Rising moisture problem crawlspace design

[moby25]

Bonjour à tous

I will explain to you the concern that I encounter in my crawlspace.
it is an extension of a house that I bought last April.

This enlargement was, from what I know done by the individual.

This extension is based on a crawl space of approx 50cm high on concrete block.
The ground is in the ground.

On these breeze blocks are placed joists spaced 50cm apart.
On these joists are placed wooden floor plates.

The concern is that in my opinion there is no waterproofing system at the foundations because the humidity rises on the joists (which are simply placed on the concrete blocks).

This humidity is also diffused on the edges of the wooden floor which rests on the concrete blocks.

However, inside the house, which is made of aerated concrete, I do not encounter any particular humidity problem.

here is a photo that illustrates my problem



I saw that there were a lot of post on the concerns of humidity but I did not see any post which corresponds exactly to my problem.

I saw that there were aquaplan type solutions, but for me it prevents humidity on the surface, but does not prevent humidity from going up inside ...?

Do you have a solution?

please

[Christophe]

We have a little the same scenario in our country.

Normally against the capillary rise there is a barrier called anti salepeter in crawl space and habitable construction, so if it has been put in place, you can seal it from the inside if not must be done from the outside if possible ...

Look at this topic, I have progressively sealed the interior with us: https://www.econologie.com/forums/humidite-d ... t7591.html

But this does not prevent condensation from the inside. According to your photo (ca "pearl"), there is that also at home.

After many hours broken in 2 in the VS, I managed to bring the humidity down by 10% ... from 99 to 90% it's better but it is still high ...

Now don't forget the purpose of a crawlspace:

Under construction, a crawl space is an accessible or non-accessible space a few tens of centimeters high located between the land and the first floor of the building and serving as insulation between it and the ground. Rises in humidity from the ground are eliminated outside the building by natural ventilation of the vacuum obtained with the peripheral air vents. They have a screen to prevent insects and larger animals from living in them.

[moby25]

good evening christophe

I had just read your post. ;-)

Do you think that in your case, the humidity could also come from the ground for lack of waterproofing?

I saw the solutions you had used.

On the other hand, I think that surface paints prevent humidity on the surface but I don't understand how they would prevent humidity from going up inside the concrete blocks?

Otherwise, I actually have a "beading" phenomenon because I had blocked the ventilation due to the extreme cold lately. I had read that it had to be done. But hey, I just noticed that you had to choose between losing calories, or chasing moisture.

I think it's better to ventilate all the same.

[Christophe]

Do you think that in your case, the humidity could also come from the ground for lack of waterproofing?

Yes certain, it is indicated on the subject: when it rained it was worse ...

On the other hand, I think that surface paints prevent humidity on the surface but I don't understand how they would prevent humidity from going up inside the concrete blocks?

They don't do it but we bury ourselves ... if you have an anti salepeter barrier it's ok!

I think it's better to ventilate all the same.

I don't think so ... not when he has negative T °! A little humidity in the VS is "normal"!

Did you measure it elsewhere?

[moby25]

Do you think that in your case, the humidity could also come from the ground for lack of waterproofing?

Yes certain, it is indicated on the subject: when it rained it was worse ...

On the other hand, I think that surface paints prevent humidity on the surface but I don't understand how they would prevent humidity from going up inside the concrete blocks?

They don't do it but we bury ourselves ... if you have an anti salepeter barrier it's ok!

The problem is that I don't know. It would seem really insane to me that there is not any but good, considering that this part of the house was made with the economy by an individual ...: - /

If the barrier is present, aquaplan would be the solution.
What I don't understand is that this summer, I had almost no humidity on the concrete blocks, but still this trace of humidity on the floor.

The assumption is perhaps that the floor takes moisture in the winter for lack of ventilation and also has great difficulty in evacuating it in the summer for lack of ventilation. (There was only one hole when I bought the house). I made a second one, but I think I'm going to redo other small ones and see what it gives.

Did you measure it elsewhere?

No I did not measure it, but this is obvious:
-this summer and ventilated no beading.
- This winter, not ventilated -> beading.

So i don't know what to do

[Christophe]

Beading in SV is not that bad ... the majority of people have never gone to see their SV elsewhere!

Uh when you talk about floor is below (VS side) or above (living side)?

[moby25]

it is VS side, habitable side, I do not see it, it is covered with parquet.

I have a lot of loss in the crawl space part. That's why I thought maybe it came from there. But, it can also be by the roof, because I only have 10 / 12cm of insulation at this level

If not for the humidity -> according to you beading is not serious, on the other hand it is not necessary that the concrete blocks are wet in depth?

[Christophe]

So if you see nothing at the top, that's fine!

Humidity must not rise up on the habitable side where it is heated.

The principle of a VS is by definition to make a buffer zone for absorbing moisture.

[moby25]

I think it goes up a bit anyway, because I saw slight traces at the bottom of the walls but nothing alarming.

Since the floor takes on moisture, it also transmits it above at the level of aerated concrete.

[moby25]

While browsing the net, I was able to glean information on the right and on the left and I think that there may be several other solutions to remove moisture from the crawl space.

- The outside of the crawlspace walls are covered with a coating.
On the outside it is very dry, while inside the concrete blocks are "filled" with water.
The coating therefore seems to prevent the wall from breathing
Replacing it with a "breathable" coating might already solve part of the problem. I think the current coating acts as a barrier.

The aquaplan inside the crawl space could be worse than better if it is humidity by capillary action.

I saw that there were also wall drying solutions like electro osmosis

http://www.sofrelop.fr/ptech.htm

or also the use of the knapen process

http://www.avamtic.fr/assechement%20des%20murs.html

Otherwise still the use of a drain ...

So before any work, I must find the real origin of the humidity on the concrete blocks.

In my opinion, it must go up by the earthen ground of the VS because the tablecloth is not far at all.