A builder planning a real 8x12 shed with us had a budget of about $2,000. The shed designer's default design came to about $3,000 in materials. The builder asked where the money goes, and which choices under and around the shed actually move the price.
The designer now answers that with a table. For the foundation, the floor, each door and the windows, it frames, prices and structurally checks every alternative against the design you are editing. Each row shows what that one change saves or adds. These are the numbers on the 8x12 starter, which has solid blocks on tamped soil, a 38-1/2" door built from the siding and two 14 x 21 windows, with materials only, before tax.
Foundation: from $0 to $422 more.
- Solid 4x8x16 blocks straight on tamped soil are the cheapest. CMU blocks cost $2.16 more, and concrete deck blocks $93.60 more.
- Gravel only under each block (a 4" bed of bagged paver base) adds about $84.
- A full crushed-stone pad adds $296 with no blocks, or $328 with them. That is mostly the stone: about 1.7 cubic yards, priced at the low end of a supplier's $120 to $255 a ton range.
- The cheap options are not free of risk. Blocks on bare soil are only as good as the soil. On soft or wet ground they can settle, so the table says so on that row.
Floor: up to $48 a change. 2x4 joists save $47.85, an OSB subfloor $41.58 and joists at 24" $27.98. All three pass, and the reasons are in the post on 24-inch joists.
Door: the biggest single swing.
| Door | Compared with the 38-1/2" site-built door |
|---|---|
| Site-built, 48" wide | $1.62 less (the cut sheet happens to pack better) |
| Site-built, 60" pair of leaves | $76.24 more |
| Site-built, 72" pair of leaves | $104.85 more |
| 32 x 80 steel prehung (Home Depot) | $219 to $231 more, about 2 hours less work |
| 48 x 72 wooden double shed doors | $352.72 more |
| 36" fiberglass prehung shed door | $536 to $541 more |
For storage, a wide pair built from the siding is cheap access: a mower, a wheelbarrow and 4x8 sheets fit through 60". A stock prehung door buys back about two hours of work and a weather seal, at a price.
Windows: $139.80 for two. Dropping both windows saves $139.80 and about 3.3 hours. The cost is light: with the door shut there is no daylight, so you would need a battery or solar light. In return every wall is free for shelving and there is no glass to break. Swapping to any other stock size costs $5 to $91 more.
Where that leaves the $2,000 budget. The parts in this table can come out of the price, but not $1,000 of it. Most of the rest is siding, roofing and framing, which other searches in the tool handle. Prices are listings seen on 2026-10-29, mostly from search-result copies, so check them before you buy.
The designer is not engineered or code-checked. Its structural checks are screening checks, and you are responsible for verifying the design with your building department.