I'm wanting to extend an existing pergola to reduce the hot afternoon summer sun reaching our outside dining area. The existing pergola beams are 360x45mm but I'm unsure of their F rating. I believe they are treated pine and look to be laminated in some way. They don't look like Glulam, but could possibly be LVL.

This part of the pergola will have only a vine cover eventually, and shade cloth initially. Looking at an LVL span table (F17), the beam dimensions I've chosen appear larger than necessary. However, these are long spans and the centre 6m beam is supported only by the 7m end beams, while it has to support the centre cross-beam(s). Am I right in breaking the 7m cross-beam (as shown) and leaving the centre beam continuous? Is the alternative of breaking the centre 6m beam and having the 7m cross beam continuous a better/worse choice?

The beam at the junction with the existing pergola will be fixed to the existing 6m beam, with a metre of overhang. The other two cross beams will meet the house ring beam above the verandah posts shown in the picture.

I don't want to use additional posts for aesthetic reasons. The one new post will be 125x125mm to match the existing pergola posts. The rafters are planned to be 150x45 treated pine F7 at 1m centres. There may be some in-between lattice work later as support for the vine if necessary.

Are my dimensions sufficient, inadequate, or overkill for LVL F17 beams? Should I be looking at other timber options?pergola-plan.jpgpergola-existing.jpg