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Detail Man 11-26-2011 10:21 AM

Basement Waterproofing & Insulating
What is the current best practice for waterproofing & Insulating a block wall basement?

MLMIB 11-26-2011 10:30 AM

your going to have to help us help you. What kind of basement is it? is it a walk out? all below grade? is there a history of water problems? is there a french drain already? are you trying to drywall it? what area of the country do you live in so we have an idea of what level of insulation fits your needs?

Detail Man 11-26-2011 11:31 AM

Basement waterproofing
North Western New Jersey

All below grade

Basement Previously finished, now recognize need to do more to prevent re-occurrance of damage from heavy rain/snow melts & hurricanes.

Has had carpet replaced before due to water damage from stairwell entry overflow.

Stud walls stand 3" off block walls. Heavy polyethelene sheeting covers block wall side of 2x4 stud framing. R-13 insulation between studs, 1/2" sheet rock finish surface.

Serv-Pro pulled carpet & pointed at likely water damage & mold growth areas but didn't remove any sheet rock.

The block wall & adjoining floor surfaces are wet for long periods. Efflorecense visible in several areas.

Mold growth test kits showed positive in all areas of basement.

Existing sump has never shown any water accumulation.

Etching & dry-lok coating walls & floors is being considered, followed by restoration of f'glas batt insulation & replacement of drywall.

Is there a better/more effective solution?

Is expanding foam on all block wall surfaces a moisture barrier as well as insulation?

Ironlight 11-26-2011 12:21 PM

I have confronted similar conditions in several houses that I have lived in and I can say with some confidence that if you don't correct the exterior conditions (grading, drains and drainage, etc.) that are causing water to enter your basement then you are undermining any interior work you do to try and address the problem.

That said, what you have cited is the correct approach. The problem is that if you don't address the cause, it has to be pinholes, no unrepaired cracks in your foundation. If not then water will find it's way back in. It's much easier to keep water away from your foundation wall than it is to try and keep it out once it's pressing up against it.

huesmann 11-26-2011 12:33 PM

Sounds to me like the water isn't getting down as far as your sump, and is just infiltrating through the walls. You definitely need to fix the grading issues around the house. If you can't, you'll want to install some kind of french drain along the outer walls, possibly even down to slab grade.

coupe 11-26-2011 03:47 PM

water is almost an unstoppable force. first off you need major regrading done outside. if water can't find a place to get in? it will make one! what is the purpose of the plastic on inside the block wall? the water gets into the plastic and runs down. it sounds like the sump bump is at best, at the high point of the floor? you could rent a jack hammer and cut a trench directing the water to the sump pump, that might help some. you could do like we did back in the 50's&60's.... dig all around the house, down to the footers. acid wash the clock, roll on tar into the block thickly, then roll plastic over the tar, but you'd practically need to sift the dirt and shovel it in by hand, any rocks or harp objects poke holes in the plastic negating the who process. fill around the footers with stone and install a french drain and pipe the water far away from the house, eve n then, the water will likely go under the footers and come up through the floor at some point, like where the floor meets the wall? or even out in the middle of the floor, like I said, "water will find a way in or make one"

whatever you decide to do? I wish you luck! the mold has got to go!!


Gary in WA 11-26-2011 09:58 PM

Fix the grading as said, pull the drywall, insulation and let us know how bad it is. As they didn't pull the bottom of drywall, now it may all be ruined from wicking water. May be just as well, you don't want a gap behind the insulation:

Look for mold on the plastic from summertime interior air trying to go out:

Mold in f.g.:

No Dryloc, no v.b. (without a sump pump), use foam board:

OR, SPF and a sump pump, diagram on pp.2:


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