Best Product to Seal a Block Basement Wall.

[RSKY]

We are preparing a sixty year old house to sell. The basement walls are of concrete blocks. After a heavy rain they seep a small amount of water thru some cracks and thru the blocks themselves. What is the best paint on product to seal the walls and what do I use to seal cracks?

 

[Fxfymn413]

How wide are the cracks? I have used hydraulic cement to seal cracks about 1/4 inch wide.

 

[dlctcg]

If the block is in good shape then IMHO there is no better product that we have used (that can be easily applied by anyone) then Sani-Tred.

Not the least expensive by any means but if the surface is properly prepped & application done via the instructions we have never had it fail & the finish is nice. I believe the oldest project we have done with it is going on 20yrs ago. Our attached garage floor used to wick water right through it... completely dry for the last 9+ yrs...

Here are pics of a project completed 3+ years ago... This is a cottage on a small lake that would have standing water in the basement multiple times a year making it completely unusable; the owner tried Dry-Loc (it Failed / we had to remove ) then they had exterior drainage professionally installed (didn't work) water was coming through the block. When we told them we would seal it from the inside & we would finish the basement as usable space & if it leaked we would pay for the damages... they looked at us in complete disbelief.

Still Dry - Some Pics - These are all from the same corner of the basement...



Walls Prepped prior & 1st coat of Sani-Tred



Typical cracks in the block (1st coat rolled on)




Cracks & flaws filled with LRB




Final Coat of Sani-Tred




Part of the finished basement

 

[grsthegreat]

problem is...this just seals water inside concrete and blocks, eroding away the rebar. this is just surface repairs. you need to remove all backfill from walls, clean and waterproof the actual walls.

i used to do this for a living years ago. i would prep cleaned wall with layer of ThoroSeal grey , then a second layer of ThoroSeal white sealer. then install a layer of Bituthane 1/4" self adhering membrane over a coat of extra adhesive. Then install a 2" Styrofoam protector board to prevent rock damage, add a french drain and install french drain rock.

i did this for many years, and have never had water infiltration.

i did it on my own house 26 years ago for basement. not a whiff of mildew many years later.

i tried to have my buddy that is building a new house do so on his foundation, but hes a lazy sack. he just brushed on some kind of thick waterproof paint, then backfilled without french drains. house is 1 year old....leaks like a sieve. cant fix stupid.

 

[Bill Guenthner]

You cannot properly patch a leaking concrete block basement wall from the inside. Anyone who says otherwise is mistaken. As already stated above, you have to do it from the outside. Without a proper repair you’re going to have to disclose the leaks.

 

[dlctcg]

So I will agree & disagree with the above statement...

Yes you can dig all the way around your foundation... disturb the soil... disturb the landscape... & seal from the exterior of the foundation... & it will solve the problem.. if done properly... but that is not what was asked...

"What is the best paint on product to seal the walls and what do I use to seal cracks?" (& for the occasional "after a heavy rain they seep a small amount of water thru some cracks and thru the blocks themselves"), we are not talking about a house that is submerged in a pond. We are talking about a basement that under normal conditions does not see water (according to the OP); which means, normally it drain well & does not see interior leakage. This tell me the block will not be completely saturated under normal circumstances & will dry out after unnormal circumstances...

You are selling... right???

I still do this for a living, 30+ yrs through out NE & depending on the situation there are more than one resolves... (again I don't disagree with the above) but to answer the OP's Question... Sani-Tred works... (it has been used in underwater tunnels (from the interior) & in ships (not saying which gov. agency.., call them)... All I can say is in our experience 20+++ yrs no failures... (and I have NO CONNECTION to them.... we were lucky to stumble on their product many (many) years ago...)

I do agree that exterior sealing does work & is the correct solution (we do it)... but not the only solution... I was answering the OP's question as it was asked....

Oh, & I don't know of a single state that you have to "disclose a leak"... If it is not leaking (& I think we work in 3 of the crappiest state to be a contractor)...

 

[Bill Guenthner]

Oh, & I don't know of a single state that you have to "disclose a leak"... If it is not leaking (& I think we work in 3 of the crappiest state to be a contractor)...

