OK, Peter, I finally went back and read Alex Wilson's article on what he perceives as a serious problem. I haven't seen the full report, but based on the summary he wrote on the Green Building Advisor website, I question the science. It seems to me that he's chosen the wrong metric and he's basing his conclusion on too many assumptions because he doesn't have enough data. You can see my comments at the end of his article.
Here's a simpler, less expensive alternative: Cut some 2-inch-thick rigid-foam insulation and glue it to the subfloor between the joists or support it with nails driven partway into the joists. Then fill any gaps between the edges of the foam boards and the joists using the canned spray foam sold at home centers or hardware stores. An even easier option is to nail the foam panels against the bottom edge of the joists and seal the joints with canned foam, but you'll lose some headroom and access to any pipes and wires between the joists. As with spray-foam kits, protect yourself and the floor from the dripping globs of canned foam. A full face shield, gloves, and a hat would be a good start.
If you’re not familiar, spray foam is a type of insulation that expands after you spray. The foam expands and seals, avoiding any type of unnecessary moisture (which can create mold) or encouraging pests to eat through your walls. It protects the lining of your house, and even can protect the heating and cooling of your house during those unbearably cold or hot days.
FROTH-PAK Foam Sealant is a two-component quick-cure polyurethane FROTH-PAK Foam Sealant is a two-component quick-cure polyurethane foam that fills cavities penetrations cracks and expansion joints. FROTH-PAK foam sealant can also be used as a sealant and void fill in many roofing applications. FROTH-PAK is chemically cured foam which significantly reduces curing time. FROTH-PAK dispenses expands and becomes tack ...  More + Product Details Close https://www.youtube.com/watch?v=ggLAUsiuI_o
The local foam installer that I used here in Hilton Head told me he looked for some peeling back of the foam. This was ensuring that it was at the perfect temperature which helped them maximize their yield (profit). I have open cell foam and it pulled away a little, and did so immediately (within minutes). They went back after they were done to any spots that pulled away too much and filled them with the touch up kit; they were looking for the top edge to roll just a little bit.  https://www.youtube.com/watch?feature=youtu.be&v=ggLAUsiuI_o
FROTH-PAK Foam Sealant is a two-component quick-cure polyurethane FROTH-PAK Foam Sealant is a two-component quick-cure polyurethane foam that fills cavities penetrations cracks and expansion joints. FROTH-PAK foam sealant can also be used as a sealant and void fill in many roofing applications. FROTH-PAK is chemically cured foam which significantly reduces curing time. FROTH-PAK dispenses expands and becomes tack ...  More + Product Details Close
Closed-cell (aka two-pound foam) is denser than open-cell at about 2 pounds per cubic foot. Its R-Value is between 6-6.5 per inch. As a result, this kind of foam is much more expensive than its counterpart. The reason closed-cell doesn't need a vapor retarder is because it already has one. It's permeance is 0.8 perm, which means it can handle cold climates without the use of an additional board or drywall. Closed-cell uses hydroflurocarbons (HFCs) as part of its makeup. However, this material has been known to have a high global warming effect. If you want a green insulation solution, this is not the material to use. A way to avoid this and still use closed-cell is by installing it alongside fiberglass batts. https://youtube.com/v/ggLAUsiuI_o?version=3

2. I talked to a building product supplier for WALLTITE spray foam, he is suggesting to use 2" or 3" of closed cell spray foam in the joists areas instead of the batts insulation. He says it will work with outboard rigid insulation. There is a location of a cantilevered floor area with steel beam so I may need to use spray foam to protect the steel beam. I would then be convenient continue to spray in the floor joist cavities and then apply 5" of polyiso outboard of the bottom cantilever floor sheathing.
Allison--would be very interested in your take on the GHG issues of foams, which have received lots of smart commentary recently. To highlight a few: architect Jesse Thompson's comments on Tom's Good vs Bad post on Energy Circle, the very thorough piece by Alex Wilson on Green Building Advisor and Michael Anschel's cautionary diatribe on Remodeling. 
Installing spray foam is easy to do and can dramatically improve a building or home’s energy efficiency and thermal resistance. Our closed cell foam is so efficient just 3 inches of foam appled inside of wall cavities provides an insulation value of over R18!. Our products are specially formulated for both new construction and existing homes and buildings.

Another thing we love about the Liquid Roof is its ability of not being damaged by freezing and other extreme temperatures. You will also appreciate its ability of staying flexible for a longer period of time. Did you know that it could also contract and expand as you roof moves? That is one of the things to look for when shopping around for this kind of product we found in the Liquid Roof. http://www.youtube.com/watch?v=ggLAUsiuI_o&app=desktop
RE: my June 12 post...We went ahead and had the attic sprayed with a Soy-based product. Stayed in a hotel for 3 nites. Still smelled a little bad but that's gone away over time. I'm very glad we didn't use the other foam as even that much outgassing of a petrochemical could have sent my wife to the hospital. Unfortunately, the spray crew didn't speak English(at least not to me) and were kinda lazy, so they ended up spraying over some can fixtures from the kitchen below that were not insulation-contact rated. So I hired an electrician to come out, pull down the cans, pull out what he thought was an appropriate amount of foam to create a big enough air space and then re-install the cans. I billed the firm for the electrician plus an extra night we had to stay in the hotel and they paid, no questions asked. Guess they knew they had screwed up.  
This stuff works GREAT ! I live in an older mobile home that had a lot of leaks when I moved-in. I worked for two years to locate and fix them all. Now I simply go over all of the repaired places once a year just to be sure everything is OK. NO LEAKS FOR 4 YEARS NOW!!  Others here use "sno proof" or something that does not stop leaks. When I tell them about my success, they don't seem to want to pay the$ for this superior product. Too bad!. I used the tape in  repairing the leaks.
With constant exposure to heat, cold, UV radiation, rain, snow, hail, high winds and possible mechanical damage, a roof can be the most vulnerable component of a building’s exterior. However, a roof’s long-term performance can be enhanced — and major roofing problems avoided — with correct design, quality materials, proper installation and workmanship, and comprehensive care.
Typical roof coating dry film thickness vary from paint film thickness (plus or minus 3 dry mils) to more than 40 dry mils. This means a roof coating actually becomes the top layer of a composite roof membrane and underlying system. As such, the roof coating is the topmost layer of protection for the membrane, receiving the impact of sunlight (both infrared and ultraviolet (UV), rain, hail and physical damage.
Spray polyurethane foam, or SPF, is the main type of 2-part, closed-cell spray foam used by insulation contractors. Large-scale insulation jobs require special equipment as well as safety gear to protect the installer from chemical fumes during installation. When the foam cures and hardens just several minutes after application, it's completely safe for as long as it stays in place.

