Efficient flat roof renovation: Securely fixing insulation boards with PU foam
Fixing insulation boards on flat roofs with PU foam is an application reserved for professional businesses and should not be performed by amateurs. At some point, the time comes. Repairs to the flat roof become more frequent and increasingly complex. Then a complete roof renovation is due. Few people know that insulation boards can also be efficiently fixed to flat roofs using PU foam.
Time savings with PU foam
Using PU foam enables a consistent and predictable installation time, regardless of the substrate material. Each insulation board can be securely fixed in just a few minutes with PU foam. In addition, the foam compensates for unevenness in the substrate of up to one centimetre, ensuring a stable fix.
The butt joints of the insulation boards can also be cleanly and permanently bonded with PU foam. After approximately 45 minutes, the foam is firm enough to proceed with further work on the surface. However, the exact drying time depends on ambient conditions such as temperature and humidity. Details can be found in the respective product data sheets. Please note that these tasks should only be performed by professional companies.
Protecting the roof structure
Another advantage of bonding with PU foam is the protection of the underlying vapour barrier and sealing layer. These layers remain intact due to the adhesive bonding.
Suitable substrates for PU foam
PU foam adheres to a wide range of common materials, including concrete, wood-based panels, fibre cement, and mineral-coated bitumen membranes. However, it cannot be used on smooth surfaces such as polyethylene or silicone-coated areas or on oiled or dirty substrates. Therefore, thorough cleaning of the substrate, free from release agents and residues, is essential.
Wind resistance and safety
In particularly wind-prone edge and corner areas of a roof, the question arises whether adhesive bonding alone is sufficient. Special PU foams tailored to the respective wind zone and building height are used here. Detailed dosing instructions can be found in the product data sheets.
Those planning a flat roof renovation must comply with the energy requirements of the Building Energy Act (GEG), particularly if the renovated area exceeds 10% of the total wall area. However, this obligation does not apply if the roof covering was constructed after 31 December 1983 according to the energy-saving regulations of that time.
