Hello all - it has been a very long since since I've been here. Happy to see Speedball is still answering questions! Here is my situation. My parents have a flat roof with a drain on it for water runoff (rain or snow melt) that goes into the attic, and then out the sophet and into the ground. This works well all year except when it gets very cold and the drain on the roof freezes and cracks. Then, when things melt, they get water into the attic, through the sheetrock, and into bathroom underneath. They are redoing their bathroom, and the contractor suggested putting a catch-basin under the drain in the attic which would be plumbed into the vent in the attic for drainage. I cautioned them against this as that is against code as all the fixtures in the bathroom (2 sinks, tub, shower, toilet) would all effectively be wet-vented. The contractor then suggested just running the basin drain to just after the p trap for the tub (he had easy access to this) which again I said was not to code (same issues as previous suggestion). No inspections are being done, so the contractor can get away with this.

The attached diagram (PDF document) is my suggestion. Note I did not draw the main drain line down to the basement, but it should be obvious as to where it is.

My questions - is there any issue with this. Note the catch basin is empty 99.9% of the year, and is not easily accessible in the attic, which is why I did not propose a p-trap right after the basin as it would be dry most of the time and not easily refilled, and I did not want to risk sewer gasses in the attic.

Thanks!

I don't like any one of your contractors solution.
1- He didn't address the roof drain or its leak. Could it be repaired or could the roof drain be blocked off and a drain run to gutters? He needs to give you more options.
2- His only option would be to discharge the run off into the city sewer. Most codes, including my own, prohibit this as as a heavy rain or snow melt would overload the sewage system and at the very least raise utility bills.
Did anyone even check the code? Let me know what you thin? Good luck, Tom

Quote:

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flat roof with a drain on it for water runoff (rain or snow melt) that goes into the attic,

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That sounds dumber than dog do-do. Who though that up. Why isn't the rain water allowed to simply drain off the roof? Never heard of someone bring rain water to the inside of the house.

If it is absolutely necessary to do this, put some heat tape on the pipe in the attic and insulate it to prevent freezing. That way as long as you have electrical service you shouldn't have busted pipes.

https://www.bing.com/images/search?q...sign&FORM=IGRE

Here are some ideas to consider.

Yeah, bringing rain water into your sewer system would very likely end in absolute catastrophe when the drain system partially backs up some day down the road and you get a real major rain storm...a very bad idea!

If ice damming is an issue around the drain they do sell thermostatically controlled heat wire similar to the one that Hkstroud suggested for wrapping the pipe itself. Here, you would have a switch wired to a convenient location (easy on/off) to a thermostatically controlled heat wire and then wrap a V pattern around the perimeter of the ROOF DRAIN itself and then follow the wire into the drain pipe through the soffit and down the outside pipe... keep the roof area and the pipe unfrozen only when needed, right? The image below shows this wire on a pitched roof, but you can see the V pattern and get the idea of the tracer wire going down the drain pipe to the OUTSIDE of your house... :)

Here is one type of heat tracer wire:

Heating Cable - Drain Line Freeze Protection / Thermwire / - Chromalox

Back to you...

Mark