Spray Foam Spray Foam FAQs s

Is spray polyurethane insulation code approved?

Yes. Building codes provide for the use of spray polyurethane insulation in the Foam Plastic section. This section of the code also describes the use of thermal barriers.

At what point in the construction should spray polyurethane insulation be applied?

Normally, spray polyurethane insulation is installed at the same point in the construction cycle as other types of insulation. That is, it should be installed after the rough plumbing, electrical wiring, and heating and air conditioning ducts have been installed. If you decide to seal the entire exterior shell with spray polyurethane, spray insulation may need to be applied in some areas before the ductwork is installed.

Are windows O.K. to have in a unvented attic that is insulated with spray foam at the walls and roof deck?

Yes. Building codes provide for the use of spray polyurethane insulation in the Foam Plastic section. This section of the code also describes the use of thermal barriers.It seems like the radiation of heat through the windows would make the attic hot. Windows in a conditioned attic are similar to windows in your home. They are holes in the insulation. The energy they allow through them will have to be made up from your heating or cooling system. Consider removing them or covering them from the inside in some manner and insulating them.

Can a building owner apply spray polyurethane foam insulation?

Not practically. Spray polyurethane application requires complex equipment and a skilled installer with training in the safe and proper installation of the polyurethane system.

Can a building owner rent the equipment and install spray polyurethane foam himself?

Great question as we hear this a lot. Unfortunately for you DIYers, spray polyurethane foam (SPF) equipment is not for rent. Installation of SPF needs to be done by a well-trained installer. It’s not as easy as it looks. There are some small kits on the market, but they are made for very small projects like sealing joints and cracks.

Can closed-cell foam be used under roof deck on a roof that has a peel-and-stick moisture barrier on the roof deck under metal roofing or roof shingles? Will sealing the roof deck on both top and bottom adversely effect the roof deck sheathing?

Closed-cell SPF can be used under a wood roof deck where peel and stick is used as a moisture barrier above the deck. Proper design is critical especially in very cold climates where the vapor drive is outward for a significant amount of time. A ventilation chute between the foam and the wood deck that is connected from the soffits to the ridge vents is an option for some designs to ensure moisture if properly vented.

I have a house built on a slab in a flood plain. From time to time, I get water in the house. To remediate after a flood, I must open up the walls about 24 inches and dry out the walls, and then replace the insulation and the sheet rock. If I could use an insulation which would not hold water and install wonder board on the first two feet of the walls it would be a big improvement. Can closed-cell foam be used in this application?

Closed-cell spray polyurethane foam (SPF) is an excellent option for you. Closed-cell SPF is listed as a Class 5 Flood Damage-Resistant Material per FEMA. This means it is “Highly resistant to floodwater damage, including damage caused by moving water. These materials can survive wetting and drying and may be successfully cleaned after a flood to render them free of most harmful pollutants.” It is the only insulation material that meets this classification. It would be an excellent idea to install closed-cell SPF into your walls the next time you have to open them up.

I'm planning to use an open-cell spray foam in the 2X6 joist between my basement and first level. Can I top it off with that Roxul Safe and Sound Insulation?

There are no chemical compatibility issues between open-cell spray polyurethane foam and rock wool insulation. You need to make sure, however, that the combination is designed properly for your climate zone and building code.

Is cured spray foam insulation toxic? We recently removed a large quantity of it and are at a loss as to how to dispose of it. It has great water retention and I was wondering if it could be broken up into small pieces and mixed into garden soil. What harmful effects are known?

Spray polyurethane foam is approved for use as an insulation material in contact with soil, but we do not know how foam scraps would perform as soil fill, therefore, cannot recommend its use for this purpose. The standard means of disposal of spray foam scraps is to dispose in normal construction waste to a landfill.

I would like to insulate the ceiling of a crawlspace with closed cell spray foam insulation. Sometimes the crawlspace floods but only with a few inches of water with a little less than two feet of space between the insulation and the water. However, with Sandy our crawlspace had over two feet of water and the fiberglass insulation got wet and I needed to replace it. Can I use spray foam?

You can use closed-cell spray polyurethane foam (SPF) for your crawlspace in flood prone areas. FEMA has classified closed-cell SPF as a Class 5 Flood Damage-Resistant material. This is the most stringent classification from FEMA’s Flood Damage-Resistant Materials Technical Bulletin 2. Search for FEMA TB2 on the internet and you should be able to find a publication that explains this further. The latest Technical Bulletin was published in August 2008. This would also be a good option for the lower sections of walls and ceilings that may be affected in a flood event.

If I install a wood stove in a foam insulated home, will it rob all the oxygen out of the air, or what steps do I need to take to insure my fire gets the proper air it needs? Also, does my attic need to be vented like if I install spray foam? Or does it need to be sealed where no air can enter?

