Insulation: Guidelines, Facts, Applications,

ABOUT INSULATION

Thicker is better In cold weather, a puffy parka holds in your body heat. Insulation does the same thing for a house. The thicker the insulation, the better it works to reduce heat flow from the inside of a home to the outside during winter, and from outside to inside during summer.
The thermal barrier of a home should consist of a continuous layer of insulation on all sides—including the lowest floor, the exterior walls, and the ceiling or roof.

Doubling the thickness of insulation will double the insulation's R-value, cutting heat loss in half. Each time the insulation layer is doubled in thickness, this rule applies. The energy saved per year by doubling insulation from R-10 to R-20, however, will be considerably more than the energy saved by doubling insulation from R-20 to R-40, because of the law of diminishing returns. In some cases, like an attic, it's worth piling on more insulation because there is plenty of room. It's much more expensive to add that much insulation to exterior walls.

It takes more than just insulation to slow heat Stopping air leaks is just as important—maybe more important—than adding insulation. Unless builders prevent air from leaking through walls and ceilings, insulation alone won't do much good. Not only are drafts uncomfortable, but air moving through insulated cavities can cut the efficiency of the insulation by as much as 50%.
Some insulation types make good air barriers, and some don't. In all cases, it's best to keep the insulation tight to the air barrier.

THERMAL BRIDGING IS CONDUCTION IN ACTION

When there is no insulation in a roof or wall, the framing is the most insulated part of the assembly. It has the highest R-value. Softwood lumber has an R-value of 1.25 per inch, so a 2x6 stud has an R-value of almost 7. As soon as you put insulation between the studs or rafters above R-7, however, the framing becomes the weak thermal link. If the framing cavities are filled with closed-cell spray foam insulation, the insulation has an R-value of about 36. At that point, the studs or rafters become a glaring weakness in the design.

Building scientists call this phenomenon "thermal bridging" because the studs or rafters bridge the space between inside and outside the thermal envelope.

If you look for it, thermal bridging can sometimes be seen from either inside or outside. Inside, it can cause a problem called ghosting, or cold stripes behind the drywall during winter. These cold stripes can encourage condensation that leads to the accumulation of dust particles on the drywall; eventually, visible vertical stripes may form. Outside, you can see the effect of thermal bridging in snow-melt patterns on roofs and drying patterns on walls.

A continuous layer of rigid foam installed on the inside or outside of a wall or roof drastically reduces thermal bridging through the framing.

R-VALUE MEASURES HOW WELL INSULATION WORKS

Heat flows from hot to cold; it can't be stopped, but it can be slowed If we measure the rate at which heat flows through a building material or building assembly—for example, a wall or a roof—we can calculate a number (the R-value) to indicate its insulating ability. The higher a material's R-value, the better the material is at resisting heat flow through conduction, convection, and radiation (outlined above). Insulation manufacturers report R-values determined by tests following ASTMstandards (for example, ASTM C518).

Common insulation types and their R-values Residential insulation materials have R-values that range from about 3 to 7 per inch. The amount of insulation installed in any given building assembly depends on the climate, the part of the house being insulated, the project budget, and local code requirements.

• Batts and blankets: R-3.1 to R-4.1 per in.
• Blown-in and loose-fill insulation: R-2.6 to R-4.2 per in.
• Rigid foam: R-3.6 to R-6.8 per in.
• Closed-cell spray foam: R-6 to R-6.8 per in.
• Open-cell spray foam: R-3.5 to R-3.6 per in.

Green homes go beyond code minimum

The U.S. Department of Energy has developed a list of recommended insulation levels for different climate zones. The climate zones are represented on the map (click to enlarge). Houses heated by natural gas, fuel oil, or an electric heat pump should use the R-values set out by the DOE and listed below as a base. Because electric heat is relatively expensive, houses with electric resistance heat need more insulation than shown in the table below.

In some parts of the country, minimum code requirements for insulation already (or may soon) exceed these DOE recommendations. For example, the 2009 International Residential Code requires cold-climate builders to include a minimum of R-20 wall insulation and R-15 basement wall insulation.

