Condensation on Block Wall Seal Gasket


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Old 10-28-15, 02:32 AM
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Condensation on Block Wall Seal Gasket

I am in the process sealing up the gaps and insulating the rim joist area in my basement. We have exposed block walls and, as part of this effort, placed Owens Corning Foam SealR Plate Gasket along the top of the block wall, held in place by weatherized 1x4. Recently I have noticed condensation along the top of the foam seal gasket and the 1x4. I made sure to the best of my ability seal the gaps along the top of the block on the exterior of our home, however that did not seem to correct the problem. I understand that the exposed block wall is not much of an insulator, so this might be difficult to prevent from happening. With that said, while researching a solution to this problem I have come across a WallCap Block Wall Sealing system offered by many basement waterproofing companies seems to be a clear L-shaped plastic molding that slips over the top of the block.

The questions I have are:
Is this WallCap system a worthwhile investment?
Anyone with experience having this sort of system installed?
Are there other alternative I should/could consider?
Thanks in advance,
Dave
 
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Old 10-28-15, 03:45 AM
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You might be creating the condensation, with the product that you installed. Below grade insulation is a funny bird.
 
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Old 10-28-15, 04:52 AM
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Thanks Pulpo I think I get where you're coming from. However, I was really hoping to help insulate and control the movement of air up through the block wall and as an added benefit help prevent the movement of critters and such.

So, maybe a vapor barrier is not the way to go here. This might sound crazy (please note I'm a new homeowner so I'm learning as I go), but would it make sense to stuff a little rock wool insulation into the top of each block? That way there would not be a vapor barrier for water to condense on.

Thanks
 
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Old 10-28-15, 05:56 AM
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I have heard so many different opinions, on below grade insulation, that I'm not sure which is correct. The fact that you haven't seen condensation until now makes me question what you have done. I'm sure that someone else will clarify everything.
 
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Old 10-28-15, 06:14 AM
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Got a picture so we can see what you have done?
I just use 2" thick foam and seal any gaps with low expanding foam.
 
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Old 10-28-15, 06:39 AM
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Sounds like the tops of your blocks were never capped with a solid block, strange. If so, your efforts are in the right direction, air seal to prevent air from circulating from the block cavities into the basement. If I'm lost, just let me know, it happens .

As for the condensation, that is coming from the basement humidity contacting a surface cold enough to drop below the dew point. In many basements this is happening a lot, it is just that the wood rim is absorbing that moisture. Your new covering is showing you that moisture.

One solution would be to detail some rigid insulation in, over, and below the rim joist. In addition to the added insulation, the rigid will block any air from reaching a cold surface. Fiberglass insulation does not block air.

I'm not sure how much of your foundation is exposed to the elements, but if those blocks are hollow all the way down, then you should insulate the inside all the way down. Again, the rigid does that best.

I'll wait for corrections.
Bud
Note, Joe, I didn't see your 2" foam suggestion, and agree.
 
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Old 10-29-15, 02:13 AM
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I apologize for a delay in my response. I have attach a few ore photos to help show what I was trying to describe. The basement wall is above ground 1.5-2 feet.
The first photo show the top of the block wall with the foam seal gasket and 1x4 at I'm using to secure it in place.
The second photo shows between the foam gasket and the 1x4 - this is the area where I am experiencing the condensation and moisture collection.
The third photo shows the top of the block. As you can see, it is wide open at the top. I really want to seal this off. Would it help to stuff rock wool into these openings before adding the foam seal gasket?
The last photo shows the upper portion of the wall and rim joist area.
Let me know if there are any other photos you would like to see.
Thanks, Dave

Attachment 58145
Attachment 58146
Attachment 58147
Attachment 58148
 
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Old 10-29-15, 04:28 AM
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Your pics didn't make it. Use photobucket.com
 
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Old 10-29-15, 05:00 AM
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Sorry about that.

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Old 10-29-15, 05:27 AM
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Stuffing the holes in the blocks with mineral wool won't hurt, but not sure how much it will help. There are now a couple of brands of mineral wool and I've only reviewed the Roxul brand. If other, check their recommendations for basement use.

If you are heating that basement, even indirectly, in a cold climate, that exposed foundation, plus a couple of feet below grade, begs to be insulated.

If covering with rigid foam or some form of finished wall assembly is out of the question, have you looked at using Perlite? I have never used it, but I do know it is used for this purpose. Link attached:
R-Values, U-Values, and Coverage Charts for Concrete Blocks from THE SCHUNDLER COMPANY

Bud
 
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Old 10-29-15, 06:26 AM
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Thanks Bud. I thought about perlite, but looks like I would need about 60 bags @$20/ea. Which is cost prohibitive right now. Also, I wonder if I should be concerned about water buildup behind the wall. Would the perlite allow the walls to drain to the sump?
I will try insulating the top of the wall and see. If I have to go the perlite route, maybe I can do it in stages. Thanks!
 
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Old 10-29-15, 07:33 AM
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Never priced it, but at that price you could cover the entire inside of the walls with rigid foam board. There are details if you go that direction.
Water build-up inside your block walls should not be happening. That solution lies outside your foundation, Ug!
Link below has illustrations for detailing the top of the wall.

A drawback for the perlite might be the installation. That link suggests pouring it in, but that is new construction where access isn't a problem. In your case it would come down to a cup at a time. Workable, but slow.

Bud
Understanding Basements | Building Science Corporation
 
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Old 10-29-15, 07:58 AM
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We haven't had an issue with water buildup since we installed the perimeter drain and sump system. Unfortunately unknown to us at the time we purchased the home, there was an issue with water buildup behind the walls and seepage through the cracks in the floor. When the perimeter drain and sump were installed, the contractor drilled holes at the base of the block and, no joke, the water shot out horizontally 2 feet. The foundation drained for about 2 days and since that time we have been dry. The sump handles the subsurface flow during the spring/fall precipitation events with no problems.
I'm going to try insulating the upper portion of the wall first. And plan a more extensive project in the future.
 
 

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