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Hi All
Looking for advice on the best way to build a timber shade arbour/micro pergola using a diy kit. It’s going on a structural slab approved by council during our house build. I’ve also reviewed the building & council codes and this will be built small enough not to need approval.
I’ve watched several deck & pergola builds from the community here and been through most of the posts but have some project specific questions….. I’ve done general D.I.Y. over the years but nothing this ‘structural’ so would appreciate some advice.
It's a simple open top design to create privacy from neighbours and shade from the western sun. (Note that this is the courtyard that opens from the master bedroom so we want something more than a shade sail for this space). I will potentially add a timber screen or bamboo thatching on the roof and back side. The proposed size is 2000mm high, 2500-4000mm long and 1600mm wide/deep;
1. Is a single lean to structure robust enough (diagram 1) or should I go for a 3 post lean to model (diagram 3)? I’ve also included a 4 post option if affixing to the wall is recommended (diagram 2)?
2. I have 3 types of exterior wall to affix beams. Option A) the grey axon JH FC cladding, Option B) white cladding over header above the door or C) the bricks? I’ve included photos of the above options plus the framing of this area taken during our build. The FC cladding looks easiest but would the brick offer greater support?
3. The slab is rated as structural and 200mm + deep. Given the fence behind has some give and this side of the house is exposed to western sun all day and direct wind/weather, I think the slab will provide better structural support. Given the position, we were intending on anchoring the posts directly to the slab using a base plate/stirrup. Will this be a strong enough alternative rather than the dig & set method?
If you’ve made it this far (thank you!) advice on any of the above is greatly appreciated. I’ll order suggested treated pine and kit once we have a final plan.
Thank you
Erin
Hi @EzzaB,
Thanks for the detailed explanation—it really helps to get a good sense of what you're planning. While your questions are mostly around a specific DIY pergola kit that we do not supply, I’ll do my best to give you practical advice.
Starting with the structure type, a three-post lean-to design (your diagram 3) will generally be more stable than a two-post option (diagram 1), especially in areas exposed to wind like yours. That extra post provides an added anchor point and helps distribute loads better. While many kits are designed to work with two posts and wall attachment, if there's any uncertainty about the strength or quality of your wall fixing points, opting for three posts is a smart way to build in additional strength and stability. The four-post model (diagram 2) would allow you to skip the wall fixing entirely, but if you’re happy to attach to the house and want to keep the structure light, the lean-to version is still a good option.
For the wall fixing, James Hardie FC cladding (Option A) and white cladding (Option B) aren't structural, so they shouldn’t be used as primary supports. You’d need to locate the timber framing behind them and use structural screws or coach bolts to fix through the cladding and into the studs. Option C, the brick wall, could potentially offer more fixing strength, but it's important to clarify whether it’s a brick veneer or solid brick wall. Brick veneer is not considered structural and may not hold bolts under load or movement over time. If you're unsure, I’d suggest fixing into the house frame behind the FC cladding—assuming you can locate the studs—would offer more predictable support.
Your plan to anchor the posts directly to the structural slab using post base stirrups or adjustable post supports is solid. A slab over 200mm deep is substantial and would usually provide an excellent base for post anchoring. Just ensure that you're using heavy-duty masonry anchors rated for outdoor structures. Given that the adjacent fence has some flex, your slab is definitely the stronger and more reliable anchor point.
Overall, your project sounds well thought out. I’d recommend doing a thorough check of the kit's installation guide (if available) or even reaching out to the supplier for specifics on required fixing methods and structural supports. This will ensure you're building to code and getting the best long-term result.
Good luck with the build—it sounds like it’ll be a beautiful, functional addition to your courtyard.
Please let me know if you have any questions.
Mitchell
