Copper Pipes in Concrete

[Paul Roberts]

I am refurbishing my utility, and want to bury some exposed 15 mm pipes in the concrete floor.

I expect I'll need to check for other pipes first, but any other considerations or advice, please?

[Michael Mcneil]

Tape them up to insulate them chemically if they are copper and put some rockwool over them too if there is room.

Before you chop out the channels? Obvious one that.

How deep were you thinking of going? :~0

[deckertim]

You should use Denso tape, which is available from a plumbers merchant. It's horrible stuff to apply, but protects the pipe from corrosion.

I am sure other members of the group will debate what type of joint to bury. I personally felt that a soldered joint made most sense if buried as compression joints can sometimes weep a little bit.

[Ian Middleton]

If you don't protect them the concrete eats them away.

A friend of mine when he moved into a house near me in 1994 (built 1974) kept on getting a "damp stain" on the lounge carpet. Anyway ripped carpet up and there was a large damp area on concrete floor. Carefully chiselled out and found two copper central heating pipes and one copper gas pipe that fed/came from the back boiler. The gas pipe was wrapped in a sticky cloth tape (Denzo tape ?) but the two copper pipes hot out and cold return to the radiators where just embedded in the concrete. Both these pipes had tiny pin prick holes all along their length very slowly leaking water causing the damp patch. He simply replaced the runs under the floot, this time putting the copper pipe in a plastic pipes (Hep2O ?) and problem solved.

[MrBlueSkye]

I concur. Copper reacts when in contact with concrete

[Michael Mcneil]

Of course copper or not, putting a plywood panel over them rather than concreting them in would be easier for future-proofing them.

[Christian McArdle]

I'd use PEX, rather than copper, my feeling is that they're less likely to leak. Also, it is better to not actually bury, but leave a trench and board over the trench, so that if the pipes need servicing, it is just a case of lifting the lino and undoing screws, rather than getting the jack hammer out and demolishing the floor and what is left of the pipes. I'd still use PEX in the trench, too.

Christian.

[mmzz]

[GB]

How do you get a smooth enough finish to the floor to lay vinyl on and not see the outline of the boarded trench? Lino may be a bit tougher, I guess.

[Simon Kelley]

My house was built in 1973 and is plumbed with stainless steel. I assume that this is a consequence of the same copper shortage.

All the downstairs CH pipework is buried directly in the concrete floors: does SS pipe survive better then copper when in contact with concrete? There are no leaks yet.

Cheers,

Simon.

[Christian McArdle]

You can lay vinyl on plywood, no problem. Ensure that you get the shuttering right when laying the concrete to give a nice 18mm step (or however thick your board is) to lay the plywood into. Also, stuff some insulation above the pipes and below the plywood to eliminate any weird convection effects. Leave a couple of mm each side of the trench

Christian.

[StealthUK]

You can buy those trays but getting it all flat is more work than running the pipes on an existing floor. I think by law now you're supposed to leave access and cannot bury directly in concrete but I doubt many do.

Regards coating the pipes, I've used a bitumen paint to cover them over rather than tape.

[Aidan]

Use PEX pipe. Install in as 'pipe-in-pipe', i.e., Pex pipe in a corrugated sleeve.

[Aidan]

PS Unless they are gas pipes in which case, of course, they have to be metal and cannot be in an unvented void. In that case, use soldered copper and wrap with Denso tape with a 50% overlap.