If all you do is “seal” the inside surface of the block then it is still leaking. More than that, concrete block that is being repeatedly infiltrated by water over years will be structurally compromised, and they know that it’s happening so they should disclose it.

 

[MossRoad]

If all you do is “seal” the inside surface of the block then it is still leaking. More than that, concrete block that is being repeatedly infiltrated by water over years will be structurally compromised, and they know that it’s happening so they should disclose it.

Personally, if I were going to stay in the house, I'd find if the problem is high ground water, or, bad drainage after rain. It sounds like small leaks after rain. That indicates poor drainage near the house. We had this problem in our first house. Heavy rain = water seeping trough the block. So I dug a trench 2' down and 2' out from the house, smeared mastic down 2' on the foundation, laid a waterproof fabric onto the mastic, and formed a U-shaped channel with the fabric in the trench. Then laid some stone and a perforated pipe in a sock at the proper drainage angle into the fabric lined trench and backfilled with stone. At the end of the pipe, I turned it 90 degrees away from the house, then into a drywell made of two 55 gallon drums with open bottoms filled with rock. Then added a nice 6x6 pressure treated edge along the stone to keep the grass out. And most importantly, I made sure my downspouts ran to areas that were sloped away from the house, and I regraded the yard to make a swale to carry surface water away, not towards, the house. From that point on, any rainwater on the surface would flow away from the house, and any water that splashed onto the side of the house would run down into the trench, through the rock, the correlated socked pipe, and into the drywells. Never had the problem again.


However, that's not what the OP wants to do.

He's asking how to seal it from the inside.

 

[Dwellonroof]

I'm looking for a solution for a block cistern which are very common in this area of Ohio. It's not feasible to dig out and replace mostly because at least one side is part of the house foundation.
I did use a product called Quick Wall for one cistern about 10 years ago but have since moved on and I don't know how well it held up but the 4 years I live there we never had any problems.

 

[gstrom99]

Either leave it alone (and disclose the "occasional" issue to the buyer), or seal it properly from outside, IMHO. Fix the drainage too (gutters, downspouts, foundation drain), that's causing it to leak in the first place.

 

[grsthegreat]

Here in idaho, when i sold my rental, the real estate company and title office had a form where i had to declare items that i knew of about property. One item was leaks in basement Or foundation. If you try to cover it up and declair no leaks….i can see future problems. If i were to cover it up and say theres an occasional leak, than i would guess your be ok.

 

[MossRoad]

Here in idaho, when i sold my rental, the real estate company and title office had a form where i had to declare items that i knew of about property. One item was leaks in basement Or foundation. If you try to cover it up and declair no leaks….i can see future problems. If i were to cover it up and say theres an occasional leak, than i would guess your be ok.

Heck, in this housing market, people are selling houses for more than they are appraised with NO pre inspections and AS IS. Yikes!

 

[grsthegreat]

Yup…and this wont bite them in the butt. No one ever remembers the last time this happened. They go and do it again.

 

[Moxie 15]

when selling a house rule number one is always TALK TO A REALTOR. They will tell you what you need to repair and what you need to disclose. Don't go off half cocked doing needless repairs and just be truthful with the realtor and your but is covered. When the buyer applies for the loan the house will be inspected by a professional inspector anyways.

 

[grsthegreat]

when selling a house rule number one is always TALK TO A REALTOR. They will tell you what you need to repair and what you need to disclose. Don't go off half cocked doing needless repairs and just be truthful with the realtor and your but is covered. When the buyer applies for the loan the house will be inspected by a professional inspector anyways.

For what there worth. I used to get reports from home inspectors from a realestate company i worked for as an electrical contractor. Id see some items like coverplates missing in living room. Panel needs labels, etc. just minor stuff. But on one house i went into attic to see about adding fan to a existing light box…and i saw SS fireplace chimney had fallen apart. It was being held inplace by bailing wire. Nothing was on report. I informed new homeowner and he want ballistic. House could have burnt down.

and i would see houses without a single smoke detector…but nothing on report. I guess you get what you pay for.

