Tiling onto Underfloor Heating with a Damp Screed

[dmtiling]

I'm having a problem, with every floor I'm trying to lay at present (due to our unsavoury weather). The tile assosiation recommend a maximum moisture content of 0.5% in floor screed to tile on. I've just shelled out £350.00 on a professional moisture meter to give me something accurate to go by. Trouble is this is still measuring 4 - 4.5% moisture on perfectly dry screed floors in my centrally heated house. The same as a three week old 4" screed I need to tile on a new build/as yet unheated house :mad2:. I've gone back to the old test method of laying a piece of polythene down (same as your tile) and checking for condensation. Wait until there is none. You will need a heater and dehumidifier to assist in drying. It is very unlikely you have any leaks in the u/floor heating, these are normally laid continuous ie no joints.

 

[diamondtiling]

Re: Tiling onto underfloor heating screed - wet !

Where is ALAN when you need him............:lol:

 

[Dan]

I'm having the same problem Laurie, with every floor I'm trying to lay at present (due to our unsavoury weather). The tile assosiation recommend a maximum moisture content of 0.5% in floor screed to tile on. I've just shelled out £350.00 on a professional moisture meter to give me something accurate to go by. Trouble is this is still measuring 4 - 4.5% moisture on perfectly dry screed floors in my centrally heated house. The same as a three week old 4" screed I need to tile on a new build/as yet unheated house :mad2:. I've gone back to the old test method of laying a piece of polythene down (same as your tile) and checking for condensation. Wait until there is none. You will need a heater and dehumidifier to assist in drying. It is very unlikely you have any leaks in the u/floor heating, these are normally laid continuous ie no joints.

I've moved this to a thread of it's own from the following thread: http://www.tilersforums.com/tile-ad...iling-onto-underfloor-heating-screed-wet.html

 

[DHTiling]

You can force dry the floor with the UFH

Heated cement screeds are not as strong as say an anhydrite screed with in-screed heating, so i personally would recommend the membrane anyway... curling can cause tiles to de-bond..

 

[dmtiling]

I've moved this to a thread of it's own from the following thread: http://www.tilersforums.com/tile-ad...iling-onto-underfloor-heating-screed-wet.html

Why???

 

[Sutwam]

You can force dry the floor with the UFH

Heated cement screeds are not as strong as say an anhydrite screed with in-screed heating, so i personally would recommend the membrane anyway... curling can cause tiles to de-bond..

I agree with Dave, screed curl is an important point. If the screed dries out too quickly the ends can curl up, due to the moisture being driven off the top layer of the concrete it makes the screed take on a slight concave property.

A membrane will not help with screed curl, but using a vapour equalisation membrane such as Detra or CI or equivalent will allow the screed to dry out slowly and the risk of curl would be dramatically reduced.

If you speak to the membrane manufacturers they would say their membrane could be used when you can walk on the screed.

 

[Dan]

Why???

Because the old thread was posted 2 years ago and I guess the guy has his floor done now. I thought as you had the same problem you might want to hear some views from the tilers perhaps?

 

[dmtiling]

mmm, thanks but I dont have a problem with cure's I have been tiling floors for twenty years. I have a problem with £350.00 moisture content measuring devices. My advice would be dont waste your money. My original post was edited and transfered to here, god knows why (thats mods for ya!):smilewinkgrin:

 

[doug boardley]

mmm, thanks but I dont have a problem with cure's I have been tiling floors for twenty years. I have a problem with £350.00 moisture content measuring devices. My advice would be dont waste your money. My original post was edited and transfered to here, god knows why (thats mods for ya!):smilewinkgrin:

if you look who moved it you'll see it was adminrrr: trying to get some fresh replies for you

 

[Gazzer]

If you have a problem with your Damp tester then talk to the manufacturer.

Ajax, our resident Concrete/Screed Guru (god bless him) has covered this subject before and stated (IIRC) that a hair hygrometer was the best method.

 

[Dan]

mmm, thanks but I dont have a problem with cure's I have been tiling floors for twenty years. I have a problem with £350.00 moisture content measuring devices. My advice would be dont waste your money. My original post was edited and transfered to here, god knows why (thats mods for ya!) :smilewinkgrin:

Already explained why

Because the old thread was posted 2 years ago and I guess the guy has his floor done now. I thought as you had the same problem you might want to hear some views from the tilers perhaps?

You pulled up a 2 year old thread and I thought you wouldn't get much of a response if it was left there as the original issue had been dealt with, 2 years ago.

 

[dmtiling]

Already explained why



You pulled up a 2 year old thread and I thought you wouldn't get much of a response if it was left there as the original issue had been dealt with, 2 years ago.

