Inverted Roof Insulation

Inverted roof insulation consists of rugged panels installed on top of waterproofing on inverted roofs. These boards withstand foot traffic and weather, repel water, and protect the waterproof membrane underneath, while also providing thermal insulation to the structure below.

What Is An Inverted Roof Insulation Board?

Inverted roof insulation boards are insulation panels that go above the waterproof layer in a roof. They are specifically built to work with inverted roofs.

These roofs are constructed with the waterproofing layer positioned beneath the insulation. In typical flat roofs, the waterproofing layer is laid above the insulation.

Inverted flat roof insulation panels are manufactured using hardy materials, usually water-resistant XPS, since they will be protecting the waterproofing membrane and supporting foot traffic or landscaping layers.

Most boards also have a specified compressive strength – usually between 300–500 kPa – to ensure they can safely handle people walking on the roof.

What Is Inverted Roof Insulation Used For?

Inverted insulation is ideal for walkable or usable roof spaces. It can be covered with gravel, decking, slabs, soil, or light paving and is common in spots like:

• Roof balconies and terraces
• Green roofs complete with soil and plants
• Roofs finished with gravel or ballast
• Walkable flat roofs on commercial buildings
• Service roofs where maintenance crews walk around

XPS boards are suitable for foot traffic and light landscaping loads in these spaces. Consult a structural engineer for higher load requirements.

FAQ

Where to buy inverted roof insulation?

You can buy inverted roof insulation online directly from Insulation Wholesale. We stock high-strength XPS boards, Kingspan inverted roof insulation, and inverted warm roof insulation in a range of thicknesses suitable for inverted roofs. Enjoy a quick order placement process, low prices and unmatched pallet deals. Everything is held in UK stock for fast delivery to your site.

What is inverted roof insulation?

Inverted flat roof insulation usually comes in the form of tough XPS boards. It is fitted above the waterproofing layer in inverted flat roofs to protect it from foot traffic and the elements while insulating the roof below. The insulation takes on the weather and foot traffic, keeping the waterproofing layer safe and dry.

How to fit inverted roof insulation

Lay the boards neatly on top of the waterproofing layer, placing them in a tight, staggered pattern so there are no gaps through which heat can escape or water can sneak through.

Add a geotextile layer over the top, and follow with your chosen finish – whether gravel, slabs, decking, or soil.

The weight of that top layer holds everything in place without the need for fixings. However, steep or high-wind areas may require additional fixings.