confused over screed drying out times for stone installation.

[bluevin123]

:mad2::mad2: Hi,
The floor that I am supposed to be tiling with Travertine was screeded just over 2 weeks ago, but im concerned over the drying out times...I have heard many people say different things, the lads at my local Tile Giant store said an inch a month at the minimum to dry out...its about 60mm thick, other stores have said 3 weeks. Is it the 1mm a day theory? which makes 2 months.

The screeders put some additive in and some feather like stuff to suppossedly make it dry out quicker, but im not so sure. I want to be able to ring the property developer and advise him to hold back as I or him dont need the floor coming up in the future.

Also, do I need thermal boards?, I would have just tiled onto the screed with white addy and back skim the tile and was thinking of expansion joints every 4mts or at door threshholds.
Any views please.
Cheers,
Vinnie.

 

[DHTiling]

What type of screed is it....?

 

[White Room]

Is this the floor that you spoke about a while ago mate, feather stuff to make it dry quicker, not sure about that.

Have you already started tiling

 

[bluevin123]

To be honest Dave I dont know,just a sand and cement as far as I know, and yeah Whitebeam this is that floor I spoke to you about before,I have not started it yet, just waiting for it to be dry/safe enough to tile mate.
Cheers.
Vin.

 

[White Room]

Are you going to lay ufh

 

[grumpygrouter]

If you are in a hurry and would be good practise anyway with travertine, why not use a decoupling membrane?

 

[DHTiling]

To be honest Dave I dont know,just a sand and cement as far as I know, and yeah Whitebeam this is that floor I spoke to you about before,I have not started it yet, just waiting for it to be dry/safe enough to tile mate.
Cheers.
Vin.

To be on the safe side i would ask...

 

[Perry]

if its screed should be 14 days concrete a 1" a month as a rule but would be best to use a membrane if you can

 

[Ajax123]

:mad2::mad2: Hi,
The floor that I am supposed to be tiling with Travertine was screeded just over 2 weeks ago, but im concerned over the drying out times...I have heard many people say different things, the lads at my local Tile Giant store said an inch a month at the minimum to dry out...its about 60mm thick, other stores have said 3 weeks. Is it the 1mm a day theory? which makes 2 months.

The screeders put some additive in and some feather like stuff to suppossedly make it dry out quicker, but im not so sure. I want to be able to ring the property developer and advise him to hold back as I or him dont need the floor coming up in the future.

Also, do I need thermal boards?, I would have just tiled onto the screed with white addy and back skim the tile and was thinking of expansion joints every 4mts or at door threshholds.
Any views please.
Cheers,
Vinnie.

The additive may have been a plasticiser which would reduce the water content and thus reduce the drying time. Alternatively it could have been a retarder which is simply to aid working time and does not affect the drying at all. The feather like stuff will undoubtedly be polypropylene fibres which is there to replace crack control steel mesh. This has no effect whatsoever on the drying time.

60mm is not technically deep enough on insulation which I presume this one will be. It should be minimum 65mm to meet the British Standard. If it is not on insulation but is direct to the substrate then 60mm will be plenty deep enough to meet the BS. If it is direct to substrate though you have the potential issue of the substrate also drying through the screed so you should try to ascertain this info before commencing tiling as it may dictate your surface prep. If direct to substrate then I would recomend the use of a Surface DPM on the screed before you do anything. This would normally then need SLC to offer a suitable surface for the addy. The alternative I suppose would be decoupling although it depends on the depths you have available.

Tile Stores who say the screed takes 3 week to dry are talking out of their orrifice. Standard Sand Cement Screed should be cured for 7 days to allow them to hydrate properly prior to beginning the drying regime. Drying takes approximately 1mm per day for sand cement up to about 65mm although this is affected by compaction. Bear in mind drying will only take place at this rate if it is kept in good drying conditions which will generally be classed as 20oC and 60%RH with good ventillation. The time taken to dry also depends on both the water content of the screed at installation and also whether it has been wetted since installation. By the sound of it you are dealing with a site mixed material so these are probably both unknowns. You cannot force dry sand cement as it will crack and curl. If there is a plasticiser in it it will not speed up the drying rate but will reduce the time by virtue of the fact there is less water in it. You should not rely on time as the indicator of dryness especially this time of year when drying takes longer anyway. You should carry out a moisture test prior to tiling. There should be movement joints in the screed as well. Typically in unheated screeds these should form bays of around 36m2 maximum with 6m maxium bay length and aspect ratio no more than 2:1. These joints should help determine the joints in yout tile face as they should reflect through the tiles.

Hope this helps....

 

[Gazzer]

Ajax, can you reccomend a good reasonably priced moisture tester for the lads ?