Drying time for concrete floor for tiling

ddea

Has anyone any information on how dry a concrete floor needs to be before it is tiled. There are lots of threads previously on timber floors. Presumably the drying times are not as long or as critical for tiles?

We have had a 2 inch concrete floor poured over a subfloor which has been in for 12 months. The 2 inch portion has been there for four weeks and we hope to tile after another three weeks and it's not the best weather for drying. We have UFH but this will not be ready to be switched on for at least four weeks so will probably not be operational until after tiles are laid. Any advice?

Endymion

28 days.

Now for the science

After 28 days the concrete has gained most of it's strength. Don't worry about the concrete being "dry". When the concrete is completely dry the hydration process stops. As long as the hydration process continues the concrete is increasing in strenght. Normally it takes and fair few years for hydration to completely stop.

So yea, anyway, after 28 days it has most of it's strenght, you're unlikely to get major chacking after this period.

Johnniep

Carnivore wrote:

28 days.

Now for the science

After 28 days the concrete has gained most of it's strength. Don't worry about the concrete being "dry". When the concrete is completely dry the hydration process stops. As long as the hydration process continues the concrete is increasing in strenght. Normally it takes and fair few years for hydration to completely stop.

So yea, anyway, after 28 days it has most of it's strenght, you're unlikely to get major chacking after this period.

Carnivore is spot on in that concrete reaches it's "characteristic design strength" after 28days. However, the concrete will continue to loose moisture long after this which can result in disolving of water based adhesives used for sticking down flooring materials (marmolium, lino etc)

I am not sure if the same problem also applies to tile grout, but best to ask your tiler/tile supplier and if necessary get a moisture meter to read the moisture level in the screed.

Hope this helps,

J

Kashkai

Sorry to hijack this thread but I'm getting an extension built at the moment that has the concrete floors laid but as there's no roof on it at the moment, its getting very wet with the rain we're having lately. Therefore, when would you start to calculate the drying period from, i.e. when the floors are poured, when the roof goes on or when the house's heating kicks in?

Endymion

Johnniep wrote:

Carnivore is spot on in that concrete reaches it's "characteristic design strength" after 28days. However, the concrete will continue to loose moisture long after this which can result in disolving of water based adhesives used for sticking down flooring materials (marmolium, lino etc)

I am not sure if the same problem also applies to tile grout, but best to ask your tiler/tile supplier and if necessary get a moisture meter to read the moisture level in the screed.

Hope this helps,

J

true, but it shouldn't affect tiling grout, as there will be tile ahesive between the floor and grout and the amouth of mater released it very little compared to normal air moisutre conetent. Allot quality floor tile adhesives today are some form of rapid set cement, so I doubt the grout will have a problem.

Prosperous Dave, 28 days from the poor. It's just a standard means of measuring and comparing concrete strenghts. The cement being damp for longer, won't actually weaken it, because, as i said, water is needed for the hydration process and as long as the hydration process continues the concrete is increasing in strenght.

Should have a fresh cement floor open to the elements is not a good idea. Rain can destroy the smooth surface, and freaze thaw action can cause flaking and cracking.

ddea

Cheers guys, thanks for the help