EXPANSION! advice needed

[cam_low]

Ok straight to the point...I haven't had the need for expansion joints until now.

I mainly do bathrooms as thats what I promote.

However I have been to look at a job today where the builder has laid the tiles (51m2) in a "g" shape ish room. The tiles are not under the skirting boards....they have cracked around the narrowest part into the other "rooms"....there is underfloor heating and the screed has cracks from the one tile lifted that we can see.

I believe the builder fired up the heating full tick and has caused this problem. The tiles are 600x400 travertine and they will be getting replaced with something less rustic.

With this I believe expansion joints (same colour Silicon as grout???) are needed and I would believe that leaving a gap all the way around the room would not be enough. Where the narrowest part of the "room" is that meets the larger ones would an expansion joint on both sides.

Regarding the floor, its been like this for a long long time now (years), as the adhesive is going to be a **** to get up would it be best to slc it or ditra the whole room?

I really want to get this right as the same problem is in the house next door and as insurance will probably be paying I can make a decent profit.

Thanks

 

[david campbell]

i would remove as much as possible then cover with slc,was there a de-coupling underlay used in this because with the heat from the ufh and a soft stone like travertine there is always going to a movement problem

 

[peckers]

I would lift the whole lot rake out the cracks in the screed and make good, you can then use slc as mentioned above if needed, I would remove the skirting and you can then leave a 10mm gap all around the rooms to give you an expansion joint and skirtings can be replaced on top of the tiles to hide this after. if there are allready expansion joints in the screed then you will have to carry the expansion joint threw to the tile. before tiling i would use a de-coupling membrane as mentioned above to take up any laturel movement caused by the underfloor heating. you can also create a movement joint in the doorways between the tiled rooms too.
Be sure to have the under floor heating turned off before work starts and not to turn it back on again for 2 weeks after tiling has finished then it should be turned on at a minimal temperature and increased slightly each day there after.
hope this helps

 

[Ajax123]

Firstly the tiles need to be lifted and then some analysis as to why it has cracked. Given the odd shape of the room I would guess simple restraint cracking but without a more detailed pisture it is difficult to tell. If you want to re lay the tiles direct to the screed the cracks will need to be properly repaired otherwise with the action of the UFH they will over a period of time simply reopen and crack or even delaminate the new tiles - back to square 1 so to speak.

A suitable repair type compound would be PHS from Isocrete or PSRS from Ardex. I guess there are others - low viscosity epoxy resin. If any movement is detected in the screed which has subsequently contributed to the cracks you will need a resin stitch which involves cutting smalll groove at right angles to the cracks and dropping a peice of steel rebar in before filling with resin.

You could you a decoupling mat to get you over some of the instability although these will not get you over vertical movement.

Have you got any pics?

 

[tfs]

Hi mate, alot of the above advice sounds about right.

I also agree that it may be best to try and uplift the existing tiles to be sure that there is nothing to major here. I think the tiles may have cracked due to the existing expansion joints in the slab, I think the tiler/ builder has tiled over the expansion gaps on the slab.

If you are incorporating these joints over the joints in the slab (which I would reccomend if it was my choice decision) then I would use an expansion strip over the slabs joint to ensure that noether the adhesive or the tile go over any existing joints

You can also buy these strips for external/ perimiter expansion gaps for where the tile meets the wall.

If this was an extention or a new build an architect would have been involved. It might be worth contacting the architect for there thoughts on this matter also.

good luck mate

 

[The Legend; Phil Hobson RIP]

As above all good advice. I always advise cusomers with ufh to go with a de-coupling membrane. All new floors imo should be commissioned before tiling commences. I find a lot of builders are unaware of the need to leave new tiling for 2 weeks before turning heat on. Also as already stated temp should not exeed 5 deg in any 24 hrs then held at optimum temp for 2 days, finally brought back down no more than 5 deg per day. As for movement joints you will find all you need if you refer to clause 6.8 and 7.16 of BS 5385:-3: 2007. Hope this helps.

 

[tfs]

sorry, just realied my previous link whas the wrong one :lol:

this is the link that i meant to post regarding expansion trims

Movement Joints | Gradusworld
http://www.axminster.co.uk/product.asp?pf_id=20849&src=froogle