We are turning our roof into an unvented roof assembly by raising the roof and blowing in SPF. We are planning to leave the existing vapor barrier down but remove the fiberglass batting and then adding 6" of SPF in all the cavities, to completely seal and insulate the house. Should we have any concerns about doing it "upside down" and not spraying the foam directly to the underside/sheathing of the roof?
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Loctite tite foam is a new generation of Loctite tite foam is a new generation of polyurethane-based insulating foam sealant that expands to fill seal and insulate gaps and cracks inside or out. It is white polymer foam based on purified and concentrated ingredients that provides 4 times more density versus conventional foams for better durability and insulation. ...  More + Product Details Close

This is in great contrast to my friend's experience. Her attic spaces were sprayed and the foam is actually pretty, and I was in her attic 6-7 days after it was sprayed and could hardly smell anything when I stuck my face up to the foam. And she did not have to clean up one speck of dust during or after the spraying. I got the name/number of the guy from her who managed her attic project, but between the time he did my house and the time he did her house, he was let go from the company who did her attic and hired by another company. He assured me everything would be the same, etc., etc., and I had no reason to believe anything had changed, but the sprayers who did my house later admitted they had never sprayed an attic before and I also found out that the foam used in my attic was from a different manufacturer. Neither my friend nor I had any idea this guy was with different company then, until the week after they filled my attic with off ratio foam, and my home with toxic vapors.   https://m.youtube.com/v/ggLAUsiuI_o
Spray foam is a chemical product created by two materials, isocyanate and polyol resin, which react when mixed with each other and expand up to 30-60 times its liquid volume after it is sprayed in place. This expansion makes it useful as a specialty packing material which forms to the shape of the product being packaged and produces a high thermal insulating value with virtually no air infiltration.
This tropic heat actually is the cause that the steel structure, which most roofs in that part of the world are built on, expands and contracts all the time. By doing so, the sun-battered steel structure causes the roof tiles to dislodge and slowly creates small openings between the roof tiles, through which rain water can run into, creating leaks that can cause much damage to plastered ceilings and electric wiring.
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. https://youtube.com/embed/ggLAUsiuI_o

Thoroughly clean the roof surface. Roofs collect oils from asphalt, chimneys, and cars plus lots of dirt and dust. Coatings don’t stick well to any of these. We recommend cleaning with an inexpensive solution of TSP or TSP Substitute in a bucket of water (follow label instructions). Use a broom to scrub ponding areas and areas of peeling coatings. Work a section at a time and hose off the dirty water. Sweep away puddles to promote drying. Do not allow wash water to dry on walls, furniture, windows, and visible surfaces. 
If you don't have the patience to slowly fill the void with spray foam through holes drilled in one of the studs, you could (if you were an experienced carpenter) use a Sawzall to remove one of the studs and re-frame the corner as a two-stud corner. Then you could either insulate the void with a fiberglass batt or simply present the two-stud corner to the spray-foam contractor as an accessible corner.

There are several types of reflective roof coatings that impart varied reflectance rates/ values. Typically, the reflective coatings are what are commonly referred to as white coatings and there are also aluminum coatings typically used with asphalt. Highly reflective white roof coatings are typically comprised of acrylics, urethanes, silicones, SBS, SEBS, and other types.
While the R value will vary, most ocSPF products have an R value of around 3.8 per inch. Unlike medium-density closed-cell SPF, ocSPF is not a vapour barrier. When installed at 5.5 inches or more, ocSPF does act as an air barrier. It is often used for interior walls because it provides sound reduction by blocking and absorbing air leakage. It is usually only recommended for indoor applications.
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.
I don't know if it's common or uncommon, but installing a layer of rigid foam above your roof sheathing in order to interrupt thermal bridging is always a good idea, and is preferable in all respects to a roof assembly without any rigid foam above the sheathing. If you decide to install rigid foam above the roof sheathing, you shouldn't use closed-cell spray foam under the sheathing; either use open-cell spray foam (which is vapor-permeable) or a fluffy insulation like cellulose, mineral wool, or fiberglass (any of which will allow the roof sheathing to dry to the interior).
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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. 
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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.
Solvent-based polyurethane coatings have excellent adhesion and when used as a base coat over asphalt, EPDM, TPO or PVC, it eliminates the need for a primer. The resulting savings on labor and material more than offsets the higher cost of the product. When top coated with silicone, it gives you the best of both worlds. It's also an excellent gutter and RV coating. http://m.www.youtube.com/watch?feature=player_embedded&v=ggLAUsiuI_o

