OSB3 T&G On Rafters for roofing.

Discussion in 'Carpenters' Talk' started by Chris1004, Oct 5, 2020.

  1. Chris1004

    Chris1004 Member

    Hi all, I've just framed a timberframe building and i've just done the rafters. We have been supplied with OSB T&G 1.7m x 0.64m.

    My roof rafters are 600 centered so this doesnt really work..

    My question is, Does the joint on the osb have to end on a rafter? Or can it end anywhere like loft boards?

    Also can i use my 1st fix paslode nails every 150mm to fix it down or does it need to be screws?

    Many thanks.
     
  2. ginger tuffs

    ginger tuffs Screwfix Select

    how many times for one question
     
    Jord86 likes this.
  3. Jord86

    Jord86 Screwfix Select

    I've just typed that size into google as in a good few years of carpentry I've never heard of those dimensions and it doesn't seem to exist. Are you sure it's those sizes? Anyway, yes the boards need to meet on a rafter, and yes use 51mm nails every eight inches or so, six inch is overkill. Set your depth on the gun to just below flush, not the deep setting.
     
  4. Chris1004

    Chris1004 Member

    Hi, its 1.69m x 634m and 18mm thick. Its come from a company in Finland but i think they also sell those sizes here. Ah thats great news about the nail gun, will save alot of time and energy nailing instead of screwing! I was thinking it needs to meet the rafter :( not sure how i'm meant to make that work. Maybe i need to cut the end of each board and get a router bit and make my own toungues..

    Sorry, i posted this question in 3 different groups i didn't think it shows up all at once.

    cheers
     
  5. Jord86

    Jord86 Screwfix Select

    What is the actual building and its purpose, do you have a picture of the roof or roof space?
     
  6. Chris1004

    Chris1004 Member

    It's a log cabin, Ontop of rafters will be a batten, Then OSB T&G then another batten, then roofing membrane, then another batten then tiles. This is the way building control want it. Il add a picture of the current state of the roof
     

    Attached Files:

    jimoz likes this.
  7. Jord86

    Jord86 Screwfix Select

    Nice project, the boards will definitely need to meet on a rafter in my opinion as they will be also acting as wind bracing/sheathing, however it would be worth contacting the manufacturer and posing the question to them. I was asking in the hope that it was a smaller building or garage or something whereby it may not have mattered if the boards didn't land on a rafter.
     
  8. Chris1004

    Chris1004 Member

    Totaly understand, Its a bloody large cabin :D got to do it right. I find it strange though that the company that sold this to the customer also supplied the osb and specified that the rafters be 600 center, fully knowing that the length of 1.69m wouldnt match 600 center..

    Very fun job apart from the dramas :D

    cheers
     
  9. Mr Rusty

    Mr Rusty Screwfix Select

    If it's fully T&Gd OSB does it actually have to meet on a rafter? I would have thought that with staggered joints it would be OK because each board would be supported by its neighbour?
     
  10. Richard_

    Richard_ Screwfix Select

    That's a lot of battens! Are the battens on the rafters meant to be at centres to match the OSB?
     
  11. Chris1004

    Chris1004 Member

    battens will just sit ontop of the rafters in the same line so it wont change the center of 600 :( So far its 50/50 answers , some saying i must have the osb ending on the rafter and then the other half saying i cant. I tried ringing the company today but they only spoke Finish XD i might try and ring building control tomorow and see what they think... although i can already guess there answer lol
     
  12. ginger tuffs

    ginger tuffs Screwfix Select

    could you cross battern at 634 centers to match sheets
     
  13. WillyEckerslike

    WillyEckerslike Screwfix Select

    I might be missing the point here but is the width at 634 taking into account the t & g overlap so that the boards would sit at 600 centres? You would take the tongue or groove off on the first edge then the joins would be correct perhaps. It's like a floorboard is actually wider on the shelf than on the floor if you get my drift.
    It has been a long day so if this is b#ll#x I do apologise.
     
  14. Chris1004

    Chris1004 Member

    Dont think so :( width we can sort out its just the length thats the issue for us, abit of a lost cause at the moment... I feel like the only options are
    1. cut the tongue of the boards and meet it at the rafter and just screw them in like that.
    2. buy osb sheets instead of tongue and groove.
     
  15. Chris1004

    Chris1004 Member

    Long day for me also up on that bloody roof in the ******* rain and wind haha. the width isnt really an issue it's the lenght of 2.69m thats the issue even if we cut the first on to end on the rafter, the next one will still overlap the next rafters by 300mm
     
  16. Chris1004

    Chris1004 Member

    Just realised on orignal comments i put 1.69m and not 2.69m.. My mistake! Correct lenght is 2.69..
     
  17. WillyEckerslike

    WillyEckerslike Screwfix Select

    If I'm right (by no means certain) it would be designed to run the boards down the rafters, not across. The offcut from the end would make the start of the next run creating the bond. It's possible BC have thrown a spanner in the works with the cross batten under the sheet material turning everything through 90°.
    Edit: Realised that battens run with rafters. Sorry. I think you should be laying the boards down the rafters.
     
  18. Chris1004

    Chris1004 Member

    I'll attach the plans tomorrow on here so we can all have a look and a think through it :D theres like 3 layers of battens now which just seems crazy to me.
     
  19. Chris1004

    Chris1004 Member

    So i rang up the manufactor and they sent me this diagram which clearly shows it's okay to not end on the rafter :) I also rang the architect and BC who comfirmed its okay! Thank god for that, Thanks for all your advice and info guys.

    How do i delete my question now or do i just leave it on?
     
    WillyEckerslike likes this.
  20. Jord86

    Jord86 Screwfix Select

    As long as they have confirmed it and the buck stops with them, then all well and good. Looks a really enjoyable job.
     

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