Finally figured out why the framing on my parents' new deck felt so off

I went through this exact same headache last summer with a cedar build. From the top, the 5/4 boards looked like a million bucks, but once I got underneath with a flashlight, I saw they’d used standard interior screws for half the joist hangers. I ended up spending my entire Saturday swapping those out for Simpson Strong-Tie SD connector screws just so I could sleep at night. It’s frustrating because the "pretty" parts distract most homeowners from the structural stuff that actually matters.

If your parents' ledger is into brick, definitely check if they used expansion bolts or if they just went into the mortar. I had to have my guy come back and install some DTT2 tension ties because the lateral load was way off. It's better you caught it now; I’ve seen too many decks start to pull away from the house after the first winter because the flashing was non-existent or the hardware was undersized. Getting a second set of eyes on those structural connections before you host a crowd is the smartest move you could make.

I had a similar scare with a wrap-around we did two years ago. The cedar decking was beautiful, but the guy we hired completely ignored the local code regarding the ledger board flashing and trough-bolts. I didn't bother marking it up myself; I called the local building inspector to come out for an unscheduled look. Having a city official point out that the 1/2-inch lag screws were spaced way too far apart carried alot more weight than my own complaints. If your parents still have a balance on the invoice, tell them to hold the final check til that contractor installs the proper tension ties. We had to insist on Simpson DTT2Z deck tension ties to meet the lateral load requirements becuase our deck is nearly eight feet up. It’s one thing to fix a few missed joist nails, but if the structural bracing is light, that’s a profesional liability they need to own up to before they move on to thier next job.

You shoud verify if those support posts are acutally notched to recive the beam or if they simply relied on carriage bolts to hold the vertical load in shear, wich is a common but egregious violation of prescriptive residential wood deck codes. I’ve seen builders bypass the requirement for a proper post-to-beam connector by just sandwiching the post between two plies, but without a dedicated mechanical fastener like a Simpson AC series cap, you’re essentially trusting the fastener’s shear strength rather than the wood’s bearing capacity. While you're under there, check the cantilever distance on those joists; if they overextended past the beam significantly, that skirt is going to sag regardless of how nice the wood looks.