Wet room Preparation

[haveagohero]

If you think you are up to it then have a crack.

The membranes aren't overly delicate but what you need to think is that you are pretty much making a bowl out of the bathroom floor using the membrane to hold the water. If you have a bucket of water and make a tiny hole in it (or even a crack) the water will eventually drain out of it, same think with your bathroom floor.

Any natural stone is more difficult to lay than ceramic or porcelain and that is why tilers charge more for laying it, you need to keep it very clean when laying it to avoid staining, it needs sealing before and after grouting but the tile and adhesive need to be bone dry before you seal as this can cause problems, the tiles can vary in thickness, they have rectified edges so any lippage stands out a mile away. When tiling with natural stone, trims are not used so the edge of the tile on display will need finished in some way also.

I would definitely back skim the tiles. Back skimming gives a much better bond between the back of the tile and the adhesive the tile is being laid into it also stops any bond issues such as dust on the back of the tile from the slurry caused when making the tile.

[Ziggy1979]

Guys thank you both again for your help!

Royaloakcarpentry, I'm sorry but I'm a little confused by the deflection point you mentioned. Did you mean that deflection becomes an issue when the floor IS rigid (as will be the case with 25mm ply and 300mm screws) but that there isn't a whole lot that can be done about it?

I watched an Impey video showing how to fit one of their formers. They lay UFH over the shower former itself and tile without SLC. Is this normal when installing their products (eg is their UFH wiring more robust than others?)? I'd thought to not lay UFH in the shower area itself for safety reasons. what do you guys generally do?

Could the reason for tiling straight onto the UFH be to avoid SLC which would negate the drop created by the former if used over the UFH on the former? Also, would SLC make the rest of the bathroom higher than the former or is the height difference small enough that the former edge and bathroom floor can be made level again when tiling by using extra adhesive on the tiles which lie at former/bathroom floor meeting point?

Haveagohero, researching the tiling was next on the list - you paint a scary picture for the uninitiated re natural stone I guess planning, dry laying, patience and constant checking for level are in order. A couple of tilers had told me ages ago that with stone tiles especially they were guided by perceived straight (grout) lines as actual straight lines can't be achieved due to inconsistent tile sizes so you have to give the illusion that they're the same size and so laid straight. Tbh I'm more nervous here than with the tanking! :). Although we (wifey) still haven't decided if it will in fact be marble.

Royaloakcarpentry, thanks for the heads up. We wouldn't be buying them from B&Q probably some stone importer. Btw is limestone softer and/or any easier than marble. My wife also mentioned liking basalt and slate...gotta love them! ;)

[royaloakcarpentry]

Deflection is a problem when the floor is not rigid. Ply does not necessarily make a floor rigid enough to tile on. You walk on the floor, it deflects downwards and then upwards as you move away, this in turn loosens the tile grout and makes it pop out. In extreme cases, tiles will also pop up.

You can lay UFH in the shower area. You can put a slurry of rapid setting flexible tile adhesive over it instead of SLC.

You do get stone which is the same size tile for tile. You also get it where sizes could be +or- 1mm, 2mm etc etc. That is the same right across the board for all tile materials. The way around it is to work in grids, as your tiler mates pointed out.

Marble is the progression of sandstone or limestone. Think it is Limestone, without looking it up. They, along with basalt and slate are all suitable. Bear in mind that slate may need grading and the chinese 5hit will delaminate quicker than quality slate.

[Ziggy1979]

Thanks for the explanation on deflection. I get it now! :). If there's no real bounce but you feel a little "give" (ie what you might normally expect with timber joists rather than solid concrete floors) would you bother trying to couple up some joists, insert extra noggins, etc or is it not really necessary? Also, are any specific grouts more forgiving over time?

It's funny what you said about the slate. About 8 years ago we were buying black granite and we were told of similar stuff with the Chinese one. At the time (possibly still today) they were dying it to make it blacker like the more expensive grades. Apparently it could take as little as a year for the staining to start washing off leaving a much lighter shade of colour!

[royaloakcarpentry]

It is experience that gives you the feel as to whether a floor is stable enough to tile on.

You can do a water test though. Glass of water full to just below the top and if any spills out whilst walking around, it isn't stable enough to tile onto.

You need flexible adhesives and flexible grout when tiling over timber floors.

In the case of a wet room, you are better of with an epoxy grout.

[haveagohero]

I would also say epoxy but this again is a lot more difficult to work with than cement based grouts

[Ziggy1979]

Ill have a read on epoxy grouts...thank you both again!

Anything in particular that makes it harder to work with - does it cure faster, hard to mix or clean up after,etc?

:)

[haveagohero]

Goes off quicker, harder to clean down and clean off tile faces, once its dry you will have a hard time shifting it from anywhere it isn't meant to be

[Ziggy1979]

Yikes...could I get away using something a little more newb friendly without massively compromising quality? Alternatively, should I apply in small sections and clean excess off quickly, etc - basically is there any advice or best way to go about applying it to not come unstuck at that point?

Thanks again!

[royaloakcarpentry]

Epoxy is much more user friendly now, than it used to be.

Just looked at a bag of BAL grout yesterday to see how long you have to leave it before using a power shower (normally use Nicabond and it is 24hrs). The BAL is a lot longer but I did notice it can be used for swimming pools.

So go with BAL cement based grout......happy days.

Just leave it for 14 days to cure before using the shower, though.

[Ziggy1979]

Awesome! Thanks!

[Ziggy1979]

Hi Guys...I'm back ;)

Just a quick one...I've been looking through the Aqua Dec Linear 2 spec and it says its 22mm thick to be used with 22mm floors/subfloors. You guys recommended 25mm ply+backer boards which I will definitely do. However, there will be a 3mm+backer board thickness (6mm?) (ie min 9mm) step between the former and the subfloor. How do you guys fix this so that the edge of the former is level with the subfloor - I'm thinking ply under the former but would rather check with you guys!

Thanks again!

Z :)