Insulating flat roof

Discussion in 'Eco Talk' started by Chriz1, Nov 17, 2020.

  1. Chriz1

    Chriz1 Member

    At the front of my house there has been a small extension extra room single story built at some stage, It's a concrete flat roof, a pitched roof has been built over it. This room below is unbelievably cold. There is no ceiling space to insulate just concrete and plasterboard fixed. How can I go about insulating this? I have tried rockwool ontop of the concrete but this hasn't made a single difference.
    See pic

    Attached Files:

  2. Jord86

    Jord86 Screwfix Select

    So how is the plasterboard fixed to the underside of the concrete?
  3. Chriz1

    Chriz1 Member

    I think its bonded no sign of screws nails and isn't hollow either!
  4. rogerk101

    rogerk101 Screwfix Select

    That concrete slab should be removed and the roof remade with insulating materials.
    As long as the concrete slab remains in place there is little point in laying rockwool on top of it because there is too much cold bridging happening for it to have much effect.
  5. Chriz1

    Chriz1 Member

    Bit of a job, I've been thinking about making fixing insulated plasterboard over the existing ceiling?
  6. robgul

    robgul Active Member

    I'd take that a stage further and fix a framework of battens to the underside of the ceiling, infill that with ~50mm celotex type board and then insulated plasterboard and skim - that all assumes you have the ceiling height. With the concrete slab it's always going to a challenge with cold - but, guessing, removal of the concrete and the cost would be prohibitive.
    Jord86 likes this.
  7. Chriz1

    Chriz1 Member

    Yes that may be an idea aswell
  8. Jord86

    Jord86 Screwfix Select

    Go with Robs idea, drill and screw 2x2 to the slab, insulate between with rigid insulation then fix 25mm insulated plasterboard over the face of the 2x2.

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