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Advice on insulated lean-to conservatory roof construction

Discussion in 'Roofing and Guttering' started by tibz, 14 Jan 2014.

  1. tibz


    14 Jan 2014
    Thanks Received:
    United Kingdom
    Hi Everyone, this is my first post here. Have tried to read and find out myself but just seem to be going round in circles!

    Basic situation is this. I have an old concrete floor, brick wall, timber window, corrugated plastic roof conservatory on the back of my house. 50's built I think. Pic at bottom

    Looking to upgrade this year and replace roof and windows/doors.

    Been doing some research and became aware of the change in building regulations in 2010 that no longer requires the conservatory roof to be 75% glazed.

    This means that building control are not interested. I have actually emailed them with my plans and they have confirmed that it will still be classed as a conservatory even with an insulated and tiled roof and therefore be classed as permitted development.

    This is great as originally I thought I would have to knock down and rebuild completely from the foundations up but now all I really have to worry about is just making sure that the construction meets modern specs for my own benefit and peace of mind.

    So I intend to take advantage of this change in Building regs and replace the roof with something a bit more traditional and fully insulated but all the time bearing in mind that the footings were only designed to take a conservatory

    Because of this I am considering the use of lightweight tiles such as tapco shingles or Decra powder coated steel tiles to keep the weight down.

    A little bit more on the foundations. They were obviously built to hold a conservatory though 25% of the outside wall is double skin brick cavity and full height making me think they must be fairly substantial. Also a lot of the weight will be taken by wall plates on the back wall and two sides (Mid terrace).

    I want the roof to have about 3 'velux' type windows in it for light

    I want to maximise inside space and keep the roof as minimal as possible. Is a vaulted ceiling the correct term? i.e. don't want a roof void.

    So here are my questions.

    What kind of construction should I use - warm or cold roof? So I have so far come to this design:

    Roof size: 6mx3m

    Timber wall plates, rafters (150mm x 47mm x 3.6m). Double rafters either side of windows
    Celotex/kingspan 150mm in between rafters.
    Pearmeable membrane on top of rafters/insulation
    Counter batten to create an air space for ventilation
    Batten then tile
    Plaster board or wood cladding on inside

    Does this sound right? My main concerns are ventilation and the risk of condensation.

    Looking on the kingspan website they detail this construction for 'Warm roof'


    Is there a better way of doing it?

    Anybodys input would be gratefully received

  2. catlad


    29 Jul 2011
    Thanks Received:
    United Kingdom
    Knock it down and start again is my advice but if you don't want to do that then you need a light weight roof ie. rubber or felt.
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  4. Bankrupt


    6 Aug 2009
    Thanks Received:
    United Kingdom
    I concur - I would demolish it and then rebuild to modern standards.
  5. noseall


    2 Feb 2006
    Thanks Received:
    United Kingdom
    The guys above are correct.

    Why spend thousands on a high-end roof only to dump the lot on a low end foundation. Does not make any sense.

    You never know, you may set off a trend and everyone in the street will copy, thus putting an end to that 'shanty' look.
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