I always use a multi tool to cut out the rot and make my own frame from cpvc and insert back in. pt dry 2x8 usually works on the garage frame splice...

Thanks! I suppose they sell cpvc in planks ? I do plan on using PT 2x8 to replace the rotted section. Since I'm only replacing the bottom 2ft, I probably have to recess the 2x8 a bit to allow for the cpvc to sit flush with the remainder of the wood.

well you can buy a cpvc door jamb kit to replace an entire jamb or make your splice out of 1x6 cpvc. either way you will be compromising the door threshold with the repair ( people door) because the threshold is nailed to the jamb from behind when the unit is assembled and dis assembly eliminates the bond . I'm not sure how much cpvc you will find at HD, they tend to not sell it in planks but most likely have the jamb kits though.

We do a lot of work that we get through realtors on addendum's to the contract after a home inspection. Usually the people want it fixed less expensively but still decent looking.

We buy from either lowes or HD a pvc door jamb kit. Use a multi master and cut the jamb above the rot, high enough that your piece is at least 7 or 8 inches. On the hinge side we will often just right at the bottom of the hinge, helps hide the joint.

Then cut a piece off the jamb kit to fit the opening. It's already made up and the right size, etc., no need for custom modification except one thing. Where the threshold is sloped, you have to cut the fatter part of the jamb at an angle cause of the way the door is built. I use the multi master for that cut as well. Then install it. I use shims behind it and behind the remaining piece if needed which they usually are to get the joints lined up.

As far as the way the threshold attaches a lot of the time they are glued down somehow and seem ok. I will put a screw through it that is then covered by the jamb when it goes in. If both sides are rotted and the brick is as well, you can pull the threshold, shoot into the end of it again, and slide the whole assembly back in.

Hope that helps.