What is the purpose of this interior waterproofing?

The slab is poured on top of this. Is my understanding correct in that this interior waterproofing is designed in case there is a leak, water or condensation on the foundation wall it would run down the wall behind this dimple membrane under the slab and into the natural drainage rather than on top of the slab or flooring? Or is it used for something else? We have Delta-MS on the exterior. Thanks.

It’s possible, but doesn’t look very thick to allow water through, but enough for termite access, though.
Is there an underdrain under the stone?
Is there going to be a vapor barrier?
Is there an exterior waterproofing installed?
Is there exterior perimeter foundation drains at bottom of ftg.?
Did you ask the contractor what it is for?
I would concentrate my efforts to exterior waterproofing.

Thanks. It’s dimpled on the side that touches the foundation wall. There is exterior Delta-MS waterproofing. There is drainage and sump.

Looks like a second line of defense, but also allows water entry should hydrostatic pressures occur if something goes wrong with the first defense system if not designed right.
Here is some reading material if it helps.


That’s it? No compacted soil/rebar on top of the gravel base, that does not look tamped either.

You can’t compact crushed 3/4" stone, but it does need to have a plate vibrator to level it out and consolidated. It is like trying to compact marbles.
Seeing the next step they plan on taking would help though. :grinning:

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To save money, at that time, you think. …

What a WAFI !!

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What is that?

yeah you got it pretty much, it’s a piece of shtt water----diverting system, its not waterprooofing.

some builders will put this crap in so that they can then say, the basement was waterproofed, no.

they put it in because it’s CHEAP and many people these days don’t know what waterproofing is.


What is it?

What is the purpose of this interior waterproofing?

To make sure Mark Andersen stays busy… :joy:

Get your perspective. But if this is in combination with Delta-MS waterproofing membrane on the exterior, I’m unsure why this gets such a bad wrap if it’s a secondary piece of the puzzle.

I looked at the installation system for that product, and appears to me like a good product.
Similar to the System 4000 by grace that I have installed before.

That is a real waterproofing system. You should not have a problem if it looks like that.

You ever see roof deck sheathing waterproofed in the attic? Lol. How long you think the sheathing would last?

Interior water management diverts water that enters under to footing.
Let’s not fool ourselves. The foundation and footing stay saturated for prolonged periods of time in the spring and fall. Without add mix prior the batch being mixed, the concrete will degrade rapidly over time.

Ever wonder why do individual do this type of band aid repair? To save money, at that time, you think. Yep!