How to finish the crawl space around the house

[lenmo]

Hello!

Our crawl space is partially open in the areas where there are terraces. The openings, about 25 meters in total, on the sides are only about 20 cm high. It's too humid in the crawl space, especially this season. There is some white mold growth on the boards that fix the insulation under the house floor.

We received a quote from an "expert," and he suggests closing the sides with isodrän boards and foam sealant (and then laying ground plastic + installing a dehumidifier). So it would be, from bottom to top: Ground (sand) / isodrän boards / (possibly foam sealant) / house wooden beams. This "solution" does not sound very long-lasting, for example, because the isodrän boards would only be supported by the ground. The boards would only be supported by loose soil. They don't weigh much, but they won't be really secure. And I wonder if isodrän is airtight/watertight. Liquid water is not the same as gaseous water.

I have uploaded some pictures, a bit poor but hope the situation is clear. And excuse me if I wrote in poor Swedish.

What do you think? Any other ideas?

 

[Du och 19till]

How long has the house been standing? Have any changes been made recently? Has it become more humid than before?

 

[lenmo]

How long has the house stood? Have any changes been made recently? Has it become more humid than before?

Thanks for the reply! It's a bit unclear, but probably half was built around '95, and the other half was extended around 2000/2001. We've only been living in the house for 1 year. The previous owner has done nothing at least since 2020.

A wooden beam had 18% moisture in June. And also more than 15% (can't remember) last fall when we had an inspection from Anticimex. The ground feels damp as well. I've ordered some wireless moisture/temperature meters.

 

[Dowser4711]

A wooden beam had 18% moisture in June. And also more than 15% (can't remember) last fall, when we had an inspection from Anticimex. The ground feels moist too. I've ordered some wireless moisture/temperature meters.

18% in June in a beam and you're considering installing dehumidifiers?
I would have a significantly longer measurement series before doing anything unless there is mold or damage already today.

Then the question is whether it needs to be enclosed and dehumidifiers installed, or if it's enough to just tidy up a bit to get better airflow.

 

[lenmo]

18% in June in a rule and you're considering installing a dehumidifier?
I would have a significantly longer measurement series before I started doing something unless there's mold or damage already today.

Then there's the question if it needs to be built in and dehumidifiers set up, or if it's enough to clear up a bit to get better airflow.

Thanks for the response! There is already white mold on the wood fiber boards that support the insulation. I'm going to buy a moisture meter to measure myself.

Anticimex and the other guy who came, of course, think we need to address this with a dehumidifier. That's what they sell themselves.
In the Netherlands, where I come from, almost all houses are built with brick or concrete, almost never wood. So living in a villa in the Swedish countryside is new to me, let's say.

The air is now very humid throughout the night and morning, and it cools down under the house. So the problem with better airflow is that it will also bring in more moisture that will condense under the house. I can understand this logic, at least.

 

[Du och 19till]

It seems to be quite well-ventilated, but it could be better if it were even more open, so that it can blow through under the house. Right now, the air might be stagnant.

 

[lenmo]

It looks to be quite well-ventilated, but it might be better if it is even more open, so that it can blow through under the house. Now the air might stand still.

Yes, it can stand still, and it doesn’t blow much at all. We live next to the forest, and the whole area is in the middle of a forest. It doesn't blow as much as next to a field, for example. And the open sides are only where the terraces are, and they aren’t very open to air either.

I will start by measuring properly, and I will try to remove the debris that is there, which might be hard to reach.