Damp garage

Discussion in 'Getting Started FAQ' started by NeilT, Jan 1, 2020.

  1. NeilT

    NeilT New Member

    Hi Ive got a 40 year old single skin garage with flattish box profile roof. The ceiling is partially insulated with polystyrene sheets in between the joists which stop the drips. In the areas where the polystyrene is missing there's a lot of condensation.
    After heavy rain the floor is very damp. A few days of dry weather and it dries out. I dont think there is a DPM.
    A couple of the walls are damp to touch and mouldy. I live in a very wet and windy place- Skye.
    Tbh Im not sure where to start. Id like it to be drier and less cold. Its only used as a store and workshop. I was thinking of finishing insulating the ceiling, laying a DPM sheet and covering with rubber garage floor tiles then insulating the metal door. Would it be worth doing the walls too? I thought of battening the walls and just sticking on OSB or something. If so, would I need to do anythi g to the walls first- I had thought of painting them with some sort of waterproof paint.
    Any advice would be welcome. Its about 10m x 3.5m
    Neil
     
  2. Tony Goddard

    Tony Goddard Screwfix Select

    What are the walls made from, cast contrete, brick or block

    What is the roof made of, felt over wood or corrugated steel / asbestos
     
  3. NeilT

    NeilT New Member

    The walls are breeze blocks. The roof metal box profile. The floor concrete. Thanks for getting back.
     
  4. KIAB

    KIAB Super Member

    Loosing battle trying to stop condensation buildup on a metal roof.
     
  5. Tony Goddard

    Tony Goddard Screwfix Select

    Agree with Kiab, single skin metal roofing attracts condenation like no tomorrow - you can get a spray on PU foam coating to apply to the underside, that works very well on metal roofing (never, never on tiles) but you have to get someone in with the kit to do it - my mate has a big workshop with just single skin tin and had that done, solved the problem immediately.

    I'd be tempted to make it a summer project to rip off the tin roof and put new double wall profile instead.
     
    KIAB likes this.
  6. KIAB

    KIAB Super Member

    +1

    And with a nice grp flat roof with insulation,will easily last 30 years, or a cheaper felt roof.
     
  7. NeilT

    NeilT New Member

    Ok Thanks for that. Ill wait till some dry weather. What about the floor. It looks like damp is coming up through the floor. Should I put down plastic sheeting DPM? I thought about that then putting some rubber tiles on top. Would that prevent the damp coming through or would it just trap it to cause later problems. I also thought about just putting the tiles straight on the floor reasoning that the damp would evaporate through the gaps. It doesn't need to be perfect. Just feel a bit drier and stop my tools rusting
     
  8. HappyHacker

    HappyHacker Active Member

    Many houses were built in the 50s and 60s with no DPC under the concrete floor the DPC was in the form of the plastic Marley tiles laid on top of the concrete. Unless there is a problem with the concrete you should be OK with tiles/dpc on top, there is no need for gaps, you want to make it waterproof.
     
  9. NeilT

    NeilT New Member

    Thanks for the reply. Thats what I was hoping.
     

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