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.
In general, cantilevered steel beams are a nightmare. If part of the steel beam is in contact with exterior temperatures, then it's best if the interior portion of the steel beam is covered on all sides with insulation. This is generally impossible (because the interior portion of the cantilevered beam generally supports a load, meaning that you can't wrap the steel beam in insulation on all sides).
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Elastomeric coatings offer effective and affordable solutions for fixing roof leaks. The coatings can be used to repair any type of roof leak. The elastomeric roof coatings can be used throughout the year because they stretch and contract easily to adjust to winter and summer temperatures. It is usually made using polymeric products such as acrylic alongside white pigments like titanium dioxide. This helps create an opaque and reflexive final product. http://youtube.com/watch?feature=youtu.be&v=ggLAUsiuI_o
Spray polyurethan foam does effectly prevent all six of these heat transfer methods from occurring. These should be the mechanisms by which you judge insulation, in addition to their R-Value. If you're uncertain about installing spray foam insulation, Energy Star has a map that recommends levels of insulation by R-value and cost-effectiveness in the United States.
In general, cantilevered steel beams are a nightmare. If part of the steel beam is in contact with exterior temperatures, then it's best if the interior portion of the steel beam is covered on all sides with insulation. This is generally impossible (because the interior portion of the cantilevered beam generally supports a load, meaning that you can't wrap the steel beam in insulation on all sides).
Spray foam insulation, when properly installed is both an air barrier and when closed cell foam is used at the proper depth a vapor barrier!  Before hiring any contractor you should establish the brand of foam being used and verify that with the named manufacture.  Please ask for ESR reports and MSDS sheets on any foam being installed in your home. A couple areas where you might consider spray foam insulation include: http://www.youtube.com/v/ggLAUsiuI_o&feature=share
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.
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.
The average price to cover 200 square feet with a foam insulation kit will run between $300 and $600 (about two to three kits). Inside these kits is something called Icynene, a foam made from two liquids that are heated and pushed through a gun on the can. When Icynene is released, it expands up to 100 times its size as it hits the surface area you're covering. These can contain a lot of gasses, making its installation a dangerous process. Even low-pressure sprayers can be harmful to homeowners' health.
Silicone coatings are typically produced by adding a catalyst and solvents to a silicone base. Because the silicone is a natural material, these coatings are bio-degradable. They can be applied to a roofing system using many different techniques, including spraying or rolling. Silicone coatings are available in many colors, including reflective white and translucent.

Note: The practice of foam insulating the attic has raised eyebrows in the building industry because "standard" roofing techniques call for the attic to be ventilated; however, in a vented attic situation it will become approximately 130 degrees in the summer. There's no reason for an air-conditioning and vent-ductwork to have to work in that type of severe conditions. By applying Icynene right on the underside of the roof deck, the severe temperatures no longer exist in the attic. In short, the attic is now a "conditioned" space of the house that is just as comfortable as any other room in the home. This is called a "Compact Roof", which means you can frame right up against it. The one drawback of using expanded foam on the inside of the roof is that this will cause the temperature of the shingles to rise, but how much is not yet known. And how much damage a rise in temperatures could cause is debatable.

How Much Is Attic Spray Foam


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. 

How Much More Expensive Is Spray Foam


Spray foam insulation is typically priced by volume, meaning your cost will depend on how much material you need to use to insulate your space, although other factors may influence price as well. In most cases, the cost of spray foam insulation is more than worth it, as it's a once and done upgrade that will not only provide energy savings in your home, but also improve your home's overall comfort.

Spray Foam Attic Ceiling


I just received this and it worked well for me. It works well for small gaps (around windows, between studs), but probably not the right tool for larger gaps (>1" or 2"). If used in larger gaps, it works OK if it is layered in. Spray a little and wait for it to set, then layer another on top, etc... This is pretty much noted by the seller. It is pretty much exactly as described and priced right, so 5 stars. If you need to do larger gaps, buy 2 part. http://www.youtube.com/e/ggLAUsiuI_o?app=desktop
Note:  A board foot is defined as a 12" x 12" square at 1" thick. Actual output can be affected by a number of factors including temperature and humidity. The theoretical yield has become an industry standard for identifying certain sizes of two component kits. Theoretical yield calculations are performed in perfect laboratory conditions, without taking into account the loss of blowing agent or the variations in application methods and types.
SPF insulation applied by professionals is usually described as either a high- or low-pressure foam and is available as either open- or closed-cell. Each type has advantages and disadvantages depending on the application requirements. The comparison chart below can be helpful in explaining or understanding which type of SPF insulation is best suited to a specific application.

How Much Is A Board Foot Of Spray Foam

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