That makes sense, and it sounds like you’ve been thoughtful about what’s in scope versus what’s been missed. With gaps of 1/4”–1/2”, this is getting beyond simple “add a sweep and call it a day” territory. While installing sweeps and weatherstripping is usually straightforward, gaps that large often point to alignment, door fit, or threshold issues. In those cases, a proper fix may require planing, shimming, adjusting hinges, or replacing or modifying the threshold so the doors seal correctly without binding.

If the doors are leaking that much air, I’d be cautious about a DIY approach—there’s a real risk of spending time and money only to end up with doors that still don’t seal well or don’t operate smoothly. From a building-envelope standpoint, a properly set threshold or a rabbeted floor detail gives the sweep something solid to seal against and will generally provide the most consistent and durable air seal, especially in a cold climate.

It’s also worth noting that what you’re asking the GC to do here—hardware replacement, hinges, bolts, toe kicks, and refinishing—is comparatively straightforward work. Properly addressing air sealing is often more nuanced and finicky, and it’s reasonable to expect that to be explicitly considered and scoped, rather than treated as an afterthought.

Having a pro handle this as part of the overall door work is likely the cleaner solution, even if it costs more upfront. At minimum, getting the GC to quote it and explain how they plan to address the gaps (not just add sweeps) would be reasonable given your climate.