1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Doubling up rafters for Velux

Discussion in 'Building' started by Jamesymoon, 29 Mar 2014.

  1. Jamesymoon

    Jamesymoon

    Joined:
    2 Jun 2013
    Messages:
    20
    Thanks Received:
    2
    Location:
    Glasgow
    Country:
    United Kingdom
    I am waiting on building approval for an attic bathroom in an existing conversion, but trying to get as much non structural stuff done while I wait. I have a question about the roof work which is holding me up badly just now.

    My architect has said that I need to double up the rafters each side of the velux. I will be bringing in a pro to do this work, but am confused as to whether the whole rafter will need doubled up or if it is only a section overlapping the cut out area. I can not see how I would get a whole rafter in as the roof is a pyramid and the window is going adjacent to the longest rafters which is nearly 6m in length.

    The other complication is that I have found that the rafter to be cut has previously been cut for a chimney which has been removed at some point.

    Any thoughts on how this would be done and if i can run pipes and stud walls around it just now.

    [/img]

     
  2. Sponsored Links
  3. pinenot

    pinenot

    Joined:
    4 Jan 2013
    Messages:
    1,728
    Thanks Received:
    230
    Location:
    Angus
    Country:
    United Kingdom
    Can you indicate the position of the Velux on the picture?
    Your Architect is probably specifying doubling up the rafters due to the current state, but as they look stick built 6" x 2"(+) possibly so wouldn't normally need to be twinned, but if it falls short of spanning between two rafters then the infill's only need be as long as required, but if it's for structural strength perhaps the Architect is specifying full length, why not ask? ...pinenot :)
     
    • Thanks Thanks x 1
  4. Jamesymoon

    Jamesymoon

    Joined:
    2 Jun 2013
    Messages:
    20
    Thanks Received:
    2
    Location:
    Glasgow
    Country:
    United Kingdom
    Thank you for your response.

    The velux is wider than the space between rafters and would be roughly where the two cross pieces (sorry don't know the correct term) which went around the old chimney are. The white panel seems like a bodge chipboard panel to fill where the chimney was.

    The velux is longer than the space between the cross pieces so I assume that they would be removed and the trimmer for the window would be above the top one by a few inches and likewise a few inches below the bottom one.

    The horizontal position would be close to or against the right hand rafter in the photo.

    As the rafter which would need to be cut to allow installation appears to have been cut since installation 1930s, doubling up 6m rafters seems unnecessary.

    I have removed plasterboard which covered all this up since the drawings were done and am just really wondering what is the norm and if the above situation is normal.
     
  5. tony1851

    tony1851

    Joined:
    23 Feb 2012
    Messages:
    10,300
    Thanks Received:
    1,556
    Location:
    Manchester
    Country:
    United Kingdom
    If the rafters need doubling-up (and it's a big 'if' because this is often not strictly necessary), then they only need doubling between points of support up the roof slope, ie between adjacent purlins, or between a purlin and the ridge. The whole length of the rafter (ie from ridge to eaves) doesn't need to be doubled.
    The trimmers (cross pieces across the top and bottom of the velux which support the cut upper and lower lengths of rafter) don't need to be doubled as on your sketch.
     
    • Thanks Thanks x 1
  6. Jamesymoon

    Jamesymoon

    Joined:
    2 Jun 2013
    Messages:
    20
    Thanks Received:
    2
    Location:
    Glasgow
    Country:
    United Kingdom
    Thanks Tony.

    I have just checked and found that there are no purlins in my roof structure. I believe that this is linked to the pyramid shape.

    I'll speak to BC and my architect about how to determine whether I need to reinforce the Rafters.

    I hope that I don't as I can not see a simple way of getting a 6m length of timber into position. If reinforcement is required are there any other options?

    James
     
  7. Jamesymoon

    Jamesymoon

    Joined:
    2 Jun 2013
    Messages:
    20
    Thanks Received:
    2
    Location:
    Glasgow
    Country:
    United Kingdom
    Any further thoughts on whether I will have to double rafters or if there are any other ways of providing support for the cut joist.

    A few google search results suggest that doubling the trimmers without doubling the rafters can help spread the load.

    Will BC be more amenable to avoiding doubling the rafters as the rafter in question is already cut?

    I intend calling them tomorrow but would like to be armed with some further options or experience.
     
  8. DIYnot Local

    DIYnot Local

    Joined:
    3 Sep 2019
    Country:
    United Kingdom

    If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

    Select the supplier or trade you require, enter your location to begin your search.


    Are you a trade or supplier? You can create your listing free at DIYnot Local

     
  9. Sponsored Links
Loading...

Share This Page