Adding a shower over bath

[Phil Addison]

I'm intending to put a shower over our bath. Question is what to do with the walls.

The existing walls were covered in painted hardboard glued to lathe & plaster by the previous owner. I've ripped it off leaving me with a slightly springy plaster surface. I'm going to put the shower over the end of the bath opposite the taps in the 'stud' wall along the lines of John Stumbles' wiki entry.

I have at present an open c/h system with 1.75m head above the proposed shower head; and in due course this may be changed to a pressurised system (possibly a combi). I think the head may be just sufficient for the time being as the existing combination mixer-tap + shower hose gives a usable shower though not power-shower level (obviously). Also the cold bath tap is fed via only 15mm, teed off the cold cylinder supply just before it enters the cylinder - not ideal! I propose to change this to a tapping on the cold tank in the attic (a la John's wiki again) fed horizontally to above the shower, then down the stud wall to the shower and down under the bath to the bath tap. I think it needs to be in

22mm to match the existing 22mm hot tap feed which arrives by an under floor route to the bath tap. The 15mm cold is noticeably underpowered when filling the bath to the extent the hot has to be throttled back 1/2 way. To improve the shower at a later date can I put a mains shower-pump under the bath or do electrical regs require a low voltage one? Alternatively could I put it in the attic if I intercept the cold feed to the DHW cylinder plus the new cold shower feed? i.e. the pump would be before the cylinder rather than after it, this having the additional benefit (perhaps?) of pressurising the kitchen tap which suffers a very long 15mm run.

Back to the walls, I'll follow the advise to use WBP ply for the shower end, but what about the side of the bath? Any preferences for just tiling the existing lathe & plaster or hacking it off and replacing with WPB, a nasty mesy job, or is that overkill? All subsequently tiled. I imagine the tiles will (hopefully) reinforce the slightly springy plaster.

What is the best way to seal the tiles to the bath (I know about 1/2 filling it with water)? Simple silicone caulking or use a proprietry plastic seal?

What about 'plastic' walls, what's that called, I have no experience of it.

Phil

[The Natural Philosopher]

surface. I'm

I think the

Also the cold

it enters the

in the attic

stud wall to

extent the hot

put a mains

Alternatively

plus the new

same prolly

Any preferences for just tiling the existing lathe & plaster

if its not flexible use it.

IOtherwise beef it up

My system, is to seal with silicone and tile OVER then then fill the gap with grout. Sure you get hairline cracks but no leaks

[Frank Erskine]

Lathe? Lath, shirley.

[John Rumm]

Leave them there ;-)

surface. I'm

I think the

Also the cold

I built a gravity fed shower for someone once with that amount of head. He bought a Trevi shower unit designed for low pressure operation. The results were adequate, in that lots of hot water fell out of it - just not with much enthusiasm. Better than an electric shower though.

it enters the

in the attic

stud wall to

There are a couple of ways of looking at this. The normal reason for the dedicated cold feed tapped off a little lower in the cold cistern than the feed to the hot water cylinder is to ensure if you drain the tank, its not the cold that runs out first. The reality is that with so little head you are unlikely to achieve the flow rates that would make this possible. Couple this with the fact that most modern thermostatic showers also have automatic shutoff if the cold fails.

extent the hot

put a mains

Alternatively

As long as "under the bath" needs a tool to access, then its outside the zones and a mains pressure one is ok.

Pumps typically work best when close to the cylinder, however this is more important with more powerful pumps.

plus the new

You can't really pump cold water into a vented cylinder. It will just pour out of the vent pipe back into the cistern.

Most preferable would probably be one of the cementious boards designed for the purpose like aqua panel. However WPB would be the next best option.

You could alternatively render the existing wall with a SBR sand and cement mortar - that will also give a reasonable waterproof backing.

(the least desirable would be plasterboard)

The trick to successfully sealing is to make sure there is enough space for the sealant. i.e. don't tile down to the bath and then hope to add a small fillet of silicone in the corner of the join. Its better to seal the wall to the bath, then tile down to a tiles thickness above the bath. Fill the bath and then fill the full depth of the gap and profile the protruding bit of silicone bead. Once dry, let the water out. That keeps the seal under compression in the gap, and far less likely to lose adhesion and pull away from either side of the joint.

There are various panels made for construction of showers. Corian is one such material, but there are others. They often have the advantage of coming with a decorative finish, so they need no further tiling etc.

[John Rumm]

Don't want a lathe in the shower - it will rust!

[Lobster]

I've installed

in our shower cubicle at home - it's basically vinyl-faced plywood which comes in sheets of (IIRC) 8'x4'. You can apply it direct to the studs, and it makes a very nice finish; looks good and much easier to keep clean than grouted tiles.

