How long before you can tile onto sand/cement screed?

[John the tile]

How long does screed take to dry before you can tile onto it? Can you tile straight onto it or does it need slc first?

Thanks

[Bri]

How thick is the screed and what type is it? Also does it contain a wet heating system?

[Phil Hobson]

1mm per day is a rule of thumb, eg 70mm = 70 days, but as above more info would help

[Dave]

1mm per day for the first 40mm and then 0.5 mm per day after that.

You can tile on it quicker with the use of a vapour equalisation membrane.

[John the tile]

Basically I was presented with a very old screeded floor that was covered in cracks and blown and delaminated from its concrete substrate. This screed is only 35/40mm thick. I dont know why it never bonded properly as it was probably done over 50 years ago.. its a 1910 house.

The 35mm thickness took the level up to the same height as the dining room. I would say the screed is very hard concrete with stones in it.

I think the substrate under the blown screed is some different form of concrete, with aggregate in it but not as rock hard as the stuff thats been ripped up.

Could anyone advise on my options prior to tiling? Ive included photos of the existing floor with cracks and some chunks taken out, you can see the rest is delaminated and also a final photo of the underneath substrate.

ThanksP1060053.jpgP1060058.jpgP1060056.jpgP1060060.jpgP1060062.jpgP1060063.jpgP1060064.jpg

[whitebeam]

They used what the builders could get hold of then, http://www.barbourproductsearch.info...file017482.pdf if going to rescreed it...that would be my option but there's some good slc that do up to 50mm rather than a screed but the price can be a bearing on price.

[craigdon]

Sand & cement screed minimum of 3 weeks (commissioned if heated screed), concrete minimum 6 weeks, andhydrite has to be totally dry is what I've always adhered to.

[Dave]

Sand & cement screed minimum of 3 weeks (commissioned if heated screed), concrete minimum 6 weeks, andhydrite has to be totally dry is what I've always adhered to.

Then you need to check your BS5385 standards..

[craigdon]

I knew one of the adhesive companies worked on 3 weeks for s/c, so have just read up and found this was BAL, are you saying they aren't working to BS? Interesting

[craigdon]

BAL Adhesives - Technical Support

Here's what I found.

[Dave]

You cannot say it is 3 weeks for all screeds etc, the drying time is based on screed depth, as above there is a set drying time at 20dgs cel , adhere to that and this will make sure a screed is dry..

Also though a screed or concrete slab can be tiled to earlier if a vapour equalisation membrane is used.. and you can also use a green screed adhesive but for efflorescence reasons i would use the membrane.