How to cheaply seal a metal sheet roof done poorly

Question

In the context of poverty, i.e. living in tin metal shacks etc. So it's all about damage control and not some fancy 6 step multi layer solution:

If the roof sheeting is leaking a lot because of gaps and short overlaps between ibr metal sheets, there's no option to redo the roof, only to plug stop what is there already. What would you do? I know the full solutions involve silver tapes or butyl tape etc. But that adds up too quickly per metre. There's also expanding foam that can be tried to fill between each sheet, but that's too difficult to apply in small quantities without wasting a lot in overflow. Plus it's just too expensive per can.

I'm thinking more along the cost lines of concrete which is affordable, obviously it's not waterproof, but there are additives that make it waterproof impermeable.

I'm thinking of putting it in like a sandwich filling between the sheets and a bit over naturally. But the problem is obviously many, cement doesn't stick well to metal. Is there an additive? Or must gravity just hold it in place? But metal expansion and contraction with temperature changes will also rip it away from the cement I imagine.

But if we just want a 99% leak reduction, would it work? Or must we still put membrane with the paint over it to block it up further?

Or do we use straight up liquid polyurethane type stuff to seal between sheets?

Answer 1

Fibered (that is, it has reinforcing fibers in the mix that help it to bridge small gaps) aluminum (fine flakes of aluminum that float to the top of the wet paint and dry in place to protect from ultraviolet light degradation) roof paint or coating is the default cheap roof repair paint for both metal and asphalt roofing.

Example, not endorsement. There are many, they are pretty much all the same, use what you can find locally.

Would it be better to use a more expensive product you can't afford - sure. And over a long time it might cost less. But I certainly know folks that probably applied this stuff every year or two for decades, and managed to keep the house sufficiently dry by doing so. And plenty of other folks including my family would use it as a stopgap for a few months or years before getting to a "proper repair."

Answer 2

If you can get the polyurethane between the sheets in such a way that it will not trap water that's probably going to work for a while if that's where the leak is.

Else you may be be better off re-roofing with second-hand sheets. new if you can afford them.

Engineered coatings are an option too, but the price quickly goes up. and if the underlying steel is in poor condition you probably won't get your money's worth.