I'm sure it's been talked about a lot but I wasn't having any luck using the search function. I'm having a new slab poured in the next week hopefully. We are going to build a room insidea of the building for room that requires a floor drain. My concrete guy will put it in if I buy the supplies. It's going to either drain to daylight or I'll make a dry well of sorts for it. My question is what do I need for the drain part in the floor? I'm in the mid west so we get freezing temps. Do I need a p trap for a dry well?
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Floor drain in new slab
- Thread starter Awag
- Start date
I just speculating here:
But Normally I’m thinking you install a P-trap right at the drain (assuming it’s in center of room or wash area) and the building slab should hold enough heat to prevent freezing unless it drops super cold.
But if you don’t install a trap and just drain to outside, you would have a nice pathway for rodents or insects into your space.
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But Normally I’m thinking you install a P-trap right at the drain (assuming it’s in center of room or wash area) and the building slab should hold enough heat to prevent freezing unless it drops super cold.
But if you don’t install a trap and just drain to outside, you would have a nice pathway for rodents or insects into your space.
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coalminer16
Active member
Most codes require day lighting the exit of the drain. If in a climate where there is freezing then I would not put a P trap. Otherwise if it will never freeze then put the trap to keep air movement down and possibly pests. I don't have a p trap and mine is daylighted. May bury a biodiffuser someday which would take care of freezing outside. Went with a trench drain and metal grating to cover. Get a good enough slope as most concrete people don't do it good enough-like the walls flow to the wall and not the drain.
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86turbodsl
Well-known member
Here's what i've done on all my slabs with drains - in cold weather areas.
NO P trap, just elbows running out of the building, into a buried french drain. If you can get the water out of the building fast enough, you won't have trouble with freezing. P traps just freeze unless heated.
NO P trap, just elbows running out of the building, into a buried french drain. If you can get the water out of the building fast enough, you won't have trouble with freezing. P traps just freeze unless heated.
kj_mustang
Well-known member
I did the same as 86turbodsl. Although I haven't used it yet. Ran the pvc drain line outside into a couple perforated pvc sections buried in gravel. You can see a couple pictures of the inside trench drain in my build album.
The village in which this is being built don't give out permits and the county don't because it's in a village. It does get well below freezing here because of that I didn't think I wanted a p trap. Looking on Menards website you can get floor drains from about 8-100. What do I want for the drain part? How do they keep from getting concrete in it when they pour and finish the floor? Thanks for your replues.
like2wheel
Well-known member
Cast iron bell trap.
https://www.amazon.com/gp/product/B0044FZ0P2/?tag=atomicindus08-20
Not totally sure, but it looks like it is designed to survive freezing water. Maybe someone else will comfirm that.
Cover it with duct tape to keep the concrete out.
.
https://www.amazon.com/gp/product/B0044FZ0P2/?tag=atomicindus08-20
Not totally sure, but it looks like it is designed to survive freezing water. Maybe someone else will comfirm that.
Cover it with duct tape to keep the concrete out.
.
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To future proof this room I'm thinking I should put rough in's in for a sink. I'll add a sanitary tee in the floor drain for it. I'm thinking for water supply to run some pvc to use later as a conduit for pex. Maybe even run a piece of pex and plug both ends. Do I have to bring it below frost line before I turn it out from under the slab or can I angle it out from under the slab before I get to frost? I'll leave it covered up for now and if in the future I want water I can dig the trench and run the water line. Do I need to insulate the pex coming up through the frost line or will the air gap in the pvc around the pex be sufficient?
kj_mustang
Well-known member
You cover the top of the drain to keep concrete out. I taped heavy mil plastic over the top of mine for the pour. Concrete finishers pulled it off when they were done troweling.
Boilerhouse
Well-known member
Cast iron bell trap.
https://www.amazon.com/gp/product/B0044FZ0P2/?tag=atomicindus08-20
Not totally sure, but it looks like it is designed to survive freezing water. Maybe someone else will comfirm that.
Cover it with duct tape to keep the concrete out.
.
This is the type of trap I have. It does a good job of collecting sand and other debris but allows water to flow through. Drain flows just under the slab, out past the garage a few feet, and terminates in a drywall that is buried about 18 inches. Never had an issue freezing. Winter temps here get below minus 30C.