When should you not use expanding foam?

When NOT to Use Spray Foam Insulation

  1. For areas that are too close to electrical boxes:
  2. For areas too close to ceiling light boxes:
  3. Open-cell spray foam on your roof:
  4. For closed-cavity spaces:
  5. If you have a history of skin, respiratory, or asthma problems:




Can expanding foam damage?

You have to consider if using foam is safe if you have anything routed inside the cavity, such as electrical wiring. So, if you were wondering whether expanding foam damages wiring the answer is yes. Expanding spray foam without carefully planning can damage electrical wiring.

Can you use expanding foam to fill gaps?

Expanding Foam Polyfilla is ideal for filling and sealing awkward gaps, hollows and cavities. It shoots liquid foam deep into cavities, creating a long lasting seal, which insulates against heat, sound and moisture.

What are the disadvantages of spray foam insulation?

List of the Cons of Spray Foam Insulation

  • Spray foam insulation does not always fill every possible cavity. …
  • Spray foam insulation might encourage water damage for some homeowners. …
  • Spray foam insulation can sometimes shrink. …
  • Spray foam insulation requires a lot of experience to get it right.

Can mice get through expanding foam?





Filling the cracks and voids with the polyurethane foam acts as a rodent barrier, as mice and other rodents aren’t able to chew through spray foam insulation. With polyurethane foam, the results are immediate. While it won’t get rid of infestations already in your home, it will prevent them from happening.

Does expanding foam cause pressure?

Low-expansion foam expands up to 30 times its liquid size, while high-expansion foam can expand as much as 300 times its liquid size, quickly putting pressure on a window frame to the point where it’s difficult to open and close the window.

Does expanding foam damage PVC cables?

Not aware of expanding foam having a reaction with PVC. Polystyrene does react with PVC and causes it to bond in a sticky mess to the cable sheath. It doesn’t matter what form it is, whether granules or solid it will react all the same.

Is expanding foam closed cell?

Closed cell foam is designed to expand to about 1″ of thickness when sprayed. With each inch offering an r-value of 7, multiple applications can be applied to achieve higher total r-values. Open cell foam is designed to expand to 3″ of thickness, meaning only one application is possible in most standard walls.

Does expanding foam damage wood?



Some expanding foam sealant products may warp or distort materials like wood. Thus they should not be used on doors or windows because they may affect how they open and close.

Can mold grow on spray foam insulation?

As a product, spray foam insulation does not attract mold. And unlike wood or metal, spray foam does not rot, rust or deteriorate. This means that an area properly sprayed with foam insulation will never become a food source or a hospitable environment for a mold colony.

Why do lenders not like spray foam insulation?

So why is it a problem for mortgage lenders? By sealing the roof space with this material, air circulation can be restricted to the roof and timbers. This can lead to condensation, which in turn can eventually lead to the rotting of the wooden roof supports.

How long does spray foam last?



With proper application, Spray Foam will last the lifetime of your home. Even roofing applications will last upwards of 30 years, with proper long-term maintenance. Spray Foam insulation adheres extremely well to virtually all substrates, and maintains its rigidity once dry.

Does spray foam crack?

The curing process after spray foam is applied inherently entails shrinkage and hardening. Not only can such shrinkage result in pulling back from stud bays and other connections – which often leads to gaps in the insulation layer – it can lead to cracking within the foam structure itself.

Will termites eat through foam insulation?

Researchers have concluded that termites do not eat the foam board insulation but they will tunnel through it. Insulation also provides potential protection from predators and also retains moisture, two requirements of termites.

Is it worth it to spray foam insulation?

If you see the benefit of insulating your new construction home correctly from the start for long-term comfort, energy savings month after month, and fewer headaches while you live in the house, then spray foam insulation may very well be worth the extra cost to you.

What can happen if the foam is incorrectly installed?



When spray foam insulation is installed incorrectly, dangerous chemical off-gassing from a poorly applied insulating agent can occur. Symptoms of chemical off-gassing may include respiratory issues and eye, nose, and skin irritation.

What are the pros and cons of spray foam insulation?

A Breakdown Of The Pros & Cons Of Spray Foam Insulation

Pros and Cons of Spray Foam Insulation
Advantages Disadvantages
Creates a highly energy efficient thermal envelope Upfront costs are high and installation is expensive
Extraordinary thermal qualities Payback takes 2-4 years
Lower ongoing energy costs Not a DIY product

What is the R-value of 4 inches of spray foam?

Spray Foam Insulation R-Value

Open cell spray foam insulation is R-3.6 to R-3.9 per inch. This R-Value is normal for open cell spray foam.

Is 2 inches of spray foam enough?



Now generically speaking, we usually recommend open cell spray foam to be 6- to 10-inches on a roof deck or ceiling and 3-inches in the walls. Closed cell spray foam should be 4- to 5- inches on the ceiling and 2- to 3-inches in the walls.

How long does spray foam insulation off gas?

Different manufacturers and installers of spray foam will insist that occupants vacate their homes – anywhere from 24 to 72 hours are the recommendations we’ve seen – to allow the foam to fully cure and off-gas.