A wealth of knowledge online. All links are checked for content. Want to know about siding, Plumbing, Electrical, and more these links will help.
HUD has a wonderful guide to Homes. Has a guide on how long appliances and other lifetime estimates before replacement.
Residential Rehabilitation Inspection Guide https://www.huduser.gov/Publications/PDF/rehabinspect.pdf
HUD Rehab guides by topic https://www.huduser.gov/portal/publications/destech/rehabgds.html
DUCTWORK HVAC https://www.alpinehomeair.com/related/Ductwork.pdf