Waterproofing with thoroseal

Random topic, but this community is a wealth of knowledge so it seems someone may have some knowledge.

I am getting some waterproofing work done to the subterranean walls of an attached garage. One of the items in the work contract was "seal foundation wall with thoroseal". My understanding of thoroseal is that it comes in a bag roughly as pictured below and you mix it up to create a thick paste that is rather tedious to apply to the walls given its thick nature. When it dries, you end up with a whitewash looking finish on the walls similar to the first image below. After the guys put their version on though, I ended up with something that looked like the second picture.



I reached out to the project manager over the phone as unfortunately everyone doing the work only speaks spanish and he claims they mixed it up in a liquid form and it works just as well. For the cosmetics, they are now putting a coat of drylock white finish paint on the walls. Now to my mind, it sounds like they used a liquid format because it is a TON easier to apply than the paste so they have considerable labor savings there. I am also a little puzzled, because I can't for the life of me find any "liquid" version of thoroseal around. Then again, I am a graphic designer and not a contractor so my knowledge is severely limited here.

The big question is how much of a big deal is this. I called and asked some questions and have already gotten some backpedaling and excuses, it is just an issue of whether I want to be a jackass or if this "liquid" version + drylock will take care of it. A big part of me feels it will probably do just fine, I just sort of wish there wasn't the seeming deception going on.

Has anyone here had any experience with these products? Thanks in advance

I would be more inclined to use a product or products made by Gripset, I assume the exterior wall was sealed prior to being backfilled and proper drainage away from the garage areas was constructed. I would avoid expedient methods and go with a proven method of your choosing.

http://www.gripset.com/product_categories.php?subcategory=80

as stated above applying water "sealant" on the inside of a block foundation is not optimal alone.For any underground wall the proper water management would be a black rubberized coating on the external wall followed by back-filled rock/gravel and a french drain system to carry the runoff away from the wall.We have a completely dry basement without need for any internal goop on the walls.Concrete esp block is very porous if exposed to constant moisture.

Two inch stone would be optimal for the backfill once the rubberized coating has set.

docjohn said:

as stated above applying water "sealant" on the inside of a block foundation is not optimal alone.For any underground wall the proper water management would be a black rubberized coating on the external wall followed by back-filled rock/gravel and a french drain system to carry the runoff away from the wall.We have a completely dry basement without need for any internal goop on the walls.Concrete esp block is very porous if exposed to constant moisture.

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While I agree, this is maintenance being done on a 1941 house and excavation of the exterior is simply not feasible given the layout of the grounds.

I hear ya....A friend of ours had a wet wall basement on an old inexpensive house and he ended up having to do that excavation as I detailed.

i am not in the business but i did have a leaking wall once...
the smartest move i made was having a GOOD building inspector inspect the work of the people doing the wall fix. (yes, they had screwed up).
totally saved my butt. inspectors are not $$, and a good one will not cost much.

blue_myriddn said:

Random topic, but this community is a wealth of knowledge so it seems someone may have some knowledge.

I am getting some waterproofing work done to the subterranean walls of an attached garage. One of the items in the work contract was "seal foundation wall with thoroseal". My understanding of thoroseal is that it comes in a bag roughly as pictured below and you mix it up to create a thick paste that is rather tedious to apply to the walls given its thick nature. When it dries, you end up with a whitewash looking finish on the walls similar to the first image below. After the guys put their version on though, I ended up with something that looked like the second picture.

I reached out to the project manager over the phone as unfortunately everyone doing the work only speaks spanish and he claims they mixed it up in a liquid form and it works just as well. For the cosmetics, they are now putting a coat of drylock white finish paint on the walls. Now to my mind, it sounds like they used a liquid format because it is a TON easier to apply than the paste so they have considerable labor savings there. I am also a little puzzled, because I can't for the life of me find any "liquid" version of thoroseal around. Then again, I am a graphic designer and not a contractor so my knowledge is severely limited here.

The big question is how much of a big deal is this. I called and asked some questions and have already gotten some backpedaling and excuses, it is just an issue of whether I want to be a jackass or if this "liquid" version + drylock will take care of it. A big part of me feels it will probably do just fine, I just sort of wish there wasn't the seeming deception going on.

Has anyone here had any experience with these products? Thanks in advance

Click to expand...

Hi there.. I have some experience with a similar product. It was very specific that you had to apply as a paste or it basically would not work. These products are basically cement, and they work by creating a layer of cement that is adhered to the inside face of the cinder block. If you add too much water to cement it becomes worthless. And the cinder block must be wet when you apply or the product dries before it bonds properly.

And yes it was a real pain in the ass to apply as a paste!! You can only do a relatively small section at a time because you have to keep the cinder block wet and move fast because if mixed properly the product starts to set after about 30 minutes and you won't be able to spread it properly anymore and have to mix a new batch. Not only that but if you had a previous coating on the wall, esp. any old paint that was flaking off from the moisture, then as possible needs to be removed so this stuff can bond directly to the cinder block.

Mine looked like the left side of your first picture when I was done. If your looks like the second picture, IMO it was probably a total waste of material and labor. They are hoping the "dry lock" paint will cosmetically stand up long enough that you won't come after them and/or they'll just blame the Thoroseal. But applied properly these products work very well.

Needless to say I own tons of real estate. In my experience nothing but exterior excavation and drainage back filled with stone and covered with silt paper will actually keep a basement dry. Be sure to at the same time incorporate your gutter drains into the pipe and also be sure to place a clean out for any blockage that may occur in the future. Also its a good idea to coat the exterior block with foundation coating and place very thick plastic onto the tar before it hardens. Roll the plastic down all the way to the bottom and under the drain. Be extra sure to dig down below the bottom of the interior floor or the water your trying to move will just end up hydrostatically pushing its way up through the floor somewhere.

This is bringing back nightmare for me of the first house I ever got dried out. I spent a summer of weekend digging that bitch up by hand with a shovel because I didn't have a backhoe and didn't want to spend the money to rent one. That was 30 years ago and I still own that house, the basement is and has been bone dry. I also put UGL on the interior block.

Good luck.

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xsn said:

Hi there.. I have some experience with a similar product. It was very specific that you had to apply as a paste or it basically would not work. These products are basically cement, and they work by creating a layer of cement that is adhered to the inside face of the cinder block. If you add too much water to cement it becomes worthless. And the cinder block must be wet when you apply or the product dries before it bonds properly.

And yes it was a real pain in the ass to apply as a paste!! You can only do a relatively small section at a time because you have to keep the cinder block wet and move fast because if mixed properly the product starts to set after about 30 minutes and you won't be able to spread it properly anymore and have to mix a new batch. Not only that but if you had a previous coating on the wall, esp. any old paint that was flaking off from the moisture, then as possible needs to be removed so this stuff can bond directly to the cinder block.

Mine looked like the left side of your first picture when I was done. If your looks like the second picture, IMO it was probably a total waste of material and labor. They are hoping the "dry lock" paint will cosmetically stand up long enough that you won't come after them and/or they'll just blame the Thoroseal. But applied properly these products work very well.

Click to expand...

Correct. Its essential that you have in your contract a phrase to the point of ... No mortar is to be rewet or used after it has started to set. Some contractors will rewet mortar after it has started to set in an effort to keep costs down. Mortar that has been rewetted will not bond properly to the block.

Thanks for sharing!