# Basement dimple membrane floor and framing



## veeps (Sep 7, 2017)

I’m getting ready to frame up a few walls in the basement. I plan to put down this dmx 1 step dimple membrane under 5/8 t+g subfloor. I already have one wall framed up next to the staircase because it’s load bearing. The bottom plate is pt 2x4 and it’s on top of foam sill sealer. 

Should I frame all my walls the same way before putting down the dimple membrane? Then just seal where the dimple membrane meets the bottom 2x4? What should I seal it with.

Or is it better to put down the dimple membrane and subfloor and frame the rest of the walls on top of the subfloor? 

It’s easier for me to frame first as long as it won’t cause problems. It is a basement and there is always moisture coming thru concrete. I don’t get any water or flooding in my basement, even when my neighbors have.


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## Nealtw (Jun 22, 2017)

Do you get water on walls and floors? Are you sure it is not condensation?


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## Half-fast eddie (Sep 19, 2020)

Whats the purpose of the product? Is it to provide a standoff to keep the subfloor above moisture? If so, then won’t the bottom plates act as dams?


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## veeps (Sep 7, 2017)

Nealtw said:


> Do you get water on walls and floors? Are you sure it is not condensation?


Yeah it’s probably condensation. I run a dehumidifier all the time.


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## chandler48 (Jun 5, 2017)

If it is wall condensation, it may be helped with installing a continuous thermal break along the walls such as ridgid foam insulation in at least 2" sheets, taped at the seams.


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## Nealtw (Jun 22, 2017)

veeps said:


> Yeah it’s probably condensation. I run a dehumidifier all the time.


Humidity goes up as temp drops, are you leaving it cold down there. 
The exterior wall needs to be sealed so absolutely no house air gets to the cold foundation. So the outside walls want to be sitting on sill gasket. and air sealed ( fire stopped) at the top.


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## Bud9051 (Nov 11, 2015)

You have a moisture problem and covering it up with fancy products will not make it go away.
Sorry, my tag line should be "I hate basements". They look like a lot of wonderful extra space but can end up being a money trap when things go wrong, that's where I've been involved. Even insurance companies are shying away from mold problems.

I can't see your basement from here and neither you or I was there when it was built. To have a dry basement is an expensive process that must be tackled when built. There's a lot of reading available and this is a good start.





BSD-103: Understanding Basements


Now that basements are becoming livable spaces keeping them dry, comfortable and contaminant free is proving to be anything but simple.




www.buildingscience.com





Bud


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## veeps (Sep 7, 2017)

Bud9051 said:


> You have a moisture problem and covering it up with fancy products will not make it go away.
> Sorry, my tag line should be "I hate basements". They look like a lot of wonderful extra space but can end up being a money trap when things go wrong, that's where I've been involved. Even insurance companies are shying away from mold problems.
> 
> I can't see your basement from here and neither you or I was there when it was built. To have a dry basement is an expensive process that must be tackled when built. There's a lot of reading available and this is a good start.
> ...


I think I might have read that same article in the past. So I don’t plan to finish my entire basement.
Basically my basement staircase is open at the top of my living room. Below is a picture of the bottom of the staircase. I need to install a door on both sides of the staircase to close off the stairs to the rest of the basement. The right side of the staircase when walking down the stairs will have a clothes closet and a large open storage area where the freezer, bulk dry food items, and paper goods storage. I intend to put XPS rigid insulation up against the exterior wall in the area that I need to finish. Then frame and over the rigid foam.


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## Bud9051 (Nov 11, 2015)

Just to note, the moisture you are experiencing is probably not coming from condensation. Much more likely it is moisture vapor passing through the floor and or the walls. But I'm not going to bug you.

Best,
Bud


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## AllanJ (Nov 24, 2007)

Get or cut a 24 x 24 inch piece of heavy vinyl or similar plastic (a heavy duty trash or leaf bag will do). Tape it flat to the floor all the way around the perimeter of the piece.

Several days later take it up. If it is moist underneth then you have moisture coming up from the floor.

Do you have a working subfloor perimeter perforated drain tile system?

If you have moisture coming up from the floor and also no drain tile system then your basement is probably not safe for a sealed floor including with dimpled membrane. Leave the floor bare.


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## huesmann (Aug 18, 2011)

Yeah, I would definitely not cover up a moisture issue...that will only make things worse in the long run.


