811 Before Shed Foundations, Ground Anchors, and Helical Piles
Sheds feel simple, but their foundations go deep. Ground anchors, concrete piers, and helical piles all penetrate the utility depth zone. Call 811 before any shed anchoring work begins.
Shed Foundation Types and Their Depths
| Foundation Type | Depth Range | 811 Required? |
|---|---|---|
| Gravel pad / surface blocks | 0–6 inches | Borderline — check local requirements |
| Concrete deck blocks (surface) | 2–4 inches | Usually not — verify locally |
| Concrete tube piers (Sonotubes) | 12–48 inches (frost depth) | Yes — required |
| Ground anchors / earth anchors | 18–36 inches | Yes — required |
| Helical piles / screw piles | 36–84 inches | Yes — required |
| Poured concrete slab (with footings) | Footings: 12–48 inches | Yes — required |
The surface-block and gravel pad approaches often don't require an 811 ticket because they don't involve meaningful excavation. However, local codes vary — some municipalities require 811 for any ground disturbance on a permitted structure. Check with your building department.
For everything below — piers, anchors, helical piles, slabs with footings — an 811 ticket is required. No exceptions.
The Private Line Risk Near Outbuildings
Sheds, workshops, and detached garages often already have power running to them — either from a prior owner's installation or from a recent project. That power conduit or direct-burial cable is a private line that 811 won't mark. If you're installing a new shed foundation near where you know (or suspect) power was previously run to an outbuilding, you need to locate that private line before anchoring.
Common private lines near outbuildings:
- Underground power conduit from main panel to existing detached garage or workshop
- Direct-burial cable (UF cable) to a prior outbuilding, even a demolished one
- Irrigation lines running along the backyard perimeter (where sheds are often placed)
- Landscape lighting wire along the fence line or property perimeter
- Low-voltage outdoor audio or security camera wiring
Ground Anchors: Specific Risks
Many shed kits sold at home improvement stores include ground anchor systems — helical or arrow-type metal anchors that are driven or screwed into the ground at each corner and midpoint of the shed perimeter. These anchors are typically 18–36 inches long and driven with a ratchet bar or power tool.
The installation approach is fast and often feels low-risk because the anchors are small in diameter. However, a 30-inch ground anchor can absolutely hit a gas line, irrigation mainline, or electric conduit. The penetration is narrow but the depth is real. Call 811 and pre-mark anchor locations before installing any ground anchor system.
Helical Piles: High Depth, Professional Requirement
Helical piles (also called screw piles) are increasingly popular for shed and outbuilding foundations in frost-prone areas. They're installed with a hydraulic torque motor and go deep — 36 to 84 inches in some applications. A helical pile installation without 811 compliance near a gas line is a genuine emergency waiting to happen.
Helical pile contractors are generally highly aware of 811 requirements — this is a professional service with significant liability exposure. However, verify before any pile installation begins that a valid, fully-responded ticket is in place.
I'm replacing an old shed with a new one in the same spot. Does the new shed still need 811?
Can I use the ground anchor system that came with my shed kit without calling 811?
Related Guides
Deck Footings
Similar pier and footing depth considerations for deck construction.
Running Power to an Outbuilding
If your shed will need power — how to handle the trench for electrical conduit.
Private Lines
The private underground lines 811 won't mark near your shed site.