More Loft Question(s) (Collar type support)

Discussion in 'Floors, Stairs and Lofts' started by amritc, 8 Sep 2010.

  1. amritc

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    Hi All,

    I am planning on creating a loft space for storage use only.

    Currently the loft\roof is supported by purlins and collar's.
    The plan is to remove the collar's as the are approx. 1.5m high from the the floor(ceiling joists).
    Reason for this that they are in the way an accessing the stored items can get a bit difficult.

    Now for the details:
    1930 Semi detached bungalow
    Roof style = hipped roof
    Loft length = 10.1m
    loft width = 7.6m
    Loft height = 2.8m

    Plan
    -Insert new longer and stronger purlin 9x3
    -Floor support Two 9x3 bolted together with 10mm steel plate sandwiched.(red)
    -Vertical purlin supports 6x3 (black)
    -Add collars(Ties) at a higher level on each rafter 6x2 bolted in.
    -7x2 at 300mm centers for joists with joist hangers.
    - Remove old collars only.

    Image one is a draft of what I plan to do.

    Loft as it is

    Wierd purlin support

    More pics in my album
    http://www.diynot.com/network/amritc/albums/

    I will be seeking advice from a SE coming this weekend and also will apply to BR. But Just would like to ask on here as there seems to be alot of people with knowledge on here.

    Questions?
    1. Steel or will two 9x3's with 10mm steel plate be ok?
    2. Two 9x3 be ok without the steel plate?
    3. As the collars are preventing the roof from opening up(assuming outwards force) will the new purlins and vertical supports, support the outward force?

    Thank you in advance
    A
     
  2. Deluks

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    It has/will be getting a staircase?
    Bungalow?
    You are prepared to put steels in?

    Screw light storage, convert the bugger! You will likely be spending a few grand anyway so might as well make it pay off in the future.
     
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  3. amritc

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    Hi,
    Thank you for your reply.
    Yes, Its a 1930's semi bungalow.
    The staircase was just an idea I had that I left in the drawing but will install a pull down ladder.

    I was going to put in steels, but then thought might be an overkill for just storage.
    Also I intend to carry out the work myself and working with wood will be much easier than trying to install steels.

    I have estimated around 3-5k for the work if it is all done by myself.
     
  4. freddymercurystwin

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    I have never done a loft conversion with timber beams instead of steels, as mentioned already you would be naive if you were to install a floor just for storage, at the very least have the floor designed so that if you or the next owner wanted to complete the conversion the floor/structure was adequate. As long as its not his first one or he's fresh out of Uni, your SE will have done dozens of loftys and will soon tell you the best way to convert it. There's too many unknowns to offer any other useful advice really.

    Typical loft conversions have the following

    Insert steel beams
    Fit new joists for floor
    Build structural timber wall off steels to support purlins
    Fit new bigger rafters parallel to the existing ones
    Remove existing ties/props etc.
     
  5. Deluks

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    Being a bungalow, a full conversion should be cheaper than a house with 2 floors. You can skip things like fire door upgrades and mains smoke alarms etc. Easier to work out what goes where structurally and less scaffolding needed.

    3-5k would get it done for you, at least just for the basic floor/roof upgrade. DIY-ing it would almost certainly get you the staircase for your 5k.
     
  6. amritc

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    Hi All,

    The SE came around today and purposed and few options.

    Option 1 :
    Joists - 6x2 to sit on existing 4x2 held together with metal screw\nail plates.
    Rafters - 7x2 to be bolted to the side of existing rafters (4x2).

    Option 2:
    Joists - 7x3 to sit next to the 4x2 bolted together.
    Rafters - 7x2 to be bolted to one side of existing rafters (4x2).

    Option 3:
    Joist - any option from above
    Rafters - 2 4x2 bolted to rafters each side of the exisiting.

    With these option he said I could remove the collar ties higher.
    Also the purlin could go as it is a split purlin and is not doing much.

    He also mentioned that once the structure was secured the wall plates will handle all the weight and force. And that the rafters and joist are securely attached to the wall plate so in doing this it would be OK.

    I just have a little doubt as joist are not connected to the rafters in order to create a solid triangle for support.
    See pics
    Option 1

    Option 2

    This is how i thought it should be done

    Any recommendations or thoughts would be grateful.

    Thanks,
    Amrit
     
  7. amritc

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    Any advice please
     
  8. freddymercurystwin

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    Option 2 will keep the floor level lower as for the rafters get your calculator out and work out which will be more cost/time effective. Deeper rafters will also lower the ceiling level. Probably worth a call to Kingspan or Celotex to check on insulation thickness's to help you decide too.
     

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