I have a 100+ year old house in North Idaho. Winters here can be pretty rough and I need to insulate big time. I am fighting with ideas on how to fix my insulation problem. Quick rundown of walls from exterior to interior. Insulated aluminum siding over original clapboard over 1x6 ship lap to 2x4 studs to 1x6 ship lap. I have already looked into spray foam applications but it is insanely expensive here due to the lack of contractors available, so that's a no go. I have considered just using standard fiberglass batts but I want more r value. With the standard batts in place I am considering placing the original ship lap back up also. Another idea is to add 2x3 framing to the exterior walls to add more depth to existing framing cavities. With this idea I would use 1/2" solid core foam boards to seal off the airflow from the exterior then use 5 1/2" fiberglass batts over that then sheetrock.

Any ?'s, comments and suggestions will be helpful. Thanks.