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99miles 09-29-2009 03:26 PM

Sealing basement walls, and filling bigger holes
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I want to seal up my basement walls. I don't get puddles of water but I can feel moisture on the walls in a few places, and a few things have gotten a little mold. There's also some primary efflorescence in one place.

1) For the big hole (see photo) where something was long ago removed, do I fill it with 2 parts mortar to 1 part sand? That's what I just read someplace. Do I just push it in there with a float or something?
2) Do I need to do anything special to the efflorescence besides wipe it off before I apply the sealer?
3) There are places where a thick skim coat was applied previously and it's coming off. Do I need to worry about removing all of it, or just what's loose? What's the best way?
4) I assume it's okay to apply drylock when the walls are already damp in some places?
5) In places the wall isn't very smooth (has sort of a gravelly or rocky look), should I smooth it off with something before sealing it? A little mortar maybe?


stadry 09-29-2009 06:07 PM

know you don't want to hear this but nothing you can do from the inside'll resolve the water that's getting into your fine home's foundation walls,,, when you're done, it might look good for a bit ( 1 wk - 1 mo ) but after that you'll be back asking the same ???s again,,, if you're not prepared to fix it, covering it up will only be a waste of time & $$$,,, look at the waterproofing page on - no financial interest as we wouldn't contract w/you nor anyone else in the atl area as a result of this reply.

99miles 09-30-2009 03:46 PM

OK, thanks. I'm not going that route right now so I'm still curious to have these questions answered.

user1007 09-30-2009 05:13 PM

I like this company's products for some the challenges you are taking on. They are a bit pricey but they work as promised. The injectibles come in handy for holes and things.

As has been mentioned, you need to address what is causing these situations in the first or you will be perpetually repairing and never really solving anything.

concretemasonry 09-30-2009 06:47 PM

99 -

Too bad you have already made up you mind.

I suggest the biggest "Band aid" you can buy.

With all the junk and coatings on the wall nothing will stick. Much of the problem is from the exterior where the moisture causes everything to not stick and make interior coatings worthless. The efflorescence is a big tip-off to excessive moisture.

Using something as silly as a mortar sand mix is just a waste of time. Motrtar is intended to be placed and comacted into new masonry joints and not as a "patch".

For your obvious open leakage points, a good removal of the junk coatings and then an opened joint with a rough roughly "dove tail" shape might accept a hydraulic cement patch that is relatively dry and forced into the opening is a proven patch for that area that can be applied when damp. Unfortunately, the water is still around your foundation and foundation walls.

Dry Lok on a damp wall is not good, but Thoroseal could work, but there are limits to the resistance to moisture from hydrostatic pressure, which you seem to have.

Big band-aids can be very expensive and definitely are always temporary (unless you are a "flipper").


stadry 10-01-2009 06:01 AM

perhaps dick has more substantial ' bona fides ' but still don't understand why anyone'd want to waste resources on methods that prove idiotic especially after reading his advice.

xypex occasionally will prevent wtr intrusion but only hides wtr penetrating wall to the depth that xypex has reach'd,,, its STILL IN THE WALL & soil acids're STILL attacking the lime in the concrete's cement leading to further hidden degradation,,, occasionally hydraulic will work but not often enough that we'd choose/guarantee it,,, hydrophyllic polyurethane grout's usually the mtl of choice for us.

obviously i'm not a fan of interior coatings in a negative situation,,, if you buy a pro's solution, you'll be calling him back - hopefully he'll have had a great disclaimer in his contract.

sbmfj 11-12-2009 02:41 PM

could efflorescence develop from humidity from a dryer? I had a dryer running without a duct for a couple of months. Or does it only develop from water intrusion from the outside?

ccarlisle 11-12-2009 06:37 PM

Fellow Montrealer: efflorescence doesn't come from the humidity in the air, it comes from water leaching through masonry and dragging salts along with it - that's what you see.

Dryer vents put back a lot of humidity into the air and in our climate, rarely - even in mid-winter - is that a good thing. I just saw this week an apartment with no ventilation and the dryer vented intot the living room! you should have seen the mould on the walls!

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