Basement: Drain or Sump Pump; Also, is Gravel Needed?

I am starting finishing my basement and I am getting conflicting opinions on a couple of items in regards to water proofing: My contract is insisting that I need to have a 4 inch (possibly less) layer of gravel in between the plastic and cement. Other contractors told me I dont need gravel. Whats the advantage of having it and is it important? Also, I wanted to put a couple of drains on the floor on my floor in the basement so that if a pipe bursts, the water goes down. But my contractor suggests that I have a sloping floor and have a sump pump at the end. Is that option better? It seems more complicated. Let me know what this community thinks. Thank you.

deva

in Plumbing 11 years and 1 month ago

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dorkofwindsor | 11 years and 1 month ago

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not an expert, just a homeowner – correct me if i’m wrong but i thought it was gravel went under the vapor barrier. I thought 2″ would do it. It helps give water that gets under your house (and it usually does somehow) a place to dissipate into the soil. And it wouldn’t hurt to put some sealed XPS on top of vapor barrier and pour ready mix directly on XPS. If you have ever seen sweating on the outside of a glass of ice water in the summer, you know what condensation is – plain old temperature changes between slab and ground can possibly produce some mustiness down the road as it sweats on the inside. I thought this was best practice in this climate, but maybe i’m wrong. I realize everyone is concerned with ceiling height. As for a long gently sloping floor, yes it is good if something floods. Like a burst water pipe, laundry hose, water heater, of some act of nature / flood – or even a flood in your neighbor’s townhouse that seeps over to yours. It will all run to the sump. Drains can be more prone to backing up you have a block in your main drain, and they need sloping to, which is more difficult for finishing a level floor job (tile wood, etc). One thing you didn’t mention, which is an amazing opportunity to do while you’re doing all this, is an interior drain tile that hooks up to the sump. I don’t think that is overkill and they are all in there doing their thing, so much cheaper than if you were forced to do this later. Golden opportunity, as they say. Good luck, i hope you report back your decisions and how it all turned out!

Townie | 11 years and 1 month ago

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I have a “dry” rat slab basement with no floor drains but still installed a sump pump pit after my hot water heater burst while i was on vacation one year. The pit is a standard size prefabricated one i purchased from a plumbing supply house. Funny thing is that on very rainy days, the pit will sometimes fill even though the floor is dry. Must be the ground water rising. I also have a shallow basement… less than 7feet deep so 120 years ago the builders must have had a pretty good idea where the water table was and when to stop digging. I would make sure you get the properly sized pit and pump to prevent rapid cycling of the pump. I think the 4 inches of gravel acts to stop the capillary action of the water in some way as well as providing a stabile base. 6 mill plastic sheet over that.

daveinbedstuy | 11 years and 1 month ago

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Yes, you will need a pump of some sort to eject the water out the main sewer line which I am assuming is above floor level like in almost all brownstones. A sump pump situation is the cheapest way to do that.

GreenThinker | 11 years and 1 month ago

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Level floor, Drain System leading to a sump pump pit, connect sump pump outlet to sewer system, have a ball valve shut off. Reason being, if water starts to back up, you close of the valve and run a hose to the sidewalk from the sump pump. As for the gravel, it doesn’t hurt to put 2 inches of gravel under the plastic.