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.

    • CommentAuthorewoo
    • CommentTimeNov 23rd 2021
    I'm converting a bit of roof space into a cupboard. It's behind the wardrobe, accessed through a hatch/door. I'm installing PIR insulation between and under the rafters.

    There's a wall at one end that supports the roof and separates the cupboard from the next room (the lounge). Photo attached. Not sure what the metal plate in the middle is.

    The end of this wall is beneath the slates/rafters and can't be insulated, so this wall will be cold. Should I insulate it? Do I need an air gap?

    Thanks for you help,
      internal wall.JPG
    • CommentAuthorJonti
    • CommentTimeNov 23rd 2021
    You could build a stud wall and so leave an air gap. Is the metal plate giving access to the chimney?
    Definitely insulate it, otherwise it will be a cold 'radiator' in the back of the cupboard and attract condensation.
    • CommentAuthorewoo
    • CommentTimeNov 23rd 2021
    Metal plate could be access to chimney, as there is a chimney there, maybe I'll try and force it open.
    Ok so I'll put some PIR there, is 60 or 80mm enough?

    What is the point of the air gap in this situation? There's nowhere for the water to go, and if I use foil backed PIR and tape it all up carefully then there shouldn't be any water, true? or no?

    • CommentAuthorJonti
    • CommentTimeNov 23rd 2021
    Posted By: ewoo

    What is the point of the air gap in this situation? There's nowhere for the water to go, and if I use foil backed PIR and tape it all up carefully then there shouldn't be any water, true? or no?


    If it were me I would want to check the construction of any new wall/insulation for things such as dew point. It not then I would want the air gap to ensure moisture had a way out.
    • CommentAuthorphiledge
    • CommentTimeNov 24th 2021
    You said that the other side of the wall is the lounge? If thats the case then theres no need for insulation over the entire wall as the wall has now become an internal wall.

    The uninsulated perimeter where it buts up to the underside of the roof was already a thermal bridge from the lounge and now its become a thermal bridge from the newly insulated cupboard. If you want to insulate the perimeter you could use a grinder to cut off the ends of the bricks at an angle, remove as many bricks as you need to slide short lengths of insulation over the chamfered bricks. Likely youll need to foam the insulation in place. Fair chance of breaking through to the lounge but only you knows if that risk is worth it.

    If there is/was a fireplace the other side of the wall in the lounge, the metal plate is almost certainly access to sweep the chimney or service a damper if fitted. Whether you cover it up depends if the fireplace is in use
    The metal plate indicates a chimney which is likely still open up to the chimney pot to keep it ventilated and dry (unless Euan knows that it is blocked at the top?). That's a route for "cold" to get down to the centre of the internal wall.

    Various options to sort that, with different amounts of effort!
    • CommentAuthorrhamdu
    • CommentTimeDec 7th 2021
    If you make the cupboard door as airtight as possible, and keep it normally closed, not much water vapour will get into the cupboard from the house.
    You then wouldn't need to make the insulation vapour-tight, only airtight enough to control draughts, dust and insects. You might of course feel that 'enough' means 100% in this case.
    • CommentAuthorHollyBush
    • CommentTimeDec 7th 2021
    Also think about heat - if the fire is in use then chimney gets hot...
Add your comments

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

© Green Building Press