Roofing

Roofing Felt.

Roofing felt is a moderate CO₂ product. Choose the thickest and most durable variant — it is cheaper per year of service life and reduces the overall climate impact over the roof structure's lifespan.

Key Figures

Carbon Footprint (GWP): 1.2 kg CO₂-eq/kg
Density: 2–5 kg/m²
Expected Lifespan: 20–50 år (afhængig af kvalitet)

What is roofing felt?

Roofing felt is bitumen-based roofing — one of the most widely used materials for flat roofs in Denmark. It is made from polyester felt impregnated with modified bitumen. It acts as vapour barrier, windproof, and waterproof. Lifespan of 20–30 years for conventional products, up to 40–50 years for the best qualities.

Carbon Footprint Compared

Natural slate 0.058 kg CO₂/kg

Concrete roof tile 0.25 kg CO₂/kg

Roofing felt ← this material 1.2 kg CO₂/kg

Roofing membrane 2.5 kg CO₂/kg

Negative carbon footprint (green) indicates carbon storage. Data based on EPD averages from ECO Platform and estimates per EN 15804.

Typical Applications

check_circle Flat and slightly pitched roofs
check_circle Vapour barrier under roof insulation
check_circle Foundation damp-proofing
check_circle Roof terraces

In Renovation

Replacing roofing felt is one of the most common renovation tasks on flat roofs. It is a good opportunity to add roof insulation and upgrade to more durable roofing.

Questions about roofing felt

What is the lifespan of roofing felt?

Conventional roofing felt lasts 20–30 years. SBS-modified and glass fibre reinforced felt can last 40–50 years. Lifespan depends on UV exposure, temperature differential, and water stagnation.

When should roofing felt be replaced?

Signs of spent roofing felt: cracks and blisters in the surface, visible polyester felt, water pooling that doesn't evaporate, and leaks in the building. A professional roof inspection can clarify the condition.

Can roofing felt be recycled?

Old roofing felt can be partially recycled in road asphalt. It requires delivery to a specialist reception facility. Many roofing contractors offer disposal as part of a replacement job.

Are there alternatives to roofing felt?

Yes — roof membrane (TPO/EPDM) is an alternative with longer lifespan and lower CO₂ over long lifetime. Green roof (sedum/extensive vegetation) is another alternative that adds biodiversity.

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