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## 3onthetree (Dec 7, 2018)

Maybe this thread has gotten out of hand. The OP said he has no water, and from what I interpreted was just stating in general that concrete passes moisture. He used both a PT plate and sill gasket on the only wall built so far.

To answer OP's questions, the dimple membrane is not designed as an air or vapor barrier. It's main purpose is to provide an insulating air space to alleviate cold concrete floors and a channel for water (not moisture) to boot. So you do not have to tape/seal any gaps, and the interior non-load bearing walls can be built on top of the subfloor.

Having said all that, you should do a moisture test and solidy your water intrusion plans, because if neighbors have water, you will have it eventually.


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## Half-fast eddie (Sep 19, 2020)

3onthetree said:


> The OP said he has no water,
> Having said all that, you should do a moisture test


He also said he runs a dehumidifier all the time, so taping a piece of plastic to the floor for a couple of days would be a simple prudent test.


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## Bud9051 (Nov 11, 2015)

The plastic on the floor to test for moisture is a "fail only" test. If wet you know you have a moisture issue. But if dry all it tells you is that today you do not (maybe). But a dry result tells you nothing about the rest of the year. Good to test, but not safe to conclude all is well.

Bud


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## Nealtw (Jun 22, 2017)

@*Bud9051* and I seldom agree about basements. But I do agree, if there is any question about moisture coming thru walls, they should not be covered up. I am not sure how you prove it one way or other.


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## Terabitdan (Dec 29, 2011)

3onthetree said:


> Maybe this thread has gotten out of hand. The OP said he has no water, and from what I interpreted was just stating in general that concrete passes moisture. He used both a PT plate and sill gasket on the only wall built so far.
> 
> To answer OP's questions, the dimple membrane is not designed as an air or vapor barrier. It's main purpose is to provide an insulating air space to alleviate cold concrete floors and a channel for water (not moisture) to boot. So you do not have to tape/seal any gaps, and the interior non-load bearing walls can be built on top of the subfloor.
> 
> Having said all that, you should do a moisture test and solidy your water intrusion plans, because if neighbors have water, you will have it eventually.


I know this is an old thread, but for future people reading this... I don’t know about the OPs dimpled membrane but Delta-FL dimpled membrane is absolutely intended as a vapor barrier and thermal break. DELTA®-FL | Dörken Systems Inc. - DELTA®

By placing a vapor barrier between the concrete and the rest of the basement, and properly taping all seams, along with a thermal break it limits the transfer of water vapor. In theory, under the dimpled membrane the humidity is equal to the soil on the other side of the concrete. Above the membrane is determined by conditioning, including the dehumidifier. 

So the walls should be built on top of the membrane and subfloor or at the very least sealed according to the manufacturers recommendations. 

The question I have for the OP is if you only do a portion of the basement floor, the moisture will just go around that portion into your finished area. What, of anything, did you do to for vapor barrier in the walls? 


Sent from my iPhone using Tapatalk


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## 3onthetree (Dec 7, 2018)

Terabitdan said:


> I know this is an old thread, but for future people reading this... I don’t know about the OPs dimpled membrane but Delta-FL dimpled membrane is absolutely intended as a vapor barrier and thermal break. DELTA®-FL | Dörken Systems Inc. - DELTA®
> 
> By placing a vapor barrier between the concrete and the rest of the basement, and properly taping all seams, along with a thermal break it limits the transfer of water vapor. In theory, under the dimpled membrane the humidity is equal to the soil on the other side of the concrete. Above the membrane is determined by conditioning, including the dehumidifier


By nature of material, all dimpled mats have a low perm rating and any air space provides a thermal break. There is a difference between using a membrane for air sealing vs vapor transmission - any holes in an air barrier defeats it's purpose; holes in a vapor barrier (actually retarder) does not affect the overall performance (think staples or overlaps in poly sheeting, joints of adjacent dimpled mat) to a meaningful degree. If there is no moisture problem, you probably have a vapor barrier under the slab to begin with so using a dimpled mat above the slab for an intended vapor barrier is moot. If you have lots of moisture then the dimpled mat provides the capillary break, and if the temperature and pressure differences causes that moisture to condensate under the dimple mat that has no drying path then hopefully you have a gravity route.


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