Realizing the need to consider proper ventilation is a very important first step when you install spray polyurethane foam in your house. Now that you’re installing a wood stove, it is even more critical. Not being a ventilation expert, I would recommend first contacting the stove manufacturer to determine how to provide proper ventilation. They may be able to help to ensure it works properly and doesn’t cause any issues.

I don’t quite understand your second question. The choice to provide a conditioned or vented attic typically depends on if you have HVAC equipment or ducts in your attic. If you attic is void of air ducts or HVAC equipment, the most energy efficient option would be to provide a good air seal on your attic floor, seal up any penetrations and create a vented attic. You would put the insulation on the attic floor. If there are HVAC ducts in your attic, creating a conditioned attic where the insulation is under the roof deck is a good option. This puts the HVAC equipment inside the thermal envelop.

How does spray foam work?

A two-part mixture is applied by trained professionals to the surface to be insulated. The spray mixture expands rapidly to fill all cracks and voids, completely and permanently adhering to wood, masonry, metal, concrete, and most other construction materials.

I have purchased a double wide in Godley Texas, and would like to know if this is a good product to spray on the underside of the double wide? Will it insulate the home better and pipes, or should this not be used?

Insulating the underside of a trailer with spray polyurethane foam is much like insulating the underside of a home in the crawlspace. It is a good idea and should help with the energy bills especially if there is no insulation there presently. Work with the foam manufacturer or contractor to select the right product for your climate. Make sure you follow all applicable building codes.

I live on a busy street and wanted to know which insulation (open-cell or closed-cell foam) would be best to install on the "road-side" wall of the home to help reduce noise from the outside traffic?

To help reduce outside noise through a wall, either open or closed-cell spray polyurethane foam is a good choice. The most important choice is to use the correct type for your climate zone.

What is the proper way to insulate a residential attic space. Is the foam applied to the underside of the roof rafters or is it applied between the attics floor joists. I have been told the it gets applied between the roof rafters?

This all depends on what benefits you are looking for. Either way will work perfectly but sometimes there are advantages for one over the other.

I would insulate the floor unless:

1. My HVAC equipment and ducts are installed in the attic. Insulating the roof deck brings these energy losses into the thermal boundary saving the lost energy.

2. The attic space may be finished at a later date.

3. I live in a hurricane zone and I have an older home where I want to increase the wind uplift resistance of the roof deck.

If we have our new home insulated with the spray foam do we need a special hood vent for our cook top?

Excellent question. I believe your question has less to do directly with installing spray foam, but more to do with creating a house that is very air tight. However, it’s good you’ve recognized that spray foam helps you create an air tight home. For range hoods in a very air tight home, you basically want to uncouple the hood from the rest of the house by providing its own dedicated makeup air system. Check out this article from the fantastic people at Building Science Corp that can air it all out for you.

I had my attic rafters spray foamed in 2010. Recently, a specialist did an energy inspection and made the observation that the batt insulation in the ceiling had not been removed and in many places the foam came down to the batt insulation but not to the plate at the top of the perimeter walls. He now recommends that ALL the batt insulation be removed and openings be re-foamed to create a complete seal. Is he correct that all the batt insulation should be removed?

Answering your question fully requires more information. It’s not clear whether the insulation installed on the roof deck is intended to be the thermal boundary of the house or was installed to reduce the solar gain acting much like a radiant barrier. A radiant barrier reduces the temperature gain in the attic taking the load off of the insulation on the attic floor. In this case, the attic is still vented and the attic floor insulation will remain. If the intent of installing SPF to the roof deck was to create a conditioned attic (non-vented) then the recommendation would be to first remove any insulation and vapor retarder from the attic floor then to install SPF on the roof deck and gable walls. The SPF should also seal off any vents from the exterior to the attic space creating a complete seal and thermal boundary that ties into the insulation boundary in the walls. Removal of the attic floor insulation allows the attic to come to equilibrium with the living space. Also, when the thermal boundary is at the roof deck, the fiberglass insulation which could also contain dust, contaminants, pest remains, etc, are now essentially part of the interior of the house. Various contaminants or odors collected over the years that were once vented to the exterior in the attic are now part of the interior of the house. It is recommended to remove the attic floor insulation when creating a conditioned attic for these main reasons.

I am trying to insulate a house roof. I have beam construction with two, in tongue and groove decking. Metal roof on the decking. I want to remove the metal, build a 2x4 or 2x6 frame on the deck, blow the space with closed-cell foam, put OSB decking, and replace the metal. I need suggestions. Should I spray straight on wood? Does the cavity need to be vented? Peel and stick on top of OSB, under metal?

Installing closed-cell spray polyurethane foam on the top side of the ceiling finish is acceptable. You want to make sure the tongue and groove decking is tight and will not allow the liquid chemicals to pass through any cracks while it is curing. I think it would be good practice to ventilate the air space between the foam and the OSB roof deck. You would also want to drill weep holes into the eaves near to top of the foam layer to drain any water that may pass through the primary roof as a roof leak.

