underfloor heating

[MRM Tiling]

Hi i have a job coming up and need some advice, it is on a concrete floor which is at least a year old and has pipe heating underneath it which has been commisioned and the screed conditioned. can i tile straight to the concrete with flexi adhesive or do i need a decoupling membrane down? also what is advised for after the tiles are laid so i can tell the customer. and one more thing can i tile from one room straight through to another or have an expansion joint where the doorframe is? need advice as i want to get it right

 

[White Room]

What tiles are you fixing down on the floor.....

 

[MRM Tiling]

600x600 porcelain tiles, sorry i missed that out!

 

[White Room]

I would do a control joint in the doorways, does the heating pipes go thru to each room or are they on seperate curcuits to each room...or is this just one room.

 

[MRM Tiling]

they are all one circuit its about 90 sq meters and 5 different area's. all the pipes start in one boiler room and go from there, obviously a fortune has been spent and i need to get it spot on

 

[MRM Tiling]

sorry i think they are seperate, as in you can control which area is heated in the house and also it was tested up to full heat getting there in 5 degree intervals and was switched off 2 weeks ago

 

[White Room]

How many m2 in each room....

 

[mattle40]

sorry i think they are seperate, as in you can control which area is heated in the house and also it was tested up to full heat getting there in 5 degree intervals and was switched off 2 weeks ago

I would put expansion joints in the doorways if the rooms are heated seperately,
I would imagine this would push ditra to its limits and i wouldn't be comfortable with the install my self

Eager to hear other opinions myself to be honest.

 

[demi34]

Ditra matting and you sleep well

 

[jimthetiler]

Hi
I presume you are laying the matting on a screeded floor.
expansion joints at doorways is good.
check screed is laid in one go,if the screed has been laid in different stages you will need to decouple where the join is,ask the customer if uncertain.
once mat or wire has been laid it will need testing,an easy test is to wire a plug on each matting and plug into the wall socket,this is safe up to 10mins but you will only need a couple of mins to know the its all working.
now you should use a latex based self leveling compound and cover the wires.
when dry do another plug in test then you can tile using flexi

 

[philipb]

Worked on a new build recently,120 mts of limestone on wet ufh,tile supplier was pushing
a new adhesive from Granfix that goes down with no need to decouple.They
supplied a procedure which was done as they advised and its been down since
december with no sign of any problems.Granfix tech will advise on its use.
Saved a lot of money.

 

[White Room]

Worked on a new build recently,120 mts of limestone on wet ufh,tile supplier was pushing
a new adhesive from Granfix that goes down with no need to decouple.They
supplied a procedure which was done as they advised and its been down since
december with no sign of any problems.Granfix tech will advise on its use.
Saved a lot of money.

Does that include natural stone tiles....

 

[philipb]

Yes it does,they even said not to bother with expansion joints,they even
guarantee the job and advise that pics are taken at every stage so they can
check it in the event of a problem.They even send a rep if you want!
I was a bit worried but didn't need to be,job is spot on.Floor temp has been as
high as 50 deg c.

 

[White Room]

Do they have a grout which goes with the adhesive....

 

[philipb]

Yes they insist that you use there grout,there tech said the problem they face
is that British standards say that decouple should be used on wet ufh in screed,
as ajax pointed out to me,and most tilers are reluctent to change,even though
its cheeper and much quicker to do the whole job.

 

[White Room]

Yes they insist that you use there grout,there tech said the problem they face
is that British standards say that decouple should be used on wet ufh in screed,
as ajax pointed out to me,and most tilers are reluctent to change,even though
its cheeper and much quicker to do the whole job.

We have a rule of thought and stick to it, must admit can't get my head round it not to use decoupling.

 

[philipb]

Yes i know,i was the same,it seemed too good to be true,but it was fine.
There is a run of tiles that is 20 mts long with no expansion joint!

 

[White Room]

Jeeeez 20mts...

 

[philipb]

I will defo use it again,major saving in time and money,on a job like that
not having to decouple and all the adhesive it takes,just to get on
with it is major.It was £900 just for the membrane.

 

[MRM Tiling]

Hi
I presume you are laying the matting on a screeded floor.
expansion joints at doorways is good.
check screed is laid in one go,if the screed has been laid in different stages you will need to decouple where the join is,ask the customer if uncertain.
once mat or wire has been laid it will need testing,an easy test is to wire a plug on each matting and plug into the wall socket,this is safe up to 10mins but you will only need a couple of mins to know the its all working.
now you should use a latex based self leveling compound and cover the wires.
when dry do another plug in test then you can tile using flexi

hi its onto concrete with underfloor piping running throughout. its a hallway with a room to tile just off it then up 4 steps into a kitchen/diner and through into a big living room, all concrete screed and most probably seperately done. im working with the builder who did it all in the morning so il take the info u lads have gave me and put it to him and work it out, thanks

 

[Ajax123]

No adhesive will prevent tiles and screeds from moving. You uncouple natural stone to help prevent differential movement. Unless the adhesive I made from elastic I would still uncouple.

also it sounds like the screed s no laid correctly as this should have movement joints. This leaves it prone t cracking which means an unstable screed. Fail to uncouple this and I think it will fail

 

[Mark S]

Totally agree with Ajax on this, should have joints in, and be de coupled.

 

[bugs183]

Yes they insist that you use there grout,there tech said the problem they face
is that British standards say that decouple should be used on wet ufh in screed,
as ajax pointed out to me,and most tilers are reluctent to change,even though
its cheeper and much quicker to do the whole job.

Sorry matey, but this adhesive really does sound too good to be true.
You really are better off uncoupling on u'f'h floors, be it stone or porcelain. Sometimes the time and the cost outweigh the problems that could happen.

As Ajax says (and he's the screed Guru) failure to uncouple could be costly. Would Granfix pay for the whole job to be replaced or just the cost of the adhesive?