I got an email from a well know agent in my area stating a few age issues.
Once a home reaches a certain age (not defined), has an older roof, plumbing or aluminium wiring, the home is not eligible for a standard policy.
Here's the info:
Plumbing: updated in the past 20 years, no poly pipe for all companies. Must be replaced. Water Heater must be 14 years or newer.
Electrical: must be updated in the past 20 years, no aluminum wiring, no cloth wiring (must be removed).
Roof: Shingle roof must be less than 12 years old, Flot Roof must be less than 10 years. Tile roof must be less than 20 years.
This will have a significant effect on both buyers and sellers. Talk to your sphere of insurance agents. I'm in Florida. Things may be different elsewhere.