We have a 35 year old Lindol log cabin in Alaska, about 28 by 32 feet, with an original sloping roof. Logs are milled to 2 3/4 inches thick, by 5 inches wide, tongue up, groove down. What are some of the alternatives to improving insulation value, and strengthening/straightening the vertical walls, which are bowing noticeably. It has some insulated siding part way around and a steep metal roof added now. We would like to add on. Is this a practical possibility?