Engineered oak flooring on new screed

[Corazones]

I had a 75mm flooring screed laid today on top of insulation and underfloor heating pipes in a new extension. I realise from previous threads that thorough drying is essential before laying 20mm engineered oak flooring (glued type, not clipped), and that I should allow something like 1 day per mm - maybe more.

My question is this - I have ordered a Rapitest damp test meter to give me a rough idea of how the floor is drying; what value should I aim for? Is zero normally achievable?

Many thanks, Alec.

 

[crazydaze]

It's usually about 4 weeks per inch drying time, as you will be floating the floor as it's engineered, you will need to use a poly sheeting membrane anyway, you just need to get the floor 'dry' it does'nt need to be 'bone dry'.

I'm not familiar with the particular tester you have, it should come with instructions of how to 'read' it's scale, also your prospective flooring will have the specs needed re: how dry the manufacturer recommends the prep to be carried out.

 

[Corazones]

Thanks, Crazydaze. I understand that this manufacturer recommends laying the engineered oak flooring on 2mm foam which they will supply - would this be counted as waterproof as with the polythene sheeting you mention, or will I need an additional barrier layer?

 

[crazydaze]

You will need a foam as described with a built in poly sheeting, or a separate sheeting.

Personally I'd lay it on TimbermateXL.

 

[Corazones]

Thanks, I'll look out for that.

Incidentally, my Rapitest arrived from Amazon and I think it will give me a good guide. It reads from 0 to 10; at present the new screed reads 10, while a perfectly dry wall in another room reads 0. If it gives even a rough guide, it will have been worth the £20.

 

[crazydaze]

Thanks, I'll look out for that.

Incidentally, my Rapitest arrived from Amazon and I think it will give me a good guide. It reads from 0 to 10; at present the new screed reads 10, while a perfectly dry wall in another room reads 0. If it gives even a rough guide, it will have been worth the £20.

That's considerably cheaper than the F-Ball Protometer that we have at work £200 odd quid! That a customer currently insists is'nt acurate as after a massive flood in their home the floor still hasnt dried out as they refuse to use de-humidifiers and keep covering the floor with rugs as the concrete is 'cold' !!

Good luck,take regular readings, you should see things start to settle/improve 3-4 weeks in.

 

[Corazones]

Thanks, Crazydave. Your reference to the dehumidifier reminds me that my son has one - I must see if I can borrow it!

 

[craighewer18]

Corazones, I am in exactly the same position as you, bought the rapitest last week too. Anyway i've been to site to test the new screed and in some parts (particularly corners) its up to 25-28% and the builders are pressuring us to lay the new floors (21mm eng & tiles) Would you say this moisture content reading is too high?

Thanks in advance

 

[Corazones]

Yes, quite definitely, Craig. Resist the pressure from your builders and wait until the moisture content gets down to about 4-5 on the Rapitest (a dehumidifier is a great help), then you can turn on the underfloor heating. Do this gently at first, one full day with the surface temperature between 20 and 25 degrees, regulating this by turning on and off (patience is needed but it is worth doing properly!). Then each day it can be 5 degrees higher, up to 40 degrees which is no problem to control. The difference it makes is amazing, and after four days mine was down to zero on the meter and I'm ready to lay the floor, which must be glued down of course - I checked with different manufacturers and they all say the same. It's necessary to give it 24 hours to cool down first, though. Good luck!
Alec.