How important is it to replace your vapor barrier once it’s been damaged?

Unfortunately it happens, vapor barriers in homes across Portland and Vancouver get damaged from a whole host of reasons. Wildlife infestations, like Raccoons and Opossums, rodent activity like rats and mice, and even flooded crawlspaces can leave a homeowner wondering how important their homes vapor barrier is, and if it needs to be replaced once one of the above has happened.

Your homes vapor barrier

First, understanding what the purpose of your homes vapor barrier is can be helpful. Your homes vapor barrier is generally a thick plastic sheeting that is placed in your homes crawlspace. In Oregon and Washington, in order for this plastic sheeting to be code, it should be black, and no less than 6mm thick. This sheeting is placed initially when the home is constructed, and covers the entire ground from the foundation walls, to the center leaving no exposed ground. Many times in older homes, there is no vapor barrier as it wasn’t required until recent years.

The purpose of your homes vapor barrier

The purpose of a home’s vapor barrier is pretty simple, it controls the humidity in your homes crawlspace by placing a barrier between the ground, and your home. The plastic sheeting acts as a barrier between what could be moist dirt and the air in the crawlspace. Here in the damp Pacific Northwest, vapor barriers will also keep moisture in the air from penetrating the soil as well, again controlling the relative humidity of your homes crawlspace.

In order for a vapor barrier to work properly, all ground must be covered, and it is generally recommended that seams are overlapped and secured together using a construction grade tape, or sealing system. It is also recommended by most crawlspace professionals that the plastic sheeting should be run up the foundation walls to provide additional protection.

Why your homes vapor barrier is important

Vapor barriers are important, especially here in the Pacific Northwest because it’s important to control the relative humidity in your homes crawlspace. A home that has too much humidity in the crawlspace will often develop musty smells coming from the crawlspace, which can be transmitted through the homes heating and cooling system. Too much moisture in the crawlspace can also create structural, insulation, and mold problems.

When it’s time to replace a home’s vapor barrier

Typically a home’s vapor barrier should last for many years, but there are times when circumstances warrant the vapor barrier being replaced. If your home has encountered any of the below issues, it can be wise to have a crawlspace professional inspect your vapor barrier to ensure it’s protecting your home the way it should.

  • You experience a water problem in your crawlspace. Water issues in crawlspaces are pretty normal here in the Portland and Vancouver area. If your crawlspace has water, and/or drainage issues, these need to be fixed as standing water creates a moisture rich environment that can wreak havoc on your home. If you have water issues in your crawlspace, the source of the water must be identified and fixed before the vapor barrier is replaced.
  • Wildlife and/or rodent issues in your homes crawlspace. If you are, or have experienced rodent issues in your homes crawlspace, it’s advisable to have a crawlspace professional inspect your home. Wildlife and rodents will not only tear the underside of your home up, they will also leave droppings and other contaminates behind. Finding and sealing the entrance sources for these critters, as well as ensuring they’ve all been evicted before cleaning up the mess they’ve left behind is important to keeping your crawlspaces air clean, which is where by some estimates 70% of a homes breathable air comes from.
  • Vapor barrier that is beyond repair, or not up to code. This can been seen many times, especially on older homes. Often over the years, with different contractors (cable, alarm systems, etc.) crawling around under your home, vapor barriers can become damaged. There are also times when past wildlife issues, or water issues were taken care of, but fixing the vapor barrier was not. Sometimes these issues can be solved by conducting simple repairs, other times the size and scope of the damage may necessitate the replacement of the entire vapor barrier. An experienced crawlspace contractor can help you determine the best course of action to get your homes crawlspace back in order.

The value of keeping your homes crawlspace healthy

Aside from what we’ve covered above, keeping your crawlspace humidity in relative proportion to outside humidity is important for the overall health of your home for years to come. Crawlspaces that are damp or wet attract all kinds of issues.

  • On the pest side of things, damp and wet crawlspaces are a haven for pests like moisture ants, and dampwood termites.
  • Structurally wet and damp crawlspaces can cause wood to rot, and home insulation to become saturated, which then loses its ability to insulate your home.
  • The health of your family can also be put at risk as damp and wet crawlspaces are a haven for mold spores that are easily transferred throughout your home via the heating and cooling ducting.

Home Vapor Barriers – How to tell if it needs to be replaced in Portland OR and Vancouver WA

Serving Customers on the East Side:


Portland | NE Portland | Gresham | Happy Valley | Clackamas | Milwaukie | Mt Tabor | Belmont | Lloyd Center | Laurelhurst | Hollywood District


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Downtown Portland | Beaverton | Tigard | Hillsboro | Cornell | Sylvan | Cedar Hills


And in the Vancouver WA Area:


Downtown Vancouver | Fruit Valley | Hazel Dell | Felida | Cascade Park | Camas Washington