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Hard Flooring

Engineered ash floor over uneven concrete floor

Hello, i'm looking to install a engineered ash floor over on the GF of our 60's ex council house. I have removed all the old layers of old flooring down to the concrete. Unfortunately the concrete floor is not levelled and is about 2-3 cm lower on on side of the room plus there are other uneven parts of the floor.
The floor supplier i ordered the floor from recommended i screw the floor down rather than a floating installation.
I'm planning to first lay a damp proof membrane on the concrete and then fix a grid of slim timber joists with 40cm spacing across the floor to level the floor. Eg. underlay the joists where the floor is lower with extra layers of timber. I would float this joist grid over the DPM and then screw the engineered floor boards into the joist grid. I would prefer to install the floor like this rather than pour a self levelling compound on the existing concrete as it will allow for air circulation below the floor boards to prevent moisture problems.
Any feedback highly appreciated if this is a recommended way to install a floor. Will it be a problem to screw the floor to the floating grid of joists?
Thank you!
Simon

4 Answers from MyBuilder Flooring Fitters

why are they recommending screwing it down what's wrong with secret nailing it through the tongue, the floating joists will be fine once you got the first line of boards in as a tip I would put a removable baton screwed to the joists at the other end to stop joists moving hope this flooring is 20mm thick anything else will be too thin to go on joists
mike ssc flooring

2015-05-18T12:30:03+01:00

Answered 18th May 2015

yes flooring must be min 20mm thick for structural work .
whats wrong with screeding up the floor then using a liquid dpm which will stop any damp also then fully stick down the flooring to give a solid feel, no bouncing or creaking.

2015-06-15T13:45:02+01:00

Answered 15th Jun 2015

Check with the manufacturer of the flooring as some will only garuntee the floor if you follow there instructions for fixings and glue etc.

2015-12-02T21:50:01+00:00

Answered 2nd Dec 2015

I would recommend secret nailing to the battens but the subfloor needs to be dry otherwise the moisture will get into the battens and subsequently into the flooring. The flooring must be structural I. e 18mm thick and the battens no more than 300mm centres.

2020-04-21T18:45:02+01:00

Answered 21st Apr 2020

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