Not particularly cheap though (though there are cheaper suppliers; and I suppose you need to compare the cost with reasonably high-end tiles) and I found it very scary cutting the panels to size - one wrong cut is an expensive mistake! Took me a long time to do, as well; I found the instructions and method quite fiddly and awkward to understand - I feel it's aimed at pros rather than a one-off DIY installation (for sure it would take about a third of the time if I had to do it again now).

David

[The Natural Philosopher]

I assumed there was an old Myford entombed there

[PeterC]

Well said, my son!

[Phil Addison]

Ooopsh sho it ish

-- Phil Addison

[Phil Addison]

Nice description, it'll be a pump then!

it enters the

in the attic

stud wall to

That's good news. So perhaps I could put the pump in the linen cupboard after all, and the existing 15mm feed would cope if its pumped? Access under the floorboards to change it to

22mm is near impossible at the mo. Its easy enough to bring a connection down from the cold storage to avoid the existing sharing of the cylinder inlet.

I put a mains

Alternatively

Good.

Due to the damping effect of the weight of water they are pumping into? Oscillatory damping, that is :)

plus the new

after it, this

which suffers a

Duh, I should have known that!!

lathe & plaster

slightly springy

Is aqua panel any easier to handle and cut than wpb? Cost?

It's marginally stable lath & plaster now. I'm assuming the best but messy way is to strip it off and fix a new backing board to the studs. I suppose I could fix the backing board over the existing plaster but that feels like a bodge.

Point taken.

Sounds good.

Probably best if I stick with tried and tested diy tiling.

Thanks for the input.

[John Rumm]

Much depends on the sort of shower you like... if you gravitate toward the big soaker head, being in a all enveloping hot rain storm kind of sensation, then you won't need a pump. If you want something to massage and exfoliate with a pressure washer like sensation, then you need a

*big* pump!

it enters the

in the attic

stud wall to

all, and the

change it to

Yup that will work fine - 15mm has adequate capacity for most showers. Using bigger pipe just means longer to wait for hot water.

If you must get new pipes in, then its surprising what can be done with a set of cable rods followed by a coil of speedfit ;-)

I put a mains

Alternatively

They blow better than they suck. If you stick a 3 bar pump on the end of a long pipe run it will probably cavitate and not work well. It needs a nice ready flow of water from the cylinder. With the more powerful ones you may need a Warix or Surrey flange on the cylinder (or an Essex one near to top on the side) to stop sucking air into the pump from the vent pipe.

Having said that, I did a stuart turner 1.8 bar pump for SWMBO's aunt once, and that worked fine without any changes to the cylinder. The cold cistern was in the loft about only about 6' higher than the cylinder.

plus the new

after it, this

which suffers a

Not only that, it will cause hot flushes ;-))

lathe & plaster

slightly springy

Not tried it personally... IIUC its heavy, but can be cut with an (old) saw.

Last one I did with a backing like you describe was with WBP ply which I then rendered prior to tiling:

think I would probably just go for the right board in the first place now though ;-)

is to strip

As long as the studs are sound and you can afford to lose 1/2" and inch of space, its a whole lot less mess!

It works if done right...

Might be worth costing against prefab panels though. (let me know the result - I need to do another shower shortly ;-)

[John Rumm]

Don't you love the way those photos always have an attractive and slightly damp female emerging from the shower or sitting on the bath. Never a hairy arsed bloke with a bear gut scratching his balls. Selling the dream and not the reality!

Can you recall how much a sheet?

What made it difficult?

[Phil L]

Can't comment on the plumbing side of things as I'm not well up on pumps etc, but it's your walls I'm concerned about.

Firstly, you'll only get one chance to make it good - you can't start ripping off tiles and re-doing stuff once the bathroom's finished...well you could but this is not what anyone wants.

Don't shy away from removing the lath and plaster - it's not a big job and if you line the bath with dustsheets, you can wrap them up and dump them outside with virtually no mess. Forget about the tiles re-inforcing the plaster - they won't, the plaster will still be springy and flexible but the tile grout won't be - resulting in cracked grout and water penetration in short time. Back to the L&P. You don't need to get all the laths off - you can board over these once the plaster's removed, which will save on some mess - the WPB can be screwed to the (now visible) studs, sandwiching the laths underneath. Then you can tile as normal, or if you are on a budget, you can use pvc cladding which I used in my bathroom 3 years ago and it still looks like new, and at £12 for 5m by 300mm T&G white, I think it only cost me £60 for the placcy and a fiver for adhesive. Like this but half the price from a local supplier:

advantages are: No grout lines to discolour. Wipes clean just like tiles Hardwearing and waterproof Locks together Installed in a tenth of the time as tiles Cheap as chips, so eventual replacement isn't as daunting Plain white so won't look 'out of fashion' in a few years time

[Lobster]

Just checked my records, and I used this retailer:

(or

- most economical (and I use the term loosely) method was to buy a kit for £400 or so which was all materials, joints, sealant, adhesive etc needed for my 1200x900mm shower. A 8'x4' sheet on its own is about £100.

