Split Purlin Repair/Strengthening

Discussion in 'Builders' Talk' started by Dave12345, Jan 13, 2020.

  1. Dave12345

    Dave12345 New Member

    Hi,

    My 1956 bungalow has an attic room boarded out which I've noticed the plasterboard is cracked above the purlin and a bit out of shape where the support beam is (half way along the wall and where it connects to the purlin stretching across the other half of the wall), so I've gone into the attic space behind the room and found the purlin seems to be splitting (it wasn't like this 5 years ago when I moved in from recollection, or at least not as bad), see here:

    IMG_20200113_075105_resized_20200113_041131768.jpg IMG_20200113_075156_resized_20200113_041132113.jpg IMG_20200113_075304_resized_20200113_041132413.jpg

    Am I worrying over nothing? I was thinking maybe use a few fixing plates to try to hold it together and stop it getting any worse, or is there a better fix that I should do??

    Thanks,

    Dave
     
  2. carl24bpool

    carl24bpool Active Member

    I would avoid nailing anything into it or screwing without pilot holes.

    I'm no engineer but if I wanted to do anything I would use a 10 - 12mm spade bit with an extension and drill the timber top to bottom then fit some threaded bar with plates and bolts both sides.

    Unless the timber has sagged massively or is causing the building to distort I wouldnt worry too much though but I wold monitor it by marking crack lengths and recording the width.
     
  3. Jitender

    Jitender Screwfix Select

    The first picture just look like natural shrinkage cracks which are perfectly normal.

    When looking closer there looks like what appears as tiny holes which would suggest woodworm.:eek:
     
  4. Jitender

    Jitender Screwfix Select

    The last picture dosnt look too good.

    Is it some type of joint?

    Can you get a better picture?
     
  5. Dave12345

    Dave12345 New Member

    Thanks Carl. Yeah, that's was my way of thinking but wanted to get a second or third opinion! Unfortunately I can't put a bolt through it as the other side is the room which is plasterboarded. I was thinking decking screws and something like these...

    https://www.screwfix.com/p/mending-plates-zinc-plated-100-x-16-x-10-pack/16050

    ...obviously a bit more heavy duty though! Is that on the same lines as what you mean?
     
  6. Dave12345

    Dave12345 New Member

    Yeah woodworm - it's everywhere up there :-( sprayed it all and seems to be dead now thankfully. Nothing on the survey other than 'couldn't inspect all timber, you may want to instruct a timber specialist for a survey'... wish I'd sued them now!
     
  7. Dave12345

    Dave12345 New Member


    Cant get another photo for a minute but yeah its a joint onto the next stretch of the purlin spanning across the other half of the wall. Not sure what kind of joint it is, seems a bit strange to have done it that way! The support is propping up the other purlin but not this one which has cracked which seems strange too!
     
  8. Jitender

    Jitender Screwfix Select

    It looks like in the past someone has splice the timber in, maybe it was badly infested.

    Think you need to get someone(s) in.

    First a structural engineer,

    also

    A rot company. You could apply this yourself.
     
    Richard Fleming likes this.
  9. carl24bpool

    carl24bpool Active Member

    Those plates wont really do much.

    What I meant was to frill a 10mm hole from top to bottom then use some threaded bar with a large square washer top and bottom with nuts on and tightened. This will squeeze the crack together. I would certainly consider this where the finger joint is as that seems to be the weak point.
     
    Dave12345 likes this.
  10. Jitender

    Jitender Screwfix Select

    Something like this in a large scale, called flitch plates.
     
    Dave12345 likes this.
  11. Dave12345

    Dave12345 New Member

    Any reason why the purlin it's joined to was cemented?!
     
  12. Jitender

    Jitender Screwfix Select

    Think they have done it to close up the gap.

    Would building insurance cover it?

    Not had to deal with them myself.
     
  13. carl24bpool

    carl24bpool Active Member

    NO idea to be fair. I can only assume that it isnt bearing any huge load. That or a wall was removed from below the join at some point.

    It certainly wasnt added to stop the crack. If anything this has caused the crack.
     
  14. Dave12345

    Dave12345 New Member

    Sorry, I get what you mean now, didn't pay enough attention to where you said drill through top to bottom! Where would be the best place to do that? Right at the end of the splitting purlin and through the joint i.e. to the left of the rafter in the last photo? Or maybe there and also one to the right of the rafter for luck?!
     
  15. Dave12345

    Dave12345 New Member

    I'm guessing was spliced because of the length - my bungalow is rather wide! Just strange they didn't join it where the support is with the wall underneath to support both sides... and why they used cement on that bit!
     
  16. Dave12345

    Dave12345 New Member

    The wall is still underneath the support. What isn't bearing any huge load? The purlin is holding up a very heavy rosemary tile roof :-/
     
  17. carl24bpool

    carl24bpool Active Member

    Dave12345 likes this.
  18. Dave12345

    Dave12345 New Member

  19. Jitender

    Jitender Screwfix Select

    If the span is large.

    I would have expected them to have used a bracing at he joint which is quite common, unless the previous ownerin attempting to make a room took it out.
     
  20. carl24bpool

    carl24bpool Active Member

    put two nuts
    In all fairness the purlin is not holding a great deal up with that join mid span. It will have very little bending strength compared to a solid length of timber. I would only assume that the stud work below is propping it and preventing further bending. Even though the roof runs above it the load is still spread up to the next purlin or the ridge and also the wall plate below. The purlin is just lessening the deflection of the rafters.
     

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