Spray Foam Insulation FAQs

What is the difference between open cell and closed cell foam?

Open cell is a low-density foam that is primarily used in household attics or walls where flooding may never be a problem. Its advantage is that it’s less expensive than closed cell and passes water through should you have a roof leak and need to know about it.

Closed cell is a high-density foam that is water and moisture impermeable. This is used primarily in walls where flooding may happen or metal buildings where a vapor barrier hasn’t been installed. It adds great structural integrity to a metal building as well as a twice the R-value per inch as open cell. This is also used for the subfloor of pier-and-beam houses to prevent moisture and air from penetrating the home.

What is the R-Value of spray foam?

Closed cell has an R-value of approximately 7 per inch. So, 2 inches in a wall is R-14.
Open cell R-value is 3.6 per inch. A 2×4 wall cavity then would be approximately R-14.

Why do I have to remove my existing insulation prior to installing spray foam.

Since you are moving the A/C boundary from the ceiling to the roof you don’t want to trap heat and moisture between the two different insulating materials. Also, building codes say you have to remove it.

My house is 2000 sq ft, why do you say I have to pay for 2240 sq ft of insulation.

Since the spray foam is now installed on the bottom of the roof, we have to calculate the added square footage taking into account the pitch of the roof. For example, a 6/12 pitch roof is calculated by multiplying the attic square footage by 1.12. The angle (pitch) of the roof adds 240 sq ft to the area, thus we have to cover 2240 square ft. There is a conversion factor for each standard pitch of a roof.

If I want to insulate my subfloor what would you recommend?

We recommend installing 2” of closed cell spray foam. 2” fulfills manufacturer recommendations for moisture and water barrier and provides an insulation factor of R-14.

How long will spray foam last in a house?

It will last the life of the home.

Will spray foam burn?

Like any building material within a home, spray foam will burn if exposed to flame or enough heat. Spray foam will burn but it does not support ignition. This means if a flame is taken away, it will stop burning.

Are there any harmful emissions?

Spray foams are safe for both you and the environment. Most spray foam products are water-blown, and do not emit HFCs or HCFCs. Extensive testing in North America have shown that no VOCs are detected after 30 days following installation.

Does spray foam support bacterial and/or fungal growth?

Spray foam insulation products do not offer any food value, therefore do not support bacterial or fungal growth. Furthermore, it also does not retain water, making it an unappealing environment for fungal spores. University of Texas has done an experiment on mold growth ability on three different insulation types (foam, fiberglass with foil face and fiberglass with vapor barrier).

What about rodents and/or pests?

Spray foam insulation offers no food value to rodents or pests. It should be noted that it would not present a barrier to their entry if they decided to gnaw through it. Therefore, spray foam should not be considered a barrier to rodents or pests.

What makes spray foam better than traditional types of insulation such as fiberglass?

Spray foam insulates and air-seals to control unwanted random air leakage – which traditional cellulose and fiberglass insulation can’t do without the use of extra sealing materials. Traditional insulations can also leave gaps and seams around electrical boxes or light fixtures (compromising performance), but foam fits perfectly around all detailing for a complete air-seal. The result is a healthier and more efficient home.