Flat roof insulation

Flat Roof Insulation: Over or Under the Roofing Material

We typically apply the insulation on the outside. There are two options available: over or under the roofing material. Both options are feasible.

• Under the roofing material:
  The roofing material is removed, and insulation boards are put in place. Waterproof material is then applied on top, followed by a new layer of roofing material. Sometimes, the roof edge needs to be raised, especially if there is less than 10 cm of roof edge remaining. Without this adjustment, there is a risk of rainwater leaking over the roof edge during heavy winds.

• Over the roofing material:
  A more economical approach is to install roof insulation boards directly on top of the roofing material, without removing it. However, the insulation level may be slightly lower with this method. We secure the insulation by adding a layer of tiles or gravel on top. The roofing material must be in good condition for this method to work effectively.

Adding insulation: Roof-on-roof insulation with a double insulation layer

Another option is to double insulate the flat roof. We add a new layer of insulation material on top of any existing insulation, a method also known as roof-on-roof insulation. The existing layer does not need to be removed; instead, we clean it before applying the new insulation layer directly on top. We then cover it with a protective layer. Usually, raising the roof edge is unnecessary, as we create a gutter track. We apply PIR insulation boards up to about 10 cm from the roof edge, a margin wide enough to maintain proper drainage without the need for adjustments to fascia boards, for example. However, we can also install a wider roof trim if necessary.

Let us perform an insulation check, and we will provide you with a customized quote without obligation.

Insulation material for a flat roof

At Nu Isoleren, we use PIR insulation boards for flat roof insulation. These are thin, lightweight boards made of hard foam with a closed-cell structure, ensuring optimal insulation performance while being resistant to moisture. The boards are also durable enough to walk on without issues. If you need to access the roof regularly or plan to use it as a rooftop terrace, PIR insulation boards are an ideal choice.

Benefit from flat roof insulation

Insulating a flat roof can lead to significant benefits. Up to 30% of the heat inside a building can escape through an uninsulated roof, which is wasteful. By insulating your flat roof, you can save hundreds of euros on your annual energy bills. Additionally, your home will feel more comfortable, and you’ll reduce your carbon footprint.

Think of insulated roofing as a cozy blanket for your home. It keeps the cold out in winter and the coolness in during summer.

Flat roof insulation for businesses and offices

Since January 1, 2023, office buildings in the Netherlands are required to have an energy label of C or higher. However, many buildings still do not meet this standard, which can lead to significant penalties, or even closure of the office. Many office buildings have flat roofs, which we can easily insulate for you. This not only results in cost savings but can also improve your energy label. Inquire about the possibilities!

Financial assistance

The government places great importance on reducing CO2 emissions. Therefore, there are various schemes encouraging flat roof insulation. When obtaining a mortgage, you can borrow extra for energy-saving measures, up to 6% of the value of your home, with a maximum of € 9,000. You can also often get a favorable loan for energy-saving measures. Furthermore, roof insulation qualifies for ISDE subsidy, which supports energy-saving measures.

Want to learn more about flat roof insulation?

For more information and a non-binding quote, please contact one of our advisors.