"Waterproofing" basement block walls


Old 11-15-20, 10:29 AM
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"Waterproofing" basement block walls

Hi this post is going to be similar to the one on 8-31-20 by another member but I need more help.

My basement walls are cinder block and have never had anything applied in the form of paint / waterproofing products. I plan on filling fine cracks with a DAP caulk product and chisleing out some of the next larger cracks. Then filling these and larger ones with a hydraulic cement. I've used this on the outside areas I had access to and it seems to have done well so far.

I don't know if brand names are permitted here but I will understand if it is deleted out of my message.
I was all set to use Drylok original or extreme version to cover all my block walls. I assumed if the surface is prepped properly (cleaned and using a product to remove florescense sp?) this should prevent most chances of water entering through the block.

Then I discover there are professional people that frown on that type of product. They show photo after photo where after some time, this waterproofing paint begins to come loose from the block. It continues to peel off the walls and will leave a terrible surface which is very difficult to remove. They don't disclose, or have their own version, what it is they use. Apparently it is a block filler. This apparently penatrates into the block for a few inches to seal it where the other paint just stays on the surface.

What a big mistake I hope I'm avoiding by not going ahead with the "waterproofing" paint I planned on using.

So... what should I use to accomplish the job as I would like to. I want this to properly "seal" the wall ....to the extent possible, so that I can maybe put up a stud wall and finish it to have a nice look without worrying that water is going to come through and push off the protective layer I thought I had so that I can know my walls are really sealed. I guess it is a "sealer" or "filler" that I need to use. Does it go on like paint, is it toxic and will it likely require 2 coats? Then if I want to leave some of the wall without putting another wall over it, what type of paint is good to use over this surface.

Thanks for your time and help.!
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Old 11-15-20, 11:28 AM
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Waterproofing is best done on the exterior side of any foundation wall. If the exterior of the foundation has not been waterproofed, as it should have been, that would be your next step.

I am one of those who is of the opinion that you should not (and do not need to) paint any type of Drylock product on the interior side. Cement can absorb moisture right out of the air, and it needs to be able to dry out. Since the ground is wet, basement walls (that are below grade) can NEVER dry to the exterior side if they are wet, they must ALWAYS dry to the interior side. So the trick is, don't let the wall get wet in the first place... waterproof it on the outside.

While we don't make it a policy to bash products, companies that sell interior waterproofing products (like Drylock) want to sell their products regardless of what's best, and diy homeowners typically are always looking for an easy and cheap way to do things... don't confuse them with the facts.

If you simply can't or won't consider waterproofing the exterior, there are better, more appropriate ways of handling interior moisture.
Old 11-15-20, 01:20 PM
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Thanks for your input. To give more details, our home was built in the late 70's and we put flexible plastic pipe at the footing level and applied some type of black "sealer" on the walls. The soil is mostly clay. Well when we had a flood condition several years ago, water was coming in through the block wall in spite of what was done... ground was saturated all the way down. We have landscaping with plastic under rock along side the house walls and tearing that all up to re-do things would be cost prohibitive. Also the flooding caused so much pressure on the block that it caused the walls to begin buckling toward the inside. This resulted in numerous cracks, horizontal and vertical. We just had a professional firm install wall anchors and carbon fiber straps throughout the basement walls at a cost of $12K !! Needed to do this to prevent wall failure.
Consequently we still have the many cracks which can't be closed obviously and water at the ground level and all the way down to the footings are a threat from future heavy rain.

That explains why our only practical chance at containing the moisture is trying to seal the inside of the block wall. I know about putting in a perimeter drain on the inside and drilling holes in the block. This isn't possible now since the carbon fiber straps from top to bottom of wall, have a heavy duty steel anchor plate attached to the cement floor. So we can't have any drainage trough along the base of the walls as the anchors have to stay put.
Not mention, we don't have the money for any other high cost projects.

I know you make a lot of sense but we can't be the first people to find themselves in a similar situation.. It may sound stupid but when you talk about the block has to dry out to the inside..... why can't the water remain in the block (to a degree) and whether it "dries out" at all shouldn't matter as long as it never exits the wall to the inside... in other words a way to seal or fill the porous face of the blocks. If this isn't done then the ads by professionals claiming to use this method of sealing the blocks would be not true.

A product called RadonSeal claims this: Permanently seal, strengthen, and protect your concrete. Seals against water seepage, water vapor and even radon gas. Safe and easy to apply, spray or roll on application........so I still have to pursue something like this under the present circumstances.
Thanks very much.
Old 11-15-20, 02:02 PM
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Can't see how they reinforced your walls (no photos) but an interior perimeter drain and an interior wall membrane is almost always possible. Might eat into the floor space but that's the price for a dry basement. But Advertising that isn't true? How can that be? LOL. I really can't add anything else.

if you have specific questions maybe try messaging Stadry. This is part of his profession.
Old 11-15-20, 04:12 PM
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our home was built in the late 70's and we put flexible plastic pipe at the footing level and applied some type of black "sealer" on the walls. The soil is mostly clay.
Foundation drains like that, which were installed 40 years ago, are likely either crushed or clogged with the fine clay that got into it. Also, many of those drains didn't drain out into 'air', so again, they just get clogged up.

I agree 100% with everything XSleeper mentioned. Now that your foundation is secure, I think your next step is to dig down around the foundation and both waterproof the outside of the foundation and probably reinstall the foundation drain. It's the only foolproof way to keep water out of your basement.

Interior french drains can help too, but probably won't be much cheaper and require the water to get into/under the basement first. It's a second option if digging outside is cost prohibitive.

And yeah - stay away from DryLok
Old 11-15-20, 06:41 PM
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You might check out these videos to see how the wall anchoring systems work. The carbon fiber version is newest and used where not practical for the other only it can straighten the wall, only keep it from moving any more.
https://youtu.be/iltVoTvkEqQ https://youtu.be/8w-toh6B4lk

We had the company on the first one do both and I did not DIY any of this.

Old 11-20-20, 08:56 AM
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our only practical chance at containing the moisture is trying to seal the inside of the block wall
Except that's not what you're doing - that is simply trying to stop the water after it's already through. You either need to install the proper waterproofing outside or a mitigation system inside.
Old 11-20-20, 05:02 PM
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fwiw, I had water issues in the 60 yr old house I got 2 yrs ago. The contractor I hired talked about 2 issues. One was water in the clay soil layer not draining. The other was the drain under the house not draining well. I found the issue with that drain pipe and installed a new section of pipe to drain into the ditch. I hired the contractor to install 2 drainage ditches in the back, one close to the house and the other further out where water seemed to be pooling. He found a small spring at the side of the yard when installing the ditches. These ditches are sloped, gravel filled w pipe and fabric. Also had all house gutters drain away from the house in ditches.
Now I have all water sources draining away from the foundation so I should have no water pressures on it. FIngers crossed.
Old 11-21-20, 06:06 AM
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Exterior French drains are often impractical or cost prohibitive post new construction.

I painted my unfinished basement walls with Drylok 30 years ago. The paint is still pretty much intact on all of the poured concrete wall but it has almost completely flaked off an 8'X10' section of the wall that is concrete block.

However, the Drylok did nothing to keep the basement dry. Water intrusion occurs at the joint where the wall and footing meet. My wet basement problem was solved by redirecting the house gutters and adding interior under slab drainage to a sump.
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