Underfloor heating hollow floor

[iana]

I have recently install electric under tile heating in my kitchen on a concreted power floated floor, previous tiles were down for 15 years with no problems. Having primed the floor as instructed laying flexible adhesive then a 6 mm styrofoam insulation board then the heating cable mat then the tiles 41cm X 41cm. Having then grouted these tiles I am concerned that he sound very hollow and have already had a hair line crack in one by dropping an object on them. The same tiles installed in the adjoining utility without in heating and installation are very solid.
Has anyone come across this problem before?

 

[jay]

Re: Underfloor heating holllow floor

:welcome:iv had no experiance with styrofoam insulation do you know who makes it by chance

 

[iana]

Re: Underfloor heating holllow floor

The product was borught from The Underfloor Heating Store I belive it is their own brand.

 

[jay]

Re: Underfloor heating holllow floor

hi is it marmox and do you remember how it was installed and what adhesive

 

[iana]

Re: Underfloor heating holllow floor

Yes it was marmox the boards were 6mm thick and it was installed with Flexible tile adheshive, soory cant remember the brand bought from tile maze.
Installtion Primer - adhesive -insualtion board - electric mat- adhesive - tile - grout as per elcetric mat instructions.

 

[jay]

Re: Underfloor heating holllow floor

sounds different just read spec sheet sounds like you have done everthing right (did you tape joints) as i said not familiar with it but someone on here might be i personaly dont like the sound of the insulation board how hard is it to squash and does it spring back :8:

 

[DHTiling]

Re: Underfloor heating holllow floor

It could be that the boards were not installed properly and that you do indeed have hollow spots under the boards,thus giving compression to that area.

 

[TrumpersUnited]

Re: Underfloor heating holllow floor

I would have self levelled over the electric mat, with tiles that size i bet there's not 100% coverage.

Is there any movement joints?

 

[Ajax123]

Styrofoam is a high density rigid insulation - It would be ideal for this type of application because of its very high compression resistance so I cannot beleive it is this assuming it is indeed styrofoam.

More likely to be Dave theory that the boards are not installed properly and there is movement in the substrate. It could also be that if the styrofoam is not stuck down properly it could "curl" causing potential for voids under the insulation with the same effect.

 

[Daz]

It could be that the insulation boards are not fully stuck, or it could be that you have some hollows under the tiles themselves. Have you tried just tapping a few tiles in different areas of the floor to see if they give off differing sounds?

Tiling over ufh wires with no slc can result in less than 100% adhesive coverage under the tiles. You may just have a localised area that needs attention.

 

[pjrich]

Re: Underfloor heating holllow floor

It could be that the boards were not installed properly and that you do indeed have hollow spots under the boards,thus giving compression to that area.

I agree with dave, sounds like air gaps under the boards.