Gavin writes from the Czech Republic: "I've just bought an old barn with 105 cm thick walls and would like to know if I'll need insulation. The climate in the area is: low humidity, 30+ Celsius in summer, -10 Celsius in winter. Vaulted ceilings on the ground floor; raftered ceiling on the 1st floor."

Answer: If your barn is in the U.S. we would typically recommend R-13 Kraft-faced fiberglass insulation for the exterior walls, and R-38 Kraft-faced fiberglass insulation with Raft-R-Mate® rafter vents in the vaulted or cathedral ceiling if it is under a deck with an asphalt-shingled roof. You should check (pun intended) with your local insulation retailer or building code official to see what is recommended in your location.