DOE-Department of Energy-recommended R-values for various parts of a house

Zone	Attic	Wall	Floor	Slab edge	Basement wall (framing cavity insulation)	Basement wall (continuous rigid insulation)
1	R-30 to R-49	R-13 to R-15	R-13	R-4	R-11	R-10
2-3	R-30 to R-60	R-13 to R-15	R-13 to R-25	R-8	R-11	R-10
4	R-38 to R-60	R-16 to R-21	R-25 to R-30	R-8	R-11	R-4
5	R-38 to R-60	R-16 to R-27	R-25 to R-30	R-8	R-11 to R-19	R-10 to R-15
6-8	R-49 to R-60	R-18 to R-27	R-25 to R-30	R-8	R-11 to R-19	R-10 to R-15

In any case, green builders almost always exceed minimum code requirements for insulation thickness. Many energy consultants, including Betsy Pettit and Joseph Lstiburek, now recommend that cold-climate homes include R-60 ceilings, R-40 above-grade walls, R-20 basement walls, and R-10 basement slabs.

Some builders go further; for example, an Illinois home designed to meet the rigorous German Passivhaus standard is insulated to nearly R-60 on every side—even under the slab.

AIR AND MOISTURE ARE PART OF THE PICTURE

Insulation can't work in a wind tunnel No matter what type of insulation you choose, it will perform poorly if installed in a house that is riddled with air leaks. Because many types of insulation (like loose fill and batts) work by trapping air, leaky walls, roofs, and floors mean poor thermal performance. For this reason, building scientists are fanatical about air-sealing. To get the most out of batts and blown insulation, every house needs an air barrier adjacent to or contiguous with the insulation layer.
Some types of insulation are fairly effective at stopping air infiltration. For example, when rigid foam is used as wall sheathing, it can be an effective barrier, as long as the seams are taped. Spray polyurethane foam creates a very effective air barrier.

But neither rigid foam nor spray foam addresses air leaks at the seams where different components meet, such as under the bottom plates of walls. An air barrier is only effective if all of these seams and intersections are addressed with gaskets, glues, or sealants.

Of all available insulation materials, fiberglass batts are the most permeable to air leakage—so permeable that fiberglass is used to make furnace air filters. Because it doesn't restrict air flow, fiberglass is often singled out and derided for its poor performance.

In fact, much of the criticism of fiberglass insulation is unwarranted. As long as fiberglass is installed in a house with an adequate air barrier, it will perform well. Fiberglass performs best when installed in a framing cavity (for example, a stud bay or joist bay) with an air barrier on all six sides.
Installation details for high-quality fiberglass batts have been incorporated into the insulation installation guidelines established by the home raters from the Residential Energy Services Network (RESNET).

For every location in a house, there are always several ways to create an effective air barrier. However, not all methods are equally easy to achieve. In many locations, including rim-joist areas, spray polyurethane foam is so much faster than alternative methods that its use has become almost universal among builders of high-performance homes.

Moisture can piggyback on air There's another benefit to stopping air: less moisture in roofs and walls. That's because most moisture problems in walls and roofs are caused by moisture transported by air. Vapor diffusionis a much smaller problem.

Moisture can accumulate in a wall or ceiling when warm, humid interior air leaks through cracks in the shell. When this exfiltrating air encounters a cold surface—for example, OSB wall sheathing—the moisture in the air can condense into liquid and puddle in the wall cavity. The same thing can happen in summer, when warm, humid outdoor air leaks through cracks in the wall. If the home is air-conditioned, the moisture in this infiltrating air can condense when it reaches any cool surface—drywall, ductwork, etc. The best way to limit this type of moisture migration is to install an effective air barrier. If air isn't leaking through cracks in a home's walls and ceilings, the problem is nipped in the bud.

Insulation can stop air Some insulation types act as air barriers, while others act like air filters. If you choose an insulation that doesn't stop air flow, it's important to install an adjacent air barrier material.

