Building a Deck, Day 5 – Cutting Posts
Concrete may not cure instantly, but it does cure quickly. The Quikrete I used (Quikrete 5000) stated that it could support a 1500PSI load after 1 days of curing. That'll be strong enough for me to setup and mount posts, and by the time I get around to add the deck boards, it will most likely be past the strength that I need it to be at.
DAY 5 - Cutting Posts
I didn’t have a water level or any fancy site levels, so I instead came up with the idea to use a standard laser level on a tripod at dusk. I setup the tripod a few feet further away from the house than my cement piers, leveled the laser (with the built-in level) and shot it at the ledger. I adjusted the height of my tripod until the laser was level with the bottom of my ledger, effectively marking where the top of my beam would rest. Mark that location, subtract 9 ¼” for the height of my beam (2x10’s) and mark a line to make the cuts for my beam. I did this for all 4 post locations and called it a night.
After sleeping on it, I realized that by just being off level a little could have thrown my measurements way off base. I was shooting from about 12 ft from the house. If my level was off by a mere 1 degree, my post could be cut ¼” too long or too short. Not the worst possible issue, but what if it was off by 3 of 4 degrees? Now we’re talking about the post being cut too long or too short by nearly an inch. Being cut too short would be a huge issue as it would require yet another trip to the lumberyard (they know me by name at this point). So, to verify my measurements, I used a 2x4x10’ on edge nailed to my ledger (eyeballing it to make sure it didn’t have a sag or a crown). Turns out my measurements were short by about ¼”. Looks like the level on my laser level doesn’t quite live up to its name – I’m sure there’s an error percentage built in somewhere in the manual, but at this point I wasn’t interested – I had what I needed. Since the posts are PTP, I need to cut them so that my deck will sit level. As the posts age and dry, they’ll shrink slightly, creating a minute pitch away from the house that will aide in shedding water. If I build this pitch into the design, it would only worsen over time.
Four cuts later, my four posts are ready. To keep them close to level after setting them up, I need a few scrap pieces of 2x4 that I can screw into stakes I’ve pounded into the ground and into the posts. Using a post-level in this instance makes this step go much faster than a conventional level:
The tricky part is even after you have screwed your posts to the scrap braced you created with stakes and 2x4, you still have to keep them relatively straight while you nail them to the post mounts in your cement. A few good smacks with the hammer on a 16d nail and the post may shift a little. Probably nothing to worry about, we’re only talking about a couple of degrees off level, but if you’re anal…..