No one looks forward to the chore that is rot repair; however, it's often necessary and should not be ignored. On the plus side, it's a task that can often be handled without resorting to farming it out to a professional, especially if it doesn't require bodywork and paint. Interior and trunk floor repairs are examples of rust repair that almost any of us can tackle, since there's not a lot of fine finish work for the most part; all we have to concentrate on is a successful and strong repair, not how pretty it is.
Determining whether a particular interior or trunk floor rot situation is repairable at home requires a bit of inspection. In other words, you want to pay close attention to the extent of the damage and look closely at not only the floor areas, but to adjacent reinforcements and supports as well. Since floor rot is usually the result of leaks in the interior or trunk areas that allow water to pool or collect rather than from water splashing up from underneath the vehicle, it often ends up getting trapped between the actual floorpans and some of the gussets and support structures too. So, take the time to really check out the situation so you don't end up opening a can of worms. That said, we all know our limitations, but on the other hand, you don't want to shortchange your capabilities either; all of us are usually more capable than we think.
Rust repair is also a task that really doesn't require a bunch of specialized tools to perform. Sure, a MIG welder is the ideal way to replace metal, but it's not the only option. In a pinch, repairs can be accomplished using rivets, and, in these technologically advanced days, even structural adhesives that are-believe it or not-nearly as strong as welds are a more-than-acceptable alternative.
Here, I'm going to give an overview of a typical floor-rust repair on a mid-'50s Chevrolet. Keep in mind that the process is pretty much the same for this vehicle as it would be for most others and hopefully will encourage those in a similar situation to give it a try-like I've said many a time: If I can do it, anyone can.
Carpeting and the old fibrous...
Carpeting and the old fibrous jute insulation are notorious for trapping moisture between them and a vehicle's floorboards, causing the type of damage shown here. But, don't despair; a bit of elbow grease, some aftermarket replacement panels, and a weekend in the garage are all you'll need to make things as good as new.
You'll want to closely inspect...
You'll want to closely inspect the floor after exposing the problem areas to determine just how extensive the damage really is. Do this from both inside and underneath the interior and/or trunk area, paying close attention to any support structures. A wire brush, safety glasses, and a punch or awl can be used to poke and prod. You'll want to start your search close to the most obviously rotted areas, gradually moving outward from the center of the damage to determine what's damaged and what's solid. The lowest areas where moisture pools will obviously be the most affected, but don't disregard high spots either because trunk mats and carpet will hold moisture against the metal almost anywhere.