A carport blows away when nothing is resisting uplift. Four things do that job, and a quote either specifies them or it does not.
What actually resists the wind
- The footing. Depth and mass, cast to hold the post down rather than just hold it up. A bolt-down plate on sound concrete is adequate for a standard single or double; open, exposed sites need cast footings.
- The fixings into the purlins. Roof sheets have to be fixed through into purlins with load-rated fasteners at the correct spacing. Sheets fixed sparsely, or into the sheet lap alone, are the usual failure point.
- Bracing. Diagonal bracing stops the frame racking, which is what lets a roof start flexing and working its fixings loose.
- Span. A larger unsupported span carries more load into fewer points. This is why a triple or four-bay carport is specified differently, not just built wider.
Where in Tshwane this matters most
Wind exposure is not uniform across Pretoria. A carport tucked between a house and a boundary wall in the Moot sits in still air compared with the same structure on an open plot. Out on the open veld toward Cullinan and Bronkhorstspruit there is nothing upwind to break a summer storm front, and uplift is the governing design case rather than an afterthought - footings there are cast, not bolted.
Shade net behaves differently again: the cloth is porous, so it sheds wind load rather than catching it, but the tensioning is then doing the work. See shade net carport options.
What to ask a quote for
Two lines settle it: the footing depth and method, and the fastener specification and spacing into the purlins. A quote that states both is comparable to another that does the same. One that states neither is not comparable to anything, and is usually cheaper for exactly that reason - the detail on kits vs supplied and installed applies directly here.
If an existing carport has already lifted or is working loose, that is a repair rather than a rebuild - see carport repairs in Pretoria.
Get the footing specified
Footing depth and fastener spacing belong on the quote - see steel and IBR carports.
Before you build
The rest are on carport questions answered for Pretoria - including how long a properly footed structure lasts: How Long Do Carports Last?.
Related detail
What do I do if the roof has already lifted?
Stop parking under it and have the fixings and footings assessed before anything is screwed back down. A sheet that has lifted once has usually elongated its fixing holes, so refastening into the same points will not hold.
Does a shade net roof handle wind better than steel?
No - it handles wind differently rather than better. The knit is porous, so it sheds wind load rather than catching it. That moves the load onto the tensioning and the corner posts instead, so it is not a lower-specification structure - just a differently loaded one.
Closing a side raises the load those anchors have to hold, which is covered under how to cover carport sides.
KB Carports builds carports in Pretoria across Tshwane - free on-site measure, and a written quote that states the steel, the footing method and the clearance height.