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Vapor barrier yielding moisture around basement window

Vapor barrier yielding moisture around basement window

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  #1  
Old 11-05-07, 12:09 PM
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Smile Vapor barrier yielding moisture around basement window

Help,

I am in the process of finishing a basement (ie, studded exterior walls, insulation batts, vapor barrier, and drywall).

I was about to begin drywalling when I noticed that moisture had formed on an outside wall with a window. The moisture was not only evident on the window pane and sill, but also (after pulling down the plastic and insulation) between the cement wall and insulation.

There is a history of moisture forming on the inside of the window and sill every fall/winter season (I live in the midwest). But what concerns me is that the moisture is now appearing on over 50% of the concrete wall.

My question is: is this all window related or does additional caulking/sealing need to be done (somewhere) prior to putting up vapor barrier?

As a side note, there is a second window on that same outside wall (about 10-15 feet away) that has no issue with moisture. Therefore, I'm assuing the window needs to be recaulked/resealed.

Please let me know what to do.

Thanks, Mike
 
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  #2  
Old 11-06-07, 03:13 AM
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Question

Question for you mike. How old is the house? Does the basement window have insulated glass? It is possible you have too much moister in the basement, I wouldn't cover it untill I got an answer to my problem. Jack
 
  #3  
Old 11-06-07, 05:46 AM
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Jack,

The house is at least 14 years old. The walls have been bare concrete since. It's a double insulated Pella window with the movable blind inside. According to the owner, the actual window doesn't leak (ie, wind, water), but she thinks that it's the cold outside air hitting (now) the warmer insulated / vapor barrier walls. She did say that every fall/winter, standing water appears on the ledge due to the excessive amount of moisture; which she controls with a fan and dehumidifier. (I've seen that before with other Pella's.)

However, and the reason I'm thinking this, there are 2 windows where only one appears to have the moisture. I was going to have her recaulk / re-foam around the casing edges and in between the creases where the concrete formed wall and original framed 2x4's meet (sorry, hard to describe).

I am hoping, with your acknowledgement, that I should try the re-sealing first. Unfortunately, I've already put up vapor barrier throughout the entire perimeter...and I would hate to half to rip it all down.

As far as too much moisture in the basement, I'm sure that the walls have cured by now. Prior to framing, the basement air "seemed" normal to me - cool, but not really musty / damp.

Thanks........
 
  #4  
Old 11-06-07, 03:33 PM
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Mike
I think it's a good idea to reseal the window I'm assuming this is a regular size basement window. I think the reason you have moisture on the vapor barrier and the basement wall , before with the dehumidifier & fan there was air movement now that you have stopped the air movement the air goes through the wall and hits the colder surface and condenses,this tells me that there is still too much moisture in the air. I would turn the dehumidifier up and wait a couple of days to see if the moisture goes away.
Jack
 
  #5  
Old 11-06-07, 05:25 PM
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That makes sense...so thanks...I needed that warm fuzzy about the whole thing!

Yes, they are both regular size windows - 5' x 4' with dual cranks / panes. They face east and I'd put them like 40" or so up from the floor; so they're 1/2 above ground and 1/2 below.

I'll take your direction and run the de-humid a few extra days. I think, tho, I'll temporary put the insulation and vapor barrier back up, like next week, and re-check in a couple of days after that just to make sure everything stayed dry. I'll keep my fingers crossed.

The thing that puzzles me is that newly built homes put up vapor barrier immediately. I don't ever remember seeing a dehumidifier present to remove the moisture. Are you saying that these walls are getting wet too?

Just wondering...thanks again!

Mike
 
  #6  
Old 11-07-07, 06:55 PM
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Mike
Those are some big windows, I now see why you might be getting moisture on them, I was thinking of a basement window like you usually see about 16" h x 32" w,with pella windows like you have they are casment with a single pane on the outside then the blinds and then what I call a storm on the inside. One thing to look for with these windows is frist that they are locked tight next check the seal on the storm make sure they are lock in place that creates a good seal between the two glasses. outside of that I'm not sure what else the moisture problem could be.In the newer homes the code in our area ( N.W. Ohio) on basements you must put 2 or 2.5" of foam on the outside of the basement before you back fill that I think is about an R-10 that helps keep that concrete warmer. Where to put the vapor barrier in a basment is always been a ? I've seen it both ways.
Jack
 
  #7  
Old 11-08-07, 12:13 PM
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I'll let you know how things go after all steps are taken.

(looks like we live in relatively the same location - N.E. Ind).

 
  #8  
Old 11-27-07, 07:07 AM
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Jack...

It's been a while, but I just received a call from the homeowner and she is seeing moisture again on the wall surrounding the basement window. The moisture is on the wall behind the insulation / vapor barrier.

