Build a Shed: Calculators in Order

A shed is a small building with all the parts of a house: a foundation, a floor, framed walls, a roof and a weather skin. That makes it a good first framing project, and it also means a mistake in the first step travels all the way to the shingles.

Settle the size and the rules first. Many jurisdictions exempt small sheds from a permit, and the model code exempts one-story detached structures up to 200 sq ft, but local rules are often stricter and often start near 120 sq ft. Setbacks from the property line apply even when no permit is needed, so check both before you buy anything.

Then work outward from the foundation. A shed on a gravel pad or concrete piers is planned in the concrete calculators, a slab in the slab calculator. Wall framing follows from the wall length, the stud spacing and the openings; 16 in on center is the common spacing and 24 in saves lumber where the design allows it. Rafter length comes from the span and the pitch, and the pitch decides the roof area, which decides the sheathing sheets and the shingle bundles.

Siding and paint are the last two material lists and the ones most often bought twice, because area is easy to under-count. Calculate them from the finished wall heights, including the gable ends. Save each list to your project list to end up with one lumber order and one finish order, and compare the total with the cost estimate for your shed size.