Best to worst at stopping airflow: Spray foam Rigid foam Cellulose Blown-in fiberglass Fiberglass batts

SHOULD INSULATION STOP VAPOR?

Vapor permeability can be a good thing or a bad thing — vapor retarders slow wetting, but they also slow drying, which may be more important. As long as you design a roof, wall, or floor assembly with these concepts in mind, then almost any type of insulation can work.

Least to most vapor permeable: Foil-faced polyisocyanurate Closed-cell spray foam XPS EPS Open-cell spray foam Cellulose Blown-in fiberglass Fiberglass batts

More on the vapor permance of insulation materials at BuildingScience.com.

INSULATE OUTSIDE THE BOX

Although residential wall insulation is traditionally installed in stud cavities, the best place to locate wall insulation is outside the frame. This exterior insulation reduces the thermal-bridging effect that studs have in a wall, because each piece of framing can act as a thermal bridge through the cavity insulation. These thermal bridges seriously degrade the performance of the wall.

The thermal-bridging effect can be partially addressed by using rigid foam sheathing—usually 1 in. or 2 in. of XPS or polyisocyanurate. Even better are wall designs that place all the insulation—6 in. to 10 in. of rigid foam—outside the framing.

When insulation is outside the frame, framing materials stay warm and dry. When stud bays are not filled with insulation, the work of electricians and plumbers is greatly simplified.
Houses with foam sheathing should not include an interior polyethylene vapor retarder.

OTHER CONSIDERATIONS

Insulation can stop air Some insulation types act as air barriers, while others act like air filters. If you choose an insulation that doesn't stop air flow, it's important to install an adjacent air barrier material.
Best to worst at stopping airflow: Spray foam Rigid foam Cellulose Blown-in fiberglass Fiberglass batts

SHOULD INSULATION STOP VAPOR?

Vapor permeability can be a good thing or a bad thing — vapor retarders slow wetting, but they also slow drying, which may be more important. As long as you design a roof, wall, or floor assembly with these concepts in mind, then almost any type of insulation can work.


Least to most vapor permeable: Foil-faced polyisocyanurate Closed-cell spray foam XPS EPS Open-cell spray foam Cellulose Blown-in fiberglass Fiberglass batts


More on the vapor permance of insulation materials at BuildingScience.com.

INSULATE OUTSIDE THE BOX

Although residential wall insulation is traditionally installed in stud cavities, the best place to locate wall insulation is outside the frame. This exterior insulation reduces the thermal-bridging effect that studs have in a wall, because each piece of framing can act as a thermal bridge through the cavity insulation. These thermal bridges seriously degrade the performance of the wall.


The thermal-bridging effect can be partially addressed by using rigid foam sheathing—usually 1 in. or 2 in. of XPS or polyisocyanurate. Even better are wall designs that place all the insulation—6 in. to 10 in. of rigid foam—outside the framing.


When insulation is outside the frame, framing materials stay warm and dry. When stud bays are not filled with insulation, the work of electricians and plumbers is greatly simplified.
Houses with foam sheathing should not include an interior polyethylene vapor retarder.


OTHER THERMAL BRIDGES


Uninsulated slab edges Window frames Wall and roof penetrations

--contact for additional details Scott's Contracting scottscontracting@gmail.com

Spray Foam- Insulation That Works-Photos Included

Scotts Contracting is available to assist in your Home and Business Insulation Needs.  I even have a Local Supplier / Manufacturer of Spray Foam Insulation- This Insulation is Soy-based Which is Green and Eco Friendly- Many of Our Missouri Farmers Grow Soybeans!!! Support our Missouri Farmers !!!  Click Here to email Scotts Contracting to Schedule a Free Green Site Inspection.

The Following Article is a Follow Up to the Prior Posts about Spray Foam Insulation from these Posts Below

• 5 Ways to Build Affordable Green-Energy Star-Rated Houses

Spray foam insulation is all the rage because of its
effectiveness at sealing a building, but builders complain
 that the added cost is significant. Because First Coast
implemented sealing procedures, the company sticks with fiberglass ...

