Spray Foam Insulation
What is it? Spray foam insulation is a type of insulation material that is applied using a spray gun. It expands upon application, filling gaps, cracks, and irregular spaces in walls, ceilings, and floors. If the desire is to create a tight envelope and an energy-efficient home, this is well worth the cost premium over the traditional insulation type.
Spray foam insulation is typically made from two main components: polyol resin and isocyanate. When these two components are combined, a chemical reaction occurs, resulting in the formation of polyurethane foam. The chemical composition is very similar to the “Great Stuff” you might buy in a can at Home Depot.
Benefits:
Energy efficiency: Spray foam insulation provides excellent insulation value, reducing heat transfer and minimizing air leakage.
Air sealing: Spray foam insulation expands and fills gaps, crevices, and voids, creating an effective air barrier. This reduces air infiltration, preventing drafts, and improving indoor air quality.
Moisture control: Closed-cell spray foam insulation has high moisture resistance, helping to prevent the growth of mold and mildew. It can also act as a vapor barrier, preventing moisture from entering the building envelope. (Pier and Beam, metal buildings, etc.)
Foam holds its r-value twice as long as fiberglass
Carlisle OCX (which we’ve frequently used) contains 14% bio-renewable, recycled materials
Disadvantages:
Cost: Spray foam insulation tends to be more expensive upfront compared to other insulation materials. The cost is typically higher due to the specialized equipment and professional installation required.
Potential health risks during installation: Spray foam insulation is typically installed by professionals using specialized equipment. During the installation process, harmful fumes and chemicals may be released. It is important for occupants to avoid the installation area until the foam has fully cured and dried.
Difficult to remove or modify: Once spray foam insulation has been installed, it can be difficult to remove or modify without damaging the surrounding areas. This can be a disadvantage if future renovations or modifications are required.
Open Cell vs. Closed Cell:
Moisture control: Closed cell spray foam acts as a vapor barrier and provides a higher resistance to moisture diffusion. It is commonly used in areas prone to moisture such as basements, crawlspaces.
Soundproofing: Open cell foam has better sound-absorbing properties compared to closed cell foam.
Cost: Open cell spray foam is ~1/2 the cost of closed cell foam.
Because the open cell structure allows some vapor to pass through, open-cell foam is a good choice in hot, humid climates, and under roof sheathing, such as in conditioned attics, where water vapor caught between insulation and sheathing could promote wood rot.
R-Value:
Closed cell spray foam insulation: Closed cell spray foam typically has an R-value of around 6.0 to 7.0 per inch of thickness.
Open cell spray foam insulation: Open cell spray foam typically has an R-value of around 3.5 to 4.0 per inch of thickness.
City of Austin Code: R-25 for SF (7”); R-49 Blown In
Carlisle Spray Foam (a brand we’ve frequently used): R3.7 per inch
Curing Time:
Typically, the foam will start to tack up and form a skin within minutes of application. This initial curing process usually happens within 30 minutes to 1 hour.
Full curing of spray foam insulation typically takes around 24 to 48 hours. During this time, the foam will continue to expand, harden, and cure into a solid state.
Fire Concerns:
Spray Foam is extremely combustible. Because of this, the manufacturers now add an Ignition Barrier to the product. It’s added during manufacturing. It is designed to prevent the material from combusting for 4 minutes.
For inaccessible attics this 4 minutes is fine.
For attics that are accessible only for HVAC servicing, the 4 minutes is fine.
For accessible attics (vertical door) the code is 15-20 minutes before combusting. This requires a fireproof paint (ex. DC315) to be applied to the SF after it cures.
Any open cell product that is installed at a depth of 11.5'' or more is required to have an additional 15-20 minute thermal barrier
