Why is my contractor avoiding a permit for our deck stairs?

That "replacement" excuse is a common tactic to avoid the permit office, but the second he changed the dimensions and the post sizes, it became a structural modification that requires an official inspection. Most local codes are very clear that any change to the footprint or structural members needs a permit. An engineer's letter is just an oppinion; it doesn't carry the legal weight of a city-signed permit, expecially if that engineer has a cozy relationship with your contractor. Bolting joists to the side of the posts is a huge red flag. You’re relying entirely on the **shear strength** of the bolts rather than having the load bear directly on top of a beam or post. In almost every jurisdiction, code requires the beam to sit in a notch or on top of the post to ensure a solid load path. Tacking on extra boards to hit a width requirement is hack work and suggests he didn't plan the framing layout before starting.

The Trex issues are just as concerning because composite decking is much heavier and more flexible than wood. If the manufacturer specs 9-inch spacing for stairs and he's pushing that, those treads are going to bounce and eventually sag. And skipping the flashing is a disaster waiting to happen. Without it, moisture will get trapped against your house and rot out the rim joist, wich is a massive repair bill down the line.

Stop all payments right now. You need a truly independent structural engineer who doesn't know this GC. Tell the contractor that the job is on hold til a permit is pulled and a city inspector signs off on the framing. If he refuses, you might need to find a new crew to tear it out and do it right, because this sounds like a structural failure waiting to happen.

I’ve seen that "tacking on" move before. It’s a total rot magnet. Gunk gets stuck between those extra boards and holds moisture right against the grain. In my expirience, those "widened" stringers turn into a soft mess within a few years. If he’s skipping flashing, he’s definatly not sealing the end cuts either. I acutally stopped a project mid-build once for this kind of "trust me" attitude. I took photos down to the local building office myself. The inspector took one look and told me it was a teardown. Best thing I ever did was get an official opinon before the final check cleared. Don't let him bully you.

Check if he used Simpson DTT2Z tension ties or just cheap carriage bolts for those 6x6s. Side-bolting without proper hardware is amateur hour. If you're running Trex Transcend, those stair stringers shouldn't exceed 12” on center regardless of what he claims. Composite is basicly just heavy plastic; it has no structural stiffness of its own.

I’d also check the ledger—did he use FastenMaster LedgerLOKs? If he skipped the Z-flashing and didn't use Grace Vycor tape, that connection is compromised. You’re looking at a bouncy staircase that’ll rack the first time you carry furniture up to that ADU. Don't let him talk you out of a proper Simpson hardware setup.

You shold call the building department yourself and ask 'em about that "replacement" rule. I've done it before and usally they'll shut that down real quick once they hear about the 6x6s. It's way better to hear it from the city than a biased pro. Check the rise and run on those steps while you're at it. If he's hacking the width, I'd bet money the tread depths aren't even consistent. That's a major trip hazard you don't want to deal with later.

Wait, what does the flashing actualy look like if it’s installed correctly? I keep seeing people say it's a big deal, but I’m pretty new to this and don't relly know what to look for. Is it like a metal strip tucked under the siding?

Also, I'm confused about the 6x6 posts. If he's just bolting the wood to the side of them instead of on top, does the thickness of the post even matter for holding weight? It seems like the bolts are doing all the hard work anyway. Does that make the bigger posts just for show or is there some other benefit?