How to Dig Post Holes for a Deck

Before our weekly deck update, we have to say: HOLY COW—you all have amazing homes! So many of you submitted house-crashing photos for our upcoming trip to Atlanta for the Haven conference, and we wish we could visit every single one of you. We’ve worked out a plan to crash as many homes as we can fit in and are a little sad we can’t get to everyone this time. We might be back in the fall for book tour events, though, so there’s always next time. Huge thanks to everyone who offered to let a toddler, a chihuahua, and two curious bloggers snoop around.

Back to business. I’m a little proud of this post title since it includes not one but two deck puns about our recent progress: leveling things and digging holes. Continuing the series from Deck Day #1, Day #2 wasn’t quite as productive as we had hoped. It happened the day after Day #1, but progress that day wasn’t quite post-worthy, so we waited until we had more to show. By Deck Day #3 we had completed a ledger board and dug all our post holes. Here’s the rundown on the last two days of work.

You might remember we left off having hung one ledger board on the brick side of the alley and prepared the siding side for its ledger. The first task on Day #2 was to hang the other ledger board against the house. For anyone unfamiliar, a ledger board is the board attached to the house that supports one side of the deck joists. We began by marking where each joist hanger would go so we wouldn’t accidentally put bolts through those spots. To make sure the hangers lined up with the ones on the brick side, I drew a small diagram with measurements to mark everything accurately. Clara contributed a very important crayon scribble.

The ledger itself was a beast: a single 17-foot 2×8. With the help of my dad, and using scrap boards to prop and level it, we got it into place and screwed it in. Bolting it took less time this side because we used 6″ lag screws into wood rather than drilling into brick.

Since the ledger attachment went quicker than expected, we decided to install the joist hangers next. Our ultimate goal for the day was to dig the post holes, but it was still early, so we figured we could get the hangers in. We worked methodically, using a level and a scrap joist to position each hanger. To take advantage of our full-length level we installed every third hanger first, then filled in the ones between. It was straightforward but more time-consuming than it looked.

We even had a small cheering section observing from the doorway. Sherry kept Clara occupied and helped with photos and decisions throughout the day.

By about 1pm, my dad and I had finished the hangers on one side. Feeling a bit hungry and less optimistic about completing all tasks that day, we chose to pause and focus on digging the post holes after lunch. Our first inspection would only check the footings, so it made sense to prioritize the holes. On paper, the layout seemed simple: two posts at the end of the deck, two for the middle of the stairs, and two at the bottom of the steps. A 3D rendering from the lumber company helped visualize the underside, which made planning easier.

Translating the plan to the ground was more involved. For the end posts, we had to determine exactly where the deck would end and set the stair angle; we chose a 45-degree angle for the stairs. We marked lines with string anchored to bolts driven into the ground. Figuring stair locations meant calculating stair length and rise; I used an online stair calculator to confirm measurements. With the calculator and a temporary workspace, we spent time staking out the stairs. We debated several styles—flared stairs, a split with a landing, or simple straight stairs—and ultimately chose classic straight stairs to fit the limited space and avoid conflicts with the air conditioner adjacent to the stairs. The railing area to the right of the stairs will likely become a built-in planter box; we’ll keep you posted as that develops.

We shifted the stair string a few inches away from the house and planned to plant a buffer next to the air conditioner so the unit has clearance. By 5pm on Day #2, two full days of work had caught up to us, and we decided to postpone digging until the next session.

Deck Day #3 arrived a few days later when my dad showed up with a two-man auger rented from the tool center. After manually digging post holes for a previous project, renting an auger this time felt like a no-brainer. The four-hour rental cost $60. I started each hole with a shallow mark so the auger blade would stay centered when we started it. The auger revved to life like a lawn mower; it’s a bit unwieldy, but not too hard to use. It takes two people to control safely—one to apply pressure and keep it steady while the other manages the throttle. Occasionally we would lift the auger out to clear the churned dirt.

Important safety reminder: always call your local utility marking service before digging to avoid hitting buried wires or pipes. We called before planning and placed our marks accordingly.

The auger handled most of the work, but we still had to tidy up each hole with a shovel and a post-hole digger to reach the required dimensions. We had rented an 8″ bit but needed 12″ holes to pass inspection, so the manual cleanup widened the holes. Once cleared, we verified dimensions: holes needed to be 12 inches wide and at least 18 inches deep due to the local frost line. We aimed for about 21 inches so we could add a few inches of gravel for drainage before pouring concrete.

Digging the six footer holes took about two hours. It was hot and humid, and by the end my dad and I were exhausted and drenched in sweat, but the holes were done. With the footers complete, we can now schedule our inspection. I’m confident in the work, but inspections are always a little nerve-wracking—wish us luck.

What projects did you tackle lately? Any auger tips or old-fashioned digging stories? Renting the auger saved time and energy compared to manual digging, so for us the $60 rental was worth it.

Psst—if you want to follow our deck progress from the beginning, we’ve documented planning, clearing the area, getting permits, demoing the old deck, and Day One of construction in earlier posts.