I am going over today to take a look at it and also to see the sealant she put on around the window casement. It appears still that the moisture is focused mainly on the concrete wall and not the window.

I'll proceed in finding a way to reseal it myself. I'm wondering still if I should have sealed off around the entire floor perimeter. I'm also curious now if other "non-window" walls have the same problem.

Mike

 
  #9  
Old 11-27-07, 01:01 PM
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If I'm understnading, it soundsliek oyu are tryinfg to seal around the window frame.

Since one is OK and one is not, it sounds to me like the seal between the two panes of glass has failed and cold air from the outside is reaching the inside pane. I don't think you'll be able to fix it. How old is the window and what is the length of the gaurantee? You might be able to get Pella to supply a new pane and replace it yourself.

I have several double pane windows in which the seal is broken and sometimes I can see moisture on the inside of the inside pane. Fortunately, the prior owner called and orderd a replacement for the largest picture window that the seal failed on and we installed it after we moved in. For our wndows, the "liftime" guarantee was only for the original owner, so he was able to get a free replacement. Now, we can't.

Good luck,
Tom
 
  #10  
Old 11-27-07, 02:16 PM
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tlogan,

What was being resealed was not the window itself but actually the area behind the window casing; that area being between the cement wall and the casement (very hard to describe the area). The windows themselves do not leak, so I don't think there's a problem with the panes - the windows are 14+ years old and have never leaked.

I did look at everything again and if I can further explain: the insulation/vapor barrier was pulled away from around the window showing an excessive amount of water droplets - enough to create small puddles down by the bottom of the 2x4 wall frame. By placing my hand behind the existing insulation/vapor barrier (not removed), I feel blown air - but, from where that air is coming is the big mystery!

I think what is happening is that warm air is coming in contact with the cold walls, and because that air is trapped behind the vapor barrier, moisture forms.

Now, I am not a physicist, but seems to me that I need to somehow block that warm air from getting in behind the insulation. I'm also thinking that it is leaking thru around the ceiling joists...since there is no insulation blocking that air flow.

I believe that if I can prevent the warm air from penetrating behind the vapor barrier, that area will remain cool and no water droplets will form.

Thanks..........

Mike
 
  #11  
Old 11-27-07, 03:23 PM
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I haven't exactly been following this whole thread, but here's my thoughts.

Problem number 1: "the insulation/vapor barrier was pulled away from around the window"

Obviously, if the vapor barrier is not sealed around a window it's going to create a problem- it's going to let in and trap moisture behind it.

The vapor barrier on the walls is probably working just fine. I'm guessing the termination of the vapor barrier around the perimeter of the window, and maybe a homeowner that won't leave it alone and keeps pulling it open to check behind it. Obviously, moist humid air would come in contact with the cold rough opening at this point.

As a solution, I would suggest that any interior trim around this window be removed. If fiberglass insulation is packed around the window, remove it. Reinsulate the window with a low pressure window and door spray foam. If possible, remove any exterior trim around the window and tape the nailing flange to the sheathing using a peel and stick flashing membrane like Tyvek Straightflash, Grace Vycor Plus, ProtectoWrap, Flash-n-wrap, etc. These steps will help reduce air infiltration around the window itself.

I'm assuming your interior stud wall leaves a rough opening around the 60x48 window, and that the homeowner can stick their fingers behind the wall and feel this moisture. So I'd suggest that instead of trimming the window and RO with a wood extension jamb, you FIRST cut some pieces of ISO Styrofoam and glue all the edges down with PL300. Poly should wrap around this ISO foam and be taped down with a housewrap tape. Once this is done, then the window could be trimmed as needed.

Also, if the walls do not have drywall on them, ensure that the top and bottom edges and any seams on the vapor barrier are sealed to the wall/floor with either silicone or housewrap tape. If drywall has not yet been hung on this wall, that would add to the likelihood of moisture behind the insulation. Hanging and taping drywall will help reduce air infiltration and the temperature differential.

Also, I would have recommended painting the walls prior to framing with a product such as Zinsser Watertite. It would help prevent moisture from entering the wall cavity through the ground and cement wall.

You'd obviously want to ensure that water is not puddling or standing around the foundation due to a bad grade or a window well that holds water with no place for drainage. Sometimes plugged gutters will drop water right off the roof into a window well and no one notices where all the moisture is coming from. Just a couple other things you could check.
 
  #12  
Old 11-29-07, 04:58 PM
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Thanks for the tips....I'm going to begin by sealing off the area around and behind the framed in walls with insulation; including the windows. This should prevent the warm(er) air from coming in contact with the cooler concrete walls.
 
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