Rising moisture problem crawlspace design

[Obamot]

Good just for info, for those interested, the cover is very wet below.

On the other hand the walls do not seem to dry, contrary to what I had announced in my last post.

This is just a finding.

... that's what I concluded ..!

[moby25]

I just took pictures in the crawl space.

I'm going to be smacked by some but actually it looks like it's drying out.



I have the impression that there is a real drying / re-humidification phenomenon surface.

The cold bridge:



Currently in the crawl space: 8.0 ° C and 55% relative humidity. But hey, the weather has been fine for several days and the air is "dry", 50/60% RH

In the home 35% RH at 18 ° C without VMC. Normally it is rather 40/45%

[dedeleco]

Amusing,

I'm going to be smacked by some, but actually it looks like it's drying out

The slap is already administered, with the lost time, because the elementary tests could have been done since January 2010 !!!

The water vapor comes from somewhere: the bare floor, certain, the more certain the outside air, the more the bathroom, the more last a rise in the walls by evaporations in the cracks of the wall, similar to the soil in fact, water vapor which condenses on cold spots.
In detective, one track should not be preferred over another without evidence duly cross-checked and tested.

The test of the bathroom without baths at all has not been done !!

A test, sticking or tacking fairly large thin plastic, against the walls in different places to be tested, allows to know if there is condensation on the outside of the paper (humid outside air which condenses) or on the inside of the paper (humidity of the wall which evaporates and is deposited on the cold plastic on the surface, like on the ground) and sometimes on both at the same time !!

At the moment the east wind, I think and therefore quite dry, and without the evaporation of the soil, it dries much faster than before !!
In wetter weather and westerly wind, with rains and much wetter air, the night air outside at 100% humidity will continue to condense on the cold portions all the more as the air is ventilated. reverse with drier wind, which dries the more the more you ventilate. !!

[moby25]

Bonjour à tous

I come back here because I found a lot of information from our friends ... Canadian or there there are a lot of crawl spaces on joists unlike France or it is very very rare.

Here is a non-exhaustive list:

- http://dsp-psd.pwgsc.gc.ca/collection_2 ... 8-102F.pdf

- http://www.cmhc-schl.gc.ca/publications ... 90-231.pdf

- http://knol.google.com/k/cynthia-freene ... ujf01c/12#

- http://www.laquakeproofer.com/crawl-spa ... fornia.php

also very interesting:

http://www.basementsystemsquebec.com/le ... rawlspace/

-> http://www.basementsystemsquebec.com/learning_center/crawlspace/oldcs_thinking.php

http://www.hydro.mb.ca/francais/your_ho ... lspace.pdf

Keyword craw space

http://www.google.fr/images?hl=fr&q=cra ... 80&bih=853

So to summarize (really very very briefly):

The old school wanted us to isolate crawl spaces from below with ventilation.

Now, a polyethylene tarpaulin is used which even goes up on the walls, which prevents the humidity of the earth from rising.

They also speak of the external insulation of the sub-basements.

Now, we are more in the perspective of crawl space heated with humidity control.

Some were right here ;-)

[dedeleco]

In Canada the phenomenon is dramatically amplified:
outside -15 ° C to -30 ° C
wetland of the crawl space at annual average T or 5 to 10 ° C which evaporates the bottom to the bottom at -15 ° C which condenses m3 of frozen water and absolute disaster on the wood of these wooden houses !!

So they don't laugh with misconceptions !!!

[Obamot]

I do not see the point of looking for solutions to thousands of km, which would be inapplicable in the case of a completely wrong building design and when everything has already been said in this thread.

You put a tarp as you were suggested, and it seems to have had an effect ... EITHER!

But since you don't do things in order, you still don't know where you are (which cause actually produces which effects). This is why I left this thread, because you endure in a total absence of pragmatism. So yes, by trial and error we get there, but as Dedelco says ... it's much longer therefore much more expensive And you will never be guaranteed not to be wrong!

[moby25]

I just wanted to share this interesting info. We are in a forum, that's a bit of the goal isn't it?

I'm going to do things in the order specified in this thread, don't panic

Otherwise I also had the misconception that the harvest occurs especially in winter when the opposite is also true.

T ° Outside summer 25 ° C, T ° Crawl space 15 -> condensation via the incoming air. Dedeleco had spoken about it here.

I would not be so categorical in saying that what is applicable in Canada is not necessarily here.

In France we are much less confronted with the problem because we make a lot of concrete.

The DTU with wooden floor on crawl space recommends a ventilation of 1/150 the surface of the floor, which is not bad, and when we read that mold problems can appear in the summer, it makes you think about these standards.

In terms of wood construction, North America, I think has a lot more return than in France, where wood construction is marginal, especially with wooden floors on crawl spaces as a base.

We can also note that the old way of doing things in Canada corresponds to that which is currently being done ... in France.

However, I agree that in winter, conditions have nothing to do with it. It would also be interesting to discuss this with our Canadian member, if he is still there?

[Obamot]

Stop your Moby tank There must be no construction in Canada that uses chipboard sandwiched in the load-bearing walls, and without external insulation to create such a cold bridge (!!!)

With the temperature differential they have there, such a building would have already collapsed, right?

Note that the problem is so huge that somewhere it was your chance!

There you acted on "a factor" and it produced "an effect" ... You were able to verify for yourself the merits of the procedure, but as you are incorrigible you did not do it in the order: so that means nothing!

For the rest it is still your home and therefore you who decides, but everything has been said ...

[moby25]

I'm not talking about my house! I should have opened a different post so as not to cause confusion ...

[Obamot]

You see, we should be careful not to be too anchored in denial or the imperative need to get reason, because that seems to prevent us from seeing the real problems. It's the kind of disabling stuff that can make you say and do nimportenawak. But it can happen to anyone.

Good we leave you to your "tests", bye and good luck.