Tiling on Newly Poured Concrete Floor?

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gocall01

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Please move if in the incorrect forum.

Short question but to date I have received conflicting answers.
- How long does a newly poured concrete floor need to dry out before it can be tiled?
It is a 60x60cm porcelain tile using White Flexible Adhesive.
I presume the current atmospheric conditions would have some bearing on it also.

Thanks in advance...
 
gocall01 said:
Please move if in the incorrect forum.

Short question but to date I have received conflicting answers.
- How long does a newly poured concrete floor need to dry out before it can be tiled?
(snip)
Click to expand...

Please post the references to this conflicting advice so I can review it.

Otherwise without knowing what you see as a conflict I cannot best advise you.

ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon as a defence or support - in and of itself - should legal action be taken.
Competent legal and building professionals should be asked to advise in Real Life with rights to inspect and issue reports on the matters at hand.
 


Conflicting advice:
Person previously involved in construction -> 1-2 weeks drying time from pour to tile laying.
Official information from adhesive company -> minimum 0f 4 weeks drying time from pour to tile laying.
That's all the info I have.
 
Both sets of conflicting advice appear to be wrong.
The old rule of thumb 1 day per 1 mm is not a million miles out.

Four weeks = 4 X 7 = 28 days/mm might do for a 30mm screed - who uses these?
so for a three inch topping screed this would average 75 days/ 9weeks/ over two months

You should at least double that for a six inch (150mm) slab, but these are only ball park estimates.
I've certainly known of slabs taking far longer to dry out - up to and including the 6 months hastalavista was talking about - because of:
(i) the additional thickness for something that dries out from the top down
(ii) poor weathering protection during the build
(iii) moist/damp local conditions
​
Tiling the slab to early will tend to seal the excess moisture in
You should read this guide by Weber to get a better understanding of the issues involved.

Builders who suggest tiling in two weeks are suiting themselves and walking away from problems.
Ask the guys who gave you that estimate what kind of follow up service they provide and ring around their "satisfied clients".

Concrete has issues in terms of its surface finish affecting the applied finish and others in relation to setting and shrinking.
This online guide from BASF gives an indication of some the issues arising.

There are advance moisture testing procedures if you want to be certain.
Moisture probes and tests which rely on surface testing are generally not that accurate.
Changes which have arisen in recent years are generally only becoming well understood now.

[broken link removed] summarizes several forms of test and ASTMF 2170 seems to be setting the standard.
The reason for this seems to be that surface tests can be wildly inaccurate, while testing the actual moisture deep in the slab offers more surety.

There are no conflicts here.
If in doubt use the longer time period.

I am not an expert in the field of slab or screed testing.
Many in the industry don't understand the limitations of wet trades.

But tilers and adhesive manufacturers are sometimes only telling you what you want to hear.


FWIW

ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon as a defence or support - in and of itself - should legal action be taken.
Competent legal and building professionals should be asked to advise in Real Life with rights to inspect and issue reports on the matters at hand.
 
Having recently finished a leisure centre, we left the walls and floors for a min of 4 weeks before tiling and then tested them with a moisture meter before we started to make sure they were in tollerance.

We also sealed the floors with a paint on DPM to ensure that the moisture in the slabs did not affect the tiling.

Hope this helps

Charlie
 
Interesting American on drying concrete - seems to ignore the contradictions between

(i) needing water to be retained for long enough to properly cure the surface of the concrete -vs- drying it rapidly to allow follow on trades

and

(ii) keeping concrete warm and wet to ensure good curing (ensuring enough water as part of the chemical reaction) -vs- keeping it wet and cool enough (particularly in more massive work) to avoid cracking and ensure strength and hardness develops (water as part of a cooling system).

Rapid cooling and de-humidifying of surface concrete can lead to a reduction in strength and hardness and poor frost resistance - plus it may only dry out the top 25mm or leaving a lot of water still in the slab.
Trapping moisture in concrete as a matter of convenience for tilers to follow on in a situation if there is a risk it could possibly be subject to frost action later seems to be a poor long term strategy.


ONQ.

[broken link removed]

All advice on AAM is remote from the situation and cannot be relied upon as a defence or support - in and of itself - should legal action be taken.
Competent legal and building professionals should be asked to advise in Real Life with rights to inspect and issue reports on the matters at hand.
 
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