If you have narrowed your shortlist to two specific designs, this is exactly the kind of decision where a side-by-side spec view saves a weekend of second-guessing. Both plans below are complete, code-aware DIY builds, but they differ on the things that matter for a backyard project — total cost, raw labor hours, footprint, and the wood species on the cut list.
Side-by-side specs
| 18x24 ft Hot Tub Pavilion Plan | 20x24 ft Hot Tub Pavilion Plan | |
|---|---|---|
| Category | Pavilions | Pavilions |
| Style | Hot Tub Pavilion | Hot Tub Pavilion |
| Footprint | 18x24 ft (432 sq ft) | 20x24 ft (480 sq ft) |
| Wood species | Mahogany | Composite (Trex / Azek) |
| Roof finish | HDPE shade cloth canopy | retractable canvas awning |
| Difficulty | Beginner | Intermediate |
| Build time | ~11 hrs | ~32 hrs |
| Materials cost | $39,925–$62,375 | $50,675–$79,200 |
| Footing depth | 36″ × 6 posts | 36″ × 6 posts |
| Concrete | 12 × 60-lb bags | 12 × 60-lb bags |
| Cut-list items | 7 | 7 |
| Build steps | 12 | 12 |
Cost & budget
The 18x24 ft Hot Tub Pavilion Plan lands in the $39,925–$62,375 range for materials in Mahogany, while the 20x24 ft Hot Tub Pavilion Plan runs $50,675–$79,200 in Composite (Trex / Azek). The first plan is approximately 27% more expensive at typical 2026 lumber-yard pricing — driven mostly by the choice of Composite (Trex / Azek) over Mahogany and the difference in cubic concrete volume between 6 and 6 footings.
Labor & difficulty
At ~11 hours, the 18x24 ft Hot Tub Pavilion Plan is rated Beginner. The 20x24 ft Hot Tub Pavilion Plan takes ~32 hours and is rated Intermediate. The labor delta is roughly 21 hours, or one extra working day on the 20x24 ft Hot Tub Pavilion Plan. If you are newer to outdoor woodworking, the 18x24 ft Hot Tub Pavilion Plan is the safer pick — it uses simpler joinery and fewer compound cuts.
Footprint & site fit
At 432 sq ft vs 480 sq ft, you are choosing between a full outdoor room and a full outdoor room. Allow at least 24 inches of clearance on every side for furniture and walking paths — that means the 18x24 ft Hot Tub Pavilion Plan needs a clear area of approximately 22×28 ft and the 20x24 ft Hot Tub Pavilion Plan needs 24×28 ft.
Material & durability
The 18x24 ft Hot Tub Pavilion Plan is built from Mahogany, while the 20x24 ft Hot Tub Pavilion Plan calls for Composite (Trex / Azek). The species choice drives the cost delta and the maintenance schedule. Pressure-treated southern yellow pine is the cheapest and most rot-tolerant for in-ground posts; western red cedar is the DIY favorite for visible parts; redwood and white oak are heritage choices that command a premium.
Verdict
For a builder weighing these two specifically, 18x24 ft Hot Tub Pavilion Plan is the faster build. If both fit your budget and yard, default to the design whose style language matches the rest of your house — a Craftsman bungalow looks awkward beside a modern slatted pergola, and vice versa.
Read each plan in full before committing: the complete 18x24 ft Hot Tub Pavilion Plan page and the complete 20x24 ft Hot Tub Pavilion Plan page. Both ship with full cut lists, hardware schedules, footing specs, and step-by-step build instructions.