Is this purlin joint a problem?

[redlion351]

Our first home (1840s railway cottage) has a gap between the joints in the purlins on both sides.

Are these likely to be a problem? We've been in the property a year, and not noticed any roof sagging (although I don't go in the loft much!)

I can see the gap is present in photos by the surveyor, but wasn't mentioned/flagged.

 

[Cubist]

Those are the most basic form of a scarf joint used to extend the length of a heavy timber. Basic because no attempt was made to employ the geometry of the reciprocal cuts in each timber to form a wedged joint. Those you have there are relying on some kind of mechanical fixings such as heavy nails or screws to hold the joint closed. Have you been able to closely examine them to determine what, if anything, is now holding them together?

If they were nailed or screwed together it's possible that shifting loads on the roof above over many years has caused the joints to open up as per the photos. Assuming this is correct then the fix would be to insert two heavy bolts and nuts to carefully pull the joint closed.

 

[Gothichome]

I would have one question for you, is there a sag in the roof in this area? I see an off dimension board on the one side. On the other the original, this suggests some has looked at this before. My fix would be to make (have made) a steel plate saddle arrangement to straddle the bottom of the purlin and come at it with heavy bolts on the horizontal rather than bolts vertical. My issue with with coming at the problem from the vertical is the tension created by tightening the bolt might draw the top beam to the bottom rather than drawing the bottom beam to the top. This would cause a sag in the roof.

 

[Helen Touzeau]

Perhaps it is the angle of the photo but the top half of the scarf appears to have wrongly the same thickness throughout.
I would suggest a steel plate straddling the left hand joint with a coach bolt though the plate into the left purlin to draw the right scarf into position, then it would be possible to reinforce with a second bolt through a pre-drilled hole into the right hand scarf and on into the top left purlin