Help!: Underfloor Heating

[ifielding]

Hi All. Another problem has raised it's ugly head. I have placed a heated floor installation in a small bathroom, electric mat type. The tiles are porcelain and good quality, been laid on wooden floor using all correct adhesive and method. I have grouted with Bal microflex wide joint. The grout has cracked which is pretty naff all round. Have any of you guys used or heard of a better system to grout such a floor with the excessive expansion and decrease with the floor temperature? The colour of grout is Ivory. Cheers!

[sus]

mapai flexi is better IMAO what is the method you used fix the tiles and what brands did you use?
sus

[ifielding]

I have bedded the mat and placed the tiles on 2 part. I use the topps tiles trade as comes in nice bucket and it is a straight all liquid to all powder mix. The cracking has taken 6 months to appear?

[malcolml]

microflex is not flexi enough for this unless a gt1 or ad flex was used with it, superflex would have been better,or mapei

[Uheat]

Hi ifielding,

As above a more flexible grout should stop this from happening in future but another possible cause is the sub-floor itself.

What is the full floor construction?

[ifielding]

Hi Aaron,

I put a brand new tongue and groove wood floor down. Then as entry #3

[sus]

If it is just the grout and the tiles are fine i would re grout. I think hss do the Fein multi tool this is a godsend for re grouting if you have 3mm gaps or bigger.

[ifielding]

Thanks for that, I have a Rotozip tool and with the tile burr I can get grout out and cut tiles. A Mega bit of kit, so looks like it will be in use on this floor.

[Uheat]

Hi ya,

If you are going direct onto Floorboards then i would definately used what Malcolm suggested and used a gt1 admix or similar.

If you had overboarded using a tile backer board or insulation board then a normal single part adhesive and grout would have been fine.

What system did you use and what wattage?

[grumpygrouter]

You don't add admixes to already modified products. If you want extra flexibility you must add the admix to STANDARD wide joint grout!

[ifielding]

It was customer supplied so can't remember, 6 months is a long time ago.
I will get the old grout out and get the GT1 mix on ht ego. Thanks.

[Uheat]

You don't add admixes to already modified products. If you want extra flexibility you must add the admix to STANDARD wide joint grout!

good point grumpy did not see that.

[ifielding]

Anyone used this stuff I have just found at a great price?

10KG FLEXI FLOOR GROUT IVORY GRANFIX

[smurf21]

If a customer supplies the wrong mats dont use without advising them of the mistake and if they insist it be used ask them to sign a disclaimer...