FAQ Spray Foam Insulation
What is Spray Foam Insulation?
Spray foam is made of a two-part liquid mixture consisting of an isocyanate and a resin mixture. These two chemicals are mixed at a perfect ratio to ensure the foam adheres perfectly to the substrate (wall) and achieves the proper R-value.
These chemicals are pumped through a specialized heating and pressurizing unit known as a reactor. The fluids remain separate until just before leaving the gun and are mixed at specific temperatures and pressures.
There are two types of foam: closed cell and open cell.
Difference Between Closed Cell and Open Cell Insulation
The differences lie in the R-value and whether a poly vapor barrier is needed.
Open Cell
Open cell (0.5lb) insulation uses air pockets to improve R-value but requires a vapor barrier. Most insulation contractors understand that open cell has sponge-like properties and must be covered by an approved vapor barrier. Open cell insulation is unsuitable for joist pockets due to its inability to act as a vapor barrier in a web joist application. Open cell insulation is ideal for sound and acoustic applications but is not recommended for Manitoba building envelopes.
Closed Cell
Closed cell (2lb) insulation does not require a vapor barrier on any substrate after being applied at 2″ thickness. Closed cell foam, such as Insulthane Extreme, achieves an R-value of R-20.4 at 3.5″ thickness. It acts as a complete vapor and air barrier when applied correctly and is much denser and more rigid than open cell foam. Closed cell foam can increase the racking strength of the building by up to 300%.
What does R-Value mean?
R-value insulation ratings measure an insulation’s ability to resist heat flow. The higher the R-value, the more effective the insulation. Home insulation should be purchased based on its efficiency value.
Most contractors may suggest more than 3 inches of spray foam in a wall cavity. At 2 inches, the R-value is 89% efficient; at 3 inches, it is 95% efficient. Adding more product beyond 3 inches provides diminishing returns and higher costs. The efficiency of your home is what truly matters!
What is a LTTR? (Long Term Thermal Rating)
A LTTR measures how insulation performs over the long term. Most standard testing evaluates the R-value immediately after installation. Asking for the LTTR provides a true value of the spray foam insulation’s long-term effectiveness for your project.
What makes spray foam better than conventional fiberglass insulation?
The LTTR of fiberglass insulation decreases over time. Fiberglass insulation’s R-value is deceptive as it assumes perfect installation without gaps or air movement.
For example, an R20 fiberglass batt has an effective LTTR of about R12 due to sagging, gaps, and other factors like house shifting and wiring. For every 1/8″ gap, you lose 50% of the R-value. Spray foam insulation guarantees no sagging, gapping, or cracking, unlike fiberglass insulation.
Can Polyurethane Spray Foam Burn?
Polyurethane foam insulation is classified as combustible under building codes but includes fire retardants to prevent it from supporting flames. Once the flame source is removed, the foam stops burning. Building codes require a thermal barrier (e.g., ½” drywall) over all foam insulation. A fire retardant coating can be applied for projects without a thermal barrier, depending on building codes.
Need more answers? Speak to one of our team members, and we’ll be happy to help!