anhydrite screed and engineered wood floor

I have a new anhydrite floor screed. I would like to lay tiles and an engineered wood floor.

The floor has been down for 1 1/2 months. The RH is around 90% RH (measured using a hygrometer).

I know i will need to wait until it hits 80% rh.

I guess i am out of luck and need to wait to tile the floor. With the engineered wood floor the underlay has a built in DPM.

I am wondering if there is any possibility that I could lay the wood on this without waiting for the floor to dry entirely. I have read elsewhere that some people lay the floor and leave the skirting off.

I've read elsewhere that if you don't let the floor dryout entirely the moisture can cause the floor screed to fail. I am a confused as to which is true.

If I need to wait until the floor has dried out entirely then I will wait but it would be nice to have a wood floor in time for xmas.

Thanks

 

The term 'DPM' built in an underlay is a little misleading. They are typically called a 'vapour barrier' but some manufacturers call them DPM's (with a *). A full sheet DPM is 250 microns (1000 gauge) thickness or above. The 'vapour barrier' attached to your underlay will only protect your floor from a slab reading 75% RH or less.

Be very careful by rushing. If you don't allow the screed to dry properly, the moisture will be trapped within the screed potentially causing failure. Things can get messy from then on.

Here's an article they may help confirm what I've said http://www.contractflooringjournal.co.uk/archive/helpfeb01_2011.html

 

75% RH is what you need to wait for.
Anhydrate is a nightmare if you don't know what your doing. So make sure your installer is 100% clue'd up on the prep side of things.
Your saying the floor is only been down 6weeks??
How thick is the anhydrate, I can say now there's very little/zero chance you'll be in for xmas, sorry...

 

Thanks for the answers.

My builder isn't clue'd up at all. Which is why i've had to resort to the internet. He has never used the screed before.

I've bought him a gypsum based adhesive, Kerakoll H40 Eco Ideal to use when we do finally tile the floor. I've also bough a hygrometer which i've been using to measure the RH of the floor.

The floor is mostly 45mm and 65mm at its thickest.

Some parts of the floor haven't been sanded (the parts that will be laid as wood). I assume I need to ask them to sand it asap as this will slow drying?

 

As well as removing the laitance, be mindful that the air humidity levels in the property will have an effect on the drying times. High humidity levels will slow the drying down and respectively, lower humidity levels will speed it up. Think of the screed as a sponge.

 

Confusingly now the contractor that laid the screed floor (from a company that does nothing but screed) came out and tested the floor. He is saying the floor is dry enough and we can start laying wood and tiles on it. He went round with some hand meter and tested the floor at different points. The entire process didn't take very long. He didn't use a Hygrometer.

The builder is now pushing for me to go ahead and get the wood and tiles laid.

The floor has now been down 51 days. My instinct is to want to let the experts do their job, and not get in their way. I'm not a builder or a flooring specialist but things don't line up with what I have been reading which has just left me confused.

 

Just to clariffy if I have a meter installed on the floor and the LCD reads 80%. Is this 80% rh? or 20% rh? The guy who came round to test the floor seemed to think a higher measurement indicated less humidity . He commented that we would not get 100%. I always though the meter reading was the RH so lower figure would be better.

 

If it says 80% RH now, you need to wait until it has dropped to either 65% or 75% depending on what you're doing with the wood.:thumbs

 

The confusion is that the Screed company is saying a higher reading means the floor is more dry.

I just spoke to them by phone to check if that what I was understanding them correctly and they said yes.

I assumed if the hygrometer says 85% that this was the RH. The screed company is saying that 85% is dryer than 80%. So 100% would be a totally dry floor.

I hope they are right and I am wrong.

 

Thanks for the clarification, I spoke to the company that makes the devices and they said the exact same thing.

I've agreed with my builder to wait for now. I will get the floor tested using a hygrometer next year -

It looks like my builder has another job so it will be feburary 2015 before we can put down a wood / tiles (provided it is dry). Hopefully 130 days will be enough for everything to dry.


Thanks for everyones help, much appreciated.