Block and beam - suspended wooden floor

Discussion in 'Builders' Talk' started by olmasters, Mar 23, 2020.

  1. olmasters

    olmasters New Member


    I need to replace my existing tongue and groove chipboard floor, due to the current one being warped throughout the flat and squeaking due to loose studs underneath.

    After removing it, the studs (32x50mm) were not secured to the rather uneven block and beam floor, nor levelled (im guessing resulting in the uneven and noisy floor previously).

    I now want to level and secure the studs ready for the new flooring. Is it acceptable for me to be screwing these into a block and beam floor (ensuring I only screw into the blocks).

    I was intending to reuse the 32x50mm studs and secure them with 6x80mm hammer in fixings + packers underneath to level. Do I risk cracking the blocks with this approach, or would I be better off bonding the studs?

    Many thanks!
  2. Greentram

    Greentram Member

    Are you in an upstairs flat? If so, I would have expected the wooden floor bearers to be separated from the floor by rubber or similar packers to reduce the transfer of impact sound.
  3. olmasters

    olmasters New Member

    I'm actually in a ground floor flat. Floors above me use the same construction.

    Question is, do I risk weakening the blocks by screwing the floor studs to them? I'd have no problem with a block wall, but realise in the case of the block and beam floor, they are just loosely placed so dont want to risk cracking them.
  4. Jord86

    Jord86 Well-Known Member

    Space the studs out at 400mm centres and tack them all together in place with a temporary batten both ends of the building, about 700mm off the walls. Then, level the whole framework as one unit, packing where necessary with plastic glazing packers. Once packed and solid, no flex, I’d use expanding foam under all the gaps and give it a few hours to cure fully.

    Then, snap a chalk line off the wall along the bearers 630mm, then fit your first row of chipboard to this line, using the front edge of the tongue as your guide to pull it to the chalk mark. Use D4 or a polyurethane based expanding glue on top of each bearer, stick two screws in each sheet of chipboard at either end temporarily to stop them moving, remove the temporary batten, then continue laying the chipboard, gluing each bearer and the tongues of the boards as you go.

    Once the floor is laid and the glue has gone off, remove the screws from the first row, and it’s job done, ready for skirting. No fixings equals no squeaks.

    This is a slight variation on a floating floor construction (my own) but as you’re on the ground floor the soundproofing qualities aren’t required as much.
    Mr Rusty likes this.
  5. olmasters

    olmasters New Member

    Sounds like an excellent plan!

    I've got a stash of glazing packers for levelling, would you advise just bonding them with expanding foam?

    I hadn't considered consider a polyurathane expanding glue - Is this an acceptable substitute for screwing to the bearers, or would you recommend this as extra insurance?

  6. Jord86

    Jord86 Well-Known Member

    Just stick the packers under wherever is needed, no point gluing them in, can’t go anywhere once the floor goes down anyway. Yes the glue is an acceptable substitute, that’s why I suggested to use it, once it’s gone off you don’t need to fix the boards mechanically. Floorboards squeak because they’re rubbing on fixings due to slight gaps. Google floating floor construction if you need an example of what I’m on about.
  7. olmasters

    olmasters New Member

    Thanks very much for your advice, its been a real help!

    Jord86 likes this.
  8. Greentram

    Greentram Member

    As another thought, if you've not already started, do you need the battens? Why not a floating chipboard floor over dense polystyrene or polyurethane board? Insulation boards are laid loose over a polythene dpm (unless you're sure there's one under the concrete), then t&g chipboard sheets are glued together to make on large sheet (be sure to allow edge clearances). No squeaks and a warm floor with a little give. Not appropriate if you want to tile it.

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