Hi Guys,
I am currently designing a pitched roof for a pergola in my back yard.
I think it'll be useful to see the design first, so here's the link: https://s17.postimg.org/nftggm80v/pergola.png
The span for the entire construction is approx 7.8m x 2.4m. The rafters are placed at 1.8m intervals. The joist on which the rafters sit will be a C24 6x2(150mm x 50mm), and the posts will be 125x125mm @ 3m, with 900mm underground, and 2.1m above ground.
The plan is the have eight 1800x1600 trellis panels fixed on top of the rafters. The boards themselves will be bespoke, I will be using 2x1 battens, although I am also considering hardwood like ceder, maple, or walnut.
I guess I am looking for some feedback. I would to know if anyone sees any flaws with this current draft, and whether there are any load issues I need to consider.
My current concerns are:
1. Do I need a ridge board ? if so
2. I feel the rafters might be place a bit too far apart (at 1.8m intervals). But they are perfectly placed apart for the trellis boards. I guess there could be buckling in event of heavy winds or snow, but I'm not sure whether I should double up and have 8 rafters instead of 4.
3. I'm not entirely sure whether the 6x2 joists will be able to bear the load. The maximum distance between the posts is 2.6m, and the dead load for the roof is ~250kg at the moment. Only 3 of the 5 rafters are placed directly above the posts. Also note the rafters/trellis panels will be coated with several coats of polyurethane, so there is little to no chance of any water penetration and thus extra weight after it has rained.
I am currently designing a pitched roof for a pergola in my back yard.
I think it'll be useful to see the design first, so here's the link: https://s17.postimg.org/nftggm80v/pergola.png
The span for the entire construction is approx 7.8m x 2.4m. The rafters are placed at 1.8m intervals. The joist on which the rafters sit will be a C24 6x2(150mm x 50mm), and the posts will be 125x125mm @ 3m, with 900mm underground, and 2.1m above ground.
The plan is the have eight 1800x1600 trellis panels fixed on top of the rafters. The boards themselves will be bespoke, I will be using 2x1 battens, although I am also considering hardwood like ceder, maple, or walnut.
I guess I am looking for some feedback. I would to know if anyone sees any flaws with this current draft, and whether there are any load issues I need to consider.
My current concerns are:
1. Do I need a ridge board ? if so
2. I feel the rafters might be place a bit too far apart (at 1.8m intervals). But they are perfectly placed apart for the trellis boards. I guess there could be buckling in event of heavy winds or snow, but I'm not sure whether I should double up and have 8 rafters instead of 4.
3. I'm not entirely sure whether the 6x2 joists will be able to bear the load. The maximum distance between the posts is 2.6m, and the dead load for the roof is ~250kg at the moment. Only 3 of the 5 rafters are placed directly above the posts. Also note the rafters/trellis panels will be coated with several coats of polyurethane, so there is little to no chance of any water penetration and thus extra weight after it has rained.
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