Fitting synthetic marble shower base.

I'm fitting a synthetic marble (Marbletrend brand) shower base 250mm off the slab so I can run the centre outlet to the corner drain (couldn't find a base with a corner outlet). I was told this type of base was rigid enough for mounting on hebel blocks at each corner. However, the instructions clearly state the entire base needs to be supported. Could anyone advise what sort of support I should construct for this base? Will it need to support the entire area? I definiteoly dont want to be building up the slab with cement by 250mm.

If you only support the corners and it should crack, then I'm sure you can guess who'll have to wear the costs. It won't be the bloke who said you can just support the corners... unless you're paying him to install it (and know how to contact him in future! ;) )

Building up the slab wouldn't be my choice either, especially if you ever need to alter the plumbing at a later date. You may be able to get away with making some box-work and building up with sand instead, although you'd have to be damned sure it's thoroughly tamped down. Otherwise it'd settle over time and create a cavity... in which case you may as well have just gone the path of a couple of Hebel blocks. :rolleyes:

I'd be inclined to look at building a timber platform with a marine ply top; the joists could be angled to cater for the drain. (ie. they don't have to be at 90° to the wall.) The problem here is that the cavity would need to be vented, while remaining as waterproof as possible.

Personally I wouldn't be happy with either of the above, but I assume the existing drain's embedded in the slab? I'd much rather break out a portion of the slab with a jackhammer/conc. saw, refit the plumbing and do another pour, thus keeping the showerbase at normal floor height. But I guess that's a bit beyond the average DIYers skill/budget range. :(

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Originally Posted by Skew ChiDAMN!!

I'd be inclined to look at building a timber platform with a marine ply top; the joists could be angled to cater for the drain. (ie. they don't have to be at 90° to the wall.) The problem here is that the cavity would need to be vented, while remaining as waterproof as possible.
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Thanks SC

I was thinking along the same lines, maybe even placing the marine ply top on top of the blocks which would be set half way between centre and outside edge of the the shower base,

When you say the cavity needs to be vented, do you mean with a p trap? Cos that's taken care of in the centre bathroom drain, where the shower runs off to

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Originally Posted by JB

When you say the cavity needs to be vented, do you mean with a p trap? Cos that's taken care of in the centre bathroom drain, where the shower runs off to

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No... I mean the inside of the boxed in section should not be sealed up air-tight, it should be given some form of vent to get a bit of an airflow going.

Even assuming you've used treated timber & marine ply and waterproofed as well as possible, those materials are only water-resistant, not water-proof. So, you need vents to allow any dampness which does get through (and it will... water is pernickety stuff. ;) ) to dry out before it causes rot/mould.

Of course, you don't really want water getting in through the vents, so you should give some thought to their placement. ie. At floor level is not a good idea. ;) If you're stripping the lining off the lower part of the wall so you can fasten your framework to the studs, you might be lucky... in a brick veneer house, if it's an outside wall there's often enough gap between the studs/top plates and brickwork to permit an air flow. Depending, of course, on whether or not there's insulation... and I'd still prefer to see a vent added. If it's on an inside wall, it takes some more thought to position a vent usefully, but not "in your face."

Geeze, it all sounds so complicated to write down, but it's really quite simple. :rolleyes:


Disclaimer: I should add that I'm not a tradesman. I'm a JOAT who makes much of my living going around cleaning up cowboys' messes. :o So the above is solely my opinion and although AFAIK it's compliant to the building code, I won't make any guarantees. My advice is only as good as the paper it's written on. :D

JB
do you want to raise the shower base up, or are you doing this to accomodate the drain? If the latter, it may be less work to chase the slab out and fit a "plumbdinger" or similar to offset the drain. Too hard to explain what they are, best bet is to go and check one out at a plumber's supply.

Skew,
what's a JOAT?:confused:

Mick

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Originally Posted by journeyman Mick

what's a JOAT?:confused:

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Jack Of All Trades... and Master Of None.

Comes from being a bushie. [shrug] I guess you could say I'm that most dangerous of all breeds: a chainsaw carrying, 'dozer driving, computer programming tree-hugger armed with a table-saw & shifter. :D

JB
you're working on a concrete slab
why not just build the height up with hebel blocks across the whole area, chase out a chanel for the drain and install the base on a motar bed?
I'd think this is much cheaper and easier than mucking about with marine ply, waterproofing, and a vent

ian

Thanks heaps for the responses. especialy Skew for your detailed plan.

Gotta say though that i like the sound of Ian's idea. When you say 'chase out' do you mean cut a groove for the drainpipe from the centre to the corner?

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Originally Posted by journeyman Mick

best bet is to go and check one out at a plumber's supply.
Mick

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I'll do that too

JB
that's what I mean,
but journeyman Mick might be on a better tack.
I think you'll want the smallest practical difference in level between the shower base and the bathroom floor

ian

I agree wholeheartedly with JMick's idea. That's how I would much prefer to see it done, although perhaps I didn't express myself clearly in saying so. :rolleyes:

Raising the floor level is a kluge. BTW, even with Ian's idea of Hebel blocks all the way (Good thinking! I'd never have thought of it.) you'll still need to waterproof it. Trust me, you do not want a damp area under your shower base!

If you chase the floor to get the pipe across,how are you going to do the connection to the base?

Tools

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Originally Posted by Tools

If you chase the floor to get the pipe across,how are you going to do the connection to the base?

Tools

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With a "Plumbdinger". :D I can't remember all the details, but basically they're made to solve problems like this, allow you to fit drains anywhere within a certain radius and final fitting involves some push in "o" ring type fittings.

Mick

You can also use a short length of flexible drain. I think that Tacron make a "flexible plumdinger"

Errmmm... yeah. Just did a google on Tacron and found their URL is http://plumbdinger.com.au/ ROFL! :D

Mmmmm. so I'll need to cut out a chanel with aconcrete saw and extend the pipe to the centre, then connect with aplumbdinger to ensure no leaks. Possible I guess. I'll also have to check 20mm into the bottom plate of the wall frame so the panelling comes down inside the rim of the shower base. Also possible, but a bit of a pain.

I'm thinking it might be quicker and less drama toraise the base, but I see the potential for water under the base. This incidentally is why I have to do the job—long term leaking had rotted the bottom plates and the bottom 18" of half a dozen studs not only around the shower but extending 8' along two adjoining walls.:eek: