What you’ll build
Each wall is two 1x5 boards stacked on edge, about 9″ deep, held together by a 1x4 cleat in the middle and 2x2 cleats at the corners. Two 48″ 1x6 boards across the tops of the side walls make the seats. 1x5 boards are less common than 1x4 or 1x6, so check what your lumberyard stocks.
Shopping list
Buy these boards. The list fits every cut onto standard lengths and leaves ⅛″ for each saw cut and ¼″ for trimming board ends.
| Lumber | Length | Qty |
|---|---|---|
| 1x4 | 8 ft | 1 |
| 2x2 | 8 ft | 1 |
| 1x6 | 8 ft | 2 |
| 1x5 | Cut to length | 8 |
Cut list
All 18 parts, grouped so you can cut matching pieces together. Exact lengths and end-cut angles for every part are in the free plan in the TimberLab app.
| Part | Lumber | Qty |
|---|---|---|
| Wall Board | 1x5 | 4 |
| Wall Board | 1x5 | 4 |
| Cleat | 1x4 | 4 |
| Post | 2x2 | 4 |
| Seat | 1x6 | 2 |
Tools
- Tape measure
- Pencil
- Speed square
- Drill
- Eye & ear protection
- Miter saw
- Clamps
Step-by-step instructions
Assemble Front Wall Panel
Lay the 48-inch front bottom and top wall boards edge-to-edge on a flat work surface. Position the 9-inch front center cleat vertically across the seam at mid-span, keeping both ends flush with the top and bottom wall edges.
Assemble Back Wall Panel
Lay the 48-inch back bottom and top wall boards edge-to-edge on the flat work surface. Place the 9-inch back center cleat vertically across the seam at mid-span, aligning the ends flush with the outer board edges.
Fit Corner Cleats to Panels
Join Lower Side Walls
Stack Upper Side Walls and Cleats
Place Top Seat Benches
Get the full plan: all 6 steps and every cut length.
Download TimberLab and open Sandbox with seats in the catalog to get every cut length and end-cut angle, all 6 assembly steps in 3D, and Timbo, the AI build helper. Catalog plans are free to open; some features, such as AI edits, require a subscription.
Sand every edge and corner smooth, check for splinters and protruding screws, and cover the sandbox when it isn’t in use to keep animals and rain out.
Change the size or design
This plan is one of the projects in the TimberLab app’s catalog. In the app you can turn the model in 3D, follow the assembly steps one part at a time, and ask for changes in plain words, such as “make it 6 inches shorter” or “add a shelf”. The cut list and shopping list update to match the new design.
Questions about this plan
How much lumber do I need to build this sandbox with seats?
The shopping list calls for 1 × 1x4 at 8 ft; 1 × 2x2 at 8 ft; 2 × 1x6 at 8 ft; 8 × 1x5 (cut to length). It groups every cut onto standard board lengths and leaves room for saw cuts and trimming the board ends.
How big is the finished sandbox with seats?
It is 48″ wide, 9 ¾″ tall, and 48″ deep.
What tools do I need?
You need a tape measure, pencil, speed square, drill, eye & ear protection, miter saw, clamps.
Can I change the size of this sandbox with seats?
Yes. Open the sandbox with seats in the TimberLab app and describe the change in plain words, such as “make it 6 inches shorter”. The 3D model, cut list, and shopping list update together.
Where can I get the full sandbox with seats plan?
The full plan, with every cut length and all 6 assembly steps in 3D, is free in the TimberLab app. Download TimberLab on the App Store and open the sandbox with seats in its catalog.
