Deck, shed and addition footing excavation with a mini excavator

Footing jobs that fit a mini excavator

A shovel or post hole digger is fine for a few holes in soft ground. Our listing names footings among the jobs the Kubota U27-4 is good for, and says it works close to foundations and fences. It earns its keep on jobs like these:

• A row of deck footings: Several footing holes along a beam line, where hand digging would take all weekend.
• Shed and shop footings: Footing holes or a perimeter footing trench, plus leveling the pad around them.
• Garage and addition footing trenches: A continuous trench laid out from the foundation plan, often close to the house.
• Carport and covered patio posts: Footings for a detached carport or patio cover, dug to the plan.
• Backfill and haul-off: Blade the spoil back around the forms after inspection and load the extra into the dump trailer.

The order that saves rental days

1. Plan and permit. Know whether your project needs a permit, and have the approved plan or deck guide in hand before you dig.
2. Mark and call 811. Stake each footing from the plan, paint around the spots and request a locate.
3. Dig. Rent the excavator once the locate is done and the layout is set.
4. Footing inspection. Pierce County’s deck guide lists a setback/footing inspection before you pour concrete. Line it up with your rental dates so holes aren’t left open for days.
5. Pour, backfill, haul. Blade the spoil back once it passes, and trailer the extra away.

Deck, shed or addition: which permit line are you on?

Unincorporated Pierce County:

• Decks: the Predesigned Deck Guide says a permit is required for any residential deck more than 30 inches tall, measured from the walking surface to the grade below within 36 inches of any edge. The county’s decks and sheds FAQ measures grade out to 6 feet from the deck, so if you are close to the line, ask which applies to you.
• Predesigned decks: the deck guide serves as your plans, with a site plan. It is not for decks over 14 feet tall, covered decks, decks closer than 5 feet to a property line or decks for a hot tub. The county’s Fast Track notice says these pre-designed plans need no engineer or architect.
• Sheds: the Work Exempt from Building Permit guide exempts a one-story shed up to 200 square feet, at least 5 feet from other structures and meeting setbacks. Bigger garages and shops need a permit.
• Additions and garages: the Customer Guide for Residential Construction lists a foundation plan in the plan set, and a drainage plan when excavation and fill reach 50 cubic yards or new or replaced hard surface reaches 500 square feet.

Puyallup: the city’s building permit page requires a permit for any addition to a house, including covered porches, decks and patios; detached accessory buildings over 200 square feet; and uncovered decks more than 30 inches above grade or serving a required exit door. Its detached accessory building tip sheet covers how many and how big.

Bonney Lake: the city’s building permit page exempts a deck only if it is 200 square feet or less, no more than 30 inches above grade, not attached to the house and not serving a required exit door. One-story detached accessory structures up to 200 square feet are exempt, but setbacks and other permits still apply.

Other cities have their own rules. Check with your city or Pierce County first. Area pages: Puyallup · Bonney Lake · Sumner · Auburn · Enumclaw.

Footing depth and size come from the plan

• Pierce County’s Residential Design Criteria bulletin says all low-land areas have a frost depth of 12 inches below grade, and higher elevations have a deeper frost depth. Look up your parcel on About My Property or ask Building technical support.
• Footing size on a predesigned deck comes from the tables in the county’s deck guide. For an addition, garage or shop, it comes from the foundation plan.
• Pierce County says to schedule inspections before each phase of work is covered up.

We rent the machine. Footing design, size and depth are for your plans, your engineer or the permit office.

811, layout and digging

• WA 811 says to contact 811 at least two, but no more than ten, business days before you dig. Private lines, like power to a shed or a septic system, are not marked.
• Service lines often run to the house, so take extra care digging footings for an addition or attached deck.
• Kubota lists the U27-4’s overall width as 4 ft 11 in and max digging depth as 9 ft 5 in (Kubota U27-4 brochure). Measure gates and side paths before you book.
• Check each hole against your string line and the plan before you call for inspection.
• L&I’s excavation rules apply to employers. WAC 296-155-657 says employees in an excavation must be protected from cave-ins by a protective system, unless it is in stable rock, or less than 4 feet deep and a competent person sees no sign of a cave-in. WAC 296-155-655 says to keep spoil and equipment at least two feet from the edge, or use retaining devices.

Haul the spoil and the old deck

Pair the excavator with the 7x14 dump trailer to haul extra dirt out and gravel in.

• Extra dirt? Pierce County’s Dirt page lists places that take clean fill dirt (no sod or debris). Contaminated soil needs a Waste Disposal Authorization from the Tacoma-Pierce County Health Department.
• Secure every load so nothing drops, sifts, leaks or escapes. Cover dirt, sand or gravel on paved roads unless you keep six inches of freeboard in the bed (RCW 46.61.655).

Tearing out an old deck first? See the debris hauling guide. Towing checks: dump trailer guide.

Day, weekend or week?

Mini excavator: At the day rate, 3 days is $1,005 and 4 days is $1,340, vs $1,050 for a week. The weekend rate is $490 (Friday 9 AM pickup to Monday 3 PM return).

7x14 dump trailer: At the day rate, 3 days is $465 and 4 days is $620, vs $575 for a week. The weekend rate is $200 (Friday 9 AM pickup to Monday 3 PM return).

Prices are before WA sales tax and the 1.25% heavy equipment rental tax where it applies. Your exact total shows at checkout.