Bathroom tiling project

[ThePistol]

Hi,

I've read the tiling sticky and various older threads in the forum, and would be grateful if any experts could clarify a few things before I start ordering materials.

Essentially, I have just about finished stripping the plaster from the room. My intention if to use standard plasterboard on the ceiling (to be skimmed then painted), cement based backer boards behind the shower (& around bath?), and moisture resistant boards every where else. I will be fully tiling all walls.

What I wanted to know is whether this sounds right, or whether I would be better off using different types of board anywhere. Also, would i need to tank the boards behind the shower / bath, it using cement based boards and waterproof adhesive & grout?

Thanks in advance

 

[Richard C]

What you propose sounds OK to me. Make sure you mechanically fix boards you are tiling onto, don’t just rely on dot & dab or the whole lot could end up on the floor. If you use a decent cement based backer board, no real need to tank it unless you have a high power, multi-jet shower or are constructing a wet room. Tape the board joints & fill with adhesive before tiling working it well into the mesh. Avaid any board joints coinciding with grout lines as far as is possible.

Waterproof adhesive/grout is standard procedure but apart from expensive epoxy based products, it’s only waterproof to the extent it won’t disintegrate when wet, it’s not impervious to water.

What size/weight/type tiles are you proposing?

 

[ThePistol]

Thats great - thanks.

Yes I will be mechanically fixing all the boards - two walls are stud anyway, and I've already battened out the other two, and fitted insulation between.

When you say no need to tank, would this also be the case for the moisture resistant boards, which would be everywhere but behind the shower / bath?

The tiles are generic floor / wall tiles - 450 x 450.

 

[Richard C]

When you say no need to tank, would this also be the case for the moisture resistant boards, which would be everywhere but behind the shower / bath?

No need to tank MR PB unless it’s a wet area i.e. around bath or in shower enclosure; however if you want to plaster MR PB, it must be primed first.

The tiles are generic floor / wall tiles - 450 x 450.

Nothing generic about 450 x 450mm tiles, they are pretty big for a wall; what are they made of & do you know the weight per sq/m? If not what thickness are they? You will have a weight limit of 32 kg/sqm over raw plaster board, 20 kg/sqm over plaster but this includes > 4 kg/sqm for the adhesive & grout & the addy must be cement powder on that size tile, not tub mix. Gypsum PB or plaster must be acrylic primed when using cement powder adhesive which will need to be flexy.

Not thinking of tiling the floor by any chance are you?

 

[ThePistol]

No need to tank MR PB unless it’s a wet area i.e. around bath or in shower enclosure; however if you want to plaster MR PB, it must be primed first.

That's fine - will be tiling straight to the boards, so no issue there.

Nothing generic about 450 x 450mm tiles, they are pretty big for a wall; what are they made of & do you know the weight per sq/m? If not what thickness are they? You will have a weight limit of 32 kg/sqm over raw plaster board, 20 kg/sqm over plaster but this includes > 4 kg/sqm for the adhesive & grout & the addy must be cement powder on that size tile, not tub mix. Gypsum PB or plaster must be acrylic primed when using cement powder adhesive which will need to be flexy.

Well each pack of 7 (which should cover 1.41sqm) weighs 25.9kg, so I make that about 18 kg/sqm, so should be ok based on the numbers above.

In terms of primimg though - would that apply to MR / aqua panel boards as well?

Not thinking of tiling the floor by any chance are you?

You're good

What gave it away..?

 

[Richard C]

In terms of primimg though - would that apply to MR / aqua panel boards as well?

When using cement powder adhesive you will need to acrylic prime plasterboard but not the Aquapanel (unless specified by your chosen adhesive manufacturer) as it doesn't contain gypsum. Priming is required with gypsum based plaster or plaster board to prevent a reaction with cement in the adhesive; same applies to gypsum based anhydrite floor screeds.

You're good What gave it away..?

If someone is tiling the walls of a bathroom, usually odds on they will be tiling the floors as well.

Is it a concrete or suspended timber floor? & what’s it made up of. Suspended timber floors need special consideration with regard to joist size/pitch/span & floor construction which ultimately determines its rigidity; correct preparation can also be critical; it’s easy to make disastrous & potentially expensive mistakes which can lead to early tile failure. It’s also important to use only quality trade tilling materials of the correct type for your tiles & tile base, cheapo own brand & DIY stuff is mostly crap.

If you intend similar size tiles you will need a perfectly flat floor to avoid problems with laying & to ensure the finished result looks good. Powder cement adhesive only of the correct type for your tiles & tile base & you will need a large format trowel.

 

[ThePistol]

When using cement powder adhesive you will need to acrylic prime plasterboard but not the Aquapanel (unless specified by your chosen adhesive manufacturer) as it doesn't contain gypsum. Priming is required with gypsum based plaster or plaster board to prevent a reaction with cement in the adhesive; same applies to gypsum based anhydrite floor screeds.

Ok - thanks. Guess I'd better buy the adhesive next to make sure I know what else I need to get. Given your point about using quality products, are there any brands you'd advise getting / avoiding?

Is it a concrete or suspended timber floor? & what’s it made up of. Suspended timber floors need special consideration with regard to joist size/pitch/span & floor construction which ultimately determines its rigidity; correct preparation can also be critical; it’s easy to make disastrous & potentially expensive mistakes which can lead to early tile failure. It’s also important to use only quality trade tilling materials of the correct type for your tiles & tile base, cheapo own brand & DIY stuff is mostly crap.

If you intend similar size tiles you will need a perfectly flat floor to avoid problems with laying & to ensure the finished result looks good. Powder cement adhesive only of the correct type for your tiles & tile base & you will need a large format trowel.

It is a suspended timber floor, but fortunatley that is one bit I have understood all the other advice on! My intention is to take up the existing floorboards, build up the joists where necessary to level the surface, then replace with 25mm wbp ply, with noggins between the joists at all of the joints.

 

[Richard C]

Ok - thanks. Guess I'd better buy the adhesive next to make sure I know what else I need to get.

Easy to get caught out if inexperienced so always best to do your research before you start.

Given your point about using quality products, are there any brands you'd advise getting / avoiding?

BAL (which I use exclusively), Ardex, Webber, Mapei (but not the Buildfix one in BNQ) will do you fine & there are others. Avoid “own brand” products & DIY shed stuff which is usually cheap crap aimed specifically at the DIY market; one that starts with “Uni” also comes to mind!

It is a suspended timber floor, but fortunatley that is one bit I have understood all the other advice on! My intention is to take up the existing floorboards, build up the joists where necessary to level the surface, then replace with 25mm wbp ply, with noggins between the joists at all of the joints.

Replacement is always my preferred option as you know exactly where you stand as far as covering any warranty goes. You may get away with 22mm or even 18mm in a low load/traffic area such as a bathroom but it depends on joist size/pitch/span; post back if you need further advice.

 

[ThePistol]

Bit of a bump, but I've now made some progress and am ready to push on, so a bit more advice on the floor would be appreciated:

The joists are 7" x 2", spaced at approx 40cm centres. The joists run the length of the room (2.4m). I intend to go for 25mm wbp. I have read that the back & edges need priming - but what with? Would the acrylic primer (BAL APD) I have got for priming the plasterboards do the job?

And what prep is needed on the top surface before tiling? I will be using BAL rapidset flexi if this makes a difference!

Thanks in advance.