View Full Version : Flexible copper in wall?

01-26-2005, 02:54 PM
My tub/shower combo in the basement has a gap at the top for floating slab considerations. The rest of the walls have a gap at the bottom, but the tub needs to sit on the concrete. Anyway, If solid pipes are used and the floor does shift up or down, the pipes would have problems.

Can I use flexible copper connectors (like those used with water heaters), or any other type of flexible hose? I'm not sure what flex pipe sections can be sealed up in the wall...


01-27-2005, 06:20 PM
No you can't use flex connects on the tub shower valve, and in no way can these ever be concealed. pipe them direct.

Floors that move, never heard of such a thing. why would they need to move?

01-28-2005, 12:18 PM
Many areas in Colorado have expansive soil. We have (in general) slab on grade basements. The expansion of the soil can cause the slab to move up and down. Consequently, all basement walls must be built with an expansion joint (1.5"). It normally consists of a 2x4 fastened to the slab, then a 1.5" gap above it, and then the wall bottom plate. Spikes are used every 2' or so to fix the bottom plate to the 2x4 on the slab, but allow vertical movement. For the shower, the expansion joint is at the top. So, the pipe can't be fixed both to the joists and to the slab, or it could be stretched or compressed.

I do need some sort of flex in the pipe somewhere. I guess I'll have to contact the building inspectors for a hint.

01-28-2005, 04:22 PM
If pex pipe is available for use in your area go with it, and connect directly to the valve, pex left with little slack in it will allow for expansion and contraction of the pipes, or even soft copper with it looped will allow expansion and contraction of the pipes.

01-28-2005, 07:32 PM
Check with a builder of log cabins. Thes cabins are built to accomodate much more movement than you have to contend with. ( Shrinkage of logs.)

01-31-2005, 04:20 PM
I asked the building inspector and he says that as long as both ends are soldered, flex is fine in the wall. I'll have to look for such a flex section, as all of the water heater ones I see have at least one screw-on end. I guess I can use soft copper tubing instead, as suggested here. I'm afraid of the PEX, since I've never used it before...

Thanks for the suggestions.

02-01-2005, 05:00 AM
Use a tubing bender and bend the soft copper into a "U" shape before connecting it to the pipes and valve. That way the "U" will flex and not create a stress on the rest of the system.

02-01-2005, 07:36 AM
Will do. Thanks!

02-01-2005, 10:03 AM
I live in Littleton, Colorado and had the same question in regards to the floating walls and plumbing.
The bldg. dept. said to just plumb the way you normally do, if the slab does float up you may get some plumbing problems but it doesn't happen overnight and you'd notice cosmetic damage first, such as cracks in drywall etc., plus other major problems for example consider what would happen to your toilet and shower/tub drains and pipes if the floor floated up but the drain pipes didn't.
I never asked about flex copper, but I think it's overkill (actually I think the floating walls are unecessary in many cases too but that's the code). So you don't really have to use the flex.
The purpose of the floating walls is of course to prevent major structural damage that would result from partition walls pushing up the floor joists and thus the rest of the house.

Gary Swart
02-03-2005, 08:14 AM
I don't know if it is really a problem or not, but be safe and do provide a flex joint. HJ's advise is the way to go IMHO. You just need to provide somewhere for the expansion/shrinkage to go without pulling against solid plumbing. Cabinet makers have to deal with solid wood shinking and expanding due to humidity changes all of the time. If a broad piece of solid wood is anchored on all edges, the piece will buckle or pull apart (split). Pretty much the same could happen with you plumbing if there is a problem with expansion/contraction.