# Forum Home Renovation Pergolas, Gazebos, Strombellas & Rotundas  Pergola beam size / span and post sizes

## crtx

Hi Guys, 
I have existing deck which i want to build a pergola over which will have polycarb roofing on the specs are below 
Fascia/ledger beam 6 meters long @ 140x45 MGP10 already existing.
side beam span is 6 meters longer single span with two posts at each end.
rafter span is 1800 meters
roof height is approx 2.5  
What i need to know is what size beam will be required for a 6 meter single span and post sizes? and what my rafter sizes and spacing should be?  
Cheers

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## shauck

Guys, double check me here, in case my morning brain isn't working well.  
I'm reading RLW 3m 
You could use F17 seasoned hardwood for the beam. It would be 2/290x35 laminated together for a max span of 6300 at 10kg/m2 so you would be limited in the future and not be able to increase the load, say with a tin roof or ceiling.  
It's as far as the standard span tables go, so if you want anything outside that, maybe one of the other guys can help. I looked at a couple of LVL span tables but they either didn't reach that span or the tables didn't allow for 10 or 20kg/m2. They're probably out there. Maybe Ringtail will chime in..... 
As far as rafters, you can use F7 seasoned softwood and you'd only need 90x45 with 1200 spacing of rafters but I reckon it would look a bit odd with such a big beam. I'd use 145x45 for the aesthetic. Maybe that's just me. I'd probably space them closer, 900 maybe. again, aesthetics. 
F7 90x45 battens, spaced at 900 again.  
For posts, I'd go for, guess what, bigger, chunkier to match the rest, at least 125x125 
I like chunkier look. And it's stronger. 
Igonore all the aesthetic advise if you will but the verandah beam is going to be a bigun.

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## crtx

> Guys, double check me here, in case my morning brain isn't working well.  
> I'm reading RLW 3m 
> You could use F17 seasoned hardwood for the beam. It would be 2/290x35 laminated together for a max span of 6300 at 10kg/m2 so you would be limited in the future and not be able to increase the load, say with a tin roof or ceiling.  
> It's as far as the standard span tables go, so if you want anything outside that, maybe one of the other guys can help. I looked at a couple of LVL span tables but they either didn't reach that span or the tables didn't allow for 10 or 20kg/m2. They're probably out there. Maybe Ringtail will chime in..... 
> As far as rafters, you can use F7 seasoned softwood and you'd only need 90x45 with 1200 spacing of rafters but I reckon it would look a bit odd with such a big beam. I'd use 145x45 for the aesthetic. Maybe that's just me. I'd probably space them closer, 900 maybe. again, aesthetics. 
> F7 90x45 battens, spaced at 900 again.  
> For posts, I'd go for, guess what, bigger, chunkier to match the rest, at least 125x125 
> I like chunkier look. And it's stronger. 
> Igonore all the aesthetic advise if you will but the verandah beam is going to be a bigun.

  Thanks for this info.. I have priced up some beams and posts and it came out to be quite expensive.  
Could you please run some figures for me again and base this on 190x45 - 6 meter continuous span 90x90 post at 0m - 3m - 6m spacings?? 
I'll run with the 140x45 rafters it will look much better agreed and 90x45 batterns at 900 spacings thanks  :Smilie:

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## barney118

> Hi Guys, 
> I have existing deck which i want to build a pergola over which will have polycarb roofing on the specs are below 
> Fascia/ledger beam 6 meters long @ 140x45 MGP10 already existing.
> side beam span is 6 meters longer single span with two posts at each end.
> rafter span is 1800 meters
> roof height is approx 2.5  
> What i need to know is what size beam will be required for a 6 meter single span and post sizes? and what my rafter sizes and spacing should be?  
> Cheers

  more clarity needed, is the pergola 6m x 6m? I am trying to understand where 1800 rafters span comes into it. based on a verandah beam 6m span where the rafters only span 1800 (RLW 900mm) a 240 x63 LVL will do the job with 20kgm2. Are you planning a skillion roof or pitched?

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## shauck

> based on a verandah beam 6m span where the rafters only span 1800 (RLW 900mm)

  See. Told you my brain wasn't working properly. Knew it.  
That would mean in F17 a single 240x45 would max out at 6.0m. Not recommended.  
If you add the extra post (now continuous span) the F17 190x45 will more than span 3.0m by a mile. Even F17 140x45 can max span 4.0m at 40kg/m2. 
You can use F7 seasoned softwood, 140x45 and it'll max 3.3m at 40kg/m2 or 4.1m at 20kg/m2.  
F7 should be a fair bit cheaper than F17 hardwood and easier to handle.

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## crtx

hey guys 
sorry about my terminology and thanks for the information. 
I'v went 190x45@6mter with 90x90 posts every 3meters so plenty of support. Ordered some polycarb 1.8meter in length as thats my roof cover. have a few more rafters to go then batterns and hopefully screw the poly down over cup weekend.

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