I have about 25 feet of sill plate and rim joist to replace as a result of termite damage. I am currently remodeling the outside of my older home by removing all the vinyl siding and the original wood lap siding beneath it and coming back with 1/2 inch foam board insulation, Tyvek, and finally cement fiber lap siding.

The home was built in 1964 with stick built rafters and the rim joist and plate to be replaced is parallel with the floor joists, there is a center foundation running north/south that supports the main support wall in the home and that also provides the main support for the stick built roof rafters---the floor joists run east to west and the section to be replaced is at one of the gable ends of the home. Sorry, but it seems that all that info is important to give, perhaps not.

I would appreciate some advice on the best way to support the outside wall while replacing the sill and rim joists--I'm thinking it may need to be done in sections rather than all at once. Brain storming it, I was thinking that I would scab in one 2x (may 2 if enough room) on top of the inside edge of the foundation in the crawl space next to the current existing sill plate (which I believe is a 2x6 or 2x8, that would leave room on the inside edge of the foundation for scabbing another 2x); my hope is that this would provide the closest support to the outside wall for replacing the sill and rim joist. Any advice is appreciated.

Thanks
Chuck

If the wall as you say is on the gable ends and a 1 story, then that wall is basically a non bearing wall. It supports very little compared to the side walls that actually have the roof rafters on.

I can't see how the stick built rafters are designed here The only real weight here would be in the center down from the roof peak where the ridge beam is set, and depending on the roof truss frame that's next to nothing.

If you can get to the end wall rafter and scab a horizontal 2x8 from that last outside rafter to adjacent rafter this would eliminate any weight below that area of wall. It may already be designed that way.

The top wall plate and wall is the only weight left. Do a 3rd of that replacement wall and no real need to brace from below

If you make sure that is supported then all is good here.

Due to termite damage, I need to replace a rim joist that supports the front wall that has a sliding door. Currently, it has a 2x6 beam that goes across the room. My question is, what is the best type of wood, e.g.. Cedar, pine, oak or redwood to insure stability.