Sorry Dan, but I didn't pull up anything. Now do me a favour and ban me before i post something i might regret. Ya ****

 

[Gazzer]

Good god Dan is trying to help out get you more replies. You folowed on from a 2 year old thread. Dan merely moved it to its own thread so you would get more response.

 

[Dan]

Sorry, we don't ban members on request.

Are you the DM Tiling based in Northamptonshire by chance mate?

 

[Ajax123]

Sorry guyd not been about much for a couple of days and have to go out this evening however quick answers

Heated anhydrite scree should have heating commissioned and be down to maximum 0.5% moisture b/w (I recomend 0.3% beause of the increase in vapour pressure when using the heating) The correct and most accurate test method is the hair hygrometer IMO although the carbide bomb can be sed provided it is done correctly. The hair hygrometer measures the way the moiture is coming out of the screed and should only be one on a cooled screed (Switch off for 48 to 72 hours prior to doing the test)

Sand Cement screed retains pore moisture within it's matrix and so does not dry to the same level as anhydrite. Typically 75% RH on a heated screed will equate to below 4%. If you test it when it is warm you will get higher results o both screed types.

If it really is still wet then use a uncoupling membrane.

 

[Ajax123]

oh by the way if anhydrite use an epoxy primer if ou are going to use a cement based adhesive. If you us a gypsum based adhesive you can use acrylic and lay it wetter but these are not recomendd for areas which are permanently or regularly wet. i.e. shower areas.

ps rush job - sorry about the typing

 

[diamondtiling]

Sorry Dan, but I didn't pull up anything. Now do me a favour and ban me before i post something i might regret. Ya ****

Is that **** what I think it is? C word?

Cheeky little blighter!! You need to have a word with yourself fella.

:incazzato:

 

[doug boardley]

lol Dom, I think maybe dmtiling hasn't acquanted himself with TF rules yet:8:

 

[dave123]

Is that **** what I think it is? C word?

Cheeky little blighter!! You need to have a word with yourself fella.

:incazzato:

No its ok, I think it started with a D not C :lol:

 

[doug boardley]

Sorry, we don't ban members on request.

Are you the DM Tiling based in Northamptonshire by chance mate?

I've heard of DMTiling in Reading Dan, maybe a member could pop round with a damp meter thingy

 

[diamondtiling]

I've heard of DMTiling in Reading Dan, maybe a member could pop round with a damp meter thingy

Or a wet haddock..........Slap!!

:ninja::ninja:

 

[dmtiling]

Sorry guyd not been about much for a couple of days and have to go out this evening however quick answers

Heated anhydrite scree should have heating commissioned and be down to maximum 0.5% moisture b/w (I recomend 0.3% beause of the increase in vapour pressure when using the heating) The correct and most accurate test method is the hair hygrometer IMO although the carbide bomb can be sed provided it is done correctly. The hair hygrometer measures the way the moiture is coming out of the screed and should only be one on a cooled screed (Switch off for 48 to 72 hours prior to doing the test)QUOTE]

How Does a Hair Hygrometer Work? | eHow.com

Sounds like tasty piece of kit, must make meself one :lol::lol::lol::lol::lol:

 

[dmtiling]

More Fun Stuff for Terrorists Carbide Bomb This is EXTREMELY DANGEROUS. Exercise extreme c

Think I'll stay clear of the carbide bomb method though, thanks all the same.

 

[dmtiling]

You lot are right clever bunch, I hav'nt laughed so much in years

 

[patrickoconnell]

I have recently built my house and using underfloor heating covered by a 65mm concrete screed. the floor screed has been laid about 1 year ago. the windows and roof have been in for the last 6 months so it has been drying out since than. The underfloor heating has not been switched on yet but I have tiled the floor using flexi adhesive. I am now wondering will I have a problem when I eventually turn on the under floor heating? Will it crack the tiles?? Any advice will be greatly appreciated.

 

[diamondtiling]

I have recently built my house and using underfloor heating covered by a 65mm concrete screed. the floor screed has been laid about 1 year ago. the windows and roof have been in for the last 6 months so it has been drying out since than. The underfloor heating has not been switched on yet but I have tiled the floor using flexi adhesive. I am now wondering will I have a problem when I eventually turn on the under floor heating? Will it crack the tiles?? Any advice will be greatly appreciated.

There might very well be problems when you turn the heating on. Expansion and contraction issues etc. Did you fit any de coupling membranes?

You might have been better starting this in a new thread, it would receive more attention.

 

[patrickoconnell]

Thanks...I'll start a new thread...