Help!: concrete floors , drying time?

[darragh]

6 inches concrete its been in 6 weeks , normally i wouldnt tile on it so soon but the client is saying the tile supplier reckons its fine to tile on, i have talked to my own supplier he reckons min 10 weeks , just wondering has anyone tiled on concrete after 6 weeks and had problems, this guy really keen to get it tiled but am worried about possible cracks , was thinkin i mite get him to sign summit sayin its his responsability if anythin goes wrong, but then if somethin does go wrong kinda defeats the purpose of tiling in the first place gonna end up costing him a fortune twice .....arhh dont no what to do , its a consvertatory with 600 x 600 polished porcleian if that makes any difference

[Dave]

6 weeks is tight.....An adhesive for tiling to new screeds can be used....these are highly flexible and slow setting to allow for shrinkage....

Or you could use an vapour equalisation membrane like durabase-ci or Ditra...

[CJ]

1mm per day drying as a rule.........so it will be ok to tile at the mid/end of July


But as mentioned Durabase ci or Ditra.

Thing is getting them to take the extra cost. Or you could use a green screed adhesive

[Ajax123]

6 inches concrete its been in 6 weeks , normally i wouldnt tile on it so soon but the client is saying the tile supplier reckons its fine to tile on, i have talked to my own supplier he reckons min 10 weeks , just wondering has anyone tiled on concrete after 6 weeks and had problems, this guy really keen to get it tiled but am worried about possible cracks , was thinkin i mite get him to sign summit sayin its his responsability if anythin goes wrong, but then if somethin does go wrong kinda defeats the purpose of tiling in the first place gonna end up costing him a fortune twice .....arhh dont no what to do , its a consvertatory with 600 x 600 polished porcleian if that makes any difference

Gettin him to sign something to say it's his responsibility would not be any good really. As a supplier of specialist products and services (i.e. tiling) you cannot exhonerate yourself legally from doin something irresponsible like putting the tiles down on a substrate which is not fit for the application. If only life were that simple. Anyway as you say it would be better to do it right so he only has to pay once. 6 weeks is no where near long enough for the concrete to dry to 75%RH ( base on 0.5 to 1mm per day for standard concrete dependning on the prevailing weather and ambient RH) - will be as you supplier says minimum 10 weeks and realistically probably even longer. I reckon for 150mm more like 20 weeks) I agree with Dave that a decoupling mat like Ditra is one very good way to go. Another would be to use a moisture suppressant Epoxy Damp Proof Membrane. There are hundreds of these available for this purpose. They are used in the contracting world almost routinely nowadays. Tremco are very good at this sort of thing - treadfast one coat I think is the product. You will probably find it cheaper than the Ditra as well.