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Insulating a 1950 house

  • 24-10-2010 10:21am
    #1
    quickdraw2
    Registered Users, Registered Users 2 Posts: 93 ✭✭


    I am trying to find the best way to insulate on a complete renovation of my 1950s house.

    I have stripped out the ceilings and walls are exposed from the wall plate to rafters, the soffit is concrete and I can see no vents,
    In fact I can see no attic vents at all in the attic.

    I am considering using rafterloc insulation between the rafters and also finishing with superquilt under the rafters.

    I really need some experienced advice regarding vents over the rafterloc,
    and would I need to install ridge tile vents.

    I am trying to avoid potential condensation problems, and preserve the air tightness to improve my BER.

    "experience is something you get just after you really need it"
    Tagged:


Comments

  • #2
    DOCARCH
    Moderators, Home & Garden Moderators, Science, Health & Environment Moderators Posts: 18,450 Mod ✭✭✭✭DOCARCH


    If you're not changing the roofing felt (it's probably some sort of impermeable felt in a 1950s house) then make sure there is a minimum of 50mm free airspace between the top of the insulation and the underside of the roofing felt.

    Ensure same airspace (min 50mm) at eaves level if insulating down over the wall plate with fibreglass insulation - in existing house the airspace can be maintianed over the wall plate when insulating by fitting a plywood 'retainer' between the rafters or using chicken wire or similar.

    At ridge you need to provide equivalent of 5mm continuous strip ventilation - this can be achieved either by ading ridge vents or by taking off all the ridge tiles and re-fitting with a fulmetal rediroll system (you can google this).

    At the soffits you need to provide equivalent of 25mm continuous strip ventilation - this can be achieved in existing soffits by installing PVC soffit vents.

    If the existing roofing felt is breathable, then free airspace can be reduced to 25mm.


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