|
| Author |
Message |
slatecreek
Member
|
# Posted: 31 Jul 2018 07:53am
Reply
We have a small cabin with a concrete floor (about 12'x14') built before they put vapor barriers down under concrete. When we close the cabin up for several weeks and return find mold growing under some of the furniture close to the floor. I'm assuming it is from the damp cool floor in the summer heat. We turn off electric, otherwise I would leave a fan or dehumidifier running (eventually off grid solar).
I ran across something at Menards called DMX AG flooring designed to install as an underlayment in areas where moisture in floors are a problem. It is HDPE dimpled plastic sheet that allows air to pass under the plastic yet prevent moisture to pass above it. On top of this you install your laminate flooring. Has anyone used this product in a damp cabin and did it work? My other option is to lay down a vapor barrier and build on top of that but my fear is the underside of the barrier would always be soaked and moldy.
|
|
toyota_mdt_tech
Member
|
# Posted: 31 Jul 2018 08:50am
Reply
Isnt there a sealer you apply right to the top of concrete? I have seen a product use to seal in basement walls. Trying to rememebr the name. But it just pours or paints on. Its a rubberized vulcanizing material.
A quick search:
https://www.homedepot.com/b/Building-Materials-Concrete-Cement-Masonry-Concrete-Water proofers-Foundation-Coatings/N-5yc1vZaq3z
|
|
DaveBell
Moderator
|
# Posted: 31 Jul 2018 09:15am - Edited by: DaveBell
Reply
Toy, i was thinking about that garage floor roll on stuff but not sure if it is a solution for this problem.
But I like the idea of the tests in this link:
http://www.contractortalk.com/f94/concrete-floor-no-vapor-barrier-129487/
|
|
DaveBell
Moderator
|
# Posted: 31 Jul 2018 09:26am - Edited by: DaveBell
Reply
I was thinking if you put something down and it assumes the same temp difference then would the problem persist? The slab and the treatment are cold, high humidity, warm sunshine = cabin greenhouse?
I found this on a forum:
"Your problem sounds like it's a cold slab. The moisture is in the air. This happens when there is no rigid insulation under a slab and the rh goes over the dew point. No paint will help this."
|
|
DaveBell
Moderator
|
# Posted: 31 Jul 2018 09:35am
Reply
Another thing I just read, the cabin was not built on a mound. Thus water was allowed to accumulate under the slab. Slate can you post some pics? Where is the cabin? Arizona or Florida? 
|
|
snobdds
Member
|
# Posted: 31 Jul 2018 11:17am - Edited by: snobdds
Reply
You need to get some air flow in your cabin when you're not there. Think about how a bathroom has a vent in the ceiling to get the moisture out after a shower. You will need passive air movement that is not tied into power. Therefore you will need an air vent down low that exhaust out near the ceiling. Natural air flow, as long as there is no reverse vacuum in the cabin, should naturally pull in cold air in the bottom and vent the warmer make up air out the top of the ceiling. This is a totally separate system from attic and or roof venting and the two venting systems should remain separate, unless you have a cathedral ceiling, if possible.
Make sure you put heavy woven wire mesh screen and a furnace filter to keep critters and dust out of the cabin.
Air movement is cheap and probably your best option.
|
|
slatecreek
Member
|
# Posted: 31 Jul 2018 03:33pm
Reply
Yes, I cannot paint or seal the floor because the moisture will lift it in time. The cabin is in Ohio, clay soil, damp often. I have a separate roof venting system, and yes cathedral ceilings.
I read somewhere here on this site about the passive air exchange system and considered this. I thought if anyone has used the DMX AG floor system and it worked I would go that route. It would give me a nice wood floor and solve the moisture issue. Deep down I know the right way to fix it is passive venting. Thanks for every ones input.
|
|
slatecreek
Member
|
# Posted: 31 Jul 2018 03:50pm
Reply
I found this and answered my own question posted on Angie's list:
I have not used that specific product, but used a predecessor bubble wrap type plastic vapor barrier/carpet underlayment sheet in my basement - it had moisture buildup and some mold from normal concrete slab vapor transmission in/under the foam-backed carpet when we moved in. I put water-barrier concrete floor paint on the concrete then laid the "bubble wrap" underlayment down (looks much like DMX 1-Step) and when I pulled a part back awhile back (after 30 + years in place) because of a water pipe leak, in an area that previously had moisture it had no moisture or mildew/mold - looked like new underneath other than that the plastic stuck here and there and pulled the paint off - maybe because I was in a hurry and only let it cure about 3 days before sealing it in with the plastic sheet.
