1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Correct insulation to use between ceiling and slate roof?

Discussion in 'Roofing and Guttering' started by sncooper, 28 Nov 2012.

  1. sncooper


    28 Nov 2004
    Thanks Received:
    United Kingdom
    Our victorian house has an original loft room.

    We had a re-roof done 9 years ago, and took the opportunity to have them install insulation above the ceiling before felting and slating the roof.

    The job does not appear to have been the best as the chimney now needs re-pointing again, and the ridge tiles are coming loose, as is the lead flashing.

    Of greatest concern is that one of the roof surveyors has informed us that we should not have had rock-wool insulation (the pink loft insulation type) installed as this can absorb moisture and rot the beams.

    We are told that it it was done today then the regulations say would use Kingspan (or equivalent) to insulate.

    Is this the case, and can the rockwool really be causing our roof to rot and eventually fall in on us?
    (we had two other quotes and they said there is no visible evidence inside.)

    It's not the horror scenario I was expecting when I asked for quotes.

    We are unsure what to do, an inspection (removing a few rows of slates) could cost £1000, where-as 'doing the job right' is expected to cost £6000.

    Thanks for reading - any advice appreciated.
  2. Sponsored Links
  3. 8aviashusband


    24 Nov 2008
    Thanks Received:
    United Kingdom
    I wouldn't get too worried about your roof falling in on you - it'll be many years before that happens, even if there is a damp/rotting problem.

    I would want to be confident that there is a ventilation space between the rockwool and the sarking felt, and that there is a route for the air to flow. This might involve fitting eaves ventilators in the soffit, but this is not difficult once you have access from outside.
    If the ceiling of your loft room is flat under the roof ridge, then there will be a triangular shaped (small) loft space above. Probably, in this area, the rockwool is laid on the ceiling, and the space above will provide a common ventilation route for all the 'tunnels' between the rafters. This would make the fitting of a few ventilating ridge tiles a useful way of improving the ventilation at the top. (Or use a few slate vents (like screwfix 45984) in the second course from the top).
    While there's work going on which involves refixing slates & ridge tiles, use your nose to see if there is any smell of damp, fungus, rotting etc. You're probably right about using Kingspan nowadays - it would be easier to use for a start, but you're stuck with the rockwool now, and I wouldn't feel inclined to replace it unless you can detect a real problem.
    Good luck!
  4. DIYnot Local

    DIYnot Local

    3 Sep 2019
    United Kingdom

    If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

    Select the supplier or trade you require, enter your location to begin your search.

    Are you a trade or supplier? You can create your listing free at DIYnot Local


Share This Page