purlin depth

[tony1851]

@OP, your second post implied a timber purlin so we have been taken up the garden path.

You do use a padstone under a steel beam; the padstone is horizontal, and the beam is vertical. You bolt a piece of 4x2 timber to the top of the purlin, and notch or chamfer it to receive the rafters - simple really.

 

[noseall]

I need to bed it into the wall both ends 100mm (4"),on a padstone. What is the technique for actually getting the purlin into place with 4" sunk in either end, without going through the party wall to the neighbours place.

Surely the 'other' end belongs to you and you can knock out enough masonry to allow beam shuffle movement?

What you need to do is have the beam (roughly) in place, cut all the rafters along with their purlin b/m cut out, then lift the beam (complete with timber plate bolted to the top flange) into place so that it slots into the birds-mouths.

You then pack and level the beam and fix the rafters to the beam. We use cramps to locate all the rafter b/m's and then fix 'em.