Extending elevated concrete slab floor over bearers and joists

[Hybrid]

Hi all,

Due to a lack of space we have extended our existing, rectangular shapped laundry by about 1.5 metres. Problem is, the original laundry floor is an elevated slab and the extended section is bearers and joists. I always thought I would just chuck down some 15mm compressed fibro sheeting and shortly after I would have a new Uncle by the name of Bob.

Now I have bought the sheet and started to think a bit more about it, I am concerned that the difference in flooring structure may expand/contract at different rates and the tiled floor that is eventually installed will end up cracking on the joint line.

Please see below to better explain the situation.



So I am after some recommendations how best to tackle this problem. I had thought about using lino instead of tiling but I really dislike lino. Not sure how well it would "hug" the sloped mortar bed too. I have never layed lino but I presume it is designed to be installed on a flat floor and not a sloped floor...

Opinions please

[Tools]

Set your tiles out from the join and have an expansion joint along its length.

Tools

[Hybrid]

Set your tiles out from the join and have an expansion joint along its length.

Tools

That idea had actually crossed my mind, thought I didn't realise that you could put in some sort of expansion joint for tiling.

Thanks for the tip, I'll go and read up on expansion joints.

[Dirty Doogie]

If the framing for the extension is solid and doesnt have any bounce I dont see that you'll have any major problems. As said above , an expansion joint in the tiles, or even a grout line in the tiles over the critical point would suffice.

be sure to use a tough waterproof membrane with bandage and bond breaker over the join in floor. Then simply scree normally and tile with a grout line over the floor join. scrape out any tile glue in the tile join and instead of grout use silicone or polyurethane sealant.