New construction


Old 03-11-14, 08:12 PM
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New construction

Building a 3 bedroom 2 bath on a slab with 18" stem wall. All the plumbing with the exception of the kitchen sink will be on the same exterior wall. Both bathrooms and laundry. Wondering what problems may arise from running all drains 8 total out and tying them within say 10 feet from the house. Venting is my main concern. I deliberately laid out the house this way to keep as much plumbing as possible in a location that's relatively easy to access if I ever have issues. Also I'm thinking about running pex in the walls verses burying. No codes apply for the location of house. Any suggestions? Thanks
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Old 03-12-14, 06:03 AM
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As far north as you are I suspect you get below freezing in winter. In that case I would do everything possible to keep plumbing out of exterior walls.

As for PEX in the walls I would much rather have it there than in the slab. There is often only one solution to supply or drain leaks in a slab and that's to cut concrete. With plumbing in the walls it's much more accessible for repairs. When building my house one of the concrete guys stepped on a floor drain pipe and broke it while pouring the slab. Luckily I saw it happen and had everything on site to immediately make the repair. The concrete guy didn't even think of saying "hey I broke your pipe" so if I hadn't seen it it would have gone unnoticed until the inspection. For that reason I'm very nervous about plumbing and electrical buried under hard concrete unless run in conduits.

As for running all the drain lines straight out of the one wall it could be done. You would still have vents running up the walls and through the roof as required by code. Outside I would install at least a cleanout at the end of the trunk drain line and depending on your layout maybe more. You can never have too many cleanouts in my opinion.
Old 03-12-14, 07:49 AM
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I agree with Dane, You can never have too many cleanouts. When I built my house, I put in several cleanouts all the way to the septic tank. Interior, all the cleanouts were within 12' of each other. It made it so much easier to snake the drains and find plugs. I also placed a cleanout in the attic for the vent. My roof was quite steep and it was easier to climb into the attic than on the roof. I ran all of my drain lines below the slab and below the drainage stone below the slab. Where the lines came through the slab I boxes out and area prior to the pour to have room for any P-traps for the toilet or tube and shower. When the slab was poured, I didn't have to worry about the pipes being broken. i also capped the outlet and filled all the drains with water to make sure there were no leaks before the concrete hardened.

For supply lines make sure they are not on an outside wall! I used copper since there was no PEX when I built my house (1980). I ran 3/4" cold/hot water supply and " lines to the faucets. All lines were in interior walls or the ceiling. After a few really cold winter in WNY, I was glad I did!
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