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I am thinking to build same small pergola in extension of alfersco
please advise me is it possible use flat beam 185 X 42mm of length 4.8 m mounted along side of house with brackets attached to rafters and for outerside beam of same length on two posts 90x90m stripup on concreate apart by 3.5 m gap. what would size can i use for Cross timber approximately 1.8 - 2 m covered by sheets for shade area from sun light.
Do i need requires council permission access the ceiling cavity attached fascia brackets through to rafters thank you.
You’re definitely thinking along the right lines @Ammy, but once a pergola is structurally connected to the house, it generally moves beyond a straightforward DIY project.
Mounting a 185 × 42 mm beam along the house and fixing it back to the rafters is a structural connection. This is typically done using purpose-made pergola and rafter connection brackets, as the load needs to be transferred properly into the roof structure. Accessing the rafters usually means lifting roof tiles, as ceiling cavity access is often quite limited, so this part of the job is usually best handled by someone experienced.
For the outer beam on 90 × 90 mm posts at roughly 3.5 m centres, you’re in a fairly typical range for a small pergola, assuming the footings are sized correctly. Concrete footings and post stirrups are critical here, as they resist uplift and lateral movement.
For the cross timbers spanning between the house beam and the outer beam, if your span is around 1.8 m, 140 × 45 mm timber is generally suitable. If you push closer to 2 m or beyond, it would be more appropriate to step up to 190 × 45 mm to reduce deflection and give a stiffer structure, especially once roofing sheets are added.
In terms of approvals, you will need to check with your local council, as requirements vary by area. Many councils require approval for pergolas attached to the house, even if they are relatively small. Because this involves fixing into the roof structure, it’s not something to assume is exempt.
Given the structural nature of the work, the need to tie into rafters, and the approval side of things, I would strongly recommend engaging a professional carpenter or builder to either carry out the work or at least assist with the structural connections and compliance. That will help ensure it’s safe, compliant and built to last.
Here's a helpful guide: How to build a pergola.
Please let me know if you have any questions.
Mitchell
