Supporting Thick Patio Posts

[mudpatch]

Hi
My first ever post.
Great forum - Ive been enjoying reading it.

Ive bought a large (5m x 6m) pergola/patio secondhand. One side of it was supported against a house but im requiring it to be standalone. Theres 3 jarrah posts 200mm diam 2.4m high on the other side, that were held in by fairly flimsy stirrups. The roofing is shingle slats. After dismantling the thing and carting it home im left with a pile of rubble (some beams broken) in the garage and stacks of slats down the side, and a couple of patio carpenters have said they wouldn’t want to touch it, or if they did, it would cost as much as a new one..cant park the car in there and the missus is getting increasingly annoyed..its already heating up in Perth and another umbrella graveyard beckons this summer.(its windy over here..)
Have finally found someone who’ll give it a go and charge me on a daily basis, yippee, but Ive been stressing over the council approval drawings and specifications.

My questions are:
1) Im worried about the weight of the structure and supporting the posts. We live in a high wind coastal area of Perth (part of the fence blew down the other week..). Ive seen the high wind post anchor from Pryda on their website and wondering if they’ll do the job; would they still be effective when theyre dug into the post, as theyre probably too narrow to fit the post between/bolt to the outside.
There are 12 collar tie beams supporting it across the structure.
2) Are there any other methods I could use to secure the posts but keep off the ground (although ive read on here that termites dont go for Jarrah. Still need to prevent rot too..)
3) How deep should we go with the concrete slab? The soil is Very sandy, almost a sanddune..
I guess I could change the roofing from the slats to reduce the weight, but it seems a shame since i went to the effort to remove and theyre stacked there ready to use..

Thanks in advance!

[Burnsy]

Hi
1) Im worried about the weight of the structure and supporting the posts. We live in a high wind coastal area of Perth (part of the fence blew down the other week..). Ive seen the high wind post anchor from Pryda on their website and wondering if they’ll do the job; would they still be effective when theyre dug into the post, as theyre probably too narrow to fit the post between/bolt to the outside.
There are 12 collar tie beams supporting it across the structure.
2) Are there any other methods I could use to secure the posts but keep off the ground (although ive read on here that termites dont go for Jarrah. Still need to prevent rot too..)

You can get stirrups especially for log posts - try Gunns, they do sell some stirrups and may be able to advise you. Stirrups definitely the best way to do it.

Hi
3) How deep should we go with the concrete slab? The soil is Very sandy, almost a sanddunes.
Light traffic would generally be 75-100mm in perth for a slab. This is not a footing and the stirrups will require separate footings somewhere around 400 x 400 x 400 - council will require this to be specified by an engineer - try Structere for standardised specifications.


I guess I could change the roofing from the slats to reduce the weight, but it seems a shame since i went to the effort to remove and theyre stacked there ready to use..
Many houses with tile rooves constructed in the 50's and 60's in Perth never had their rooves tied to the walls, the weight of the tiles held the roof on. Change over one of these rooves to tin and you must tie the roof to the walls to an engineers specifications. The posts and stirrups will hold the weight of the tiles without a problem if the footings are done properly and the stirrups are appropriate.

[mudpatch]

Thanks for the responses Burnsy.
I rang Gunns and they only do a 300mm stirrup. Although im thinking thats a decent amount going into the concrete, still worried about them only being on the one metal leg. I'll try Pryda tomorrow for the U shaped ones.
Im hoping council wont be too strict about the engineers specifications if I quote a larger than average footing..maybe up it to 5-6000..
Cheers!

[Burnsy]

You need the stirrups that look like a t , not the U ones. The bottom of the posts get slotted centrally with a chainsaw and the top tongue of the t gets slotted into that and bolted on. U stirrups on round posts look ugly and are not good as you usually end up with only the heartwood siting in the stirrup after you cut them back to fit. If you can not find a supplier of big t stirrups make some up out of 200mm x 8mm flat bar and then get them hot dip galvanised.