copper pipe under finish floor

Hello Sami,

You don't say whether these copper pipes are used as water supply hot?/cold? or as a waste/drain pipe.

Here in New Zealand, both water supply also waste pipes of both copper and PVC/uPVC, are allowed to be buried in concrete.

The pipes are wrapped in DENSO tape - a greasy wide cloth tape, impregnated with a special grease. (Your hands get quite soft after using DENSO tape)

The wrapping prevents local corrosion, also differential expansion/contraction of the concrete/pipes without damage.

Denso information is here:

http://www.densona.com/Index.htm

You may have local rules regarding your situation, of course....

Usually a larger diameter plastic pipe (type?) is run through the slab as a chase, allowing removal and replacement of the utility piping. I know of someone who had to tear up the slab to repair a failure. You don't want to go there!

You sure don't. An entire subdivision had this problem in a suburb of Tampa, Fl.

Denso tape is great. It really does the job, but I never found a good way of getting the residue off my hands. Talk about sticky !

Hi sami,

You didn't say if this was an all new construction of a refrubishment. Either way I think you can get away with simply burying the pipes in cement. Question is, do you want to ? For a little extra cost you can lag them and enclose them in some sort of conduit. If you need to access the things at a later date ( Kitchen re-design etc) you'll be able to do so. Take the extra hour of work and somehow enclosure them before 'burial'. If you go for an enclosure type thing, make sure there is no water-hammer effect before you cement them in. Good luck.

Certain concrete mix will ruin copper over time and if you have no alternate way to run the new pipes you are going to be so sorry you didn't spend the $20 for PVC chase or as the actual pipe. PVC pipe in concreate as water pipe is great with no problems that the metal ones have. I always had favored copper over PVC but after a college corse in materials I now understand the PVC has great uses and done right nothing beats it. But at least put conduit chase runs under concrete to get to places later as you never know what may cause a failure. Minor earthquake could could shear a pipe in slab with not much other damage and there you are stuck with no means to fix other than eexpensive repair when you could have avoided it. Part of all my plans in building building and systems as an engineer always incorporated backup or redundancy systems in case of primary failures. Have saved all spent on all projects for redundancy by the money saved in one failure we had.

No. No. No. No.

Do not install copper pipe in concrete. Under any circumstances. Ever.

Early in my career we had a pipe failure which flooded a school over the holiday period. A tiny leak x 2 months = $1m in damage. We had the pipe removed for forensic analysis - it looked like a rat had gnawed it. Tiny little pits burned into the copper by some chemically active particles in the concrete. Through the Denso tape.

Your sink must have a waste which will be at least 40mm PVC. Run 3 together. 1 for waste, 1 for power wiring, and 1 for 2 no. PVC water pipes. (Even if you don't have power wiring, you must have a ground/earth to your sink). Now, your water is protected and even if it leaks you can get fair warning without the water migrating through the floor and appearing 20 metres away causing great confusion.

Cost of PVC pipe - $40

Cost of not digging up your new floor - priceless

Only use copper if protected use Denso tape as others have suggested installing a PVC duct with long radius bends is a good idea as a conduit in which case you should use polybutylene pipe. Which ever option you select Polybutelene pie is the best option as it is corrosion free and can take hot water. Don't use PVC

These Links may help

http://www.pexconnection.com/

http://www.hep2o.co.uk/

Copper & concrete as the others have mentioned is not a good thing. I believe the US code books do not allow the 2 to come into contact. Alot of plumbers use a plastic color coded sleeves just through the concrete. I'm not a big fan of this method, because you can't replace the copper if you need to. This best I've seen is useing a poly sleeve for everything going under the slab. There are other products other than copper or pvc than work well "aqua-pex" is a good one. I don't believe that the code allows you to install pvc under slabs. Usually a product with no joints.

concrete contractor