•  Retrofit reduces energy use by 60 percent

Instead, he uses 2 x 6 studs, spray foam
insulation, and metal bracing to make the
studs rigid. "The studs are energy highways,"
he says. He then wraps his houses
 in 1.5 inches of foam board, which creates a thermal break. ...

• $1 Dollar Spent Earns $2 Dollars

Seal for Leaks with, caulking and
 spray foam, from anything that is
sticking out of your Home. This could
come from the Air Conditioning Unit,
various wires for Telephone and Cable
lines. The Power Line or Electric Line. ...

• 10 Great 'Green' Home Improvements

Certain materials used to seal these
 leaks—such as caulk, spray foam,
or weatherstripping—can qualify for
federal tax credits. "It's something that
homeowners can do easily," Thull says.
 "And there are a lot of different products out ...

Insulation That Works

With closed-cell spray foam, the benefits go way beyond R-value

by Steve Easley

These days, it's not an exaggeration to say that almost all homeowners expect their homes to be durable, energy efficient, safe, and comfortable. But this is especially true in coastal markets that cater to high-end clients who demand supreme quality and impeccable performance from their homes. Even in today's markets, which are euphemistically described as "relaxing," there seems to be no shortage of wealthy home buyers snapping up second-home properties along the coveted coast. If you build in this market, it's this kind of discriminating home buyer who will most expect you to get things right.

In more than 25 years of consulting with builders on ways to reduce callbacks, I've spent most of my time solving problems related to heat and moisture transfer through buildings, because this is often where builders — even very good builders who deliver well-appointed homes to the coastal elite — get things wrong. Most of the serious (read "expensive") performance failures are moisture related, and a good number of these are closely tied to the thermal performance of the home. Yet I am surprised how often the insulation is installed without much thought or understanding about how it works. Consequently, very little attention gets paid to the details that really matter. Typically, fiberglass — selected as the least expensive option up front — is jammed in the walls and stuffed around electrical wires, plumbing pipes, and HVAC ducts, then covered up as soon as the municipality allows. The result is gaps, compression, and hollow voids that compromise occupant comfort and increase the building's energy loads. A sloppy insulation job can also lead to moisture problems by creating thermal conditions in walls and ceilings that promote condensation, wetting, mold growth, and rot.


Batt insulation works best when it is fully lofted, not jammed into the tight spaces (above). Compression of the batt reduces the number of air pockets that provide the material's insulation value. It also leaves a hollow between the insulation and the drywall, creating areas where air can circulate. These voids can siphon off energy and may create conditions for condensation and moisture problems.

Bright Star
The updated Energy Star label for homes provides a quality standard that can guide builders away from these problems. New program requirements have raised the level of quality in the program, making it a label that savvy home buyers will more likely be looking for. As of January 1, 2007, a home that qualifies for an Energy Star label must pass a "thermal bypass inspection": a rigorous assessment of a home's air barrier. The bypass inspection requires builders to follow the EPA's Thermal Bypass Inspection Checklist — a 25-point list of details aimed at stopping the movement of heat around or through the insulation. Thermal bypasses — the defects that most commonly reduce the energy performance and comfort of homes — typically result from missing or compressed insulation, missing air barriers, and gaps between the air barrier and the insulation.


The Energy Star Thermal Bypass Inspection Checklist must be completed by a certified home energy rater. However, in order for a home to qualify for the Energy Star label, up to six items may be verified by the builder to minimize required field trips by the rater.

In my opinion, this checklist is one of the best guidelines to come out of the EPA's Energy Star program, and I think it substantially raises the bar for thermal and moisture performance of building envelopes. Of particular value to builders, the 86-page Thermal Bypass Checklist Guide (available free online at www.energystar.gov; search "Thermal Bypass Guide") provides a very practical and comprehensive look at reducing air infiltration. It should be required reading for anyone who's serious about building a quality home in any climate, but especially in demanding coastal climes.

