Prepare Your Gravel Shed Pad: A Detailed Guide
A properly built gravel pad is one of the simplest, most durable foundations for garden sheds, studios, cabins or workshops. It provides excellent drainage, prevents frost heave, deters weeds, and creates a level, load-bearing surface. Below is a step-by-step guide, complete with dimensioning, material recommendations, and construction tips, so you can build a gravel pad perfectly sized for your structure.
Why Choose a Gravel Pad?
- Drainage: Freely drains water away, keeping your shed floor dry
- Frost resistance: Minimizes frost heave in cold climates
- Cost-effective: Cheaper than poured concrete or full slab bases
- DIY-friendly: Requires basic tools—shovel, rake, tamper/plate compactor
- Weed control: With a proper membrane, prevents weeds from pushing up
Sizing Your Gravel Pad
Margin Recommendations
Industry best practice is to build the pad slightly larger than your shed to:
- Ensure full bearing under the floor bearers
- Provide a working/drainage perimeter
- Prevent shed edges from sitting in mud
Common margin: Add 1 ft of gravel pad around each side.
Example: a 12 × 16 ft shed → pad = (12 + 2) × (16 + 2) = 14 × 18 ft
Door-Side Clearance
If you’d like extra clearance for door swings, steps or a small ramp, add an additional 1 ft at the door end:
Example: 12 × 16 ft shed with a 2 ft front margin → pad = 15 × 18 ft
| Shed Size | Pad Margin | Pad Dimensions |
|---|---|---|
| 12 × 16 ft | 1 ft each side | 14 × 18 ft |
| 12 × 16 ft | 1 ft sides + 2 ft front | 15 × 18 ft |
Materials & Tools
Materials
- Weed-control membrane (geotextile fabric)
- Crush-and-run gravel (¼″ – ¾″ angular stone)
- Pea gravel or fines (optional ⅛″ top layer for smooth finish)
Tools
- Tape measure, stakes & mason’s string
- Shovel and garden rake
- Plate compactor or hand tamper
- Spirit level or laser level
- Wheelbarrow
Step-by-Step Construction
1. Choose & Mark the Site
- Pick a level area, or plan to level it.
- Use stakes and string to outline the pad area. Add 1 ft extra on all sides (e.g., for an 12’x16′ shed, mark 14’x18′ or 15×18′).
2. Excavate the Area
- Dig 4″–6″ deep. For sloped ground, dig deeper on the high side.
- Ensure the bottom is roughly level.
3. Build a Frame
On level ground, a gravel pad can stand on its own without a perimeter frame. However, on sloped sites or where you want crisp, defined edges, install a border of pressure-treated 4×4s or 6×6s. Fasten the corners securely with screws or brackets, then drive 12 – 18 inch rebar or spikes through the sides to anchor the frame in place. Use a level to check that the frame is flat and square before filling.
4. Lay Landscape Fabric
Lay down a layer of geotextile or landscape fabric across the excavated area before adding gravel. This barrier prevents weeds from growing through the pad and keeps the gravel from migrating into the soil below. Overlap adjacent pieces by at least 6 to 12 inches to avoid gaps, and secure the fabric with landscape staples so it stays flat while you work. Trim any excess after the gravel is in place.
5. Add and Compact Gravel
Spread two to three inches of gravel at a time, rake it level, and compact thoroughly before adding the next lift. Continue in layers until you reach 3 to 4 inches of well-compacted gravel. As you go, maintain a slight drainage slope of about one to two percent (roughly 1/8 inch per foot) so that water sheds away from the pad rather than pooling beneath it.
6. Level and Finish
- Check with a long level or straight board across the pad.
- Fill in low spots and re-compact as needed.
- Make sure water can drain away from the pad (slight slope is okay).
Installing Your Shed Skids & Floor
With the pad complete, you’re ready to set the shed foundation skids. Lay the pressure-treated 4×4, 4×6 or 6×6 timbers directly on the compacted gravel surface. Use a long level or laser level to confirm they sit evenly across the pad, and adjust as needed by shimming with pea gravel to achieve a flat, stable base.
From here, you can proceed with the floor framing, as per your shed plans.
Maintenance Tips
- Inspect annually for settled areas; add & compact gravel if needed.
- Keep vegetation clear from the pad’s edge to prevent weeds.
- Re-level before any major heavy equipment placement inside the shed.
By following these guidelines, sizing your pad correctly, installing a proper drainage slope, compacting in layers, and maintaining yearly, you’ll have a stable, long-lasting gravel foundation for any structure. Enjoy your dry, level, maintenance-free shed base for years to come!
