Heritage Buildings 101: Guidelines & Hazards
  shared from NAIMA Canada

The roof structure of heritage building may or may not have insulation and/or barriers for air tightness. Before installing these layers in a retrofit, there are important steps to make in preparation.

LISTEN...

Attic insulation is one of the most common energy efficiency retrofits in older buildings. The area must be properly prepared for the new material addition:

• Ventilation: Improper ventilation of attic spaces can contribute to moisture building up, especially in cavities that are packed with new insulation. Care must be taken to properly arrange ventilation at roof soffits and ridges.
  
• Where rafters / trusses meet walls at the lowest part of the slope, adequate airspace must be allowed between new insulation and the underside of the roof deck. This space can be maintained with foam plastic or cardboard rafter baffles.
• Attic Hatches: Insulating and air sealing the attic hatch must be done to mitigate leaks and heat loss.