Questions about tiling a floor.

[foxhole]

I agree, and any leak in the kitchen is liable to turn chipboard to mush or expand and pop off the tiles.

 

[tpt]

if, for whatever reason your going to ignore the good advice so far due to height\cash constraints etc then consider another option.

Instead of overboarding with 6mm ply and wasting your money, overboard it with backerboard - take a look at http://www.nomoreply.net/

its designed to go over floorboards, and its 6mm at the thinnest. you glue it down using no more nails type adhesive, screw it down too (though its unlikely to bite too well into chip) and then tile over with flex adhesive.

You've got more chance of this lasting than ply.

All the options above are better than this, treat this as a last resort

 

[tictic]

screw exsisting chipboard down every 150-200mm to joists...which is easily done(follow the screws/nails that are already down,just give the line of screws/nails a tap with a hammer and you will hear if they are fixed into joists)..
clean/brush the floor
prime the area with sbr up floor then when dry across the floor..

use this...
http://www.bal-adhesives.co.uk/products/single-part-fastfle

run a line across the floor and up the walls to mark your joists..

using 6mm hardie boards or aquapanel or as tpt says no more ply..
follow mfr inst...glued and screwed/brickbond
and a good flexy grout..bal/weber/mapei/ardex....just make sure your spacing off tiles is within the tolerance off the grout off your choice/colour.

 

[kimbers]

Have managed to do something about the height issue and have gone for 18mm ply.

From looking at the chipboard, its difficult to tell where the joists are underneath as i want to screw into the joists where possible. There doesn't appear to be much in the way of nailheads etc which would indictae where they are.

Is there a easy way/tip for figuring out?

 

[tictic]

have you swept/cleaned the floor and maybe get on your knees and look for tell tales signs....

 

[kimbers]

Strangely enough the only telltale signs is the fact there seems to be nothing, no nails or screws.

The chipboard is 600mm wide x 2000mm long & interlocking.

I'm assuming the joins between the chipboard sits on the joists themselves, which i assume are 600mm apart??

 

[Richard C]

Strangely enough the only telltale signs is the fact there seems to be nothing, no nails or screws.

Perhaps there aren’t any; nothing would surprise me!

I'm assuming the joins between the chipboard sits on the joists themselves, which i assume are 600mm apart??

They won’t necessarily & that’s the whole pint of T&G crap board; standard joist spacing is 400mm (or 16” in old money). I’d still advise you take the lot up & start again.

 

[mikeyd]

Strangely enough the only telltale signs is the fact there seems to be nothing, no nails or screws.

Are you sure it's not a floating floor then?
In other words chipboard above insulation on top of concrete. No nails or screws anywhere.

Our house (built 1930's) has a concrete kitchen floor, which I was told by a builder was original. The rest of the ground floor is original joists and floorboards.