Gym Summerhouse / Best way to deal with flooring on concrete pad?

Discussion in 'Builders' Talk' started by rjsdavis, Aug 4, 2022.

  1. rjsdavis

    rjsdavis New Member

    Hello to all

    I'm building a summer house, that will be used as a gym. It's 5mx4m, and has a concrete base (nearly 7 tonnes worth!). The timber frame is sat on the concrete base, with a DPM between them. The building is fairly standard 4x2 timber frame / 18mm plyboard outer (but inner) walls / Rhinovent moisture barrier / Cedar T&G cladding (outer skin) on baton frame. I'm basically copying an Oakwood Garden Rooms build from their many YouTube videos!

    I've just installed the insulation, and am getting to do the first fix of wiring, internal vapour barrier, internal walls, and then flooring...

    This is my question: How to best floor it?

    I think my two options are basically:

    1: Lay the rubber gym floor tiles straight onto the DPM, so that the concrete base is directly taking all of the weight of everything that will be inside (Power cage / Olympic weights / treadmill / rower / x-trainer etc etc)

    2: Create a false floor, by laying 2" x 2" joists directly down onto the DPM / Concrete base, insulate the joist gaps with 50mm rigid insulation and then lay 18mm plyboard on top of joists, and then lay the rubber floor matting on top of the plyboard.

    I'm inclined to go for option 2, but in doing so, wondered about good/strong spacing between the joists to take the weight of everything that will sit on top of it. I always go super-strong as a general principle (roof joists are doubled up/paired 5x2's as the span is more than 3m for example to take the weight of a full snowfall for example), so I was thinking the floor joists should have 300 or 400mm spacing?

    Does it matter if they are laid front to back / side to side? (Genuinely don't know if that's even a relevant question!) I would probably also be inclined to chop up some additional 2x2 and insert them as noggins to keep them evenly spaced and secure.

    Would be grateful for any thoughts on the flooring?

    Many thanks in advance for any replies.
     
  2. MRY

    MRY Screwfix Select

    (2) is just about what I've done, but battens and Jablite directly on concrete floor, 350mm-ish spacing 'cos that worked with the cheap reclaimed ply I used (edges required trimming), noggins simply laid between battens to support cut ends of ply sheets. Then Visqueen over, then the ply on top. I don't think it makes any difference which way you lay your battens.
     
  3. rjsdavis

    rjsdavis New Member

    Thank you for the reply MRY. Appreciated.

    This sounds just like my plan then... I should have mentioned that I would have put a vapour barrier down over the joists/insulation and underneath the plyboard floor.

    Have you used yours as a gym as well? Ifso, how has it stood upto all of the weight of the equipment just sitting on it, and somewhat rougher abuse like your cleans and shrugs??
     

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