Living Spaces Over Garages Living spaces over garages create conditions that demand careful attention to insulating the floor. Yet it is difficult to support the insulation in this cavity, and oftentimes the insulation falls onto the garage ceiling. This separation between the insulation and the living space floor creates a thermal bypass that compromises the value of the insulation. Air easily infiltrates in at the band-joist area over the top of the insulation, which scavenges away heat. This often freezes plumbing pipes, creates cold floors, and can lead to major mold and water damage. Builders often try to solve the problem by supplying forced-air heat near the plumbing, but this only succeeds in pressurizing the space with warm, humid air. As this air exfiltrates through the exterior cracks, it can condense and lead to even worse moisture and mold problems at the band-joist areas.

The issues are easily solved with ccSPF, which sticks to the bottom of the subfloor so insulation and air barrier are always in contact. The foam also stops air infiltration. It is a good idea to wrap any plumbing with a thin layer of fiberglass insulation before spraying foam over it to make servicing the plumbing easier.

An Insulation for All Reasons
I've included in this article a short catalog of some of the problem areas addressed on the Thermal Bypass Inspection Checklist that I find are frequently missed.

What stands out about all of these problem points is that they can be difficult to get right with inexpensive fiberglass insulation unless a builder is working with an experienced and service-minded insulation crew. However, these problems are easily avoided when using closed-cell spray foam (ccSPF) insulation. This alone provides a strong argument for always using ccSPF, but it's certainly not the only reason.

There are many reasons why ccSPF makes particularly good sense in a coastal home:

• It has a high R-value of 6.5 to 7 per inch.
• It absorbs a negligible amount of water. It can even be used as an effective secondary rain barrier and is the only FEMA-approved insulation for flood-resistant construction.
• It does a good job of controlling diffusion.
• It has good air barrier qualities to reduce airflow into and out of wall cavities.
• It expands to fill voids in hard-to-
insulate areas.
• It provides some structural integrity to the frame (see "The Structural Properties of Foam," page 26).

Steve Easley is principal of Steve Easley Associates, a company based in Danville, Calif., that provides building-science training and quality assurance for builders nationwide. All photos by the author.

Attic Knee Walls These are areas where the insulation on the back side of unsheathed walls is exposed to outdoor temperatures and airflow. They are often adjacent to ventilated attic areas. The Energy Star Thermal Bypass Inspection Checklist requires that an air barrier be placed on all sides of the insulation. This means that the back sides of knee walls need to be sheathed and sealed. Thin-profile cardboard sheathing with ccSPF works well here. Since ccSPF is air impermeable, the insulation does not have to fill the entire cavity, and it meets the air barrier requirement. Some codes require R-19 insulation, which is difficult to do in a 3 1/2-inch space with batt insulation, but 2 inches of ccSPF provides about R-19.5.

Sloping Roof Areas The sloping areas in a cathedral ceiling can be the sites for significant thermal bypasses. These areas are not only difficult to insulate but are difficult to ventilate. Yet ccSPF solves both problems. Placing ccSPF directly on the underside of the roof deck also creates a secondary rain barrier, and because of ccSPF's high R-value and low permeability, moisture is not likely to condense on its surface, eliminating the need for cavity ventilation.

Band-Joist Areas The band-joist area is typically a major site for air infiltration. These areas are usually very poorly insulated, causing one of the most significant thermal bypass areas. If the home is under a positive pressure (air pushing out from inside) in a heating climate, the air is likely to be at a high humidity level. This can cause frost, and eventually mold, to build up on the back side of the band joist. In a cooling climate that is under negative pressure (air pulled inward — a condition that's commonly caused by leaky HVAC ducts), this can pull hot, humid air from outside, where it is likely to condense and lead to mold problems. The sealing properties of ccSPF will reduce these air-infiltration and energy-loss problems in this troublesome area.

Attic and Crawlspace Bypasses Attic and crawlspace bypasses are penetrations into the living spaces. Pipes, ducts, flues, and electric wires are the most common reason for these penetrations, and the best way to seal them is often (but not always) with ccSPF. Because ccSPF expands and seals, it does an excellent job of filling voids that allow conditioned air to escape. However, ccSPF should not be used to seal around high-temperature areas such as combustion appliance flues.

