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Insulating a garage - some advice needed on the floor and approach

Discussion in 'Building' started by Adam_36, 13 Jan 2020.

  1. Adam_36

    Adam_36

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    Hello

    I've got a standalone garage outside my house. It's single brick (over 110mm think as it's 2 courses) and I want to insulate it. The reason I want to do this is for storage purposes and I've got electric running to it so I can keep an oil radiator or something in there to keep the temperature controlled >15c.

    I've decided to build a false ceiling inside it, so that there isn't' any load on the roof structure and I've already vented the garage at both ends to ensure the insulation in the roof space doesn't end up all damp. The ceiling will be a fairly standard approach with a good, thick wool insulation at the top.

    I've order Kingspan Kooltherm K18 50mm/12.5mm Insulated Plasterboard and I'm going to mechanically fix it using treated roof battens that have a DPC behind them as per the instructions.

    The query I have is with the floor. There is a solid concrete floor at the moment and I know that there are a couple of options here using a floating or screed based approach. I realise that I will need to put down a DPM and then something like kingspan or Celotex on the floor - perhaps 20/25mm super-strength stuff with either a floating floor using 18mm chipboard / or screed.

    I cannot afford for the floor to be raised to much because I intend to install a highly insulated garage door to keep it "functioning as a garage". I hope that I'm within my right to do the work I want given that this garage is completely standalone and I want to store stuff in it! I expect building control will probably say otherwise.

    With the DPM for the floorI read that someone's advice was to take this up the wall beyond the DPC in the brick by 20-30cm. Would I be right in saying that I do this first before installing the walls with the battens with the DPC? or do I do that once I've battened out the walls and fixed the Kingspan Koolterm to it?

    Any help would be most appreciated


    Adam
     
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  3. noseall

    noseall

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    Just leave the wall DPM long (300mm or so) so that it can be lapped onto the floor, should you wish to improve the floor retrospectively.
     
  4. Adam_36

    Adam_36

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    Thank you for the reply noseall.

    Are you suggesting that I don’t run the damp proof sheet up the existing garage walls before I batten it out? Perhaps just up what will be the internal wall leaving some spare for future floor hight?

    Will it be OK that the DPC on the bricks is higher then the floor?

    Reading up on Kingspans stuff it creates a vapour barrier so I guess if I batten and take that all the way to the existing floor sealing the joins etc then put a DPM down and then the floating floor will this be OK?


    Adam
     
  5. DIYnot Local

    DIYnot Local

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