Tiling to heated screeds.

[DHTiling]

Morning tiling peeps..


I have always been led by adhesive manufacturers , that when tiling to a wet heated screed the heating MUST be off!.


I have just sat and read the latest technical publication from the TTA and it states that the heating should be turned off but in cold weather the heating can be on so the screed temp should is held at 15 dgs cel ...

Now when i have asked adhesive comps , they say NO it must be off as you are force drying the adhesive by heating the screed during the tile installation.

So here is my take on it : If in the summer the screed temp is around room temp , so let's say 15 dgs cel to 20 dgs cel .. So what is the difference in keeping the screed warm to 15 dgs cel in the winter.. ?

IMO the TTA have it spot on and i have tiled to a screed that was held at 14 dgs cel whilst i tiled it... and i have also tiled to a bloody freezing one as this is what advice the builder was given and this was to 100% turn it off during the tiling process.

So i know what i will be doing from now on as i do not like the cold when tiling :smilewinkgrin:

 

[jonnyc]

I do same as you nowasdays.dont mind heating 15degrees but this is only after the correct drying time adhered to with no force drying

 

[DHTiling]

So , would you not force dry a screed Jonny . ?.. say a Calcium sulphate one.

 

[jonnyc]

Sorry I was not clear enough.
i was referring to sand/cement screeds
with anhydriite it is different.
my understanding is that these types can be force dried and in fact on most anhydrides I have fixed on they have had to force dry to get screed dry enough

 

[Ajax123]

No sure about electric but you would find I almost impossible to hold a screed a 15degrees with a wet UFH system. However. Have always been of the belief that doing so would not be detrimental to the addy because the onus temperature for adhesives is 20degrees plus or minus 5 or so. Were you to stick rigidly to the rules on temperature I guess there would be litte tiling done over the last few winters...

 

[DHTiling]

Sorry I was not clear enough.
i was referring to sand/cement screeds
with anhydriite it is different.
my understanding is that these types can be force dried and in fact on most anhydrides I have fixed on they have had to force dry to get screed dry enough

A cement screed will dry faster any ..

My point is when you are working in an empty house and it is sub-zero temps out side and very cold in doors , it is good to have the heating on low , one to keep the room warm enough to tile above 5 dgs and the second is to keep the tiler warm lol lol ..

 

[DHTiling]

No sure about electric but you would find I almost impossible to hold a screed a 15degrees with a wet UFH system. However. Have always been of the belief that doing so would not be detrimental to the addy because the onus temperature for adhesives is 20degrees plus or minus 5 or so. Were you to stick rigidly to the rules on temperature I guess there would be litte tiling done over the last few winters...

That is true because as we know it is fed from the manifolds and then distributed through out the zones , and it will be at it's warmest near said manifolds.

But a well balanced system will suffice IMO to keep a room and above screed a certain temp to aid in the chemical hydration of the adhesive and not hinder ..

it is a stupid grey area where not all comps are obliging to sing from the same hymn book .. So i will stick with the advice i get from the TTA.

At the end of the day they do the standards for tilers

 

[Dan]

Would you turn it on until near 15 then turn it off or let it go above a little? Assuming its gonna cool again quite quick.

 

[Diggy]

Trouble I see is if it is a largish area , as you tile you're essentially insulating said area. If the stat is in that zone it might make the next area/zone work harder/get hotter and go above the the temp required to reach your 15ºC?

Diggy

 

[Ajax123]

That's my point. You can't turn a wet system on at 15. Most systems start at between 25 and 35 degrees flow temperature. This would give you a surface temperature between about 20 and 30 degrees.

 

[DHTiling]

That's my point. You can't turn a wet system on at 15. Most systems start at between 25 and 35 degrees flow temperature. This would give you a surface temperature between about 20 and 30 degrees.

The ones I have tiled to have stats that come on at low temps...?

 

[Diggy]

25 - 35 seems a bit high to me.

Diggy

 

[Peter]

Good logic from the TTA. Suppose it's no different than tiling a conservatory floor on a hot day. Don't like tiling freezing cold sites in December when you're breaking ice off your water buckets, using 1º water and with a similar room temperature. That's further outside fixing guidelines than a lukewarm floor.

 

[andy8758]

The difficulty here is that all under floor heating systems radiate heat. At the point of the thermostat it may be 15 degrees, but at the wire/pipe it will be higher. So at the point of radiation is the adhesive at risk of thermal shock? Better idea might be to have the heat source to warm the room away from the adhesive to raise ambient room temperature and therefore improve adhesive setting times (e.g. central heating system).