# condensation problem



## Stone (Mar 23, 2009)

I am not sure if this is the right place for building envelope questions but here goes. Does this sound plausible: Two year old house with condensation showing up inside a wall. The wall is two story, six inch studs, insulated with plastic sheeting over insulation and then drywall. Outer part is plywood with tyvek and then two layers of 15 pound felt, with lath, scratch coat and manufactured stone installed. East facing wall in northern Ohio. The theory is that the stone absorbs water and the sun drives the vapor inward all the way to the inner plastic where it condenses. This only happens in the summer. The problem first showed up as water dripping out of an electical outlet.
Has anyone ever experienced something like this and does anyone have a solution going forward for other jobs like this. On this particular job the drywall is being replaced and the plastic eliminated, as a start.


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## Tom Struble (Mar 2, 2007)

is the house air conditioned?it's getting condensation on the insulation side of the plastic?


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## Stone (Mar 23, 2009)

It is air conditioned but the insulation is getting wet.


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## ExtremePride (Oct 27, 2010)

Around here the walls need to be able to breath. With the vapor barrier on the inside and two layer of felt on the outside it's pretty mush sealed up. I don't know about your area though, you could try running several dehumidafiers.


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## Rio (Oct 13, 2009)

What a nightmare... As the vapor barrier traditionally goes on the warm side maybe it is as Tom suggests that the air conditioner is getting the wall so cold that moisture is condensing, but it's a little tough to think that the moisture would be in the stone and then go through the two layers of felt. There's no possibility of leaks from above into the wall?


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## Tom Struble (Mar 2, 2007)

Stone said:


> On this particular job the drywall is being replaced and the plastic eliminated, as a start.


before you rip it maybe a good idea to have a plumber do a check for a super small leak anywhere in the area of the problem wall.I have seen where what seems to be a condensation issue stemed from a leaking pipe


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## TheHardWay (Jun 9, 2011)

I think the problem is the vapor barrier placement. While you do have cold weather issues to deal with in the winter where the vapor barrier placement is correct, the fact that you have hot summers with AC running is exactly the issue. 

If your weather in summer could at all mimic a Florida environment, being hot and humid, then that is the issue. Moisture WILL find its way through felt and certainly stone and mortar will absorb and transfer moisture. Since moisture vapor will transfer from hot to cold and from high concentrations to low, it would make sense that it would settle on the insulation side of the plastic.

I have remodeled 100 homes in our area that were constructed that way (often with concrete block) that were completely moldy from a vapor barrier behind the drywall. My suggestion is to work with a local building science specialist or MEP to solve the issue.

Good luck!


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## TimelessQuality (Sep 23, 2007)

Stone said:


> insulated with plastic sheeting over insulation and then drywall. Outer part is plywood with tyvek and then two layers of 15 pound felt


Kraft faced insulation?.. 

That would make 5 vapor barriers


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## Stone (Mar 23, 2009)

There is no plumbing in the wall and no Kraft paper on the insulation. Flashing and window leaks have been ruled out. Now I know that manufactured stone and mortar gets wet and holds a lot of water, and felt paper is designed to breathe, but how the water vapor gets through a layer of tyvek has me puzzled.


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## Winchester (Jun 29, 2008)

tyvek lets water vapour through. that's how tyvek works.

vented air space between the cladding and sheathing would have helped.


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## GettingBy (Aug 19, 2010)

Stone said:


> how the water vapor gets through a layer of tyvek has me puzzled.


Tyvek measures 58 perms. How this translates to how much water in how long a time, I don't know.
If the water is stored and then released this gets to be pretty hard to figure out.


