It seems odd, but roof design is very important when it comes to mold growth in your attic. This is not due to moisture penetration through your roof system, but rather the potential condensation buildup as your home experiences vast temperature differences between the inside and outside air.

Let’s briefly discuss the main roof designs.

You’ll notice in the image below that all four sides of the roof come all the way down to the exterior walls of the home. Referring to our R-value table above, it would be easy to achieve the required insulation in the middle of the roof; but what about all around the perimeter?

Simply put, it is not possible. What does that mean? Since heat rises to the ceiling inside all homes, and the limestone ceiling drywall allows heat to pass through, the heat escapes into the roof structure where the heat is held in by the insulation.  If the perimeter of the home has far less insulation due to vertical space, that means the heat or cool when it’s hot, from inside the home is colliding with exterior heat / cold of the outside. We geek out more on insulation in further modules of the course, along with dew point and condensation issues. Ultimately, this roof system allows warm and cold air to engage each other easily and quickly along the edges, creating possible condensation in the attic spaces, and, hence, unseen / unknown mold growth.