Rusted Through Holes

[Iowaner]

For those who do restorations, what do you do about rust holes that have literally eaten all the way through the floor.

I mean you could just weld a patch over it but trying to restore I would think that would be a big no-no with a big extra chunk of metal over the hole.

Is there a proper way to handle it when trying to do a classic restoration?

[HahnandWoodwardAutoResto]

The short answer is to repair it using a "Butt Joint". This is where you cut and fit the repair panel to an exact fit without any overlap at all. It is a lot more trouble than an overlap joint but it will result in a much nicer finish job.
Different repairs often require different plans, but generally follow the same basic methods.
This is the way I've been doing it for nearly 40 years:
First, before grinding, sandblasting and/or cutting out the bad area; determine as best you can how extensive the rust out is. Do this with as little destruction as possible to find how large of a repair panel is necessary. By leaving the area intact you can utilize it to facilitate the shaping of the repair panel.
Next start making a template with some heavy paper. (In a body shop we usually just used masking paper.) I'll mark cuts in red and bends in blue. A crayon works well for convex creases like wheel opening edges.
Transfer the template to sheet metal utilizing some spray glue (the spray glue for sandpaper will allow you to remove the template from the metal). Make your cuts and basic bends. Remove the template with assistance of some heat. Then do your hammer shaping.
When your panel fits like a glove attach with some screws or clamps, trace around the edge of it for your cutting line. Remove panel, cut out the old area to be replaced and do your final fitting of your replacement panel.
If an area is not visible save yourself a lot of time and trouble and utilize the lap joint. Just be sure to seal all edges with seam sealer.
At Your Service, Bill Hahn

[Saya]

I wouldn't buy it. It seems like that would be more hassle than it's worth , unless you have a limited edition or something.

[Austin]

I avoid rust holes like the plague. It's a deal breaker for me.