We're replacing siding on our two-story house currently. We can do most of it okay, but our two-car garage has a slanted roof, which mean you can't just put a ladder up there. We're thinking about just hiring it done, but it'd be a lot nicer it we could do it ourselves somehow. How could you do this? Could you maybe make some kind of scaffolding? How would you do that? Would buying some step ladder with different length legs work? Here's a pic:
Werner makes ladder leg levelers (say that 5 times fast) that fit their ladders. I'm not sure if it's the safest solution for a pitched roof though. If you did decide to do this, I'd really consider having a temporary stop beneath the bottom foot of the ladder and possibly on the wall you're leaning it against as well.
Another solution would be an articulating ladder that you can set up as a step ladder with two different length sides. I have the Werner 17 ft aluminum ladder, and it's awesome. It does weigh 40 lbs though, so my wife doesn't like to use it very much.
They would probably use some kind of scaffolding. For example, they make arms that attach to an extension ladder for holding scaffolding. You could put the ladder against the side of the house to support one end of the scaffolding, and have the other end sit on the roof.
If the roof material is strong enough (like roofing slate) and the framework beneath it is strong enough to support extra load you can just put a ladder onto the roof (ladder parallel to the roof surface) - it will distribute load and safely transfer it to the roof framework.
The ladder has to be rigid and extra care needs to be taken to avoid stepping or putting concentrated load directly onto the roof. The ladder will need wide hooks to hook it up to the top of the roof.
use a ladder with a ladder jack on the one side and on the other place a plank scaffold or walkboard 24 footer or so...to span the distance between the ladder jack and the peak or the roof on the other and bungie the plank to the ladder and ya can go up higher to reach the peek if needed..but mostly keep it level..this way you can safely do it..
Build a temporary scaffold using well braced 2X4s and thick cross beams spanning the garage roof. You may need a support somewhere in the middle, on the garage roof. Or you may rent scaffolding.
I'm sure you have found a solution by now but for anyone else searching for the answer to this problem, I have much simpler and safer idea. First you need a step ladder, extension ladder, a walk board, and a ladder jack. You should be able to rent what you don't have locally for a small amount.
To set up, once you have put the siding on as far as you can reach from the roof, put the extension ladder with the ladder jack on the ground and run the walk board from the roof peak to the ladder jack making it level. Once you run that as far as you can reach, raise your extension ladder (you will probably need to move it over) and straddle the ridge with the step ladder and run the walk board between the two.