On flat roofs, the position of the insulation layer significantly affects the performance and durability of the roof system. There are three main types based on the insulation placement: the warm roof, the cold roof, and the inverted roof.
Warm Roof: The Standard Solution
In a warm roof system, the insulation is placed on top of the structural roof deck, with the waterproofing layer above it. This configuration protects both the insulation and the roof structure from temperature fluctuations and moisture, helping to extend the lifespan of the roof and reduce the risk of internal condensation.
Advantages:
- Better protection of the structural deck against thermal stress
- Lower risk of internal condensation
- More energy-efficient
Cold Roof: Less Recommended
In a cold roof setup, the insulation is placed below or between the structural elements (e.g., between rafters), while the waterproofing membrane is applied directly on top of the roof deck. This design makes the structure more exposed to temperature changes and increases the risk of condensation, which can lead to cracks in the waterproofing or timber decay.
Disadvantages:
- Higher risk of condensation
- Roof structure remains subject to temperature effects
- Lower energy efficiency
Inverted Roof: For Specific Applications
In an inverted roof system, the insulation is installed above the waterproofing membrane, protected by a ballast layer such as gravel or paving slabs. This type is ideal for roof terraces, green roofs, or renovation projects where the existing waterproofing remains in place. It’s essential to use moisture-resistant, pressure-resistant insulation, and to ensure the roof structure can bear the additional load.
Applications:
- Renovation of flat roofs without removing the existing membrane
- Green roofs or terraces with increased loads
- Situations where mechanical protection of the waterproofing is required
A more detailed article can be found on our website eu.iko.com: “Do you know the difference between a warm, cold and inverted flat roof?”