Digging an inground trampoline involves precise excavation to create a safe and functional space for the trampoline frame and mat. This comprehensive guide will walk you through the essential steps to achieve a perfectly flush installation.
Essential Pre-Digging Steps
Before you even think about picking up a shovel, thorough planning and preparation are crucial for a successful and safe inground trampoline installation.
Plan and Measure Your Space
- Trampoline Size: Confirm the exact diameter of your inground trampoline kit. This will dictate the size of your excavation.
- Location Choice: Select a flat, level area in your yard. Ensure it's clear of overhead obstructions like tree branches and power lines. Allow for at least 6-8 feet of clear space around the trampoline for safety.
- Marking: Use spray paint or stakes and string to mark the precise outer perimeter of your trampoline's hole.
Check for Underground Utilities
This is a critical safety step!
- Call 811: In the United States, call 811 or visit 811 before you dig a few days before you plan to start digging. This service helps identify and mark the location of underground utility lines (gas, water, sewer, electric, communication) to prevent dangerous and costly accidents.
Gather Your Tools
Having the right equipment will make the job much easier and more efficient.
- Measuring Tools: Tape measure, level (long spirit level or laser level).
- Digging Tools: Round-point shovel, spade, pickaxe (for rocky soil), wheelbarrow for moving soil.
- Marking Tools: Spray paint, stakes, string.
- Optional Equipment: Consider renting a mini-excavator or a skid-steer loader for larger trampolines or tough soil conditions, which can significantly reduce labor and time.
- Safety Gear: Gloves, safety glasses, sturdy work boots.
The Digging Process: Step-by-Step
Excavating the hole for an inground trampoline requires careful attention to dimensions and shape. Follow these steps to create the ideal pit.
1. Dig the Initial Flat Layer
Begin by excavating a consistent, flat layer across the entire marked circular area.
- Uniform Depth: Dig out 10 inches of soil evenly across the entire marked hole. This creates a uniform base layer for the trampoline frame.
- Level Check: Regularly check the depth and ensure the bottom is as level as possible using your tape measure and spirit level.
2. Create the Inner Bowl-Shaped Hole
After the initial flat layer, you will dig a smaller, deeper, bowl-shaped hole in the center. This design is crucial for accommodating air displacement during jumping and preventing the mat from touching the ground.
- Inner Hole Diameter: This inner bowl should be 2 feet (24 inches) less in diameter than the overall size of your trampoline. For example, for a 12ft trampoline, the inner bowl would be 10ft in diameter.
- Bowl Shape: Excavate this inner section in a bowl or dome shape, ensuring the center is the deepest point. This rounded profile facilitates air movement, which is essential for a good bounce.
- Specific Depths:
- For 12ft and 14ft trampolines, the inner bowl needs to reach an additional depth of 36 inches (about 3 feet) from the bottom of your initial 10-inch dig. This means the total deepest point from the original ground level will be approximately 46 inches.
- For 8ft and 10ft trampolines, the inner bowl should be an additional 30 inches (about 2 feet 6 inches) deep from the bottom of your initial 10-inch dig. The total deepest point from the original ground level will be approximately 40 inches.
3. Check Dimensions and Level
Throughout the digging process, constantly verify your measurements.
- Depth: Use your tape measure to ensure you've reached the correct depths at various points in the bowl.
- Diameter: Confirm the diameters of both the outer and inner holes are accurate.
- Level: Use a long level or string line to ensure the outer rim where the trampoline frame will rest is perfectly level. This prevents the trampoline from sitting unevenly.
Trampoline Hole Dimensions Guide
To help visualize the dimensions, refer to the table below, which incorporates the specific digging requirements:
| Trampoline Size | Outer Hole Diameter | Initial Even Dig Depth | Inner Bowl Diameter | Inner Bowl Depth (from initial 10") | Total Deepest Depth (from ground) |
|---|---|---|---|---|---|
| 8 ft | 8 ft | 10 inches | 6 ft | 30 inches (2 ft 6 in) | 40 inches (3 ft 4 in) |
| 10 ft | 10 ft | 10 inches | 8 ft | 30 inches (2 ft 6 in) | 40 inches (3 ft 4 in) |
| 12 ft | 12 ft | 10 inches | 10 ft | 36 inches (3 ft) | 46 inches (3 ft 10 in) |
| 14 ft | 14 ft | 10 inches | 12 ft | 36 inches (3 ft) | 46 inches (3 ft 10 in) |
Managing Excavated Soil
You'll be surprised how much soil comes out of a hole this size! Plan ahead for what to do with it.
- Redistribution: Use the soil to level uneven parts of your yard, create a berm, or build a raised garden bed.
- Disposal: If you have excess soil, consider hiring a skip (dumpster) or finding a local landfill or landscaping company that accepts clean fill. You can research local waste disposal options in your area.
Ensuring Proper Drainage
Water accumulation in the pit can lead to issues like rust, unpleasant odors, and structural damage.
- Gravel Base: Lay a 4-6 inch layer of gravel at the bottom of the deepest part of the bowl to promote drainage.
- French Drain: For areas with poor natural drainage or high water tables, consider installing a French drain around the perimeter or leading from the pit to a lower area or storm drain. Learn more about effective drainage solutions.
- Sump Pump: In extreme cases, a small sump pump connected to an outlet can be installed in a basin at the lowest point to remove standing water automatically.
Safety and Finishing Touches
Once the hole is dug, you're ready to install your trampoline and add the finishing touches.
- Secure the Frame: Assemble your inground trampoline frame according to the manufacturer's instructions and carefully place it into the excavated hole. Ensure it sits level and flush with the ground.
- Retaining Wall (Optional): Many inground trampoline kits come with a retaining wall system. If yours doesn't, or if you're building a DIY solution, consider a sturdy retaining wall (e.g., timber, concrete blocks, or specialized inground trampoline wall kits) around the perimeter of the outer hole to prevent soil from falling into the pit.
- Fill Gaps: Backfill any gaps around the trampoline frame with soil, ensuring it's compacted to prevent settling.
- Safety Padding: Always install the safety padding over the springs and frame as per the manufacturer's instructions.
By following these detailed steps, you can successfully dig and install an inground trampoline, providing a fun and safe recreational space that seamlessly blends into your landscape.
