Foundation options, explained

Skid foundations — pressure-treated timbers laid on gravel — are the fastest and least expensive option, and work well for smaller, lighter buildings on level, well-drained ground. They're also the easiest to adjust if your site isn't perfectly flat.

Pier foundations (concrete piers or helical piles under the frame) lift the building off the ground, which helps on sloped sites or anywhere drainage is a concern. They cost more and take a bit more labor, but they age well and keep wood framing away from standing water.

A concrete slab is the most permanent choice and the best base for a building you'll heat and use year-round, like a home office or studio — it also simplifies interior finishing since the floor is already flat and solid. It's the most expensive option and the hardest to change your mind about later.

Soil matters as much as budget. Sandy, well-drained soil is forgiving; clay-heavy or frequently wet soil pushes you toward piers or a properly drained slab. When in doubt, a local contractor can assess your soil in an afternoon — cheaper than guessing wrong.