 

[MossRoad]

My father would inspect homes for HUD as a part-time job. Man, the things he'd find. And, the things he said you couldn't find without tearing into the plaster or drywall. You better not miss anything that's reasonably visible, because if the person paying for the inspection finds that a reasonable and thorough inspector should have caught something, you're toast.

So, they go after the previous home owner, or the builder well before the inspector.

 

[Larry Caldwell]

problem is...this just seals water inside concrete and blocks, eroding away the rebar. this is just surface repairs. you need to remove all backfill from walls, clean and waterproof the actual walls.

i used to do this for a living years ago. i would prep cleaned wall with layer of ThoroSeal grey , then a second layer of ThoroSeal white sealer. then install a layer of Bituthane 1/4" self adhering membrane over a coat of extra adhesive. Then install a 2" Styrofoam protector board to prevent rock damage, add a french drain and install french drain rock.

i did this for many years, and have never had water infiltration.

i did it on my own house 26 years ago for basement. not a whiff of mildew many years later.

i tried to have my buddy that is building a new house do so on his foundation, but hes a lazy sack. he just brushed on some kind of thick waterproof paint, then backfilled without french drains. house is 1 year old....leaks like a sieve. cant fix stupid.

Even more primitive, I used roofing tar and 30 lb. felt over the ThorSeal.

 

[Hay Dude]

One of my first homes had basement leaks. It’s usually the same problem. Incorrectly sloped ground outside with a combination of overflowing gutters and clogged downspouts or downspouts blowing water right down next to foundation wall.

What cured my problem with wet walls involved little work inside. I installed new oversized 3x4 downspouts into 6” PVC that carried the water about 15’ from the house walls. I dug rainwater retention pits 15’ away from foundation, lined with fabric and filled with stone. In the center of the pit, before filling with stone, I placed a vertical perforated PVC pipe with a “T” at the top. My pvc pipe from the downspout runs at a slight fall into the T. Pop up cap on the top.
Never a drop of water after that.
Builder set house too low on the lot.
I dug 4 of them. Took a little while and cost some money, but I had a backhoe so it was easy for me.

Waited another year to make sure everything was thoroughly dry and staying dry, then installed a finished basement gym and playroom for the kids.

 

[RSKY]

The wall that water is sometimes seeping thru was painted with a product called Sta-Dry more than forty years ago. That stopped the leakage until the last five or six years. There is enough moisture coming thru to wet the floor about a foot or 18" away from the wall after a three day heavy rain. It dries up after a couple days. A light rain or anything except a 'gully washer' causes no leaks. The old paint has deteriorated just enough to allow the minor seepage.

ALL basements in this area seep some water. All I want is a suggestion for a product that will stop the seepage without spending a small fortune.

RSKY

 

[Larry Caldwell]

The wall that water is sometimes seeping thru was painted with a product called Sta-Dry more than forty years ago. That stopped the leakage until the last five or six years. There is enough moisture coming thru to wet the floor about a foot or 18" away from the wall after a three day heavy rain. It dries up after a couple days. A light rain or anything except a 'gully washer' causes no leaks. The old paint has deteriorated just enough to allow the minor seepage.

ALL basements in this area seep some water. All I want is a suggestion for a product that will stop the seepage without spending a small fortune.

RSKY

The first place to look for foundation leaks is the roof. Get that water away from the house.

The second place to look for foundation leaks is upslope. If surface runoff is a problem, install a French Drain.

You can dig the exterior of the foundation out and waterproof the exterior where waterproofing belongs. Then install new foundation drainage. I assume this is what you think will cost a small fortune, but moving dirt is not that expensive. Talk to a concrete contractor about how to proceed, since waterproofing is part of any new basement construction. Look for advice specific to your situation. Off the top of my head, pressure washing may get the old concrete clean enough to accept waterproofing, but that would depend on the concrete. The project will also screw up your landscaping

Any of these solutions may require a sump and pump if you don't have natural drainage. Avoid pea gravel. It plugs up and turns worthless. The foundation or French drain should be backfilled with septic drain rock, and the drain line goes at the bottom.