Is it normal to use stacked 2x4s as a temporary support for a garage header?

Those 2x4s are essentially acting as **critical points of failure** right now becasue they haven't been laminated or braced to act as a single unit. When you stack studs vertically without nailing them togehter, they don't share the load effectively. Instead, each board acts independently, and since they're alredy starting to bow, they’ve likely already exceeded thier reliable service load. A single 2x4 is surprisingly strong in compression, but only if it stays perfectly straight. Once it starts to deflect, the physics shift from compression to bending, and it’ll snap or kick out with very little warning.

The 'friction-fit' method your neighbor is using is a classic example of survivors bias. Just because he’s done it a dozen times doesn't mean it's safe; it just means he hasn't hit the specific set of variables that cause a collapse yet. Shims are great for leveling, but using them as the primary way to wedge a structural support under a top plate is a gamble. A disaster waiting for a breeze. If a gust of wind catches that roof or someone bumps one of those sticks with a lawnmower, those shims can spit out like a watermelon seed, and the whole side of the garage will come down.

In framing, we ussually build a **temporary wall** or at least nail three 2x4s together to create a solid post. Nailing them every 12 inches prevents them from bowing away from each other and significantly increases the axial load they can carry. You also need lateral bracing—basially a diagonal board nailed from the top of your temporary post down to the floor or a staked block—to keep the bottom from sliding out. If you see those studs bowing, you're right to stay away. The wood is literally telling you it's struggling. A proper jack post or even a solid 4x4 whould be the bare minimum here. What he has is a house of cards held up by luck and gravity, and when this kind of setup fails, it fails catastrophically and instantly.

The concentrated point load being applied directly to the top plate without any horizontal distribution sill is a textbook invitation for localized crushing of the wood fibers, particularly since the perpendicular-to-grain compression strength of standard SPF lumber is significantly lower than its parallel-to-grain capacity. Furthermore, those friction-fitted shims create a high-torque pivot point that effectively transforms the support assembly into a loaded spring, where any minor lateral displacement could result in an instantaneous release of kinetic energy. If he hasn't calculated the actual tributary load of that roof section, he's essentially gambling that the shear strength of his top plate can withstand a force it was never intended to support in isolation.

I've seen guys like this. They think they're geniuses 'cause they haven't died yet. If I were you, I’d keep my car parked down the street. It ain't just the garage coming down; if that roof shifts even an inch, it's gonna tweak the whole frame. He'll never get the doors or windows to line up right again. He's making a massive headache for his future self just to save five minutes with a nail gun. Total amateur hour.

Quick update — I showed my neighbor the point about localized crushing, and he actualy listened! He threw a horizontal plate in there to spread the load. However, the individual studs are still separate and bowing like crazy. He still refuses to nail them together because he wants to reuse the lumber later. If they start to kick out, is there any way to brace them safely without disturbing the setup?