plying over uneven joists.

[Versatile69]

I've done few bathroom jobs in the tiling world now, and have come across problems when taking old floor boards up in old houses esp in bathrooms. When I lay and screw down the ply ready for tiling it always tends to bow down in the middle or wherever the main traffic area is.

I always tend to "blob" the tiles up where it droops, but i know the the addy only has a certain tolerance when doing this.

Would i be better off putting wooden spacers under the ply and offering it up to level? Or should I be using self leveling.

Basically need advice which is the cheapest and easiest option and one that isnt going to come back and bite me on the :yikes:.

 

[DHTiling]

Mapei fibre plan is suitable for levelling timber floors...

 

[Versatile69]

Thanks for the advice, but it says this product is for cermaic and naturalstone tiling only, can I use porcelain tiles on it?

 

[grumpygrouter]

Thanks for the advice, but it says this product is for cermaic and naturalstone tiling only, can I use porcelain tiles on it?

Porcelain is a ceramic tile only fired at a higher temperature and pressure, so in answer to your question, yes you can. it is the adhesive that is important with porcelain tiles, you need to use a flexy adhesive and flexy grout. if your ply is "bowing" though, that might inidcate a deflection problem and you need to sort this out first!

 

[Colour Republic]

Hi ya Versatile,

I'd go for SLC, Mapei Fibreplan as Dave says is very good on timber floors

Can I ask what you mean by 'blobing' the tiles, do you mean dot and dab?

 

[doug boardley]

go for slc mate, the problem with shimmying timbers is that the shimmies can work loose sometimes

 

[TJ Smiler]

Sorry to open up such an old thread but i am currently in a bathroom where the joists are out of plumb (badly) Have checked to see if they are damaged or rotting or worked loose at one end but they are fine and set at 350mm apart...... I'm not a lover of going down the shim root and would normally screw 18mm ply and then either SLC or 6mm Hardi.

The trouble is with this job i am completely governed by a height restriction and doing it either of these ways will bring me above the height. I am thinking that maybe i could use a 12mm ply (if i drop extra noggins in) then SLC with fibre latex (Webber) in order to hit the height, flatten out and remove deflection (like i say i know i would have to put a ton of noggins in) Whats your thoughts/suggestions please lads/lasses?

Never used 12mm ply direct to joists before so not sure of it's boundries.

Thanks all

 

[Concrete guy]

I'd be inclined to bolt new joists in parallel to the existing, but sorting our the level problem at the same time.

It removes a great deal of faffing and probably wouldn't cost any more in the long run.

5x2 timber would be enough for this (6x2 would be belt and braces). Coach bolts would be preferable but I've done a similar thing with timberloks and they worked a treat and were far less hassle.

 

[TJ Smiler]

Great idea mate, the trouble is there are an absolute ton of pipes running all over the place (this is the same job as the one with the door frame you helped me out on). Would be a hell of a lot of chopping the wood up to fit in between the pipes.

Having second thoughts, the only reason i am not using 18mm ply and then fibre latex is because the one i use by Webber has to have a minumum depth of 10mm when poured over timber..... If i could get that down to 5mm i would be within the required height and could do the rest with the addy (thinking 7001) Any ideas of latex that can go as shallow as 5mm on timber?

 

[padtheplumber]

I've had some Tilemaster SLC from Tiletown a few weeks back - I'm pretty sure the minimum depth over timber was 4mm