How to build a freestanding pergola?

funky-millar

My cousin is wanting to erect a 4.1 X 5.0m free standing pergola.  It will be single span with only four posts in each corner.

What kind of 100x100 posts would you advise to be exposed to the weather elements?

How do I read the span tables for this to determine the size of beams.  Im assuming 240x45 or there abouts would be rough size.

Can i simply notch out the tops of the 100x100 for the bearers and use bolts M10s for these and also use stirrups on the bottoms concreted into ground?

If the length of the pergola is 5m what space could i get away with for additional joists etc and can these simply be joist holders installed.

If there is overhang needed for a visual impact are you better to install the joists above the bearer and notch out or have separate pieces each side with joist holders?

And if installing a sheeted roof does it need to have 15 degrees minimum pitch for water runoff and there fore gutters installed?

EricL

Hello @funky-millar 

Before you begin, I suggest checking your local council's rules and regulations regarding the size of your pergola. I suspect that there are height and size restrictions that must be followed. Because of the size you'll be building at, I propose engaging the services of a draftsperson to draw up a basic plan for you. They'll be able to integrate all of your requests into the plan including the pitch of the roof and the overhang you're looking for. Plus, it will be safe, built to code and will pass inspection. 

In regards to reading span tables, I suggest looking at this discussion - How do you read span tables? by @dowd_hardware. It gives a very good example of how to read span tables.

Here is a link for ideas and inspiration: Top 10 most popular pergola projects

I also suggest having a look at this guide - How to build a pergola

If you need further assistance, please let us know.

Eric