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What span between posts for small pergola?

Just Starting Out

What span between posts for small pergola?

Building a small pergola to cover bbq deck at side of house. 3400 long x 1500.wide.
question is can 140x42 losp span 3000mm between posts? Do I need to upsize or even use glulam? Finding it hard to interpret online spam tables, help appreciated.

Roof is lightweight polycarbonate. 

Bunnings Team Member
Bunnings Team Member

Re: 138x42 losp span?

Welcome to the Bunnings Workshop community @dunsboroughdiy. It's brilliant to have you join us, and many thanks for your question about timber spans.


According to our supplier Woodhouse's span tables, it appears you'd require either a 280 x 42mm 5.4m F7 H3 Treated Pine Primed LOSP or 240 x 54mm GL8 to span 3000mm. Or, you could use the 138 x 42mm 3.6m F7 H3 Treated Pine Primed LOSP and have a post in the middle.


You might note this is a span table for verandahs, but in absence of a span table for small pergolas with lightweight sheeting, this is the one we'd have to follow.


Please let me know if you have any questions.



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