Question about crawl spaces

[Mr. Bloom]

Yes, we have dirt crawl space with a vapor barrier and a sump pump and 10 vents as well. I'm surprised that even living on a hill, we have a lot of moisture in our crawl space due to heavy clay soil. In wet periods, there is always condensation under the barrier.

Even with all this, we still had winter musty smells. So, we installed an ultraviolet air cleaner which was the best money we ever spent.

Absent musty smells, there are instruments that can measure the moisture content in your wood to determine if it's a problem.

Many who put down moisture barriers believe that they should cover every square inch...but I understand that it is problematic to do this as the house needs some moisture to keep the wood from warping, etc. So, I understand that it is best to leave 10% uncovered around the perimeter, but when you do the math, you'll be surprised at how small a gap it takes to get that 10%.

[MommyBird]

It should be dry.
You may need to install a French Drain system If you do not have one.
Outside the foundation would be step one.
Inside the foundation with a sump pump would be step two.
Make sure your foundation vents are providing adequate air movement. You can add fans.

A damp crawlspace is a house health issue that should not be ignored. It affects the health of the occupants as well as the house due to premature structural damage.
If you live in an area prone to termites, moisture is an invitation to infestation. Mold is a danger for humans and pets.

I would have a professional look at it. In our area the pest control companies also handle moisture testing and abatement.

I am not an expert but my husband is a commercial contractor.
Buildings are a major part of our life.

We have built 5 homes. One during El Nino, which masked the fact that our home was affected by an underground spring. Hubby had the experts analyze the issue and then he spent weeks under the house retrofitting a french drain inside the foundation, replacing the vapor barrier and installing a sump pump. Worked perfectly and everything dried out.

[Bike Chick]

Had a dirt crawl space in a prior home with a vapor barrier. Because of the clay soil and no drainage, water and condensation collected under the vapor barrier and caused severe mold problems in our home.

[sarahkonamojo]

Yes your crawl space should be dry. We do have a vapor barrier.
Depending on how damp your crawl space is... If it is minor a humidistat controlled fan could be enough.

Best to find the source of the moisture and fix it.

Sarah

[GLC1968]

Yes, part of our house has a crawl space - the other part has a full basement. We do have a vapor barier in the crawl space as well, but I have no idea if it is damp underneath. Based on the fact that everything is prety much always damp all winter, then my guess is that it is moist underneath, but we haven't looked. Maybe we should.

We do have a french drain and two sump pumps keeping our basement dry. The pumps run pretty much from November to June (gotta love the PNW). We also have a hand operated one that we will install inline in case we lose power for an extended period, but we've been lucky so far...

[staceysue]

My husband says that it's normal for the dirt underneath the vapor barrier to be damp but, if the vapor barrier is doing its job, it should be dry inside the crawl space itself. He said if it's actually muddy there may be a drainage problem.