Hard to tell how much of the benefit was from the concrete paint and how much from the vapor barrier, but I would not put it down on bare concrete without sealing/waterproof painting it first.
One thing to be careful of - how the vapor barrier is vented, because if you seal it tight to the walls around the edges it is no different than 6 mil vapor barrier polyethylene because there will be no place for the vapor underneath it to go, but if you don't provide edge venting it can cause mildew/mold growth along the base of the walls.
This is one thing their instructions don't accomodate - they advertise the benefits of moisture escaping from under the emmbrane, but then say to place it tight against the wall, so there is no way for the moisture to escape. hence, at least if installed as they recommend, with a damp concrete I would expect mildew/mold to form along the baseboards and bottom of walls, especially in a cold basement environment. In that respect, I don't see this is any better than regular visqueen or bubble-wrap plastic underlayment at a lower cost, so I do not stand convinced this product offers any added advantage for its significantly higher cost.
|
|
|
rockies
Member
|
# Posted: 31 Jul 2018 06:30pm - Edited by: rockies
Reply
A plastic bubble wrap product would not be my first choice since it still allows moisture to become trapped under the plastic. All that moisture has to go somewhere and the quicker it evaporates the better.
The other thing I suspect is that you have a cold floor which is uncomfortable to walk on. A better choice would be a product like "Drycore" which creates an air channel under the osb subfloor to allow the concrete to dry. You also get a much warmer finished floor and the rigid plastic dimples and osb surface will give you a firmer feeling floor when you walk on it (you'll always have some flex with bubble wrap under a laminate finished floor).
http://dricore.com/nw/index.php
|
|
slatecreek
Member
|
# Posted: 31 Jul 2018 10:11pm
Reply
The dry lock is the same product only with an osb backer board. This DMX product is not a bubble wrap but a hard plastic dimpled sheet in roll form. They claim the DMX AG is better than dry lock because there is less seams and they provide sealing tape for the seams. In my opinion they both have the same issue, sealing the product to the wall and trapping moisture underneath. Cold floors yes, but we have a few fiber mesh rugs and slippers to solve that until the wood stove warms up.
|
|
toyota_mdt_tech
Member
|
# Posted: 1 Aug 2018 08:54am
Reply
OK, found the drylok
http://www.drylok.com/products/drylok-extreme-masonry-waterproofer.php
But as many mentioned, sealing it is one thing, but I think the warm cabin air contacting cool cement floor is probably the condensing issue. Must be high humidity there? I would just add in some vents to keep air moving when not in use.
|
|
Wilbour
Member
|
# Posted: 1 Aug 2018 01:30pm - Edited by: Wilbour
Reply
One thing to remember is if you vent out you must vent in as well. The drycore idea may work at keeping the furniture dry from the condensation forming. I suspect this is your main issue. Perhaps a vapour barrier on the concrete and drycore on that?
My issue is what happens to the water trapped under the false floor?
Perhaps you vent it around the perimeter?
We have a similar problem in our house basement. Our flooring is tile directly on the concrete floor. When it's hot and humid (much of an Ottawa summer) I get water pooling on the floor if there is no air flow.
What has helped is a dehumidifier of course but in hard to reach areas like under the couch I put a small fan on a timer. 30 mins on, 30 mins off
It seems to be just enough to keep the air moving. We also make sure our furniture does not have fabric skirting.
|
|
DaveBell
Moderator
|
# Posted: 1 Aug 2018 03:24pm
Reply
Is there a landscaping/drainage issue???
|
|
rockies
Member
|
# Posted: 1 Aug 2018 06:15pm
Reply
You don't want a plastic vapor barrier on top of the concrete, that will just create a pool of water under it.
If you do use Drycore or a similar product keep it about an inch away from the walls.
|
|
|
