If you're about to have your home insulated with spray foam insulation, you know you have to choose between open and closed cell versions of the foam. Like any other product, these options have their advantages and disadvantages. However, one particular category of advantages and disadvantages involves moisture and water absorption. The way the two types of foam interact with water -- a concern when you are dealing with potential roof leaks, condensation, or humidity -- can affect your home and the life of the insulation. Here's what to consider when choosing spray foam based on what your home could encounter.

The Problem

Spray foam insulation is either going to absorb moisture -- open cell does this -- or block it, like closed cell would. Closed cell can sometimes also block moisture from drying properly, meaning the material next to the insulation stays wet and develops issues with rotting. Yet with open cell, too much moisture can work its way into the insulation and up toward the roof material, eventually rotting the roof material.

Internal Moisture

A very common problem is that the humidity in the crawlspace or attic will become too high. This can happen because internal humidity (from inside other rooms in the house, like bathrooms) is leaking up into the space or because condensation from a temperature difference is forming in the space.

If you're in a cold region, the condensation is likely to be the worst offender. Humidity from your warm home forms condensation on the insides of the home just like you'd find condensation on the warm side of a glass holding cold water. If you live in an area that gets very cold, you should use closed cell foam because you're going to be more concerned about that internal moisture seeping up rather than external moisture seeping down into the house. You could add a vapor barrier and use open cell foam, but that may be more work than you want to deal with.

Hurricanes and Torrential Rains

Every house has the risk of having a roof leak, but in areas known for hurricanes and heavy storms, the risk of a leak goes up substantially. Open cell will show moisture damage more easily, should rain get in through the roof, and closed cell will not, meaning it may take longer to see internal damage if you have closed cell.

But in areas with hurricanes and strong storms, you need to get the roof inspected more frequently anyway to ensure no damage has resulted from the storms. So, if you have closed cell, you'll likely find the damage pretty quickly and be able to fix or replace any problem areas and materials. But with open cell, while you'd still find the roof damage quickly, the moisture from a leak would move further into the open cell insulation than it would into closed cell. So not only would you have to repair the roof and adjacent materials, but you might have to replace a lot of the insulation as well, leading to higher repair costs.

Other Considerations

Insulation style does not have to be its only defense when it comes to moisture. You must be sure that your roof stays in good condition, that the insulation is installed properly, and that your bathroom and kitchen fans work properly considering the size of your home and the size of the rooms. Adding air conditioning and a dehumidifier to your attic or crawlspace also helps control the amount of moisture that the space has to deal with. If you are in an area that has relatively moderate weather, it might not be a matter of using open vs. closed cell foam, but rather of ensuring everything is installed and maintained correctly to keep excess moisture away from the insulation.

If you want more help in choosing a type of foam, talk to insulation installers like Energy Home Insulation Inc now. Local companies will know which types work best in your area and what additional steps you can take for the best experience.

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