Waterproofing corners where basement floor and wall meet?

tigerninetyOctober 8, 2012


We're moving toward finishing our basement (2x4 framed, insulated, drywall, etc). We've had some minor seepage issues in the past and are taking a multi pronged approach to water management; we're making a lot of progress. (Significant regrading outside away from house; heavy-duty plastic sheeting attached to house to five feet out covered with mulch; new window wells with covers; sanded interior cinderblock walls that will get new coats of drylock).

In a recent rain, however, I noticed a couple of places where there was a small amount (about one foot long) of dampness where the floor meets the wall. I'm going to redo the plastic (upgrade to 20-mil and double attach to side of house), but I was wondering if anyone would/could recommend some kind of sealant that works particularly well at this intersection of basement wall and floor?



Thank you for reporting this comment. Undo

I've used Tremco Permaquik 300 as cove sealant on the outside of the wall/footing joint. All inside "solutions" will be less effective than stopping water before it enters your basement.

When finishing your basement walls, it is important to use moisture tolerant materials, such as EPS or
XPS foam board insulation in the correct thickness and XPS under the baseplates.

Here is a link that might be useful: Bulk Water Control Methods for Basements

    Bookmark   October 9, 2012 at 9:58AM
Thank you for reporting this comment. Undo

Thanks for all of the above, particularly the link to the PDF. A couple of followups, if I may...

First, based on your post and the content of the PDF, I think I'd lean toward XPS (or EPS? difference?) against MOST of the cinderblock walls with 2x3s to frame, and additional, unfaced batt insulation before the drywall. This would primarily be to facilitate running electrical and for a cleaner look, relative to going with the XPS and furring strips followed by drywall. Also, the DOE calculator recommends R-11 in the basement in the Washington, DC area. Am I missing anything here?

Second, however, there is a section of wall where I think it would make sense to go with XPS held in place by furring strips (drilled into the wall) followed by drywall. But the 'DIY-assistant' I'm working with seems to dislike the idea of making holes in the cinderblock walls if it can be avoided (to reduce seepage risk, etc after dry lock). Is he being overly sensitive to that?



    Bookmark   October 10, 2012 at 7:23AM
Thank you for reporting this comment. Undo

EPS (expanded polystyrene) is the lighter weight less dense material used in EIFS stucco systems and coffee cups. Because it must be thicker for the same R factor, it's not used much in inside applications. But it's cheaper.

I, too, hate making holes in concrete block! If it's a straight wall, adhesive can be used with fewer anchors. And when you anchor, drill into the ribs.

But it's very important to have the foam boards tight to the foundation wall. A neat trick John Straube of Building Science told me of is to use cedar shims between the boards and the framing.

Here is a link that might be useful: Building Science Corp: Basement Insulation Systems

    Bookmark   October 10, 2012 at 11:48AM
Thank you for reporting this comment. Undo

Thanks again for your posts. I apologize if this is covered elsewhere, but if I'm putting XPS/EPS on the cinder block walls, then 2x3 framing, with batt insulation and then drywall, why NOT use faced batt?

My builder guy seems to think faced batt would be best "just in case" re: moisture.


    Bookmark   October 23, 2012 at 6:22PM
Thank you for reporting this comment. Undo

The faced batt acts as a vapour barrier, trapping moisture inside the wall, especially in the summer when the hot outside air moves toward the cold inside air in your basement. (See BSC link below for detailed explanation.)

Vapour barrier and fiberglass on basement walls spells mould.

Since you're insulating the basement, don't forget the rim joist area at the top. Pull out any fibrous insulation; air seal with spray foam and/or caulking then use closed cell polyurethane spray foam or cut XPS to size, press fit and caulk.

Photos: Building Science Corp.

Here is a link that might be useful: Basement Insulation Systems

    Bookmark   October 23, 2012 at 8:18PM
Thank you for reporting this comment. Undo


Thanks for the reply.

Please forgive my persistence on this, but I'm sure I'm going to have to work this further with my builder-guy.

I get the idea about the movement of vapor in the seasons. So, I WILL use XPS against the cinder block, followed by 2x3 framing. So, based on what I understand, the XPS is performing the role of vapor barrier up against the cinder block. AND it is ensuring that the vapor from the INSIDE doesn't have a cold surface (eg bare cinder block) to condense on.

My question (and I'm fine with the unfaced batt, but my builder-guy seems perturbed by it) is: if I've got the XPS as vapor barrier and insulator, how is the facing (toward the interior) on batt doing harm? Exterior vapor shouldn't get through the XPS and (in theory) interior vapor shouldn't even make it to the XPS.

So, I'm sure I'm missing something, what is it?

Thank you!


    Bookmark   October 27, 2012 at 8:32PM
Sign Up to comment
More Discussions
Which drywall to use in the basement?
Hi, I am finishing a basement that is under the attached...
basement flooring - tile or finished concrete
we're planning a reno that will include expanding and...
water in unfinished basement
Well its in the 50s here in NJ and the snow is melting....
How to re-do the stairs for my basement remodel
So I'm undergoing a simple remodel of a small basement....
Basement wall insulation
Hello, I live in a 1952 English bungalow in Chicago...
Sponsored Products
Royal Heritage Home 3 Ply Flat Waterproof Portable Pads - Crib - Set of 2 Multic
$20.14 | Hayneedle
Patio Living Concepts Outdoor Lighting. Catalina Black Outdoor Floor Lamp with a
Home Depot
Polaris P916 Bamboo Ensemble Chrome/Hardware
Amber 3528 LED Strip Light 60/m 8mm wide 5m Reel
RGB-pixelpro-bullet-8 RGB PixelPro LED Bullet
Skyline Blue Patio Love Seat Cover
$29.99 | zulily
Pet Gear Special Edition Stroller-Full Size-Blueberry - PG8250BL
$129.99 | Hayneedle
Patio Living Concepts Lamps Catalina 34 in. Outdoor White Table Lamp with Straw
Home Depot
People viewed this after searching for:
© 2015 Houzz Inc. Houzz® The new way to design your home™