Double bearer connection to timber stumps

[ChrisKappa]

Hi all,

I am in the process of building a covered 6m x 4m alfresco area as an owner builder.

I have commenced building and have all of my stumps in the ground (yes, timber stumps into the ground, too late to talk me out of it!).

The roof will be flat with a slight pitch down towards the roof of the house, supported by 3 roof extenda brackets on that side and supported by an alfresco beam supported by three 150x150mm posts along the other side.

My question is about how to connect the double bearer for the deck onto the stumps along the edge of the deck furthest from the house, particularly on the corner posts where the bearer and the joist interact "on" the post.

The obvious answer (I thought) would be to notch the bearer 45mm along the front edge of all of the posts (30mm for the 100mm posts) but then for the corner posts, also notch the side edge to sit the joist on top of the bearer but effectively inside the post. But should I be concerned about notching into contiguous posts that are supporting roof load?

As for the engineering, the only part of the job that had an engineers report is for the the remove of some existing wall for the install of a new window and door. The approved plans do not contain any connection details either.

Appreciate any help, no one seems to be able to assist and AS1684 doesn't address this specific issue.

[RossM]

Not rally enough info provided to offer any meaningful advice - you should post some plans of the intended layout.

However, it sounds like you are proposing to finish the deck edges flush with the posts. Frankly, I would not do that. Better to cantilever the bearers and joists a bit past the posts so the posts sit inside the deck by at least one deck board width. Easier to finish & no need to compromise the posts by notching at the corners. Of course, this should have been designed at the start, as you may now have the posts in line with other elements such as house walls.

[ChrisKappa]

Thanks Ross - I have attached the subfloor layout from the plans as well as an elevation.

As you can see, they subfloor was drawn up to not have any cantilever. The 2 corner posts supporting the roof load are 6000mm apart with my longest bearer (all materials delivered already) is 6040 so I don't have enough timber to go beyond the stumps anyway.

Perhaps it is possible for me to swap out the continuous 6000 bearers for 2 (doubled) shorter lengths with the join at the center post?

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[riverbuilder]

A 150 x150 post will support a lot of load, heaps. Think of it this way: on a typical brick veneer tiled roof house, the roof is held up by 90x 45 studs at 450 or 600 centres, each stud usually has a truss and all the local rooftile load on it, a lot of weight. your posts are 4 times this section size of a stud. Unless you plan on having dance parties for teenagers who eat a lot of KFC and Mcdonalds on this deck, the posts are fine and you could comfortably recess out 75% for the beams.
edit: you could comfortably recess out for the beams AND LEAVE 75% of the post to carry the load. They’re big posts, they will provide good bracing as well. Seal or paint all cuts and checkouts in posts and beams, they will last much longer.