Remodeling a bathroom on a slab and have 1 question in particular but would also love to hear other tips. Question being are you allowed to sweat pipes under the slab? Or are you supposed to use the flexible copper roll? Obviously we need to reroute some copper. What's the best way to go about what will be covered in concrete afterwards?

Hi MWM

You are NOT allowed to sweat pipes underground, so you should use the rolled refrigeration tubing that is approved of for underground water piping in your area just like you thought.

Another option would be to use PEX thermoplastic tubing, but again, no fittings underground. The PEX tubing is MUCH cheaper, but they bang you pretty hard on the fittings. Labor is also faster here, but you need special tools to work with PEX, so it may or may not be reasonable depending on how much work you are doing here... ;) The place you purchase the PEX may or may not be able to rent the tools, so ask real quick if this interests you... may save you time/money/hassle!

Mark

No sweat joints underground, use at least L copper coil or K copper is even better, but more expensive and a little harder to work with. Use armiflex pipe insulation on pipes where they come through the concrete. You could also cover the copper with visqueen before backfill.

Now if we are rerouting existing copper how are we supposed to move it without an underground joint?

Copper joints under ground need to be either flared, or brazed. Either is acceptable by most codes. I would stick to Type K copper for all underground copper (most codes require it anyway). Above ground in the dwelling, L or M is fine.