Every contractor knows that careful choice of insulation and expert installation can improve the air conditioning efficiency of any building. Roof insulation reduces temperature fluctuations inside the house. If you insulate your roof correctly, your air conditioning bills could be reduced by as much as 20%. 

However, many of us find the sheer variety of insulation overwhelming. To help you overcome this hurdle, we’ve compiled a list of the factors that matter when selecting insulation material for the roof.

Choosing Roof Insulation: 3 Factors to Consider

Does it matter whether you live near the seashore? Or that you live in a flat-roofed house? Is your budget big enough? Let’s see how these and other things will influence your choice of roofing insulation products.

1. Climate

Cold climate insulation demands differ from those of warm climates. In warm and humid climes, there’s a high amount of moisture and heat in the air clamouring to get inside the house. Roofing insulation for houses in such areas should, therefore, have excellent:

• Thermal efficiency
• Water resistance
• Durability

So, you’re looking at materials with a high R-value. Denser materials are preferable because they block vapour penetration better. 

Houses in cold climates benefit more from cold roof insulation, where the solution sits below the roof frame and between the rafters. Cold roofs use ventilation to control air movement, which, in turn, controls the temperature and keeps indoor humidity low. If you live in a coastal area, your roof’s insulation should control the humidity so you don’t end up with a mould problem.

2. Type of Roof

The two common types of roofs are flat and pitched roofs, and each should be insulated differently.

For flat roofs:

1. Ensure the highest level of moisture control. Warm roofs are the best choice for this since their design discourages the formation of condensation. 
2. If you install a cold roof, ensure there’s sufficient ventilation and a vapour barrier to control moisture build-up.

For pitched roofs:

1. You can choose between the cold loft system, where the insulation goes over the ceiling, and the warm loft system, where the insulation goes below the rafters.
2. Avoid pushing insulation into the eaves, as it will block airflow.

3. Types of Roof Insulation

Different materials are used to insulate the roof, but they all have numerous common characteristics:

• They are dense
• They offer good humidity and temperature control
• They are good thermal barriers
• They are rigid enough to withstand the weight of human traffic on the roof and attic, snow, heavy rain and ballast.

Pick or combine:

Spray foam

Spray foam is a good choice for roofs in warm environments. It’s an excellent heat and air barrier, and the correct application prevents air leaks and stops the transmission of heat.

Foam Board

Are you worried about extreme wetness? Rigid foam boards can insulate the roof against water. Thicker foam boards offer a much higher level of insulation against moisture, but there are thinner foam boards that work great for areas with low moisture content.

Reflective/Foil Insulation

Remodelling the house for the summer? Consider adding reflective insulation. It works by reflecting radiant energy away from the house. In the hot summer weather, the aluminium foil blocks the heat from getting inside the house, and in the winter, it retains heat within the house so that it doesn’t get cold. 

Blanket Insulation

Blanket insulation can help increase the amount of insulation in your roof. This is a flexible kind of insulation designed in the shape of rolls and batts. You place it between beams and joists and tuck it into any open space between the roof structure, like where the rafters and joists meet. Pull the roll or batt to expand the material to capacity and ensure it’s packed tight and fills the spaces.

Conclusion

When you know what insulation materials and techniques to use for your roof type and climate, it becomes easy to customise a solution that keeps your roof adequately insulated. With good insulation, you’ll notice that indoor temperatures stay within a comfortable range, and your energy consumption stabilises due to improved efficiency.

FAQs

• How do I know if my roof needs insulation?

If the temperatures inside the house keep changing, or you can feel drafts sweep through the house, if there’s moulding in the roof or attic or if there are ice dams on the roof, your roofing needs insulation. Higher energy bills than usual are another sign that your insulation needs upgrading.

• How often should I inspect or replace roof insulation?

Inspect your roof insulation every few months or whenever you notice insulation-related problems such as dampness or frequent temperature changes. You should also inspect the installation after severe weather, as unusual weather conditions can damage the insulation.

• Will adding insulation make my attic hotter in summer?

Properly installed insulation minimises heat transmission and regulates air circulation, ensuring heat does not build up inside the house during summer.