The roof is a prime target for heat to both enter and exit a home. As the summer sun bakes the roof cladding, heat can move through and into your home. During winter, indoor warmth rises to escape through the ceiling and roof. Roof insulation will help block this pathway and help you keep heating and cooling costs to a minimum. Following are several helpful pointers to consider when picking insulation for your house.

Insulation Types

When selecting roof insulation, you'll come across both bulk and reflective varieties. Bulk insulation like wool bats, for example, is filled with air pockets that hinder heat transfer through the material, blocking it from flowing through to the other side. This insulation goes on top of the ceiling plaster. 

Reflective insulation, which is typically laminated foil, works differently. Rather than hindering the flow of heat, reflective insulation bounces radiant heat away. The reflective blanket goes underneath the roof cladding to block solar radiation, whether the cladding is made of tiles, metal, or other material. It needs a little space between the shiny upward-facing side of the foil and the roof cladding to work effectively.

Some composite materials combine both insulation types. For example, wool bats might have foil on one side, and thus they work in two ways.


All insulation is designated an R-value that specifies how much resistance it provides to heat transfer. Insulation with higher R-values blocks more heat than those with lower R-values. Your contractor can advise on what rating your insulation should have, which largely hinges on the local climate. If you live in a region with harsh, hot or cold weather rather than in a temperate climate, you may require insulation with higher R-values to keep your home comfortable. 

Making things more complicated, reflective insulation has a down R-value and an up R-value. The down value refers to the foil's ability to block down-flowing heat from the sun, which is why it may be referred to as the summer R-value. The up R-value (or winter rating) refers to the insulation's capacity to stop the heat that flows upwards. With bulk insulation, the R-value is the same regardless of the direction of the heat flow. The rating will often vary depending on its thickness, as thicker material tends to block heat more effectively.

Roof insulation will make your home much more energy-efficient, allowing you to turn down both heating and cooling while maintaining a comfortable space.