Basement waterproofing

[Learninggal]

Folks - we had done exterior waterproofing but it didn't do a 100% job especially with very large rain events in NYC so now doing indoor with one sump pump and a channel throughout. Can you check pics to see if it's ok? They only did the demo on the tiles this morning and looks like they didn't do it right at the perimeter but about 8" off which I guess is to avoid cutting the wall studs. Is that ok or will it cause future issues? Thanks

 

[d.mcfarland]

As long as the current wood doesn't touch water you're good. Hopefully they have some kind of plan. The job isn't "right" but significantly cheaper it seems.

The current dig up might prevent some hydrostatic pressure under the slab, but not a whole lot from the walls i'd say.

 

[Learninggal]

Thank you. do you this should also be tested once they've laid out all the gravel, should I test by by using a garden hose to pour water perhaps into the opposite area where the sump pump is or no need. It's a 25x25 basement so wonder how many hours will it take for water to get to the sump pump. Apart from water getting to the sump pump, what else should I look for? I'm assuming there should be no water visible by the tiles in the basement or that'll indicate water pooling or the 4" channel pipes not connected properly

 

[DGersic]

Is there actual drain tile under there somewhere?

 

[The Cobbler]

curious how they plan to install the dimpled plastic membrane

 

[Junkman]

I would take the walls down and replace them after the work is done. I would make sure they install a perforated pipe with a sleeve to keep dirt from entering the pipe, then bring the pipe to a central location and install a plastic 55-gallon barrel to collect the water, so the sump pump can eject it away from the cellar. Then fill with crushed stone, lay a layer of 6-mil plastic over the stone, and pour fresh cement. You can also place a piece of plywood against the wall so that any water that might come through the wall falls into the new drain, ensuring the plastic doesn't get in the way of the new French drain.

 

[Learninggal]

All good advice, thank you and looks like contractor is following these things. One confusing thing is the way they have installed the membrane. In the picture below you see the top is below the bottom. Shouldn’t it be the other way around? They said the water needs to go behind but to me, it’ll touch the wall and then go to the channel but I think too should be on top of bottom as the channel is 6 inches from wall to avoid the footing

 

[BombShelter]

What kind of exterior waterproofing did you do? Bentonite injections are highly popular with these old-school stone walls. I would never put dimple board on the inside, in fact I've asked Dorken about using this product inside and they don't recommend it and it's not in the installation instructions.

https://www.dorken.com/media/docs/products/Installation-Guides/DELTA-MS-Installation-Instructions.pdf

It kind of looks like they were hitting bedrock, that's why there's no traditional footing. When you take that floor out your crossing your fingers that wall doesn't implode, I just saw that situation three weeks ago. Make sure they seal all those plastic edges up, that area has the potention to turn into a mold/mildew farm and you don't want to breath it.

 

[pcmeiners]

It kind of looks like they were hitting bedrock,

Not in NYC, the most your going to hit is a mixture of gravel and sand, in Brooklyn and Manhattan, Queens and Staten Island for a residential foundations. Bedrock is many feet below.. Personally the exterior walls should have been excavated again and redone correctly. As to the present work, there be be very high moisture concentration in the space between the stud wall and the membrane once sealed, excellent for mold and termites; I lived on Staten Island and there are definitely termites in NYC, best you order Termidor sc off Ebay.