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Raised floor in wet rooms


jamiehamy

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Hiya all, 

 

It's getting near that time where I have to raise the floor in two of the bathrooms - one for the shower space and the other a platform for the bath and through into a wetroom/shower area. 

 

The bath is heavy - 180kg and the shower bases will be 25mm Lusso stone. 

 

My thinking thus far is to build a frame up using 3 layers of 45x95mm at 300 centres with WBP ply glued and screwed. I would ensure gaps for the shower and bath wastes are inbuilt. 

 

Any hints or tips for this approach?

 

Thanks!

 

J

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WPB varies in quality so perhaps shop around to compare. Will also need priming before putting the stone down. Many people suggest using PVA to prime wood but  some places advise against as water can soften PVA. Perhaps consult the tile adhesive makers like BAL.

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  • 2 months later...
On 4/19/2017 at 20:53, recoveringacademic said:

 

Ditto.

@NickfromwalesApologies gents, I never saw the responses on here.

 

The floor is a concrete topping and the pop-up soil pipes are not in great positions (but as per drawings). With a bit more experience and confidence in what we were doing (2 years ago now!) we could probably had the right 40mm waste pipes popped up through the concrete in the right places with shuttering, but we didn't (did for our en-suite for some reason!). Although tbf to us, we had no idea what sort of baths or showers we were going to get, although we could have left cutouts in the concrete I suppose, but they weren't in the drawings. 

 

Where we are is that we have a 110mm soil pipe popping up we need to connect the showers wastes to(andtoilets and sinks). However, the architect has specified an AAV on both which means we can't connect without a raised floor? - which we actually don't mind anyway, particularly in the main bathroom where the whole shower and bath will be on a step up with uplights. 

 

I've attached the drawings for the two affected rooms - red being the room, orange being bit proposing to have a step up. 

 

Ayy thoughts? Be gentle!

 

 

bathrooms.jpg

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@jamiehamy

Ok cheers for the update :)

What is the invert ( the distance between the bottom of the outlet on the WC pan, to the bottom of the soil pipe where it reverts back to horizontal after the fall ) as you can petition not to have an AAV on the stack if the invert is, iirc, less than 1300mm. You can further reinforce that petition by fitting an AAV ( anti-vac ) trap on the basin so you have air admittance there. 

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19 minutes ago, jack said:

Which one is yours? :P 

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Pretty uncommon I guess to sink the bath so there's no height difference between tiled floor and floor of the bath? 

 

Less chance of the elderly overbalancing, easier to get your leg over etc.

 

;)

 

 

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18 minutes ago, Onoff said:

Pretty uncommon I guess to sink the bath so there's no height difference between tiled floor and floor of the bath? 

 

Less chance of the elderly overbalancing, easier to get your leg over etc.

 

;)

 

 

 

Years ago, a boat builder friend decided to try and optimise the space in his very tiny bathroom in his cottage.  He moulded up a large GRP box, then made up a rotating bath/washbasin and worktop contraption that fitted to bearings at either end of the tray.  The tray was recessed down into the floor and had a drain running from it.  It worked pretty well, as it allowed both a bath and a washbasin and worktop to be fitted into the same space.  Most of the time it was just a toilet and washbasin, but if you wanted a bath you just undid the lock, swivelled the thing over so the bath was on top and locked it in place again.  The taps were on the wall, so worked for both the bath and the washbasin.

 

He managed with it for years, but had to build a proper bathroom when he got married..................

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On 7/11/2017 at 11:39, Nickfromwales said:

@jamiehamy

Ok cheers for the update :)

What is the invert ( the distance between the bottom of the outlet on the WC pan, to the bottom of the soil pipe where it reverts back to horizontal after the fall ) as you can petition not to have an AAV on the stack if the invert is, iirc, less than 1300mm. You can further reinforce that petition by fitting an AAV ( anti-vac ) trap on the basin so you have air admittance there. 

Hi Nick, 

 

So none of the 3 are greater than 900mm from bottom of outlet to the horizontal revert. Is this the type of trap I'd be looking for then? http://www.screwfix.com/p/mcalpine-antisyphon-bottle-trap-white-40mm/20226 

 

I've had a good check and for the main bathroom, I'm happy having the bath raised anyway with the shower, For the guest en-suite, the soil pipe is in such a rotten location that we'll have to raise the shower tray to get the toilet soil to meet it - slightly unfortunate but not end of the world. In our en-suite it's all fine and shower tray will be flush with the floor tiles. 

 

For the bath *arriving tmrw but got sometime before planning to fit) - it's a stone resin one - 4x2 at 300 centres best? This might be a daft question but I'm assuming we tile the whole area under the bath bar the area for the waste connections and then place the bath on top? Don't fancy tiling an oval but the weight of the bath makes me worry about tiles cracking?

 

Jamie 

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image.thumb.jpg.f6a3f2a7798269e9577d53c193fe8b92.jpg

 

Ignore the mess, but that gulley ( square ) is where the waste will exit from the centre of the stone resin £3k bath that will reside there, all 88kg of it. 

When full of water, and a human being is sat in it, I recon a good 330-350kg needed to be allowed for. 

I beefed the joists up to offset the extra weight and then simply 22mm P5, 9mm plywood ( PVA glued and screwed at 100ish mm centres ), and then tanking membrane, UTH, adhesive and tiles. 

The only thing that would cause cracking would be movement in the subfloor. 

Firstly, is your bath a claw feet bath or mounted flat on the floor?

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o.O That's a whopper. 

If your floor is still up then I'd suggest some full depth noggins as I did on this job. IMG_5984.thumb.JPG.0793cbb02b42397450c5472c0bcf7b32.JPGIMG_5985.thumb.JPG.c3da85edab2d287e6eb8f619ae35bbeb.JPGIMG_5988.thumb.JPG.97a318b456b68d4154eb69367905f3c1.JPG

 

As these Ee kinds of baths require you to mutilate the floor to get the trap accommodated, I decided to go back to the drawing board. I didn't like the tanked floor having a bloody great big hole in it so I decided to put a 110mm storm water gulley and trap and make that off to the tanking membrane. The idea being that the coin flip waste on the bath just has a thread extender fitted to it as a dip pipe and that simply directs the bath water straight down into the trapped water below. Rodding will be a piece of cake and the flow rate that it will handle is crazy.  

This is the first time I've done one like this but what's not to like? ?

The tiles will get Sikaflex'd to the membrane to keep it all hydraulically tight, and a ring of SFx will go under the bath to 'seal the deal' by bonding the bath to the tiles, thus leaving no escape route for the water if it ever blocked. Not that it will....it's chuffin 4" dia!  

Couple more 50p sized blobs of SFx at 6 to 8 locations under the bath and it should be bombproof, and the fastest emptying bath in Britain. Wales at least ?  

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