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Hi @dogbural,
You’ll need to reach out to the manufacturer of that pergola kit to confirm the exact footing specifications. Most manufacturers provide recommended footing sizes and installation requirements for their systems.
It’s also important to keep in mind that footing sizes can vary depending on your local soil conditions and the wind rating of your area. For that reason, it’s best to check with your local council first. The pergola may fall under the size limit that doesn’t require approval, but if approval is needed, the footings will have to comply with the building code for your region.
We do carry a similar system called TOJA Grid and if you’re interested in that option, I’d be happy to help find the footing specifications or provide advice on using it. However, since the Modaprax system differs, your best source of accurate information will be the manufacturer directly.
It’s common practice to add a layer of compacted gravel, around 100mm thick, at the bottom of each hole to help with drainage before pouring concrete. Adding a short section of rebar or a reinforcing cage through the centre of the footing can improve strength, especially in softer soils. To make sure the three footings are level with each other, you can run a string line or use a laser level across the footing locations to mark consistent height points before pouring the concrete. Once set, this will ensure the pergola sits level across all posts.
These are general guidelines only, so I’d recommend confirming the exact footing requirements with the pergola manufacturer or your local council before starting the project.
Please let me know if you have any questions.
Mitchell
Hi @dogbural,
You are on the right path, and your timber selection is solid rather than excessive. The 125 x 125 cypress posts are a good choice, and the 190 x 45 beams spanning 3 m and supported at both ends should be fine for a pergola of this size. The 140 x 45 rafters are also more than adequate. However, as with any structure like this, it would be best to run your plan past a builder or your local council for verification.
Notching the posts for the beams is the strongest method, but if you are not confident, bolting the beams directly to the posts is acceptable. Use two M12 galvanised cup head bolts per post connection with large washers. If you want extra reassurance, adding a structural bracket as well is fine, especially in windy areas.
A 300 mm rafter overhang is very comfortable, and 600 mm is still acceptable with your rafter size, provided everything is well fixed. For fixing rafters to beams, sitting them on top of the beam and fixing them down with two galvanised structural screws per rafter is a simple and reliable option. A notch is not essential, and joist hangers are generally unnecessary for this style of pergola. Another option is to screw through the face of the beam into the ends of the rafters.
Please let me know if you have any questions.
Mitchell
