porc's and grout cracking on ditra on screed - TilersForums.com

[m3fitter]

cracks opening on heating and closing on cooling means a serious problem caused by the floor trying to belly upwards due to thermal expansion. This wil be the result of one of, or a combination of, two things. first thermal expansion and second lack of facility for movement in the form of movement joints.

have you put any movement joints in your 90m2 of porcs??

The main cracked area only has a max diameter of 4.6m wall to wall, left 6-8mm expansion to plaster, on commercial or swimming pool surrounds would allow schluter / genesis expansion joints every 5m linear, but domestic, multi room, largest area is 30m2 in a room.. cracking is not in an isolated grout line.. but over a 30m2 area, fine cracks, definitely expansion in all directions ?

 

[Diggy]

Didn't see it asked above so , was the UFH commissioned prior to fixing?

Diggy

 

[m3fitter]

Yes, ufh turned on and ran for 2 weeks prior to tile fixing, turned off 72 hrs before we arrived.

 

[Ajax123]

The main cracked area only has a max diameter of 4.6m wall to wall, left 6-8mm expansion to plaster, on commercial or swimming pool surrounds would allow schluter / genesis expansion joints every 5m linear, but domestic, multi room, largest area is 30m2 in a room.. cracking is not in an isolated grout line.. but over a 30m2 area, fine cracks, definitely expansion in all directions ?

That's fine then ... A least you did your bit right so they can't come after you. I can imagine it looks a right mess given the temperatures they are running. This is one for the underfloor heating supplier to pick up and deal with IMO.

- - - Updated - - -

Yes, ufh turned on and ran for 2 weeks prior to tile fixing, turned off 72 hrs before we arrived.

Have you been paid?

 

[m3fitter]

yes.. the developer can see for himself, the technique, materials supplied installed.. all technically correct.. as i said to him, in 24 years i have never had 1 tile crack on a floor, let alone 6, and happen twice on the same tiles, its a UFH problem, and the cracking grout, which dissapears when UFH off, well says it all.. personally..i think the system isn't balanced at flow to run at 37.5-45 approx to achieve an ambient 22-28 air temp as you quite rightly stated. Thx.. arrrrr. was bugging me, as don't like to see my work trashed :-(

 

[Ajax123]

yes.. the developer can see for himself, the technique, materials supplied installed.. all technically correct.. as i said to him, in 24 years i have never had 1 tile crack on a floor, let alone 6, and happen twice on the same tiles, its a UFH problem, and the cracking grout, which dissapears when UFH off, well says it all.. personally..i think the system isn't balanced at flow to run at 37.5-45 approx to achieve an ambient 22-28 air temp as you quite rightly stated. Thx.. arrrrr. was bugging me, as don't like to see my work trashed :-(

yes I can understand that but in consolation at least it's not your fault.