What Happens If Spray Foam Insulation Gets Wet?

Eli Smith
by Eli Smith

When spray foam insulation gets wet, it is easy to get worried over what may happen. You may wonder if you have to throw the whole thing out. Thankfully, damp spray foam insulation is not the end of the world.

If your spray foam gets wet, it will eventually dry out again. Spray foam that is wet for an extended period is likely to deform and potentially expose insulation in your wall. It would require a considerable amount of water for most spray foams to deform.

Below, we will go through how that answer may vary depending on the type of spray foam you use. We will also go through what to do should you find a water leak in your walls insulated by spray foam.

What Type Of Spray Foam Is Water Resistant?

There are three significant types of spray foams available:

  • High-density spray foam
  • Medium-density spray foam
  • Hybrid spray foam
  • Low-density spray foam

High-Density Spray Foam

High-density spray foam is water-resistant. You often find it in use for construction projects that emphasize quality. It is a type of closed-cell spray foam.

It is also wind-resistant, as its sturdiness adds to the structure. Because of this, you can expect it to be the most expensive type of spray foam available on the market.

Medium-Density Spray Foam

You will commonly find this in locations that require high amounts of R-value. As a result, it is water-resistant. It is also a type of closed-cell spray foam.

It is also in attics and walls where there is a lot of noise outside. It is less water-resistant than the high-density spray foam.

Hybrid Spray Foam

If an insulation spray foam advertises itself as water-resistant, you will want to look for the section that refers to it being open- or closed-cell. This answer will depend on whether or not it claims to be this.

Check the product description and with the company’s customer service department. In this case, it is best to say no.

Low-Density Spray Foam

Otherwise known as Open-Cell spray foam, this is often used in situations where you have a lot of cracks and seek soundproofing. As a result o the open cell structure, it is not considered water-resistant. It is known to absorb water if exposed for too long a period.

Closed-cell spray foam is the most water-resistant. Because of this, high- and medium-density foams are what you should prefer in humid climates.

What Should I Do If I Find A Wall Leak With Foam Insulation?

Based on our findings above, you only need to be particularly worried if you have open-cell spray foam. Closed-cell spray foam will prevent this water from moving anywhere significant, and it is likely to seal the issue for you already.

Follow these short steps:

  • Turn off the water
  • Remove the damaged insulation with a utility or heat knife
  • Put in new insulation

If you need to remove wet insulation from your wall, be sure that you are wearing gloves. Seal the water leak before reapplying any further insulation.

What Should I Do If There Is A Flood With Foam Insulation?

Floodwaters often contain contaminants that you do not want in your wall. Given that floods can cause your house to be affected by a massive amount of water, you will need to replace the foam.

Using a moisture meter, you will be able to tell how much of the foam absorbed the moisture. Most likely, the closed-cell spray foams will absorb little to no water. Test them regardless of any assumptions, as you do not want to play with any potential chemicals in your walls.

Can Mold Grow On Spray Foam Insulation?

For further details on the topic, we recommend you check out our more detailed article—the short answer to this question: No.

Spray foam insulation is typically naturally resistant to water. As a result, it is an uninhabitable place for mold spores and things like that. Unless you have an exceptional amount of water, you aren’t likely to find mold growing near closed-cell insulation.

Open-cell insulation is more likely to be affected by water, but It is not known to attract mold. If you have mold in this area, you may look to other factors.

Can You Use Spray Foam Insulation On Your Roof?

We all know that the roof is a haven for potential damage. Because of that, you might think that you can’t use spray foam on the top. However, you can use any closed-cell spray foam.

Do not use open-cell spray foam on a roof. If you receive a roof leak during an extended rainstorm, there is a chance that your top will heavily deform. Also, open-cell spray foam is not sturdy.

Is A Hybrid Insulation System Waterproof?

In this case, a hybrid insulation system is a combination of insulation rolls and spray foam. For simplicity’s sake, we can also assume that the spray foam is closed-cell, which is the most waterproof option.

In this case, these can be pretty effective combinations that will allow one system to take over when the other method fails.

When thinking of fiberglass insulation, these also suffer from some of the same issues that come from open-cell spray foam. Meaning that as more water goes to the insulation, it is more likely to be less effective.

In the case of fiberglass insulation, it does not dry out quickly because of the material. You may have to tear out the wall, locate the leak, and allow your insulation to dry out.

Can Foam Board Insulation Get Wet?

When comparing spray foam to foam board insulation, it is clear that closed-cell spray foam is the winner. While they are also mold-resistant, boards are more likely to retain moisture with air pockets located on the board.

If you find that your foam board is wet, apply the same process as you would with insulation rolls. Tear out the wall to survey the damage and see if you can’t dry out the insulation. If there is mold, you will need to replace it.

Where Should I Not Use Spray Foam Insulation?

  • Near electric boxes
  • Near recessed ceiling lights
  • Around people with a history of respiratory problems
  • If you are uncertain on how far it will expand

While spray foam is an excellent way to insulate your home, it isn’t great in a small number of circumstances. It mainly concerns near any electrical components, as spray foam can be flammable.

Like with regular insulation, you will want to exercise due caution. If you are uncertain of how to proceed with this, it isn’t a terrible idea to consult with someone who has used spray foam insulation before.

Eli Smith
Eli Smith

I'm a guy who becomes the expert of whatever I stumble upon, writing-wise. I've written tons about cool home products, home improvement, and smart technology in the home. I'm also the proud father of a kiddo born on new years, making my holidays very busy.

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