How do I prevent rust on inside of window wells?
by
Eleanor Korf
I have corregated metal window wells that have rust appearing on the inside through small pin holes. They do not need to be replaced for a long time but they look awful. I can paint them to make them to look better, but rust streaks would begin to form again. Is there any barrier that can be put on the inside of the wells before painting that would keep rust from leaking through? The wells are deep because they are egress windows from a basement living area so I would like to have them look good. Would something like bondo work if it could be put on in a relatively thin layer so that patches where the bondo was placed would not looked like the surface was patched. Or could bondo be troweled on to make a smooth inside surface? Or? Or? Or? I would appreciate any ideas.
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Bondo would be a good solution. You would need to clean with a vinegar solution to cut through the galvanizing on the metal. Smooth it ou as best as you can. Sand once it's hardened. Prime and paint.
You can also use a rust reformer. It's a spray paint that converts rust to a paintable polymer coating.
https://www.homedepot.com/p/Rust-Oleum-Automotive-10-25-oz-Rust-Reformer-Flat-Black-Spray-Paint-248658/202623091
I would recommend removing all the rust first, if you'd like to even the surface out then yes a bondo would work. Keep in mind that regardless of the cover you go with, without getting the rust off completely it will return. Use an Etching primer to paint the bare metal before applying bondo or paint. Rustoleum makes and "Rusty Metal" paint/primer.
Rusted window wells cannot be repaired - only replaced. The reason for this is the window well is grounded. If the well installation bolts connect to the metal window frame, and if the window frame is connected to the rebar, it has become grounded. If the window well is connected to the concrete wall, and if the attaching bolts touch the rebar, it is grounded. The only proper way to mount a window well is to be 100% sure the well is NOT grounded.
What happens if the well is grounded? There becomes a very low electrical charge between the well and earth (ground). This creates electrolysis and the well becomes the anode. The well, over time, will begin to eat itself up as the sacrificial metal. There is NOTHING you can do except break the connection at the point the attachment bolt(s) make connection to ground. Sometimes this can be done but it's very difficult to do and only verifiable if you have a electrolysis tester. It's better just to replace the well; usually with a wider well to assure you don't reconnect to ground. I suggest hiring a contractor who knows what they are doing and has the proper test equipment to confirm the new well is isolated from ground.