How can I cut a hole through metal siding to open up a doorway or window?

Question

There is an outbuilding on the property I'm buying that appears to be made of cinderblock. at some point in the recent past, it looks like somebody attached a bunch of metal siding to the outside, and in the process they closed off a bunch of doors and windows.

I'd like to turn those back into doors and windows.

Clearly I'll have to remove some of the metal siding to do so. However, I'm unclear on how to do this. For example:

• What kind of hand or power tools will I need to use to cut doorway holes and window holes out of the siding?
• What processes or specific steps will I undertake to use those tools to cut those holes?
• Will I need to take the siding off of the building before cutting it, or can I cut it while it's attached to the building?
• Will I approach the cuts from the interior, or the exterior?
  • If from the interior, what do I do about the windows where there is glass between the interior and the siding?
• There appear to be bits of wood stuck between the siding and cinderblock. Do those require special attention? Are they structural? Can they simply be cut through using the same tools and processes as the metal siding?
• After I cut a hole through the metal siding, is there anything I need to add around the edges of the hole for aesthetics, for safety (in case the metal is sharp), for water retardation, or for air sealing?

Pictured below: a shot of one of the closed-off doorways from the interior, and a shot of one of the left-open doorways from the exterior.

Answer 1

I'd go with offset aviation snips to cut the sheet metal either start where sheets overlap or drill a half-inch pilot hole 4" from the edge and spiral out from that.

Sheet metal has sharp edges wear work gloves.

A sabre saw would also work but may scratch the surface finish. sawing sheet metal is VERY NOISY. An angle grinder will make an even worse racket and burn the paint near the edge leading to accelerated rusting.

Straight snips will not work on the sheets while they are in place, but if you remove them they can be cut, but it's tricky, you probably want a helper spreading the cut.

Answer 2

I agree with other answers regarding using tin-snips to cut the metal. You will, of course, end up with a sharp metal edge all the way round which should be buried under trim at the opening (as shown in your picture of a properly finished door).

You will need to get creative with door casing molding of some sort if you intend to use the existing door jambs to swing the door from, otherwise you would tear our all existing jamb work and start from scratch with new jambs and moldings.

Those batten-boards that span the opening were used to fasten the siding. You will obviously need to cut those out too (you would not use snips; use a wood saw of some sort). You will need to ensure they are still secure. The ends would be buried behind your new door jambs or hidden by exterior trim molding of some sort.