Wet block against rigid foam insulation (Insulpink) - What to do?

court623March 14, 2011

We recently finished our entire basement with Owens Corning Insulpink (rigid foam insulation) against our dry block walls. We have french drains inside and exterior french drains with a sump and thought we had all of our problems solved. Unfortunately, we just got hit with massive rains, snow melt, etc. and found that the block got wet (my husband tore out a corner of the wall to see what was going on). Amazingly, the floors are fine. The water was seeping through the block and dripping down to the french drains. We are getting conflicting opinions on whether or not we need to tear out everything to dry out all the block. Owens Corning is saying that as long as the insulation is against clean block, mold won't grow. Basement waterproofers disagree. Any thoughts?

P.S. We are currently working with landscapers to trench around the exterior of the house and run lines to the street to avoid any more water collecting around the house. All our gutters are already tied to an underground line that's running to the street.

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Assuming the XPS is 1" thick, the perm rating is about 1 (ratings vary by brand). That makes it by definition semipermeable. But in any case, it's a vapour retarder, not a vapour barrier. So eventually the blocks will dry and not support mould growth. Where you see mould on blocks is when the moisture is never stopped.


Delta membrane keeps water off the foundation wall; and any
water that passes the barrier quickly flows to the footing drains.
Photo: DeCicco Homes

It's unfortunate that a plastic dimple membrane wasn't installed on the exterior foundation wall when the footing drains were put in.

    Bookmark   March 14, 2011 at 1:21PM
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court623

Thanks for your response, worthy. Our insulation is actually 1.5" thick. I think it's mold and mildew-resistant. Hopefully, your answer still stands. Here's a link to the product:
http://insulation.owenscorning.com/homeowners/insulation-products/insulpink.aspx

It's too bad that we didn't do some type of exterior membrane. We were suckered into painted tar as the barrier which obviously wasn't good enough

    Bookmark   March 14, 2011 at 2:20PM
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The perm rating on even 3" of Owens-Corning Formular is .6, still semi-permeable.

The plastic membranes have been around for more than 20 years in North America. As far as I'm concerned, any company that does exterior waterproofing without using a membrane (and cove sealant at the joint of the wall and footing) shouldn't be calling themselves a waterproofing company. In fact, the membrane was mandatory for several years under the Code I build under. Some custom builders here even apply a spray elastomeric or peel and stick membrane and the plastic membrane. The big cost and aggravation, as you probably know, is digging down along the foundation.

Excuse me if I'm obvious. But until you solve the water penetration problem, hold off applying any moisture sensitive materials to the interior framing.

    Bookmark   March 14, 2011 at 6:59PM
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The perm rating on even 3" of Owens-Corning Formular is .6, still semi-permeable.

The plastic membranes have been around for more than 20 years in North America. As far as I'm concerned, any company that does exterior waterproofing without using a membrane (and cove sealant at the joint of the wall and footing) shouldn't be calling themselves a waterproofing company. In fact, the membrane was mandatory for several years under the Code I build under. Some custom builders here even apply a spray elastomeric or peel and stick membrane and the plastic membrane. The big cost and aggravation, as you probably know, is digging down along the foundation.

Excuse me if I'm obvious. But until you solve the water penetration problem, hold off applying any moisture sensitive materials to the interior framing.

    Bookmark   March 14, 2011 at 7:02PM
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court623

Considering the basement is already finished, we don't have the option to "hold off applying any moisture sensitive materials". Unfortunately, it's already done. I was just wondering if we solve the exterior problems by setting up burms, trenches and drains to the street, and we're able to keep any more moisture from coming through the block, can we leave the finished basement as is? Or should we be ripping everything out, down to the block to dry it out and start over (hopefully, not what we need to do)? We are hoping that the block will be able to dry behind the Insulpink without creating a mold problem and we can just do the exterior work and be done. Any other thoughts?

    Bookmark   March 14, 2011 at 8:01PM
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the basement is already finished

That could change the story. If you haven't already done so, ASAP use lots of heat and dehumidification--even rent industrial dehumidifiers--to draw out the moisture. Mould does love drywall, wood and hidden areas. When that's done, you might want to test suspicious sections for dangerous mould. (See link.)

A couple of builds ago, a neighbour's wall started leaking. My fault, he figured, as I had removed a row of his hedge that was on my property. So he "designed" a system of weeping tiles to pick up surface moisture. The installer (my grader) agreed with me it wouldn't work. But, heck, money is money! A couple of months later, in bitter winter, a crew excavated eight feet down by hand along the foundation, found the settlement crack and patched it. No more water.

Maybe your system will work better.

Here is a link that might be useful: Inspectapedia on mould

    Bookmark   March 15, 2011 at 10:08AM
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