Terror was probably the biggest single factor - doing something wrong and writing off a £100 panel so much head-scratching, checking, double-checking before making any cuts or trims, drilling holes etc!

But for example, my shower is in an alcove approx 1.2x2.2m high, and of course none of the corners are perfectly true, so you have to trim the back panel to slot into that rectangular hole pretty well perfectly; very little margin for error. I'm sure a more competent and confident joiner than me would have had it done much quicker!

I didn't find the instructions particularly clear, either TBH (you use bespoke extruded alumiumium joints in the corners, and more bespoke trims/seals at the front edge, shower tray and ceiling)

David

[Phil Addison]

before it enters the

tank in the attic

the stud wall to

in 22mm to

to the bath

after all, and the

change it to

What happened to Hep2O, last time I was doing diy that was all the rage!

can I put a mains

one? Alternatively

Sucking in air will be a function of the actual flow rate achieved surely? I can appreciate problems with a big pump trying to work into a high resistance tho; but don't the manufacturers give a flow vs head characteristic so one can predict the performance, like the c/h circulators offer?

I'll have to start collecting pump info. Any favourite ones, or ones to avoid?

cylinder plus the new

after it, this

which suffers a

I wasn't going to connect it to the bog!

end, but what

lathe & plaster

slightly springy

way is to strip

backing board

[Phil Addison]

Actually there is a complication, and I might just do that. We are having guests staying in 3 weeks and I have to get it servicabel by then, but ultimately I want to pust the long bath wall 18" into the next to room to make the bathroom a bit bigger at the expense of the adjacent room, so I'm warming to your ideas below.

This is true, I must admit the dust will be confined to the bathroom so not at all insurmountable.

There isn't much springiness but I do tend to agree tiling on it isn't a good idea.

I'm warming more and more to this.

out. But is it really the PVCu Soffit Board that you used? And did you run it horizontally or vertically. I'll pop along to Wickes and have a look at it.

Hmmm... back to the drawing board.

-- Phil Addison

[John Rumm]

Still available, just for some reason I have always preferred speedfit.

Yes in the sense that if you are pumping into more flow resistance, the required delivery rate to the pump will be less. The main issue is that you are depending on gravity to feed the pump and so need as little flow resistance there as possible.

They do normally - e.g.:

> Having said that, I did a stuart turner 1.8 bar pump for SWMBO's aunt

Not used that many. Stuart turner always seem to get good reviews, and I think quite a few in this group have had good results with them.

[Phil Addison]

tho; but don't

performance,

shower resistance to draw the load line on it. Looking at a random Mira spec sheet its lacking the corresponding flow vs pressure chart or any hint of resistance; just states inlet is required to be maintained at 0.2 to 5 bar LOL. So if they are all like that choosing the optimum* pump sounds a bit of a guessing game.

*Adequate but not too much pressure (excessive noise etc).

[John Rumm]

tho; but don't

performance,

Depends really on what you want from a shower...

With most "normal" showers (i.e. not a soaker head, or something with body jets), most of the flow resistance will be at the shower head unless its miles from the pump, so you can mostly discount the pipe run I would expect.

Reports from aforementioned aunt were favourable regarding the 1.8 bar one. Although her sprogs said it was "much better" but could still do with even more oomph (this may just reflect the fact they were not paying for the water or heat!) IME by the time you reach 3 bar, then you are comparable with most mains pressure showers. In my previous place, we had about 3 bar from the mains through a combi, and that was a very good shower - you did not really need full throttle on the controls. In this place we have a slightly knackered Aqulisa power shower (knackered in that the "power" bit has never worked, but the mixer section was ok). I have just shifted that over to high pressure operation (3.5 bar), and much to my relief it did not immediately spring a leak or fly apart. Tap full open on that is getting on for excessive now.

None of them are particularly quiet - although its more of a problem for the people not in the shower! Mounting them in such a way as to stop them "sounding" through the building structure (most come with rubber "tails" to make the final joint to the pipework to stop them shaking that) helps. Possibly even screw them to a concrete slab, and then sit that on some foam rubber.