Does the expanding foam have serious hydraulic qualities?? If sprayed behind studs will it move, warp or lift building material?

It is not recommended to spray or pour spray polyurethane foam in a wall cavity because the expanding force may cause damage to the interior or exterior sheathing. The best solution is to install the foam when either the interior or exterior sheathing is removed during a remodel.

I am looking at having spray foam insulation installed in an attic space that we will be converting into a large walk-in closet. My concern is what effect will the foam have on my asphalt shingles? I've been told it will be no problem and I've been told it will shorten the life of my shingles due to the extra heat. I'm assuming that you are installing the spray polyurethane foam to the underside of the roof deck. The concern here is with an unvented attic where insulation is installed directly under the roof deck, the shingles may degrade rapidly due to the increased heat caused by the insulation.

This concern is over exaggerated. There are a couple excellent papers and presentations written by Building Science Corporation (www.buildingscience.com) that cover their research regarding shingle life in unvented attics. They conclude that in Las Vegas, one of the hottest locations in the US, the average roof deck temperature difference between a unvented attic and a vented attic is 17 F. This is from research that they conducted on actual homes. This difference would only be less in the rest of the country. They have also determined that asphalt shingles installed over VENTED roof decks in hot-dry climates are generally warmer than the same shingles installed over UNVENTED shingles in a hot-humid climate like Orlando.

Finally, the difference in color from white and to black creates a larger temperature difference than unvented versus vented roof decks. The argument for these points is that shingle manufacturers do not have separate warranties for different climate zones or different shingle colors. The small increase in shingle temperature due to vented versus unvented is insignificant compared to other factors.

Do I need to take any precautions when finishing an un-vented attic space with a spray foamed ceiling/roof? Do I need a plastic barrier or anything before applying sheet-rock to the attic joists? The space will be air conditioned and has windows, but is otherwise un-vented.

To help reduce outside noise through a wall, either open or closed-cell spray polyurethane foam is a good choice. The most important choice is to use the correct type for your climate zone.

I am considering using the product under the house in crawl space (subflooring) as there is no insulation (old structure. What considerations are there as to existing termite bond, future termite infestation (termite resistant properties?). I understand the material is not cellulose based but is it termite resistant?

If you are installing spray polyurethane foam (SPF) up against the underside of the floor in the crawlspace, then your termite inspector can continue to inspect for termites around the perimeter. If you are installing SPF on the walls of the crawlspace, then you need to leave an inspection strip around 6″ wide on the walls.

If we foam spray our garage open rafters do we need to put dry wall underneath?

Spray foam must be protected by a thermal barrier such as 1/2″ gypsum wallboard. In a garage, this rule would apply.

I have recently had close cell insulation sprayed in a metal building The contractor was suppose to install 2" of foam and states they sprayed 5 coats of insulation However the actual thickness is 1"-1-1/8" He is claiming the foam did not expand as it should have but that the material for a 2" of foam has been sprayed. I don't know what to believe .

Based on the information you have provided, this does not make sense. For one, 2″ of closed cell spray polyurethane foam (SPF) would typically be applied in one or two passes or “coats” as you say. It makes me wonder what the contractor was installing if they said 5 coats? A coat typically applies to paints or coatings, not SPF. Also, if you were specified 2″ and only received 1.125″, then something is wrong. Claiming that the foam did not expand as it should is not your fault but either the contractor’s or the chemical supplier’s. Nothing about what you have said makes sense to me. Either there is some misunderstanding or you have not received what asked for. I would ask for a better explanation from the contractor.

When can spray foam be installed?

Spray foam insulation is professionally installed at the same point in the construction cycle as other types of insulation. That is, using traditional building techniques, spray foam should be installed after the rough plumbing, electrical wiring, and heating and air conditioning ducts have been installed, but before the interior walls are completed in new construction. In some cases spray foam also can be applied in older buildings or structures, to the inside of roofs and under floors after construction has been completed.

Will re-roofing damage foam under the roof

This is a great question. Both open-cell and closed-cell spray foam insulation adhears extremely well to the underside of roof decks and the rafters surrounding them when installed correctly. I have not heard of any evidence to support your theory. This should not be a concern when applying foam to the underside of a roof deck.

Won't sealing my building with spray polyurethane foam lead to indoor air quality problems?

Your building does need to be ventilated in order to maximize indoor air quality (moisture levels and contaminant levels). Most design professionals will advise you to seal the structure as tight as possible and provide the necessary ventilation through the heating and air conditioning system. Many systems employ a highly energy efficient “air exchanger” which is designed to pre-condition (either warm or cool) the incoming outside air with the outgoing exhaust air. In this manner, you can build an extremely energy efficient exterior shell using high-performance spray foam insulation while still providing controlled and energy efficient ventilation.

Everything you ever wanted to know about spray foam insulation...

Just a few of the questions you may have.