FAQs About Spray Foam Insulation (SPF)

spray insulationSpray Polyurethane Foam (SPF) insulation is a topic that often rouses a few confused glances among home and building owners. The concept of applying a liquid insulation that transforms into seal seems almost counterproductive, and the initial cost can make some reconsider using it.

But, after a bit of research, many skeptics realize that not only does spray insulation have powerful environmental and health benefits, but it can pay for itself in energy savings and tax breaks.

Lingering Questions

We’ve compiled a few SPF FAQs for you – as a professional contractor – to share with home and building owners to better explain this often-puzzling subject, and shed some light on how it can positively impact a home or building:

What if spray foam gets wet due to inclement weather?

This is a question to comes up frequently for those who live in hurricane areas. In fact, home and building owners in these areas are looking to make their structures more resilient to high-pressure winds and rain, as many are susceptible to water and structure damage.

Closed cell polyurethane spray foam, which is the type recommended for insulating external walls, is actually hydrophobic. This means that water does not absorb within the material and runs off, protecting a building from damage.

SPF insulation also has the advantage of acting as an air barrier, preventing moisture from being blown into the building. These reasons – along with fact that it has the highest R-value on the market – is why FEMA requires spray foam to be applied in buildings that are being renovated in areas often struck by inclement weather.

Can spray foam be used over existing insulation?

The short answer to this is no. Not only will leaving old fiberglass batts in an attic increase the risk of mold and mildew, spray foam will not be able to properly adhere to the surrounding structure, negating the positive properties of the air and water barrier.

This is why spray insulation should always be applied to a clean, dry surface that allows the material to cure properly and form a tight seal.

What impact does applying spray foam in an attic have on the HVAC system?

This answer depends on the building or home, as well as the existing system that is already in place. SPF insulation is designed to encapsulate an area, sealing out air and moisture while keeping heat in, which can be a difficult task if the current HVAC requires outside ventilation.

So, if the current system requires atmospheric combustion, or the need for vents outside to function properly, then spray foam should not be installed in the home until there has been an investment made in a sealed combustion, direct vent or power-vented appliance. These types of systems can function in airtight environments and don’t require holes cut into the building’s roof.

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