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. Read the numbers together with function, lifespan, detailing and the specific building element.
- Carbon Footprint (GWP)
- 1.2 kg CO₂-eq/kg
- Source: estimatee based on the EN 15804 average
- Density
- 2–5 kg/m²
- Expected Lifespan
- 20–50 years (depending on quality)
How to use this assessment
The assessment of roofing felt is a first decision basis. Carbon numbers, density and lifespan give a point of comparison, but the material must always be read together with structure, moisture, fire requirements, detailing, maintenance and the condition of the existing building. A good material choice is therefore both a data question and an architectural judgement. The useful next step is to clarify which questions should be examined further before the material is specified in a project.
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
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.
Related Materials
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