Do I need a foundation for a carport?

Yes — every carport needs a solid foundation to anchor into. A concrete slab or concrete piers give the strongest fixing, but a sound asphalt drive or timber decking can also work with the right anchors. What matters is that the posts are bolted into something that won't move, because the roof of a carport acts like a sail in high wind.

Concrete is the most dependable option. It gives you decades of service, and it takes heavy-duty expanding bolts and ground anchors without complaint. The trade-off is cost — a full slab is the most expensive route, which is why many carport owners use concrete piers under each post instead of paving the whole area.

Asphalt can work, but only with the correct ground anchors — ordinary fixings will pull straight out the first time a decent gust of wind gets hold of the roof. If the asphalt is old and crumbling, don't trust it at all: cut holes about 30cm across and at least 50cm deep at each post position, and pour concrete piers to bolt into.

Gravel can't hold a fixing directly, so it always needs concrete piers — again roughly 30cm in diameter and a minimum of 50cm deep. For cantilever carports, which carry the whole roof from posts along one side, dig the piers deeper and wider still.

It can, provided the decking itself is sound. Fix the posts with heavy-duty coach bolts driven through the deck boards and into the joists below — never into the boards alone. If the joists are undersized or the deck flexes underfoot, put the carport somewhere firmer.

Mark each post position from the kit's instructions, then dig holes no less than 30cm in diameter and 50cm deep. Mix the concrete at 1 part cement to 2 parts sand to 4 parts aggregate, pour, level, and then leave it alone — allow at least 5 days for the concrete to set before you bolt the carport down. Rushing this step is the most common assembly mistake we hear about.

Not necessarily steel mesh. If you're pouring a full slab, fibre mesh mixed into the concrete does the reinforcing job for a domestic carport and costs much less than sheets of steel mesh. For simple piers under each post, no mesh is needed at all.

Digging and pouring piers is honest DIY territory if you're comfortable with a shovel, a level and a wheelbarrow mix. A full slab is harder to get flat and level, and a carport fixed to an out-of-level base will fight you through the whole build — so if in doubt, pay a local groundworker for a day and start from a true surface. We've supplied around 1,100 buildings a year for decades, and the installs that go smoothly are nearly always the ones that started with a proper base.