Another thing we love about the Liquid Roof is its ability of not being damaged by freezing and other extreme temperatures. You will also appreciate its ability of staying flexible for a longer period of time. Did you know that it could also contract and expand as you roof moves? That is one of the things to look for when shopping around for this kind of product we found in the Liquid Roof. http://www.youtube.com/watch?v=ggLAUsiuI_o&app=desktop


Clean and free the roof surface of any debris and then dry the surface using a cloth. If you happen to have a current coating on the surface, check for adhesion. Consider removing loose coating, repairing, cleaning and then checking the area. Remember to use Energy Guard without thinning it because it is sold ready for use. Containers should not be left open except for a short period of time. You must also ensure that you check for any existing coating adhesion before opening Energy Guard. For application, you will require a brush preferably a bristle brush (synthetic) or a short nap roller. You can also use a good airless sprayer with a 0.031 or 0.027 tip to apply the coatings at (3000 psi/1gpm). You will also need water for cleaning up when you are done.
SPF, a spray-applied cellular plastic, is made by mixing chemicals to create foam. Those chemicals react very quickly, expanding on contact to create foam that insulates, air seals and provides a moisture barrier. When properly installed, SPF forms a continuous barrier on walls, around corners and on contoured surfaces. It resists heat transfer very well and is an effective solution for reducing unwanted air infiltration through cracks, seams, and joints.
Open-cell is also known as half-pound foam. It has an R-Value of 3.5-3.6 per inch, and its density is bout 0.5 pounds per cubic food. Low-density foams like these are made partially from raw biological materials Carbon dioxide or water is also used in the makeup. Open-cell uses far less material than closed-cell, but its R-Value is lower. Also, open cell requires a vapor retarder (like gypsum wallboard) and is riskier when used for roof sheathing. It's not highly recommended that you use open-cell insulation if you live in a cold climate unless you have that extra barrier. You should also compare how much money you spend versus how effective the open-cell insulation is wherever it's installed.

In the early days of insulating attics, people believed the insulation was a heat source. That’s not the case, as the insulation is actually a barrier between two areas of different temperatures. As for the “hot roof” theory, the unvented attic system could make the temperature of the roof go up a little, but this increase won’t cause damage to your shingles.
Sta-Kool 780 Siliconized Acrylic White Elastomeric Roof Coating Sta-Kool 780 Siliconized Acrylic White Elastomeric Roof Coating is a high quality flexible white acrylic roof coating. Product is enhanced with silicone for improved water resistance adhesion and life expectancy. Product resists cracking peeling while offering tremendous durability and long term life. The coating forms a durable protective barrier which ...  More + Product Details Close http://www.youtube.com/v/ggLAUsiuI_o&feature=share
The RV roof coating is a sealing, weatherproofing and waterproofing product that is used in recreational vehicles, campers and trailers, to name some. It works effectively in sealing the roof’s membrane from water and moisture that would otherwise build up and cause damage to the roof. When unattended, the buildup can eventually leads to leaks inside the RV, causing so much discomfort to your loved ones.

Spray Foam Polyurethane


I had a hole in the drywall in our bathroom that was about 2 in x 5 in that I used Great Stuff to fix. I am impressed with the characteristics of the filler. It filled the hole completely in a few seconds of application. I will warn anyone using it though to make sure you don't fill the hole entirely flush to the wall because this stuff continues expanding after you apply it. I didn't think about that but no big deal really because you can sand it which is exactly what I did, and then applied spacial and paint and it is almost as good as new. For the price this was a heck of a deal because I only used a tiny amount and now am left with nearly a full can. I guess I will have to find somewhere else to use it now. Great product, ... full review
A. You can use closed-cell spray foam that way if you want, although you should realize that the spray foam will prevent the roof sheathing from drying inward. This approach should only be used if the roof sheathing is bone dry, because it will never dry when sandwiched in this manner. Most building scientists would prefer to see fiberglass rather than closed-cell spray foam under the roof sheathing in this type of assembly.

I've seen this only once, and it was with closed cell foam, but I've heard of it happening with open cell foam, too. I don't know the details, but I've heard it could result from a bad batch of chemicals, improper mixing, or too high a temperature. Whatever the cause, it's not a good thing. The photo below shows how the spray foam pulled away from the studs. A little bit of uninsulated area like that adds up to a lot of heat loss/gain when the whole house has that problem, as it did here.

How Much To Spray Foam Basement

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