tiling oven floorboards and quarry tile

implosion

Hi ,

my kitchen floor is made up of floorboards on 4" x 2" joists and quarry tile on the sink end and at the chimney hearth (we had the chminey stack removed). So If I was to lay porcelain tiles on this floor, are the joists strong enough to take on the weight and how do I deal with different surfaces ?

Thx

justjohn

you will have too level it or step up the tiles around harthe.

What do you mean by the different surfaces???
Most ahesives will stick the tiles...

Would tend to lay ply and tile on the ply wood.

implosion

cheers JJ, my friend (who's had kitchen and bath floors tiled, said that different surfaces (floorboard and quarry tiles) will expand at different rates, and that job has to be done right otherwise a tiles will crack at the lines where floorboard meet quarry tile.

He said that the floorboards need to be boarded over with ply, but what do you do over the quarry tiles ? Glue the ply onto them ?

justjohn

i had to go over floorboards to harth with ply but the boards were nearly flush with harth. i just drilled the harth(which were covered in victorian tiles) and put rawl plugs in and screwed the ply to the harth. ....job done

All depends how flush your boards are to the quarry tiles...

depending on how uneven your floor is , will depend on the thicknes of the ply....

implosion

the quarry tiles are slightly higher ( say 2mm) at the joint, then start to slope downwards. So there will bulging effect. I know I could simple break them but would rather leave them in tact.

What thinkness of ply would you recommend considering my joists ? Is it worthwhile ripping out all the floorboard and putting 25mm ply instead, and then pouring a levelling compound over the quarry tiles I want to keep the gain in floor height to a minimum. Floor tiles seem to be 9-10mm thick, then there the glue thickness as well as the ply.

andyhop

Over board floor with minimum 15mm plywood Or take back to joists and board with 25mm plywood, Herringbone or extra timbers to prevent joists twisting

Use decoupling membrane to prevent lateral stress

Tile with a S2 adhesive such as Mapei Keraquick and mix with Latex plus

implosion

if going down the 25mm ply route, do I pour levelling compound on the quarry tiles, or just glue thin ply on top (The quarry tiles are really hard and couldn't easily drill into them)

andyhop

implosion wrote: »

if going down the 25mm ply route, do I pour levelling compound on the quarry tiles, or just glue thin ply on top (The quarry tiles are really hard and couldn't easily drill into them)

Are the quarry tiles well fixed?

I would personally removetiles and take back to substrate, Weberflex SLC can do 50mm depth in one hit

implosion

yes, they are pretty soild from what I can judge. So prefer to leave them in place.

In terms of the ply fitting, how far apart should the screws/nails be ?
Should the sheets be tightly butt jointed ?
And does it matter if joints all line (or should they be laid in half cross widths) ?

andyhop

implosion wrote: »

yes, they are pretty soild from what I can judge. So prefer to leave them in place.

In terms of the ply fitting, how far apart should the screws/nails be ?
Should the sheets be tightly butt jointed ?
And does it matter if joints all line (or should they be laid in half cross widths) ?

Screws every 150mm, leave 3mm between boards and try and stagger board joints

Other option is 6mm Hardibacker cement board, this is bonded with cement based tile adhesive and screws

implosion

Thx again andy, Went to local toppstiles. They do 600x1200 hardie boards for tenner each. Works out similar price as the 25 mm ply . Can the hardie board be glued on top off quarry tiles, or is the levelling compound still required? If no need for the weberflex, does that mean I dont have to concern myself with difference in lateral movement?