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## Tom Struble (Mar 2, 2007)

how were the windows ruled out?please some pics this may be a good place to bring in some thermal imaging.i know your thinking vapor drive but the vapor most likely would be condensing on the sheathing or the inside vb.it most likely wouldnt show up in the ins itself


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## Tom Struble (Mar 2, 2007)

GettingBy said:


> Tyvek measures 58 perms. How this translates to how much water in how long a time, I don't know.
> If the water is stored and then released this gets to be pretty hard to figure out.


forget the perm rating of the tyvek,the wall will be as permiable as the felt is


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## Tom Struble (Mar 2, 2007)

Winchester said:


> tyvek lets water vapour through. that's how tyvek works.
> 
> vented air space between the cladding and sheathing would have helped.


maybe if this is actually the problem.3 plies of paper,wire lath is providing some air space


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## Stone (Mar 23, 2009)

This is a two story stairway bumpout with one window at the landing. A very knowledgeable independant inspector working with the builder's carpenters opened up the drywall in enough places to thoroughly check things out. I wasn't there this time but I did the original wall prep and stonework, and had investigated the problem last summer without tearing anything apart. The inspector had never seen this exact set of facts and put it down to a perfect storm of things that caused this but didn't offer any solutions to keep it from happening again. Builder understandably has put all stone jobs on hold until this is figured out. If there really is no water leak then the moisture is either coming in from the outside or somehow coming out of the house and getting past the plastic sheeting. 
A vented air space could be a solution but hard to do. Maybe a manufactured rainscreen system would help or perhaps foamboard instead of plywood. It would seem if moisture vapor really could drive in like that there would be problems all over the place and maybe there are but usually they are hidden. I have been doing this a long time and have never seen this problem before but I am willing to learn something new and change my ways.


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## CompleteW&D (May 28, 2011)

> This is a two story stairway bumpout with one window at the landing....


So if it's a bump out, there must be some sort of roof structure above the bump out correct? I'd wager dollars to doughnuts there is a teeny-tiny spot on that roof structure allowing water down the inside of that wall cavity. Then the heat from the outside is turning that small amount of water into vapor. Look really hard at the roof structure and I'll bet you'll find your culprit.

Follow up: It may even be small enough that it only allows a very small amount of water in and only when it's a driving rain coming from a certain direction. Pulling the interior drywall and doing a hose test might be the ticket to finding your problem.


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## Tom Struble (Mar 2, 2007)

stone are you familiar with this product?
http://spiderlath.com/index.html


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## Stone (Mar 23, 2009)

stone are you familiar with this product?
http://spiderlath.com/index.html

I am familiar with spiderlath although I never used it. Actually I was offered a free roll but I couldn't find a builder who was willing to be a guinea pig and I didn't have a private job going at the time. From what I've heard from other masons, the stuff is expensive, a pain to use, and real hard to scratch coat. I haven't heard anything good about it except from the salesman. I don't know if any manufactured stone companies have endorsed it yet.


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## loneframer (Feb 13, 2009)

Just a theory, so take it for what it's worth.

First, the plastic is most likely not a perfect VB. There are perforations through it as you stated with the electrical box and possibly switches, window opening, door opening, etc.

Second, the stone/mortar should be sealed, but probably is not.

The stone/mortar absorbs and draws moisture in, where it permeates the first layer of paper, where it has little airflow, if any. The double layer of paper helps to drain water away, but will still become wet and allow moisture through to the layer of Tyvek.

Now, the morning sun beats on the wall, heating the stone, causing the water to evaporate, or vaporize. The heat builds and the water vapor is driven through the Tyvek, where it condenses on the warm side of the cold VB, which in turn saturates the insulation.

Now that the moisture has condensed, it's trapped behind the Tyvek until it can evaporate and pass back through as vapor, as opposed to felt, which is hygro-expansive and will wick moisture back through.

My guess is, keep the two layers of felt, lose the Tyvek and possibly go with a Kraft faced insulation which will allow some drying back into the home, due to the AC removing moisture from the air and pulling it through openings in an imperfect VB.

Thoughts?


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## Tom Struble (Mar 2, 2007)

i would say that either the ply or osb sheathing is alot less permiable than all the layers of wrb and i would think this ''vapor drive'' would stop there


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