

The big advantage is that the ductwork is inside the thermal envelope. However, while a ventilated attic can flush some heat out through the vents, an insulated roof deck fights its whole battle at the roof surface. Also, the air conditioner has to treat the additional air volume of the attic space.

Beyond that, an insulated roof deck contributes more heat to the house than an insulated attic floor does. Heat transfer is proportional to the temperature difference, and also to the area of the surface. In a ventilated attic on a hot day, the top surface of the ceiling insulation may hit 130°F -- a 55°F difference with the 75°F interior. But the deck of an insulated roof in the direct sun may reach 170°F while the attic reaches 85°F, for a difference of 85°F across the insulation. That wider temperature gap drives faster heat gain. And that faster gain is multiplied by a greater area, since the roof area is anywhere from 5% to 40% greater than the ceiling area, depending on the pitch of the roof (not to mention the gable ends).

So with an insulated roof deck and a sealed attic, it is very worthwhile to block that solar gain right off the bat: Use a lighter tile, white shingles, or a more reflective metal. In our study, the sealed system with dark shingles did about 9% better than a ventilated attic with dark shingles. With a reflective roof, the sealed attic would likely post savings of 25% or 30%. Even matched with white shingles (with a reflectance of 25%), we estimate that the insulated roof would have scored about a 13% savings compared to the dark shingles and vented attic. Also, it's worth noting that we carefully sealed the ductwork in all the test houses, to avoid confusing the results. If the ducts are leaky, the benefit of a sealed attic is much greater, because those leaks can't communicate with the outdoors.

Options for Stopping Rooftop Heat Gain
Field research at the Florida Solar Energy Center (FSEC) has found several effective ways to limit rooftop heat gain in sunny conditions. Using a highly reflective roofing material (top) is the simplest and most effective: It stops the sun's energy before any heat is absorbed, so that even the roof sheathing and framing stay cool. If the existing roof is dark colored or the customer prefers a darker roof, heat can still be blocked by adding a radiant barrier foil just below the roof deck (middle). Savings from this method are roughly comparable to the saving achieved with reflective roofing; however, some conductive heating of the attic space will still take place, and the roof deck and shingles will experience some increased heat stress. A third option is to increase the insulation between the attic and the living space below, and to run the hvac ductwork within the conditioned space rather than in the unconditioned attic. This method has a smaller effect on cooling loads than the reflective or radiant barrier roof systems but is effective at reducing heating loads as well as cooling loads, making it the most cost-effective option in mixed heating and cooling climates.

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Smart Choices
Good roof details can save energy anywhere in the country. But climate and other building details do affect the choices. Here's how to approach the decision:

Northern climate options. If you build in the North, reflective roofing materials or radiant barriers bring only modest savings. Adding insulation in the attic is a much more cost-effective upgrade. Insulation cuts both heating and cooling costs; and the heating savings in northern winters add up to much more money. (For the full benefit, it's important to run ductwork within the insulated envelope -- winter or summer, ducts in the attic will bypass the ceiling insulation and reduce its effectiveness.)

Not that cooling doesn't matter up north, however. In summer, attics get hot everywhere. So even in the North, reflective roofing or radiant barriers may be worth installing simply to improve summer comfort and to reduce peak loads on the air conditioner. But if you want a reflective roof in the North, look for a material like Galvalume that is both reflective and low-e: This conserves attic heat during the winter as well as providing a summer cooling benefit.

Southern choices. Down south, reflective roofs are a no-brainer -- they're money in your pocket. Air conditioning is the big energy cost, and reflective roofs can cut it by a third in the hottest months. Increasing the attic insulation can't hurt, but reflective roofs are more cost effective, particularly if the ductwork runs through the attic.

If you're stuck with a dark roof, attic radiant barriers can achieve savings comparable to a reflective roof's performance. But if you use radiant barriers under an asphalt shingle roof, you're wise to also choose white shingles, just so the shingles themselves won't get quite so hot.

Good ductwork location and reflective or radiant-barrier roof construction bring independent benefits, but they also complement each other. If you have a dark roof and a hot attic, bringing the ductwork below the insulated ceiling will help quite a lot. If the ducts are in the attic, switching from a dark roof to a reflective roof can help. But combining the two tactics -- applying reflective roofing and bringing the ducts inside -- provides the greatest total benefit. In a hot climate like Florida's, your summer cooling loads could drop by as much as 40%.



By Danny Parker ,Danny Parker is a senior research scientist with the Florida Solar Energy Center. Article Supplier: http://www.jlconline.com/cgi-bin/jlconline.storefront/4c224d630329c28327180a32100a05df/UserTemplate/69

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12.29.2010

6 Tips for an Energy-Saving Roof






On Wed, Dec 8, 2010 at 6:21 PM, ebuild <ebuild@bpr-media.com> wrote:
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ebuild Decks Quarterly

Special Report:

