Gravel, blocks or concrete: what your building should sit on

A building sitting on the wrong base will rack, stick at the doors and rot at the runners. It is the cheapest part of the job to get right and the most expensive to fix.

Gravel pad

For anything up to about 12×20, a four-inch compacted gravel pad extending a foot past the footprint on every side is ideal. It drains, it stays level, and it keeps the treated runners out of standing water. Crushed stone, not rounded pea gravel — rounded stone rolls and will not compact.

Concrete blocks

Blocks on undisturbed soil work for small buildings on ground that already drains well. They are what we use when we level on site. The risk is settlement: one block sinks half an inch over a wet winter and the door stops closing. Perfectly fine, but check it each spring.

Concrete slab

Required for any garage, and worth it for a workshop. Four inches, reinforced, with a thickened edge. It has to be cured before we deliver — usually a week in warm weather, longer in the cold. Get the dimensions from us before your contractor pours, because a slab an inch out is a problem you cannot fix afterwards.

What we will not do

We will not set a garage on gravel, and we will not set anything on ground that holds water. If we look at your site and say it needs work first, that is not upselling — it is the difference between a building that lasts thirty years and one that lasts eight.