Substrates...

[Rich]

I have put a few posts up on here about tiling differend substrates and have got some suprising replies. So I wanted to put up some info on different surfaces for tiling onto, to help others on here and also to get some feed back from the old hands. Il leave out the technical bits and let the guys much more in the know than I to add as they see fit...

Structural backings (Walls)
These are parts of the building, most of the time this is brickwork. Brickwork is a suitable surface to tile onto as long as proper preparation is carried out but is often not flat enough.

Insitu Finishes (Walls)
These are finishes that are applied to the wall to bring it into line. Plaster and sand and cement are the most common types of insitu finish. Good sound plaster is one of the best surfaces to tile onto. Render has a recommended max weight (tiles, adhesive and grout) of 40Kg per M2.

Preformed Backings (walls)
These are backings that are manufactured elsewhere and bought at the desired thickness. These are usually plasterboard, chipboard,Plywood and backerboard etc. These can be very good surfaces to tile onto.
-Plaster board is a very good surface to tile onto also as it is flat and can hold a lot of weight, bare plasterboard has a recommended max weight of 32kg per m2. Tile adhesive bonds better to plasterboard than plaster, so bare plasterboard is a far better surface to tile onto than plasterboard that has been skimmed. Skimmed plasterboard has a recommended max weight of only 20kg per m2.
As a rule of thumb, avoid fixing ceramic tiles thicker than 12mm onto bare plasterboard and 8mm if the plasterboard has been skimmed (bare in mind that porcelain and stone can be a lot heavier than ceramics).
-Ply wood must be boil and water proof and of exterior grade, ply that has been treated with resin or fire proofing chemicals are often not suitable to fix to as the chemicals make bonding difficult.
-Tile backer boards make a very good surface for tiling onto as they are the only performed surface that has been designed for the purpose. Unlike ply and plasterboard, tile backer boards are not effected by water, so any moisture that finds its way through the grouting or from behind will cause little or no problems to the board. Backerboards do not need to be primed before tiling and (Marmox) tile backer boards have a recommended max weight of 64kg per m2

Sand and cement screeds (floors)
Good sound screed is one of the best substrates to tile onto. All screeds must be left to cure completely before tiling to allow the screed to shrink as it dries and to allow the screed to dry, as moisture released from the screed will cause problems with bonding and grouting. As a rule sand and cement screeds must be left for at least 3 weeks (depending on thickness and environment) before tiling with standard adhesives. There are ways around this is it is not possible to wait this long but nothing is as good as letting it dry naturally. Before tiling all cracks in the screed need to be repaired by cutting out any loose screed and filling any holes with a sand and cemen mix. Uncoupling membrane (Shluter Ditra) can bridge gaps of up to 3mm.

Insitu Concrete
This is fine to tile onto but is rarely flat enough or level enough to do so and more than often needs a screed or a SLC. Concrete needs to left for a min 6 weeks (depending on thickness and environment) before tiling. As with sand and cement screeds there are ways around this suchas uncoupling membranes and special adhesives but it is always best to leave it to dry naturally.

Anhydrite screeds
These can not be tiled over like sand and cement screeds. A process of removing the laitance must be carried out. Anhydrite screeds must be left for 1 day per mm of screed up to 40mm then 2 days per mm ontop of that.

Timber floors
More and more floors are being over laid with ply before they are tiles as it is reletively cheap, easy and can be installed by almost any trade. However ply in not an ideal substrate to tile to for many reasons. ply will rot when in contact with moisture and swells with water and temperature. This is made worse by people installing incorrect ply (treated or not WBP) or not installing it properly.

• The Ply must be BWP and exterior grade
• You shouldnt ever use ply thinner than 15mm
• If possible the ply should be left in the room it is going to be laid in over night before being installed
• The underside and edges of each board must be sealed
• The boards should be screwed (not nailed) down at 300mm centres (or less),
• The boards should not be butted up together, a gap of 2-3mm should be left between them
• The joints beween boards should be staggered and should not correspond to the joints in tiles laid ontop
• If there is and deflection in the floor after this it must be sorted out before tiling
• Some adhesive manufacturers advice to prime the top of the ply and others do not, check before tiling.

I use a 2-part adhesive when tiling on to ply but most tilers use a single part and have no problems. Ideally a ply wood floor should be covered with tile backer board, this will give about as good a substrate as possible.

Chipboard
I dont like chipboard

If unsure about tiling onto any of these surfaces, Id recommend putting up a post on here and getting advice from the experts...

[Dave]

Top post Rich..

[Rich]

Why thank you very much.
As I said I would like others to add anything they feel I have missed, It was only intended as an overview as I thought Id leave it to the likes of you and Ajax and the other experts to fill in the blanks.

[mikethetile]

a very good post

problem is these posts drop off the front page and the questions answered here are asked again and again

is it possible to make it a sticky

[Rich]

A sticky??

[Dave]

Maybe if we merge all of Dylante's ( Rich's) info threads into one, then i can sticky it..

If i sticky too many small threads then it takes up space in the top part of the said forum.

So maybe a name for the thread title and i can merge them..

[Rich]

Ah. Now I get it.
Il leave that down to you Dave, name it whatever you think

[Scott]

How about a FAQ section??

[whitebeam]

At the top of the page Scott there's a FAQ

[Scott]

At the top of the page Scott there's a FAQ

shows i never use the home page, just the updated list! #


Id use the arms too if i could get in!!!! (HINT!) lol

[whitebeam]

PM Dan or Dave for acsess or one of the mods can open the doors

[doug boardley]

only admin have the keys Mark

[whitebeam]

Cheers Doug

[Scott]

I did all that and registered on the website for tilers in my area etc but still cant get in?

Dont really wanna PM again as dont wannt be seen to hassle! I did ask if they needed any further info?

[whitebeam]

They won't mind, pm them Scott your've done a few posts

[doug boardley]

it's not a hassle mate, your post count is well up and above the normal "arms" requirement, I can only assume your pm got lost in the post

[Scott]

I PM'd Dave instead

[doug boardley]

Where's the door to the Tilers Forums Arms?

[Dave]

I PM'd Dave instead

Just need to details now..

I have left a pint in the pumps before that Doug drinks it all.