Roofing Products
6 Tips for Specing and Installing an Energy-Saving Cool Roof

Few home builders or homeowners opt for energy-efficient cool roofs, says California building science consultant Steve Easley, because that typically means the roof has to be white. But that's changing.
Now manufacturers-with the help of research conducted by the military-have devised a formula for treating shingle-topping granules so darker colors-as deep as forest green, brown, and even "cool" black-also reflect enough heat to make a difference in how hot the home's attic gets and how high the owner's cooling bill soars.
Combine the new technology with California's Title 24 stipulations that require pros to increase the roof's efficiency, and cool roofs appear to be gaining acceptance, especially among green builders. Add to that the attention of contractors and consumers looking to earn points toward green certification, or who just want to reduce a home's overall energy costs, and reflective or cool roofing materials-available in asphalt, metal, and composite-could slowly move into the mainstream.
If you or your customers are considering a cool roof, which in some cases carries a higher price tag than traditional asphalt shingles or metal, here are seven facts to consider:
1. Heating bills. A reflective roof can help keep a house cooler when the hot sun beats on it, but it will not lower a home's heating bill, and may even slightly raise it. It makes sense to install a cool roof, which reflects heat but does not absorb it, only where the summers are extremely hot or humid. Most residential cool roofs are in southern and southwestern states, although homes where the summer air is especially humid-in cities like New York, Washington, or Indianapolis, for instance-also are candidates. Still, the Cool Roof Rating Council says cool roof owners may pay slightly more to heat their homes, although the summer savings outpace the increased heating bill.
2. Performance ratings. The Cool Roof Rating Council uses two measures to rate the performance of cool roofs. The first, solar reflectance, refers to how much of the sun's energy is reflected by the roof. The other, thermal emittance, measures how well the product releases any heat that it does absorb. Both use a scale from 0 to 1, with those measuring closer to 1 performing best.
3. Energy Star savings. The council estimates that a cool roof can save a homeowner 7% to 15% in cooling costs. Energy Star recognizes cool roof products that reduce peak cooling demand by 10% to 15%. To obtain the Energy Star label, steep-slope products must have an initial solar reflectance of at least 0.25. Three years after installation, the roofing product must achieve a solar reflectance of 0.15 under normal conditions. Energy Star does not require third-party certification of performance. The council, which measures performance but does not impose minimum levels, verifies that the products perform at the levels stated by the manufacturer.
4. Long-lasting results. Some studies claim that cool roofs last longer than traditional products because they do not absorb heat. Tucson roofer Daniel Roberts says that's true. "Darker shingles naturally will cook at a hotter temperature and tend not to hold up as well as the lighter color," says the founder and owner of Castle Roofing. "A good rule of thumb in Arizona: The lighter the shingle the better, not just for reflection and energy savings, but for the shingle's life itself."
In fact, notes Roberts, he was installing light-colored shingles on Tucson rooftops long before "cool roofing" became an energy-efficiency buzzword. "It's nothing new."
5. Insulation issues. Thick insulation and radiant barriers can cancel out the need for a cool roof. Roberts notes that placing a cool roof over an attic with 10 or 12 inches of insulation will result in only "negligible" additional energy savings. Easley agrees: "Even if you reflect 90% of the heat, that doesn't mean you'll reduce your energy bills by that much," he says, "because the codes already require that you have insulation in the attic." For homes with air conditioning ducts in the attic, though, cool roofing makes sense, he notes, especially if the ducts leak.
6. Higher prices. Some pros find cool roofing products garner more interest than sales because of their higher price tag. In the Northeast, for example, Tamko's Lamarite slate composite cool roof shingles cost $80 more per 100 square feet installed than the non-reflective Lamarite products, estimates Tim Lutrell, a Tamko vice president.
"A lot of folks ask about this stuff, but as you go to higher prices, some folks get scared off," agrees Scott Heitmeier, business manager of steep-slope roofing for ABC Supply. "That's something that has to be dealt with if these products are truly going to gain their share in the market."
On a final note, while there are a variety of methods to increase a roof's efficiency-by upgrading insulation, for example-cool roofs make sense for many regions. Most of Los Gatos Roofing's customers opt to install cool roofs for the extra protection against the heat, notes co-owner Randy Brown.
Sharon O'Malley is contributing editor to Building Products magazine and ebuild.com.


Custom-Bilt Metals. Titan Cool Roof is a two-coat system with a minimum solar reflectance of 25%--and up to 70% on lighter colors, the maker claims. When applied and cured on properly prepared substrates, the material demonstrates color stability, chalk resistance, durability, abrasion resistance, chemical resistance and flexibility, the manufacturer says. 800.826.7813. www.custombiltmetals.com.

MonierLifetile. The concrete roof tiles in the manufacturer's Hartford Slate collection exceed LEED requirements for reflectivity and emissivity. The color-through tiles resist surface damage and degradation, the company says. The series comes in a variety of light and dark colors, including charcoal brown blend (pictured), and is available in northern and southern California and the Pacific Northwest. 800.669.8453. www.monierlifetile.com.

CertainTeed. Landmark Solaris shingles, which comply with Energy Star guidelines, are available in deep hues, including heather blend, resawn shake, burnt Sienna, and weathered wood. The product can reduce the roof's surface temperature by 20% during warm months, the maker says, and is designed to resist winds up to 130 mph. The shingles are rated by the Cool Roof Rating Council and meet California's Title 24 requirements. 800.233.8990. www.certainteed.com.

Eagle Roofing. Approved by Energy Star and rated by the Cool Roof Rating Council, concrete Cool Roof Tiles can save 10% to 30% on air conditioning bills, the firm states. The tiles come in multiple profiles and colors. 909.822.6000. www.eagleroofing.com.

DaVinci. EcoBlend roofing tiles, which offer the look of slate, reduce solar heat gain to save homeowners 7 percent to 15 percent on cooling costs, the firm states. The product is rated by the Cool Roof Rating Council and by Energy Star. It is 100 percent recyclable, does not release or discharge toxins, and has an anticipated life span of 50-plus years, the maker says. 800-328-4624. www.davinciroofscapes.com.

Tamko Building Products. Lamarite slate composite shingles now come in five energy-saving cool colors that reflect the sun's heat instead of transferring it to the attic. The product, which is rated by the Cool Roof Rating Council, comes in widths of 5, 7, and 12 inches, and in five colors: terra-cotta, pale olive, cool grey, natural sand, and almond shell. 800-641-4691. www.tamko.com.
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