Underfloor pipe

[Kdminx]

Hi all, project living room is in the final planning stages and I'm just about to order the stuff and book the week off work.

I'm routing some network and speaker cable and need to run a chase in the concrete floor to accommodate these. I'm planning to make 2 parallel cuts with my grinder approx 20mm apart and 10-20mm deep then chisel it out with my power drill, lay the cable, screed over and job done.

The problem is there is a gas fire on the wall, the gas meter is on the exact opposite side of the house and my chase runs perpendicular to where I imagine the gas pipe might be.

The house is a modern timber framed house built by a volume house builder. Would you expect a gas pipe to be just under the surface? Do I need to hire a metal detector? Do the usual hire places even have metal detectors? If the pipe is going to be 300mm down the I can crack on unconcerned.

Your help is much appreciated.

(Btw I put the question I n the plumbing section 'cos it's about pipe)

 

[Dan Robinson]

It might be in the ceiling. You need to be 100% sure before you start.

Maybe dig a small exploration hole?

 

[Galoka]

Dunno about the gas pipe, but if you haven't done something like this before, be prepared for a crazy amount of dust that will get everywhere. I used one to cut chases for pipes in a wall for a shower, and the whole room just disappeared in a cloud of dust.

Assuming you are living in the house, tape up the door gaps well, open windows and wear a hat and use a good mask and goggles (IIRC, even with goggles the dust still irritated my eye a bit, coming in through the ventilation holes) It was a horrible job.

 

[Kdminx]

Yep, I've cut chases before in walls. Having a friend hold the Hoover pipe close to the blade helps even if it takes a while to clean the Dison filters.

I was thinking of maybe using the grinder and power chisel for the length of the chase except for the ft or so where I imagine the gas pipe might be. That bit I might chisel by hand.

Surely there are people on here who chase concrete floors all the time and can tell me the way to do it.

 

[longdogs]

Might be worth trying the building forum.

 

[GavThePlumber]

I chase floors all the time, but cutting through a gas pipe is not really a concern to me because i will isolate the supply before hand and fix the problem should the need arise.

Standard detector won't work in a concrete slab as you have rebar holding it all together.

You need to go hire a signal genny from a hire shop.

 

[Agile]

Its very unusual for any domestic floor slabs to have any steel reinforcing in the UK.

You can buy a metal detector for about £14 from the screwfix/toolstation places or online for less by post from China.

One of them should be able to identify the gas pipe coming from the fire and track its location.

They are most often about 80-100 mm down in new builds BUT that cannot be assumed at all.

Turn off gas at meter before any cutting.

Tony

 

[Dan Robinson]

Well theres over 100 houses on my estate with them:




Which means there is a sizeable chunk of Welwyn Garden City with them too.



that is a core sample of my ground floor slab. there are at least 5 pieces of steel bar running through that.

The company that built my house and the houses around me also built the houses in the Panshanger area of Welwyn Garden City. It is certainly not a small company .

 

[denso13]

Its very unusual for any domestic floor slabs to have any steel reinforcing in the UK.

It's not unusual at all, in fact it's quite common. Stick to plumbing.

 

[GavThePlumber]

I can not remember a time when a slab was poured without rebar above the insulation, i didn't think building control would sign such a thing off.

Will check building regs, i could be completely wrong

 

[GavThePlumber]

Dan, did you use a standard diamond core for that? if so what was it like after? I go through wall ties all the time, always though it massively reduced the life of them though.

 

[Dan Robinson]

Let's just say it wasn't one of my best core bits .

 

[newbuildinstaller]

10 years of new build plumbing for nearly every big builder and I can tell you only Bellways ran gas pipes in the floor.

Also they were in the SCREED, The way they do it is the subfloor is made usually block and beam the insulation is put on that. We then come in and run the gas pipe (coated copper inside climaflex lagging 12mm thick) The rebar etc is all in the sub floor the screed is just poured.

Either way if your house is just a Barratts/Persimmion/Yuill/Wimpey/Boweys/Mcinerney/NB Clark/Gleeson/Bett Homes/David Wilson/Gentoo/Kendalcross/FHM/etc etc the gas will be in the joists....... (I would guess)

 

[newbuildinstaller]

10 years of new build plumbing for nearly every big builder and I can tell you only Bellways ran gas pipes in the floor.

Also they were in the SCREED, The way they do it is the subfloor is made usually block and beam the insulation is put on that. We then come in and run the gas pipe (coated copper inside climaflex lagging 12mm thick) The rebar etc is all in the sub floor the screed is just poured.

Either way if your house is just a Barratts/Persimmion/Yuill/Wimpey/Boweys/Mcinerney/NB Clark/Gleeson/Bett Homes/David Wilson/Gentoo/Kendalcross/FHM/etc etc the gas will be in the joists....... (I would guess)

Edit.... if yours is timber frame (very new last 2-3 years) the gas will 9 out of 10 times be in the floor. This is because the only other ways to run gas in these properties are surface mounted (looks crap) or TracPipe(costs a fortune)

 

[GavThePlumber]

10 years of new build plumbing for nearly every big builder and I can tell you only Bellways ran gas pipes in the floor.

There must be regional difference to how the BCO wants and will accept for him to sign things off then, it is majority in the floor here and is normally marked out for us, due to us having to avoid radon sumps due to particularly high levels of radon gas in the area.