ᐅ Building a Double Carport

We are planning to build a double carport/small garage, entirely from wood with a trapezoidal metal sheet roof, possibly clad on three sides (this would be added later) and with a sectional door. It will be used to shelter our two cars and also to store a bicycle or lawn mower in the rear area (which is why there will be a door at the back).

The available space is 6.40 x 6.20 m (21 ft x 20 ft), and we want to fully use the 6.20 m (20 ft) length from outside edge of post to outside edge of post or cladding. We have plenty of room for the roof overhang towards the lawn or driveway. The width should be 6.0 m (20 ft) from outside edge to outside edge of posts to allow enough space for the lateral roof overhangs (one side borders the property line).

How would you recommend building it? Using H-post brackets with individual pad footings directly in the ground, or two rows of formwork blocks/retaining wall blocks on three sides all around, into which the post brackets would be concreted? The latter probably has the advantage that the wooden exterior cladding won’t be directly on the ground to avoid moisture or snow piling up, and no water from outside can seep into the carport, right? Do the formwork blocks need to be placed on a strip footing, or is it enough to set the first row halfway into the ground on a compacted recycled base?

The posts will be spruce structural timber (KVH) measuring 12 x 12 cm (5 x 5 inches), and the exterior cladding will also be wood, for example, lap siding or similar. Is 6 x 12 cm (2.5 x 5 inches) timber sufficient for the roof structure with 60 cm (24 inches) spacing, or would it be better to use, for example, 8 x 12 cm (3 x 5 inches)? The trapezoidal metal sheet profile (anti-condensation coated) will be installed directly on top. The floor surface will remain as it is, currently gravel.

What do the planner, the building authority (building permit/planning permission office), and the structural engineer say about this?

Here, you won’t get a reliable answer regarding structural stability.

You have already realized that timber should not be in direct contact with the ground.

For this project, you definitely need a structural calculation.

And while we’re at it. A building permit / planning permission is also required. ;-)

For us, no building permit / planning permission is definitely required, as I have already checked. Since the average wall height does not exceed 2.75 m (9 feet) and no property boundary longer than 9.0 m (30 feet) is built on, small garages (which is apparently the official term since a carport only has open sides) are exempt from registration. It would be different if we made a gable roof out of it and it became correspondingly higher...

Okay, I can have the structural engineering done, that’s no problem...

"Exempt from registration" does not mean that building regulations do not have to be followed.

Therefore, a structural stability certificate is required, which will specify the size and thickness of the beams needed in each location.