How Thick Does a Concrete Slab Need to Be for a Shed or Garage in Christchurch?

A concrete slab for a standard residential shed or garage is typically 100mm thick. That is the minimum recommended thickness for a slab that will carry foot traffic, light storage, and a standard passenger vehicle. Most residential garage slabs in Christchurch are poured at 100mm.

If the garage will be used for heavier vehicles, a workshop with machinery, or large storage loads, 125mm is worth considering. The extra thickness adds cost but also adds strength and reduces the chance of cracking under load over time.

Ground conditions matter as much as thickness. A slab poured on a well-compacted gravel base will perform better than a thicker slab on poor ground. In Christchurch, it is worth having the sub-base assessed before pouring, particularly on older properties or sections that have been built up with fill. The base preparation is often more important than the concrete thickness itself.

Steel mesh reinforcing is standard in most residential slabs. For a garage or workshop where you want the slab to last, reinforcing is not something to skip to save money.

If you are not sure what your site needs, a quick conversation with a concrete contractor before you commit to anything is the best starting point. Most will give you a straight answer on what the ground requires.

Ready for a quote? Talk to a Christchurch Concrete specialist about shed and foundation slabs.