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How to plumb bathroom for a on slab house

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Kinney-man

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Im currently designing my house, im an engineer with a decent amount of experience I'm just very confused when it comes to plumbing. i even designed my house around having all fixtures on one wall for simplicity. however, i have two main questions and any help will be gratefully appreciated. First, should i run my 4" main drain right under my fixtures or should i have it offset as in the PDF's attached? Second and most important, how would you pros plumb my bathroom setup? im very confused when it comes to venting. i understand the science with the P-traps but i just dont know how to lay it out. can i use a air emittance device instead of running a tall vent? I live in Quakertown PA and will be building a small 24x50 house on slab and will have the plumbing underneath the slab of course. thank you all in advance!
 

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Geofd

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Maybe I missed your door, but have a friend who has a slab and your setup up is the same except the tub is the long way on the wall, what ever you do make sure there is access to the tub drain put a clean out on the tub drain with an access panel I had to open the closet wall in the same friends house to access their tub drain, in another friends house they had an access panel and a clean I had to snake the tub drain
I was done quickly because of the access panel
 

Mitchell-DIY-Guy

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Let the pros comment on venting, and burying the pipes in the slab and other code issues. I'll just add my two cents, and you can spend these pennies as you wish.

1. Nobody has ever said, "Gee, I wish I had buried my pipes in concrete". Have you considered a crawl space? Makes a LOT of utility work--draining, supply, electrical, HVAC so much easier...the first time you need to remove finish flooring and jackhammer the slab to fix something, you'll remember that.

2. You have the point of use for kitchen and bathroom showing supplies on an outside wall. You run a far more risk of problems such as freezing pipes when you do that versus interior walls in the climate of the northeast.

3. Similar to #2 above, your plates etc. in the cabinets will become freezing cold in the winter, and I'm not kidding. Doesn't matter if your walls are insulated or not, if your cabinet doors are closed, and the cabinets are on an outside wall, they WILL be cold. I had 6" stud walls with 6" of R21 insulation and the contents of the cabinets were freezing in the winter. We were on a 5 block crawl space, concrete floor. There were no supply lines in the outside walls.
 

Kinney-man

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Let the pros comment on venting, and burying the pipes in the slab and other code issues. I'll just add my two cents, and you can spend these pennies as you wish.

1. Nobody has ever said, "Gee, I wish I had buried my pipes in concrete". Have you considered a crawl space? Makes a LOT of utility work--draining, supply, electrical, HVAC so much easier...the first time you need to remove finish flooring and jackhammer the slab to fix something, you'll remember that.

2. You have the point of use for kitchen and bathroom showing supplies on an outside wall. You run a far more risk of problems such as freezing pipes when you do that versus interior walls in the climate of the northeast.

3. Similar to #2 above, your plates etc. in the cabinets will become freezing cold in the winter, and I'm not kidding. Doesn't matter if your walls are insulated or not, if your cabinet doors are closed, and the cabinets are on an outside wall, they WILL be cold. I had 6" stud walls with 6" of R21 insulation and the contents of the cabinets were freezing in the winter. We were on a 5 block crawl space, concrete floor. There were no supply lines in the outside walls.
You made some really good points! I also truly agree, It is a bit scary to have the pipes buried.
 

Mitchell-DIY-Guy

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I used to have, in a different home than that mentioned above, a toilet whose supply line would freeze up in those "polar vortexes" and "Canadian air masses" that we'd have, where the temperatures, extended, were near zero. Turned out to be some minor flashing/caulking issue on the siding/roof transition that let come cold air come in. Once that was sealed up, the problem went away. BUT, pipes on outside walls in cold climates are just asking for trouble.

Given the option, I'd do a basement or at worst, a tall crawl space. Always flat, cement floor and insulated walls.
 

Mitchell-DIY-Guy

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It is a bit scary to have the pipes buried.
I grew up on Long Island, New York--in the postwar boom of cheap tract housing. While our home had a basement, there were large tracts of homes nearby, smaller homes on a slab with radiant heat and pipes buried in the slab. I know of several friends who had those homes and had issues after a number of years, and though probably most of those homes still stand, I'd bet NONE of those buried pipes are still used for heat.
 
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