811 Before Deck Footings: What You Must Know
Deck footings are the deepest excavation most homeowners ever attempt — and they go exactly where utility lines run. Here's the full 811 process for deck construction.
Why Deck Footings Have Elevated Risk
Three factors combine to make deck footing installation one of the higher-risk residential excavation scenarios:
- Depth: Frost-line requirements force footings into the 36–60 inch range where major utility service lines run
- Equipment: Power augers used for footing holes operate at high torque — a line strike can be violent and instantaneous
- Location: Decks are typically attached to houses, placing footings near the service entrance where electric, gas, and water lines converge
Frost Line Depths by Region
| Region | Approximate Frost Depth | Example States |
|---|---|---|
| Deep South / Southwest | 0–12 inches | FL, TX Gulf Coast, AZ, CA (coastal) |
| Mid-South / Mountain West | 12–24 inches | GA, AL, SC, NM, NV |
| Mid-Atlantic / Midwest | 24–36 inches | VA, MD, KY, MO, CO |
| Upper Midwest / New England | 36–48 inches | OH, IN, PA, CT, NY, OR, WA |
| Northern Tier | 48–60+ inches | MN, WI, MI UP, ME, ND, MT |
Always verify your local frost depth with your building department when pulling a deck permit — the required footing depth is specified in your permit.
Step-by-Step: 811 Process for Deck Footings
Mark all footing locations in white before calling
Stake or paint each footing location before submitting your ticket. This precision helps locators focus on exactly where you're drilling. Deck footings are point loads — a few square inches of ground. Precise pre-marking gives you the most accurate locate possible.
Submit 811 ticket and specify footing depths
Include the planned footing depth in your ticket description: "Installing 6 deck footings, 12-inch diameter, to 42-inch depth." The depth information helps locators understand the severity of conflict if a line runs near your planned footing locations.
After locate, assess each footing location individually
Walk each footing stake and look at what's nearby. A mark 20 inches from a footing may be outside the tolerance zone — but if your footing is 12 inches in diameter, the edge of the hole extends 6 inches from center, putting it only 14 inches from the mark. Think in terms of the footing hole edge, not just the center.
Call the utility for depth on any close marks
If a yellow (gas) or red (electric) mark falls within 36 inches of any footing center, call the utility and ask for the approximate burial depth at that exact location. Many utilities will give you this information — it's in their interest to prevent a strike.
Hand-dig pilot holes at any footings near marks
Before using a power auger on any footing within 24 inches of a mark, hand-dig a pilot hole to 18–24 inches first. If you hit nothing, the remaining deeper portion can proceed more confidently — but continue with care to full depth.
Relocating Footings Around Utility Marks
If a footing location conflicts with a utility mark, you have several options: shift the footing along the beam line (usually 12–24 inches moves it out of conflict), move the entire deck footprint slightly, or use a helical pile (screw pile) installation which can sometimes be directed away from utility paths. Discuss footing relocation with your deck designer or structural engineer before making changes — footing locations are often constrained by beam span limits.
My deck permit requires footings to 48 inches. The gas line is marked at 24 inches in that location. What are my options?
Can I use a Sonotube form right up to the edge of a utility mark?
Related Guides
Fence Posts
Similar post-hole auger risks — complete guide.
Wait Times by State
How long to wait after submitting your ticket.
Private Lines
Private lines 811 won't mark near your deck site.