I discovered this twisted underpurlin. Due to the twisting, the beam is sitting on the edge of the strut. I don't want the purlin to deform further, thereby falling down from the strut.

Question: Does this needs to be resolved and how? I am thinking about a heavy square tube, connecting the underpurling with the strut, affixed with 10mm screws?


  • The beam (larch) is about ~20cm wide.
  • The strut is about a meter high and sits on a horizontal post, the post rests on the concrete deck slab (do I have the right terminology here?).
  • The carpenters didn't made a elaborate joint, but only drove a nail askew up. (May they burn in perdition).
  • The strut has no support that prevents tilting.
  • The structure is about 30 years old.
  • I am not aware of water intrusion or similar damages.
  • Location is in Italy, so I am not bound by US building codes, but still interested in expertise from all the world.
  • The roof beam is in fact two roof beams. The second beam is starting over there. I was told that is common here. The roof beams are supposed to be fixed to the horizontal beam with nails or screws.
  • The lower right beam isn't in danger of droping. It rests on a brick wall for the entire length, except for the last 40-50cm on both ends.
  • The roof beams are doubled. There is another roof beam above the visible horizontal boards. Those two beams are connected with nails. Over the second beam there is a final layer of boards. The space in between is filled with insulation material. I strongly hope that the second layer of beams are overlapping with the lower layer, but have no means of verifing.

Detail enter image description here Wide angle shot enter image description here


1 Answer 1


Thanks for clarifying that we are looking at two separate beams landing on the twisting underpurlin. I find the very small/short bearing of the lower/right beam on the twisting underpurlin concerning. I would consider adding additional reinforcement beyond what I mention below, to keep the lower right beam from dropping in the event of further rotation or movement walking that small surface right off the edge of the underpurlin (or just to a small enough area that it crushes.)

enter image description here

To restrain from further movement, strapping the face of the underpurlin to the face of the post with nail-attached steel reinforcements should work. Steel is strong in tension, and it should keep the two together and restrict further movement.

More extensive rebuilding could also be attempted, though that's also getting quickly into "hire an engineer to design the remediation plan" territory, while strapping the thing so it does not get worse is basic.

  • Reminds me of a poorly done post-and-beam construction, with inadequate fastening between the members.
    – SteveSh
    Sep 25, 2022 at 23:10
  • Is filling the space with a wedge a good idea?
    – RedSonja
    Sep 26, 2022 at 7:29

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.