Home  5  Books  5  GBEzine  5  News  5  HelpDesk  5  Register  5  GreenBuilding.co.uk
Not signed in (Sign In)


Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.

Buy individually or both books together. Delivery is free!

powered by Surfing Waves

Vanilla 1.0.3 is a product of Lussumo. More Information: Documentation, Community Support.

Welcome to new Forum Visitors
Join the forum now and benefit from discussions with thousands of other green building fans and discounts on Green Building Press publications: Apply now.


    I had a plan for a cold roof on the dormer I'm building - here isn't enough headroom for a warm roof. The original plan was to have 50mm air space above 120mm Celotex in the roof space. In haste, I went a bit off plan and fitted the rafters into joist hangers at the outside end, rather than supporting them on a beam. The way I've now installed the rafters means the ends are closed.

    The building inspector pointed out my error, and my heart sank. I'd expected I'd be required to make a substantial re-build. However, he just said to make sure the vapour barrier was airtight and call it a sealed roof. I understand what he's suggesting, and I know the importance of sealing the roof really well (no lighting in the ceiling) but I imagine that even with the greatest care, there'd be an air leak somewhere, and the space would eventually become damp and there'd be no way for it to dry out. So even though I have building regs approval, I'm hesitant to go down that route.

    Any suggestions that don't involve reinstalling the rafters (I've temporarily fitted OSB on top of the rafters to give me a dry workspace while I sort out walls and floors)? I can't drill holes in the supporting beam, as this would compromise its strength, and anyway wouldn't provide anything like the planned for air flow.


    • CommentAuthortony
    • CommentTimeJul 28th 2016
    Yes you can drill holes, it will occasionally get damp from condensation but the sun will boil it away.

    Series of 20mm holes should cure it and it is not a major problem with none

    Alternative would be to add door stop on top of rafters and leave a slot at the front or above the joist hangers.
    I can do a bit of door stop. Thanks.
    • CommentAuthorMike1
    • CommentTimeJul 30th 2016 edited
    I wouldn't be at all happy sealing the roof. The doorstop solution would be preferable - or maybe 25mm roofing battens over the top of the rafters and at 90° to them, and ventilate in that direction instead?
Add your comments

    Username Password
  • Format comments as
The Ecobuilding Buzz
Site Map    |   Home    |   View Cart    |   Pressroom   |   Business   |   Links   

© Green Building Press