Frequently Asked Questions
How does Spray Foam work?
Does spray foam meet building codes?
How does Spray Foam compare to fiberglass and cellulose insulations?
Can I keep the existing insulation in my attic?
Can I store my things in my attic?
Does my attic need to be vented if Closed-Cell Spray Foam is applied to the underside of the deck? Doesn’t my house need to breathe?
Do I need to worry about indoor air quality?
What is R-value?
What is the difference between Open-Cell and Closed-Cell Spray Foam?
Is Spray Foam good for soundproofing?
Does Spray Foam contain formaldehyde?
Does spray Polyurethane foam insulation contain any VOCs or CFCs?
Is it toxic?
How long does Spray Foam last?
How is Spray Foam installed?
Does Spray Foam absorb moisture?
How does Spray Foam Insulation control moisture movement and condensation?
Does Spray Foam Change Over Time?
Will Spray Foam strengthen my house?
Can Spray Foam be applied directly to electrical wiring? What about low voltage wiring?
Spray Foam is sprayed on as a liquid which reacts and expands in place. This expansion seals all cracks and crevasses in your wall’s exterior. The result is that air can no longer slip in. Your house will be less drafty and more comfortable. Air leakage can introduce moisture into the wall cavity resulting in wet insulation, mold and mildew. With the sealing effects of Spray Foam, it is not a concern.
Spray Foam has the approval of all four major building codes in the United States and Canada. Spray Foam is recognized as a thermal and air. Closed-Cell Spray foam is all three: a thermal, air and vapor barrier. It is one of the most extensively tested insulation products ever.
Spray Foam is more expensive than fiberglass and blown-in cellulose. However, it is the only one that immediately and consistently reduces energy costs. There are many differences, but most important, Spray Foam is a true air barrier.
Fiberglass in any form, such as blown-in, batts or roll, is not an air barrier. It will not stop air leakage. Blown-in cellulose will slow down air leakage, but is not complete total air barrier. Fiberglass and blown-in cellulose have significantly lower R-values per inch.
What’s more, they can sag, settle, and shift over time leaving sections in the wall cavity and attic un-insulated or under-insulated. Fiber insulations can hold moisture and become breeding grounds mold and mildew. Closed-Cell Spray Foam resists mold and mildew. It is not a food source.
Spray Foam completely adheres to the wood substrate and sheathing. It is a permanent barrier to heat loss and air entry. Its solid matrix strengthens the structure. Fiberglass products and blown-in cellulose are not permanent barriers to heat loss and air infiltration.
An unvented or closed attic assembly is one of the most popular applications for Spray Foam. The short answer is that the removal of the existing insulation is required by code. The existing insulation poses a safety hazard for the applicators as it often obstructs their proper footing. Moreover, it can trap odors.
The long answer: When your mechanical system or ductwork is in the attic, an unvented attic assembly yields the greatest amount of energy savings. The retro fitted area is considered a semi-conditioned space. The thermal envelope is being moved from the attic floor to the roof deck.
For the attic assembly to perform properly, no vapor or thermal insulation barrier can exist between the occupied area and the attic. The removal of the insulation is required to ensure that an airtight seal is created with the Spray Foam along the top plate of the exterior walls.
In addition, the existing insulation can leach the odor created during the Spray Foam installation. This leaching action can cause the Spray Foam odor to linger indefinitely.
Rodents and other pests can inhabit attic spaces. If scat, dirt and remains of these pests are not removed from the attic floor, the odors and allergens associated can enter the inhabited space of the residence.
International Residential and Building Codes require all attics sprayed with Spray Foam to only be used for the servicing utility and mechanical systems unless they have been Appendix X approved. Some foam manufacturers offer Appendix X tested and approved foams.
Green Dog Spray Foam does offer applications of such foams. If you opt to choose Spray Foam that has not been Appendix X approved, an approved thermal barrier, an interior finish system or intumescent coating must be applied if you intend to use the attic for storage.
No, the application of Spray Foam to the underside of the roof deck eliminates the need to vent the attic. Venting of attics primarily came about as a way to eliminate condensation buildup on attic insulation resulting from temperature differences between the inside attic walls and the interior of the building. Unfortunately, this venting also allows cold air into the attic in the winter and warm air in during the summer.
With Spray Foam, a thermal and moisture gradient is provided allowing the space to become semi-conditioned within 5-10 degrees of the interior house temperature. This prevents the development of dew point conditions in the attic.
Your house DOES need to be ventilated, BUT most home engineers, building scientists, and the US Department of Energy recommend sealing the structure as tight as possible. Then provide necessary ventilation through your air conditioning and heating system. Many systems employ an ‘air exchanger’ that preconditions incoming outside air to control humidity and energy efficiency. This type of design used with Spray Foam creates a true thermal envelope.
No, you do not. Spray Foam actually contributes to improved indoor air quality. Unlike other insulators, Spray Foam does not have any loose fibers that can transport throughout your home. Because it reduces air infiltration, Spray Foam reduces dust, allergens, mold and mildew. Spray Foam provides a healthier, draft-free environment with no harmful emissions that can cause allergic reactions.
New Construction: If you are sealing the entire building envelope, it is necessary to have the HVAC contractor install an ERV system that provides a continuous source of fresh air into the building. Most building design professionals will advise you to seal the building structure as tight as possible and to provide the necessary ventilation through an air exchanger attached to your heating and air conditioning system.
In winter, this simple machine brings cold fresh air from the outside and passes it by the warm stale air being expelled. This allows the fresh air to pick up the heat from the stale air, maintaining energy efficiency while providing a continuous supply of fresh air.
