Spa, shed, and modular building weights

Name: Spa, shed, and modular building weights
Creator: Antero Trail

Dry-weight bands for spas by seating, a per-square-foot shed heuristic, and the user-supplied rule for modular buildings.

This is the exact table the Crane Cost Estimator runs on. Cite it as: Antero Trail, "Spa, shed, and modular building weights", anterotrail.com/tools/reference/modular-spa-shed-weights. Primary sources are listed with each value and at the bottom of the page.

DRY (empty) set weights for the modular_spa_set crane scenario (PRP-CALC-2). Spas are sized by seating capacity band (dry weight only - a crane never lifts a filled spa). Sheds are sized by a footprint lb/SF heuristic derived from a cited prefab wood-shed anchor. Modular buildings vary too widely to band - they require a user-supplied weight. weight_high_lb is the conservative (heavy) end of each band.

Access date for citations: 2026-07-12.

spa bands

Modular/office units span from light job-site trailers to multi-ton finished units; no defensible band exists - a user-supplied weight is required.

Shed weight estimated at 16.2 lb/SF (cited prefab wood-shed basis). Metal, insulated, or finished sheds differ - supply a known weight if available.

shed LB per SF: 16.2

band ID	person min	person max	weight high LB	single source flag	Source
spa_2_5_person	0	5	700	not published	WATSONS
spa_6_8_person	6	8	1,000	Spa dry weights vary by cabinet, jets, and pump count; the 6-8 person band top (1,000 lb) covers most residential units but confirm the data plate for large/luxury models.	BULLFROG

WATSONS. How Much Do Hot Tubs Weigh - mid-size acrylic spa dry weight range 700-1,000 lb; small (2-5 person) units at the low end (~500-700 lb dry) (blog.watsons.com)
BULLFROG. Bullfrog Spas Model A8 (6-8 person, 7'10" x 7'10") - dry weight 758 lb; industry 6-8 person acrylic spas run 700-1,000 lb dry (Watsons range). High end 1,000 lb used. (www.bullfrogspas.com)
ECO TRADE CO.. 10x12 Do-it-Yourself Wooden Storage Shed with Floor - shipping weight 1,936 lb over 120 SF = 16.1 lb/SF; corroborated by industry 10x12 range 1,200-2,500 lb and 12x16 ~2,000 lb (Homestead Supplier). Rounded to 16.2 lb/SF. (www.ecotradecompany.com)

All sources on this page

WATSONS. How Much Do Hot Tubs Weigh - mid-size acrylic spa dry weight range 700-1,000 lb; small (2-5 person) units at the low end (~500-700 lb dry) (https://blog.watsons.com/blog/how-much-do-hot-tubs-weigh)
BULLFROG. Bullfrog Spas Model A8 (6-8 person, 7'10" x 7'10") - dry weight 758 lb; industry 6-8 person acrylic spas run 700-1,000 lb dry (Watsons range). High end 1,000 lb used. (https://www.bullfrogspas.com/spas/a-series-hot-tubs/model-a8/)
ECO TRADE CO.. 10x12 Do-it-Yourself Wooden Storage Shed with Floor - shipping weight 1,936 lb over 120 SF = 16.1 lb/SF; corroborated by industry 10x12 range 1,200-2,500 lb and 12x16 ~2,000 lb (Homestead Supplier). Rounded to 16.2 lb/SF. (https://www.ecotradecompany.com/products/10x12-do-it-yourself-wooden-storage-shed-with-floor)

These calculators produce planning estimates from published public rate schedules. They are not a formal quote. Confirm equipment, access, and pricing with a licensed operator or rental yard before you rely on any number for an estimate.