Kinds of Insulation Materials for Flat Roofs

Since flat roofs have a slight slope, they need reliable and robust insulation. Therefore, as you install your flat roof, it is important to think about the right insulation. By insulating your roof, you improve the longevity of your roofing system. Another reason for protecting your roof is to keep enough heat inside when it’s cold and outside when it’s hot.

However, finding the right insulation materials for your flat roof can be challenging because roof insulation has been continually changing and adapting. Nevertheless, several roof insulation materials are known to offer the best insulation for flat roofs.

Expanded Polystyrene (EPS) Insulation

The Expanded Polystyrene insulation materials feature closed-cell structures in which holes circle the beads. They are also hydrophobic. This means that this insulation material can easily absorb large amounts of water. Compared to XPS insulation, the EPS insulation has lower thermos resistance.

Since EPS insulation is lightweight and stiff, it can be cut for accurate installation between the various sizes of roofing binds. Plus, it can be used alongside other roof insulation materials to deliver the desired R-value and tapers. You can even use this material as an added layer of insulation for old roofs.

Compared to other roof insulation materials, EPS is more cost-effective and offers a steady R-value over the roof’s lifecycle. Furthermore, this type of roof insulation is versatile and compatible with various roofing systems, including concrete, fully adhered, and mechanically fastened roofs. EPS roof insulation is also known to reduce heating and cooling costs by about 30 percent annually.

Extruded Polystyrene (XPS) Insulation

Extruded Polystyrene insulation is made from foam plastic, and therefore it is ideal for roofs that require high water and thermal resistance to keep excess moisture away. When this material is fully immersed in water, its water absorption rate is only 0.3 percent. Its closed-cell structure makes it resistant to moisture. It is also the ideal choice for you if you want high compressive strength.

XPS insulation can be used under various types of single-ply roofing membranes. However, it has to be covered by boards to protect it against excess solar heat. It is also not ideal for black roofs because of its heat absorption capabilities.

Polyiso Insulation

Polyiso roof insulation features a thick closed-cell foam that is normally placed under the roofing membrane. This board can be either one inch or four inches. Plus, it can be either flat or elongated. Polyiso insulation is highly efficient, especially in warm weather. But it’s not practical in extremely cold weather.

Talk to a professional roofing contractor for advice on the best insulation material for your flat roof.