In the summer, the opposite occurs giving the same results. In this manner, you can build an extremely energy efficient exterior shell using spray Polyurethane foam insulation while still providing controlled and energy efficient ventilation. Remember, you only have one chance to “build it right and seal it tight.” Don’t let old fashioned fears deter you from building an efficient home. Any qualified HVAC contractor can advise the builder and owner on how to properly ventilate.
Retrofit: Attics, crawlspaces and basement walls. Because air enters the building envelope when we open windows and doors, through house vents such stove and bathroom, and from the other air gaps that cannot be reached behind drywall and plaster with a typical spray foam application, you do not need to worry about your house being sealed too tightly.
R-value, sometimes referred to as “thermal resistance”, is a measurement of the insulation’s ability to resist heat flow. The higher the R-value, the better the thermal performance of the insulation. The R-value is based on test methods established by the American Society of Testing and Materials (ASTM). Refer to the R-Value Fairy Tale article for a comprehensive review of the R-value myth.
Open-Cell Spray Foam or one-half pound foam is identified as one-half pound per cubic foot. It is made up of tiny cells of foam that are not completely closed. The cells are broken and air fills all of the ‘open’ space inside of the material. The foam has a fluffy appearance. It is soft, similar to a foam sofa cushion.
Open-Cell Spray Foam has an R-value ranging from about 3.4 to 4.5 per inch depending on the manufacturer. It is a very good insulator and excellent sound insulator.
When sprayed, open cell foam expands up to 150 times its initial state. The excess foam is shaved off the studs, leaving a flat surface over which dry wall or other material can be applied. Open-Cell Spray Foam qualifies as an air barrier at 4.5" inches of thickness.
Closed Cell Spray Foam, or two pound foam, is identified as two pounds per cubic foot. The cells are closed and packed tightly together. The closed cells are filled with an inert gas that helps the foam rise and expand to up to 30 times its original state.
Closed Cell Spray Foam is a greater insulator due to its denser properties. Closed Cell Foam has an R-value ranging from 6.6 to 7 per inch depending on the manufacturer. At one inch, closed cell foam qualifies as an air barrier. At two inches, it qualifies as a vapor barrier.
When cured, Closed-Cell Spray Foam is lightweight yet extremely dense, so it contributes greatly to the structural integrity of the building. It is both an air and vapor barrier, it resists the growth of mold and mildew, and it deters rodents as it is not a bedding material.
An example of Closed-Cell Spray Foam insulation that we benefit from every day is the insulation found in your refrigerator and freezer. It is the ideal insulation choice for windy, damp and water prone locations, such as coastal areas, below grade, crawlspaces, or for the whole house. Closed-Cell Spray Foam is the only FEMA approved flood resistant insulation material. While it is more expensive than open cell foam, it is the product of choice for most of our clients.
Both Open-Cell and Closed-Cell Spray Foam are effective for reducing noise from outside sources by sealing cracks and gaps that allow sound to travel through the walls, floors and ceilings into the building. Of the two, Open-Cell Spray Foam has the best soundproofing capabilities for media rooms, music rooms, for separation between commercial and residential spaces, between floors in apartment buildings and condominiums, and home offices.
A resounding no, it does not contain formaldehyde.
No, Spray Foam does not contain any VOCs (Volatile Organic Compounds). Nor does it contain any formaldehyde, bleach, CFCs (Chloro Fluoro Carbons) or HCFCs (Hydro Chloro Fluoro Carbons).
No, Spray Foam is NOT toxic. Usually within 24-48 hours of application and with proper ventilation, there are no hazardous fumes present in the building.
Spray Foam will last the life of the building. As an inert, long lasting polymer, its ability to reduce heat and cooling loss is constant.
Spray Foam is sprayed into the wall cavity in between the wooden studs with specialized equipment. The foam is sprayed on as a liquid, but within two to ten seconds, the liquid will turn to foam and expand filling every nook and cranny, sealing all gaps and permanently adhering to the stud cavity.
Because the cells in two pound Closed-Cell Spray Foam are closed, properly applied Closed-Cell Spray Foam will not absorb water. That is why it is recommended for below grade applications, crawlspaces and attics. Open-Cell Spray Foam, while an excellent insulation product and air barrier, is susceptible to moisture. That is why we do not recommend it for application in certain areas of the building structure.
Most moisture problems in houses are due to moisture entry from air leakage introducing indoor air to outdoor air. This exchange causes condensation. Because Closed Cell Spray Foam is both an excellent air and vapor barrier, this source of moisture is virtually eliminated.
No, it is inert. Its physical and insulating properties are constant.
Yes, the structural integrity of Closed-Cell Spray Foam is one of its ‘fringe benefits.’ Closed-Cell Spray Foam is rigid foam with superior adhesion to all substrates. As a result it provides exceptional performance in improving wall and roof deck racking strength, making a top seller for windy locations or locations prone to tropical weather.
Don’t get confused: Open cell foam does not contribute to the structural integrity of a building.
Yes, Spray Foam can be applied directly to electrical wiring. Recessed lights or other fixtures may require a certain amount of air circulation around them for cooling purposes. We can address this on a case by case basis.
Knob and tube wiring cannot be encased in Spray Foam. We suggest upgrading your knob and tube but if that is not possible, we need to avoid the knob and tube. Spray Foam has been thoroughly tested. It is not a concern to electrical authorities. Nor is it corrosive to any metals whatsoever. However, low voltage wiring is more sensitive. If care is not taken, a short could occur. We do our best to take notice of these wires and avoid spraying them.