Expert: Dave Johnson - 11/27/2009

Question
This is a simple question. I want to build a pergola flat ( not pitched). The length of the area is 6 metres. The width is 2.5metres. The height would be 2.5 metres.

I want to know how many beams we need lengthwise and widthwise.
for e.g. if i get say one wooden beam 6 mts in length how many would I need to put width wise and how far apart,

I will probable put a light clear roofing.

hope you understand my question. How far apart should the beams be on the width,

Rgds
Thomas

Answer
Hi Thomas,
First, I think it would be better to put the joists (beams) the short (2.5 metres) way.
That way the beams span are shorter and are stronger. In the length of 6 metres, you should
use 11 pcs. 2.5 m.
The sides will have to be posted on each end and in the middle, and use a beam at least 4"x8".