Shorten common rafters & wall plate

Discussion in 'Carpenters' Talk' started by Crazyhorse, May 25, 2020.

  1. Crazyhorse

    Crazyhorse Member

    I’m looking for some help and advice regarding my extension roof.

    I have a close boarded roof where the sarking is in good condition. My ceiling joists are set high up the common rafters.

    my new side extension is having the hip roof done, but he’s not created valley plates. Is this acceptable for the Jack rafters to go straight into the sarking and do the original rafters need reinforcing?

    where I’m planning on making the door the existing window has a concrete lintel to support the common rafters these need to be removed. But how do I support the rafters once shortened?

    The pictures are ****, but hopefully you can see the window to come out and the area of old roof.
     

    Attached Files:

  2. Jord86

    Jord86 Screwfix Select

    To avoid confusion, you mean lay boards not valley plates, and cripple rafters not Jack rafters, though regional dialects probably vary :)

    What's on the plans? If the sarking board is in good condition and an inch thick, then I can't see a problem, though it's difficult to tell off your photos. He's made life more difficult for himself building it the way he has, but we've all got different methods of building for the same result. It looks pretty decent so far. The original rafters shouldn't need reinforcing unless their rotten, and its again very difficult to see your window situation, but if I've read it right, you'll need to fit either a L10 lintel or a steel/timber beam with truss shoes fixed on to take the rafter ends. Though I don't know why you're concerned with this aspect as they should be doing this as part of the build?
     
  3. Would not be happy with him not fitting layboards and fitting the jacks to chipboard sarking.
    I also do not understand why anyone would use chipboard for sarking in the first place, a little bit of a leak and it will just fall apart.
     
  4. Jord86

    Jord86 Screwfix Select


    I agree with you, but how do you know it's chipboard, it's hard to tell what's what off the photos?
     
  5. Thought it looked like chipboard in photo 1 Jord, I could be wrong though and it's not.
     
  6. Crazyhorse

    Crazyhorse Member

    Thanks guys,

    so the sarking is pitch pine (I think) Gould condition, tarred in places. I’ve attached a picture of the internal window, so directly above the window is the lintel on that the wall plate and then approx 2ft above ceiling height. The top of the window is around 5-10. The wall plate is around 6ft from internal floor and the ceiling slopes to ceiling joist height.
    Can’t see any where to attach a new lintel to attach rafter ends as it’s a corridor.
     

    Attached Files:

  7. Jord86

    Jord86 Screwfix Select


    Again, it's very difficult to comment accurately as we're not there in person, but the lintel would go higher up into the raking part of the ceiling, supported on the adjacent walls, the rafters would be cut back to suit and supported off the lintel/beam.
     
  8. Crazyhorse

    Crazyhorse Member


    Don’t think there are any adjacent walls?
     

    Attached Files:

  9. Jord86

    Jord86 Screwfix Select

    Either I'm not getting it or you're not, quite probably it's me. Looking at the plan, the main house wall that the door will be in will have a lintel/beam sitting over the door opening, with the existing rafters cut into and supported off that.
     
  10. Crazyhorse

    Crazyhorse Member

    There is already a lintel there but it’s at the top of the window which is around 5-10. That is the top course of brick work.
    So to lift the lintel and wall plate it would be the whole roof lifting.

    The rafter practically sits in the window fram. The only thing above is lintel wall plate roof.


    Hope my dodgy drawing helps
     

    Attached Files:

  11. Jord86

    Jord86 Screwfix Select

    Then you may have issues unless you have the height to fit a near enough full sized door, around 80 1/2 Inches to the underside of lintel, via cutting and notching the house rafters to suit. This issue should have been explained to the bloke that cut the roof on before he did so, and rather than use lay boards he should have cut in Valley rafters.
     
  12. Crazyhorse

    Crazyhorse Member

    I’d did say it needs cutting out and he said it’ll be fine.. will have to speak to building control when he comes to inspect.
     
  13. Crazyhorse

    Crazyhorse Member

    Resolved this way.!!


    rafters either side of the door opening (those remaining and still bearing on to the wall plate) would be doubled up and either bolted together or more commonly fixed with timberlok fixings. A horizontal timber (trimmer) (50x150) would be installed at a higher level and secured to the double up rafters in jiffy type hangers. The rafters that are cut short (above the door opening) are nail fixed to the trimmer. In effect the trimmer replaces the wall plate and distributes the laid to the doubled up rafters either side - similar to installing a velux roof window.
     
  14. Crazyhorse

    Crazyhorse Member

    Anybody an idea of how many Rafters I can remove and use with the trimmer? It’s under the hip so shouldn’t have a lot of weight I guess??
     

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