When & How To Use Spray Foam Insulation

One of the most effective and efficient ways to insulate a home or building is to use spray foam insulation. It is often used by homeowners and contractors who are looking for a quick, customizable, and durable solution.

While spray foam offers many benefits, it’s also important to understand its challenges. It can degrade commonly used materials, and the compression of the insulation after installation can often cause damage. Cardboard baffles are a perfect example of a material that does not pair well with spray foam because it will degrade over time and can also collapse during installation. Polystyrene baffles often suffer the same fate since they aren’t made to accommodate the weight of all insulation types.

Brentwood’s AccuVent product, unlike its cardboard and foam counterparts, is manufactured not just to withstand spray foam, but to act as a template for it. Made of durable, recycled PVC, AccuVent acts as a baffle and rafter vent in one that is designed to have spray foam applied directly to it.

What about unvented attics?
In unvented attics, the type, R-value, and thickness of insulation is even more important than it is in a vented attic. This is because the insulation is responsible for separating the conditioned air in the home from the unconditioned outdoor air. Unvented attics are normally within the thermal envelope of the home, meaning they maintain a similar temperature to the living space.

An unvented attic needs insulation that, in the winter, will be impenetrable by conditioned air. If warmer air penetrates the insulation and warms the roof deck, it can cause ice and snow to melt, resulting in costly and damaging ice dams. In the summer, the unvented attic must be able to resist heat leaking in and warming the cooler, conditioned space. If warm air constantly leaks through the insulation, it will decrease home efficiency and raise energy bills.

Thus, spray foam insulation is a popular choice for unvented attics due to its low permeability and ability to fill small gaps, reducing air leaks.

Preventing Overspray
Spray foam, while an efficient and trustworthy insulation option, is not as cost effective as other types of insulation, like batt or blown insulation. Thus, when installing spray foam, it is essential to prevent overspray and only pay for the necessary amount of insulation – nothing more. To prevent overspray from raising costs, a barrier to keep insulation out of the soffits is necessary. Many installers build their own barriers out of rigid insulation, sealing the gaps with canned spray foam.

AccuBlock can accommodate spray foam in both vented and unvented attic assemblies. It’s made to prevent overspray, keeping insulation out of the soffits and reducing the cost of installation. In a shallow-pitch vented roof assembly, AccuBlock can also be used as a wind-wash barrier to ensure insulation maintains its efficiency.