will this floor need ventilation

5 Nov 2009
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United Kingdom
my new extension needs to have the floor compleated,,, up to now it as mot,,visqeen,, 4 inch kingspan,, then 6 inch of conceat all passed by building control,, i now need to finish it by bringing it up approx 3 inch which i can by boarding it over with ply or chipboard ,,, can i do this ,,, or do i need to create ventilation ???? between the concreat and the ply
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As above.

Are you proposing to lay the sheets of ply or chipboard directly on the concrete or are you intending to first lay "joists" and then fix the sheets of ply etc to the "joists"?

3" is a lot of height to make up before laying your final finished floor - for instance, if you are only using 3/4" boards you would need four layers of 3/4" ply to pick up 3".

Screeds of semi-dry sand and cement are typically used to on concrete slabs to raise the floor level.

Both concrete slab and screed need a drying time.
I would like to raise the floor on 2x2 and 22mm ply I have done this on a previose extension but was told by a mate I should have ventilated ?
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yes woody hes a 62 year old bricklayer been doing it all his life,,, thats why i had second thoughts if what i was about to do was correct,, as im a plumber i suspected that i was in the wrong,, just go to show allways check advice,,, thanks both for the replys i prefer the wood floor for pipe access ETC
As said, the floor you describe does not need ventilation. There must be some isunderstanding between you and your bricklayer friend. Maybe he thinks you are talking about a timber suspended floor which would need ventilation.

Interesting punctuation by the way.
PS. Is the main house a suspended floor or solid concrete floor? If so he might mean that you should provide ventilation through your new solid extension floor to maintain ventilation to the main floor. Just a thought.
thanks jeds the exsiting house is soild floors ,,, but he may have not been aware of that

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