Hot & Cold Water Under Slab

[anthonydad]

I am involved with a golf course clubhouse project where the owner wants the hot & cold water piping installed under the slab. The building is located in the Northeast and is a single story, wood frame commercial occupancy with unheated attic & drywall screwed to the roof trusses.

Since the pipes would freeze in the attic, my recommendation is to install the piping in soffits below the ceiling. I am concerned about leaks under the slab & overall cost of running homeruns to each fixtures from a manifold. I won't install large branch & tee mains under the slab - too much liability. There are large shower & toilet rooms with flush valve fixtures, so the homeruns will be 1" in some instances.

Also, don't hot water lines need insulation under slabs? Seems like quite a heat loss travelling from the water heater to the fixtures in the cold earth.

The owner must be from California because we typically avoid running domestic water piping under slabs - we're used to basements or dropped ceilings.

Any comments/recommendations?

 

[Gary Swart]

Water leaks in slabs is a frequent topic. It is my nonprofessional opinion that installing pipes in a slab is one of the more stupid things that people do. It is not a question of "if" there is a leak, but "when". You only have to go back a couple of posts to read about the latest.

 

[Sponsor]

 

[Rancher]

Having lived in Calif, Ariz, and New Mex where 99% of the homes are built on slab, I know of only one person who has had a problem. They do make a poly sleave to provide some protection from the ground. I insulated my hot water and re-circ lines, but that is not normally done.

Rancher

 

[rudytheplbr]

Re: Hot and Cold water under slab

If you are running copper dist. lines use Type K, bring them back to a central point, and do all your tie-ins ABOVE THE SLAB. If you're using PEX, or similar, I would do the same, no joints below grade, 'cause you may get leaks, and you are probably familiar w/those.

Good Luck,
Rudy

P.S. Be sure to sleeve the pipe where it comes up throught the concrete, with 1" pipe or larger 1-1/4" perhaps.