Questions about shower pipework

[amfisted]

Morning all

Just about to start my bathroom refurb. The rip-out commences a week tomorrow, though I'm doing it in stages: bath out, fit a shower tray and thermostatic shower with shower panels, and at a later date, replace the sink and WC.

Question is about what kind of pipework to use under the floor to feed the shower. I read here that its not wise ( for obvious reasons) to use copper compression fittings under the floor, so my first instinct is to use soldered copper. However, I've just been looking at a video on YT where the chap uses plastic under the floor, but copper up the wall to the shower valves. I'm wondering just how trustworthy plastic pipework would be under a floor, and whether forum members would recommend it. Its a suspended wooden floor, by the way, with a decent void underneath in a bungalow.

Another question is about the termination of the pipework where it exits the wall to the shower valve. I've noticed that some YT videos show the fitter terminating the pipework through a wooden board, presumably to give it some stability and a surface for mounting the valves. I was planning to channel the wall out and secure the pipes in the channel with clips then plaster up. Do I need a board behind the shower panel to provide stability for the shower mixer bar, or would mounting on a shower panel be sufficient?

Many thanks

 

[CountryFan]

Is this pipework going to be subjected to freezing conditions? If so, you'll need to insulate obviously and in which case I'd recommend copper.

 

[endecotp]

I'm wondering just how trustworthy plastic pipework would be under a floor

I think newbuild houses use plastic for just about everything.

 

[Madrab]

If it's just a normal indoor bathroom shower etc then plastic should be fine. Make sure it's got inserts and it's properly inserted and give it a tug backwards just to help bed the teeth into the pipe. What should be noted though is when bringing the pipework up the wall that it needs to be clipped regularly and properly and especially where it it will be exiting the wall.
Make the last few feet up and out of the wall in copper and use a soldered elbow. Clip it well so it's nice and secure. That will allow you to use a shower fitting kit and it's associated screws through the wall, without the danger of hitting a push fit elbow, which is considerably wider.

Fitting kits should use 50/60mm screws so you'll need to drill into the wall and use plugs. Better that way anyway to ensure the bar is nice and secure, the wall board, unless it's the really expensive 12mm backed PLY/MDF, isn't suitable to secure the fitting/shower securely enough.

 

[Madrab]

P.S. >>> If there is a large void or it's a stud wall then a wooden brace supplies a perfect mounting backer to allow the fitting kit to be screwed into. If the wall is tight onto brick though then that would normally be drilled and plugged.

 

[amfisted]

Many thanks for the responses, much appreciated.

I've decided to go for copper for two reasons:

1)Although I'm sure plastic is very easy to work with, I'm used to copper.

2) I've an (admittedly illogical) antipathy towards plastic because of an incident that happened a few years ago when two plastic connections parted from a shower fitting due to poor installation ( not mine) and caused a major flood in a previous house.

Also noted the remarks about insulating pipes where there's a possibility of freezing, and the very helpful guide to fitting the last few feet of pipework to the shower.

One last question: is it the case that the hot control on a mixer shower is always on the left?

 

[Scally-Ho]

The conventional UK plumbing layout is usually hot on the left and cold on the right

 

[Dereekoo]

The conventional UK plumbing layout is usually hot on the left and cold on the right

Which I believe is due to when it was just a cold hand pump for water the majority of people were right handed so cold is on the the right,right???

 

[Madrab]

Which I believe is due to when it was just a cold hand pump for water the majority of people were right handed so cold is on the the right,right???

Actually no - the current standard with hot on the left and cold on the right is primarily for people with impaired vision - it reduces the risk of scalds and burns if they know the hot tap is on the left.

 

[amfisted]

Just one more thing ( as Columbo might have said).

Pondering the best way to work out where to drill the holes in the shower board for the shower outlets. I'm thinking "cut the board to size, offer up to the wall, push slightly against the outlets ( perhaps with some tape on the inside surface) and hope that it leaves two nice neat circular marks on the back of the board". But I'm also thinking that not holding the board in quite the right place is possible and likely to lead to inaccuracy. Is there a better way?

 

[Madrab]

There are really only 2 ways to do it , cut the board to the pipe or set the pipe to the cut board. If it was me and I was fitting the board then I probably wouldn't cut the board to the pipe, I'd look to pipe up to the cut board. It needs to be 150mm centres and dead level. Figure out where you want the shower - height, position etc. Offer the board up to the wall and get it into it's final position. Then mark the board and cut the holes, then mark the wall through the holes and pipe the final part of the supply up accordingly. The board just has to go back in exactly the same place.

If It was a clients job then the cuts would be left to the joiner or tiler.

 

[Scally-Ho]

IMO it is always best practice to work via measurements. After cutting the back board to size and offering it up to ensure exact fit, measure where everything is going and then transfer those measurements to the board and then doublecheck before cutting. If unsure where to measure from, find yourself a fixed point and measure everything from that point, then you cannot go wrong

 

[amfisted]

Many thanks, both. All set for the start of operations on Monday, but I may well check back here from time to time with more questions.

Looking forward to it now :0)

 

[Madrab]

Only thing I'll add is it's much easier to adjust pipework if it's out, not so easy to adjust a wall board once it's cut.

 

[amfisted]

Only thing I'll add is it's much easier to adjust pipework if it's out, not so easy to adjust a wall board once it's cut.

Very good point, yes..