How long does it take for concrete to dry?

[Floorist]

Another concrete link.



http://www.cement.org/tech/cct_drying.asp

 

[TNT]

Another concrete link.

http://www.cement.org/tech/cct_drying.asp

Thanks for that! I'm going to be having engineered hardwood installed for a customer soon, part on an old, existing concrete slab, the remainder in an adjoining new addition. The new concrete has been down about 6 weeks, and I'm still out about a month on the install. The guy wanted 3/4" wood, but I told him since we were below grade, I wouldn't sell him that. He first said that he could never be convinced to stray from solid, then asked what below grade meant.

Said I wasn't trying to convince him of anything - but would refuse to sell him solid for below the land line, underground. I didn't care if it was only 6" under. People always seem to cave in when you tell them to go somewhere else.

Tia

 

[Nick]

I won't mess with 3/4 above grade .
Accident waiting to happen in my book .

 

[FYIfloors]

I am really enjoying the links your posting Floorist. I have just finished testing a concrete floor that has been installed since July 2010, it is below grade however I would have to say it is one of the most efficiently programed jobs I have ever worked on and they have done everything right DPM, waterrpoofing etc. So the GC is really upset his timber installer is getting readings over the recommended RH% and wanted a second opinion.

My readings too, are over the reccomended RH% and are in line with the installers so he accepts the outcome however he has asked me why this slab is not as dry as he had hoped especially after 12months and 9months fully enclosed.

My answer is.....the average relative humidity in Auckland NZ is 75-78% so trying to dry a floor naturally to an RH% below the atmospheric conditions is not going to work in his favour but to his credit the MVER was only 1.5% above where it needed to be.