Help!: Screed Types and Drying Times

[Kraken]

I hope someone can help me with some advice please. I am having an extension built woith about 75m2 of ceramic tiling planned for the floor. The builder is putting underfloor heating down (water based) and is going to screed over the top. I have now been told that I must wait 4 weeks until I can tile and I have the tiler booked for Monday. The screed is not due to start until Wednesday this week.
1. How long should I wait for the screed to dry before I can tile?
2. Is there a rapid drying admixture I can insist the builder orders in the screed (it will be readymix)?
3. I have also heard there is a "green adhesive" you can but - does it work, how long do I need to wait before screed and tiling and are there any drawbacks?
Thanks
Colin

[Rich]

I hope someone can help me with some advice please. I am having an extension built woith about 75m2 of ceramic tiling planned for the floor. The builder is putting underfloor heating down (water based) and is going to screed over the top. I have now been told that I must wait 4 weeks until I can tile and I have the tiler booked for Monday. The screed is not due to start until Wednesday this week.
1. How long should I wait for the screed to dry before I can tile?
2. Is there a rapid drying admixture I can insist the builder orders in the screed (it will be readymix)?
3. I have also heard there is a "green adhesive" you can but - does it work, how long do I need to wait before screed and tiling and are there any drawbacks?
Thanks
Colin

Hi, Im afraid so, it is so important to have the screed totally dry before tiling. There are materials on the market that say that they can be used sooner (like green screed adhesives and some decoupling membranes) but they also say that it is always better to give the screed the correct time to dry. I would much rather phone the tiler up and apologise then risk ruining the floor.

[Kraken]

Thanks Rich. What about screed acclerators like Contopp? I have a 100mm screed going down and don't think I can wait 100 days!! I have also been told that using a dehumidifier will help but am worried that might dry out the screed too quickly and cause cracking.
Colin

[Dave]

The biggest problem you have isn't the drying time.. you need to commission that wet heating before you can tile..

It is 21 days before you can commission a cement based screed , this is to allow it to fully cure and harden.. and if it was an Anhydrite screed then it would be 7 days.. so either way there is no rush here..

When you commission the floor this can also be used to force dry it... so you are looking at 30 days minimum..

[Ajax123]

As dave says the drying is not the primary time limiter. You can get sclreeds which dry in 24hours for a price but he fact remains that the underfloor heating must be comisisioned and run prior to tiling. If a cement screed is use it should be properly cure by covering with polythene for 7days following installation. Then 21 days later comission the heating. Also make sure the screed is properly jointed