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.

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MitchellMc

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.

Mitchell

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