The Structural Properties of Foam

Recent research conducted at the University of Florida has demonstrated that closed-cell spray foam (ccSPF) applied to the underside of roof decking effectively bonds the sheathing to the framing, significantly increasing uplift resistance. The study, conducted by Dr. David O. Prevatt and funded by Honeywell and Huntsman, two makers of ingredients that go into ccSPF, found that 3 inches of the foam sprayed between framing members provided a threefold increase in uplift resistance as compared with traditionally installed roof sheathing panels. While these results sound impressive, Dr. Prevatt points out that the increase provides the same benefits as increasing the nailing schedule to a 6/6 schedule (every 6 inches along panel edges and every 6 inches in the field) from the usual 6/12 schedule. What was perhaps most impressive is that using only spray foam to glue the sheathing to the framing provided almost as much resistance (178 to 209 psf) to uplift as does 8d common nails (205 psf) installed at the 6/6 schedule. This suggests what may be the biggest structural advantage of a foamed roof assembly — reducing the likelihood of a roof blowoff when the sheathing doesn't get nailed off with enough nails or when too many nails miss their mark.


A test panel (left) in a study at the University of Florida simulates a roof assembly consisting of 1/2-inch OSB fastened to 2x4 framing at 24-inch centers. The framing bays have been filled with closed-cell spray foam. During the study, the assembly was placed on a pressure chamber and a vacuum pump (above right) drew a vacuum that was increased in 15-psf intervals until the assembly failed and the sheathing popped off the framing. For the fully foamed assemblies, this occurred at around 240 psf. The assemblies that had ccSPF fillets installed failed at 160 psf. The assemblies with sheathing alone nailed only with nails (6/12 schedule) failed at about 75 psf.

The uplift study also evaluated the benefit of installing a "fillet": a 3x5-inch bead of ccSPF in the corners between the sheathing and the roof framing. The fillet method effectively doubled the uplift resistance of the baseline assembly of 2x4 framing on 24-inch centers sheathed with 1/2-inch OSB nailed on a 6/12 schedule.

The uplift study is one of several recent studies of the structural properties of ccSPF. Tests conducted by Building Science Corporation (BSC) to evaluate the impact resistance of wall systems showed that conventional wood-framed walls do not have the same impact resistance as impact-resistant windows. (That is, walls consisting of studs, 1/2-inch OSB sheathing, housewrap, and siding cannot sustain the impact required by the ASTM E1886 and E1996 missile test, which hurls a 9-pound 2x4 at 50 feet per second.) The only test panel in the BSC demonstration capable of resisting the required impact load included a layer of 1/2-inch OSB sheathing between 1-inch foam insulating sheathing and 2 inches of ccSPF sprayed between 2x6 studs. Surprisingly, BSC found that a wall with foam sheathing, housewrap, and ccSPF (no OSB) performed better in impact tests than a wall with housewrap and OSB sheathing.


When a roof is not likely to be replaced anytime soon and the sheathing nailing can't be verified (on a tile roof in good condition, for example), contractors in Florida are beginning to employ the "fillet method." This practice uses closed-cell spray foam to help bond the roof sheathing to existing framing and provide a secondary water barrier.

The BSC study notes that walls may not have to be built to the same standard as windows, despite these surprising results. When a window fails under impact, the resulting hole in the wall (the entire window) is relatively large, providing a big enough hole to internally pressurize a home, which often leads to catastrophic failure. When a wall fails, the zone of impact is marginally bigger than the impacting face of the projectile. Such an opening may not be large enough to have a catastrophic effect. — Clayton DeKorne


Scotts Contracting is available to assist in your Home and Business Insulation Needs.  I even have a Local Supplier / Manufacturer of Spray Foam Insulation- This Insulation is Both Closed and Open Cell Soy-based That is Green and Eco Friendly. Click Here to email Scotts Contracting to Schedule a Free Green Site Inspection.

Build Green Scotty


--
Additional details or schedule a Free Green Site Evaluation at: Scott's Contracting
scottscontracting@gmail.com