Expanded Polystyrene Sheets Directly Under Laminate?

Discussion in 'Builders' Talk' started by wau5, Nov 24, 2022.

  1. wau5

    wau5 Active Member

    Got a bedroom over an unheated garage, the only thing between them is a concrete floor/osb sheet/ some 2mm foam underlay and a laminate.
    a Massive heatloss...

    Was wondering how could I insulate the floor as quickly as possible with the least effort in the cheapest way...
    Came up with the idea to just take up my current laminate, and pop under 50mm sheet of EPS100 Expanded Polystyrene & put the old laminate back.

    Tried to search if someone has done such thing and couldn't find anything much.
    Is this idea Doable/anything I'm not aware of or haven't thought about why this idea could be a failure/structurally unstable/dangerous etc?

    The sheets of Polystyrene I can get here are 50x100cm in size, if the OSB wasn't so darn expensive here now I would probably put another sheet of OSB over the Polystryene, wondering If I can make do without it...
    I'm aware that the correct way would be to insulate the ceiling of the garage,however It would take me 5x longer to do in my situation.
  2. Cris 11

    Cris 11 Active Member

    My last house I used 100mm jabalight polystyrene sheets laid directly on a concrete floor and 18mm t+g chipboard flooring on top worked O.K apart from being a bit creaky and springy when walked on, didn't bother me but missus didn't like it so pulled it up and screeded it instead.
  3. Abbadon2001

    Abbadon2001 Screwfix Select

    isnt access much easier in the garage, vs having to pull everything up in the room?

    You could put some proper insulation, 150mm thick in the garage, and make a much bigger difference I would expect?

    Would seem the logical choice to me, doing it internally is only ever going to make a minor improvement.
  4. Abbadon2001

    Abbadon2001 Screwfix Select

    if you add 50mm to the floor height, how will that affect entry and exit of the room, doors etc... also?
  5. wau5

    wau5 Active Member

    No problem there, thanks for bringing this up!
  6. wau5

    wau5 Active Member

    Logical yes, however In my case it would take me probably 5x longer to do it from the garage and I would be leaving massive thermal bridges due to the way the house is built.
    VS in the room above it's fairly easy.
    I reckon in actual performance in my case that 50mm will do almost just as good vs 100mm from garage side+ the thermal bridges that remain.

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