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Air vents in the roof

  • 30-03-2007 11:02AM
    #1
    arghh
    Closed Accounts Posts: 89 ✭✭


    I have put in two air vents in the roof to vent the attic. The area of the roof is 42 x 29 feet and 4 ft high.Someone told me that its better to have a vent at each gable in the blockwork that it creates better ventilation.Is there a rule of thumb as to how many vents you have per sq ft? I have seen houses that have many and some like me that have only the few.I know that having the right ventilation is important to stop rot and and woodworm. Do I have enough or can one have too many?


Comments

  • #2
    muffler
    Registered Users, Registered Users 2 Posts: 46,749 ✭✭✭✭muffler


    What type of house and what type of roof is it? Pitched, lean to ???


  • #3
    arghh
    Closed Accounts Posts: 89 ✭✭arghh


    its pitched doormer style block with tegral slates.The measurment between the joists and the ridge board is 4 feet. The angle of the roof is 35degrees


  • #4
    muffler
    Registered Users, Registered Users 2 Posts: 46,749 ✭✭✭✭muffler


    Vents in the gables wont help with keeping the underside of the roof free from condensation. You will need both eaves and ridge ventilation and a min. 50mm clear air space between your insulation and the underside of the felt.

    Details here

    I updated that link as it didnt appear to work


  • #5
    arghh
    Closed Accounts Posts: 89 ✭✭arghh


    Thanks Muffler


  • #6
    kravist
    Closed Accounts Posts: 160 ✭✭kravist


    Im planning on getting my attic insulated with "Under Slate Roof Insulation", apparently making my home compliant with "Part L" of current buliding regulations. The insulation gets sprayed onto the underside of the felt, making an airtight seal, thereby resulting in better insulation.....so im told.
    Am i about to waste money, should a roof not have some air movement?
    Am i going to end up with a very warm attic, and everywhere else freezing?


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  • #7
    Slates
    Registered Users, Registered Users 2 Posts: 351 ✭✭Slates


    arghh wrote:
    its pitched doormer style block with tegral slates.The measurment between the joists and the ridge board is 4 feet. The angle of the roof is 35degrees
    This roof will require high and low level ventilation as it is a "warm roof"

    The equivalent of a 25mm open run of ventilation will be needed at eaves

    The equivalent of a 5mm open run of ventilation will be needed at ridge, you will also be required to provide a 50mm space between the insulation and the underlay to allow ventilation flow through


  • #8
    lastbuilders
    Registered Users, Registered Users 2 Posts: 304 ✭✭lastbuilders


    When I was doing my self build I counter battened the roof too to aid with ventilation.

    Lastbuilders


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