With my deck holes dug and approved by the county inspection, the next step was filling them in. There’s a bit of irony in digging only to immediately fill, but that’s how it goes. Like when I set fence posts last year, I started each hole with a couple of inches of gravel for drainage. Local deck pros recommended gravel beneath the concrete we’d pour to secure the posts. Our holes were dug at least 21″ deep, so adding 2–3″ of gravel still left the required 18″ depth for our county.
As I poured rock into one hole, dirt started hopping—hidden frogs had been hiding down there. I rescued the little hoppers before continuing.
I checked other holes for critters, though I still missed a big toad at first.
After rescuing him with gloved hands, Clara got an impromptu nature lesson while watching from inside.
I love this shot—not for the iPhone paparazzi moment but because I can picture Clara explaining: “See, Burger, this is a frog. It goes ribbit ribbit.” They were both fascinated.
Once the holes were clear of frogs and had about 3″ of drainage rock, it was time to set the concrete footings. Some readers suggested precast Dek-Blocks, but those aren’t allowed in our county. We could use other precast concrete blocks, but I decided to mix my own concrete. The precast blocks would have required square 12″ x 12″ holes and flat bottoms, which would mean more digging and leveling. Mixing concrete seemed easier since it fills irregular holes and levels itself. Plus, concrete came with my lumber order from 84 Lumber.
To mix, I opened each 60 lb bag in a wheelbarrow and added water until it reached a creamy consistency, stirring with a garden hoe.
My first batch was a bit soupy, so I reduced the water for later batches. It still cured fine and naturally leveled at the top, which is ideal for setting posts.
Mixing and pouring was straightforward but brutally hot—our county had a heat advisory that day. I worked in the shade when I could and stayed hydrated, though it was still exhausting.
I finished pouring concrete in all 12 holes, though by the end I was too hot to document each step. Here’s a shot I took later that evening.
The next day, additional materials from 84 Lumber arrived after the county required more posts and girders when they revised my plan. It wasn’t a huge order, but it included the 4 x 4 posts I needed for the next phase.
I ordered 12-foot posts, which let me get three posts from each piece—efficient for a relatively short deck.
The ground slopes away from the house, so I staggered post heights to match.
This step was more complex than setting fence posts because these posts would support 2 x 10 girder boards running the long way beneath the deck. Joists span the short way and rest on the girders. Joists must align with the rim boards attached to the house (the rim boards here provide lateral stability rather than primary joist support). The photo below helps illustrate the layout.
Before installing posts, I set up guides to ensure alignment with the rim boards.
After temporarily hanging joists at each end, I ran nylon string between their bottoms to represent the top of the girders where the joists would rest. The string was a lot easier than trying to hold an 18-foot 2 x 10 in place temporarily.
With the string taut, I set a post in its hole and used a post level to hold it plumb while marking where the string hit the post—this indicated the top of the girder.
The county allows either metal post brackets or notching the post to support the girder. I chose to notch the posts because it felt secure and was a method I’d seen before. Using the top mark, I measured and drew where to cut the notch so a 2 x 10 would sit at the correct height.
I cut the notch with a reciprocating saw and then moved the post back to check the fit against the string and plumb it with stakes.
To secure the posts long-term, I could have packed dirt around them, but I preferred Quikrete no-mix concrete—an approved method in our county and the same approach I used for the fence. You pour the dry powder, add water, and it hardens quickly—much easier than mixing full concrete.
I repeated the string-mark-notch-stake-cement routine for the adjacent post. It took a few hours in the heat, and by the end I was exhausted, but the posts were secure and I had a legitimate reason to stop until the concrete cured.
On the third workday it was girder day. I would have liked help lifting the 18-foot board, but my dad was out of town. I clamped the girder to the notched post and used a sawhorse to hold the other end while marking and notching the corresponding post. After cutting, I plumbed and checked everything—post alignment, girder slope for drainage, and joist height—then secured the post in place with no-mix Quikrete. The girder’s weight held things steady while it cured.
With one side set and the girder temporarily nailed and clamped, marking the middle post was straightforward. Each girder is supported by three posts. The opposite side required two girders that meet at the middle post, so I temporarily set a joist across the center as a height reference before notching and setting those posts.
Clara remained captivated by the action—she even brought an octopus balloon to watch. By the end of another very hot day, all six posts were set in concrete and all girders were temporarily held in place. The girders will be doubled up (two 2x10s), a step that will require an extra set of hands when my dad returns, so I left them temporarily secured for now.
There are two more posts and a girder needed to form the angled edge of the deck—two empty holes remain toward the lower left in one photo—but I wanted the main girders in place before tackling that. Overall it’s been a productive few days. Once the girders are doubled and the joists go in, decking boards will follow and the space will really start to look finished.
What outdoor projects have you been working on? Are you tackling your own heat-filled builds, or taking a more relaxing approach like a beach day?