Replacing some pieces of lap siding

[BadDog11]

I’m new to this site and also new to home improvements. I do consider myself handy and mechanical so I figure I should be able to pull this off.
I did watch a video online about replacing pieces of lap siding and I think I have it pretty figured out. My problem also seems to now include having to replace some of what’s behind the siding. There are some bad looking pieces and when we get a lot of rain it does leak into the garage. It looks to be the lap siding and then some sort of drywall and then the studs. I don't know for sure but shouldn’t there be some sort of wood in between the siding and studs?
And I pulled a couple small pieces of the lap siding off and about the bottom 12 inches are some other kind of drywall or something that has a putter netting layer.
So my question is once I get all the lap siding off that needs to be replaced and see how much of the wall needs to be replaced do I take all the “drywall” that needs to be replaced off and replace with drywall or wood? Can I use “wafer board”? Should I put some kind of waterproof paper layer over the wood before putting the lap siding on?
I did try posting a few pictures so show some of what I’m working with.
Thanks for reading and I appreciate any advice I can get

 

[bud16415]

Welcome to the forum.



It looks like what you have is Masonite siding and also sheet Masonite behind it. This stuff was used a lot back in the 80’s. It held up ok higher on the walls but lots of time water got to it low and broke it down like you are seeing.



You can patch it as you go like you plan or remove the bottom several rows and change it all. Doing that would make replacing the under sheathing easier along with covering it with a water resistant layer.

I haven’t done a lot with it as I’m not a pro. We should have some pros along shortly with more advice.

 

[joecaption]

It's failing because both the siding and that wall shield never should have been installed that close to grade.
The best, but not cheapest way to fix this is to install 5/4 X 6 (make sure to use 5/4, not 3/4) vinyl lumber at the bottom of the wall, a strip of aluminum Z molding, (and yes OSB will work)a strip of lattice to kick out the bottom of the siding, then the new siding.
The vinyl lumber gets attached to the studs, not over the sheathing.
Make sure to mark the exposure line on the new piece of siding before trying to tap them in place so it comes out even.
Even that wall shield should have been at least 2' above grade.