What rafters to use for pergola design?

[diy_hausdesigns]

Hi all 

Just seeking some advice. I'm planning to building a simple pergola (none covered with no purlins). I am unsure whether to use 90x45mm or 140x45mm for the rafters over a 3.8m span

Sketch of plan 

Sketch of the connection

The 90mm looks good and makes the whole project easier to build and manage. Here is a sample with some leftover 90x35.

But I suspect the 140mm may look better despite it taking a bit more time and effort to build.

Would love any input !!?

[Dave-1]

Afternoon @diy_hausdesigns 

Id definently go with the 140mm, mainly to stop any potential sagging down the track. Are you going to replace the house attachment points or cut the timber to suit?

I think it will bring the corner together nicely, It will provide a bit of shade and just make it feel more contained. Just having a second look at the way you have extended the posts up from the fenceline has me wondering if it may be better spreading the weight down the whole wall instead of just that top section? I know the open pergolla may not appear to be weighty but as soon as it gets wet and windy it will be heavier then what you may think.

Dave

[diy_hausdesigns]

Hi @Dave-1 

Thanks for the speedy response.

Appreciate your insights ! 140mm it is 😁

Planning to cut the timber to size for the house side and use the brackets which are attached to the ledger behind (already painted same as fascia).

I'll add a other support along the fence as well as you recommended - think that's a great idea to share the load.

Hugely Appreciate your help !

[Dave-1]

Howdy @diy_hausdesigns 

lol I was just procrastinating and staring at the screen instead of going out and finishing my bench for my deck hahahaha Yeah I really should go do a little more

Dave

[MitchellMc]

Hi @diy_hausdesigns,

@Dave-1 is on the money here. Although 90 x 45mm will physically span the distance, once it gets wet it will sag noticeably. Also, I think 140mm will look more aesthetically pleasing overall.

Mitchell

[diy_hausdesigns]

Hi @MitchellMc 

Thanks for further validating that. I will definitely got with the 140mm. I'll update you all once I get it started 😃