Everything you need to know about roofing waste

Are you renewing your roof or demolishing a shed and have a lot of roofing waste to get rid of? This doesn't belong in a construction and demolition waste skip – you need to order a separate roofing waste skip for it. Why? It all comes down to how roofing waste is recycled. This waste is processed differently from mixed construction waste.

Roofing waste consists of roofing gravel, bituminous waste (also known as roofing felt) and tar-containing material. Other construction waste, such as wood or stone with roofing felt stuck to it or other insulation material attached, also counts as roofing waste. Using tar-containing material in roofing has been banned since 1983, but because many houses were built before then, there's a good chance you'll come across tar-containing material when renovating or removing your roof. Roofs built after the ban often used rolls of roofing made from bitumen.

Bitumen is a popular type of roofing used mainly on flat roofs. It's a liquid extracted from crude oil, to which synthetic fibres are sometimes added for elasticity. It's the most widely used material for flat roofs, but it can also be used on gently pitched roofs. The advantages of bitumen are that it works well with insulation, is waterproof and is fairly easy to repair. Although most roofs are currently made of bitumen, the material is facing growing competition from EPDM, a synthetic form of rubber, and PVC, which is made entirely of plastic.

Roofing used to consist mainly of tar felt, tar mastic and tar roof coating, made from crude tar. Before use, the crude tar is distilled into coal tar pitch. This substance often contains a high concentration of polycyclic aromatic hydrocarbons (PAHs). These substances are formed by the incomplete combustion of carbon-containing materials, such as wood. You can recognise tar-containing material by the fact that it's often stuck to remnants of insulation, is tougher and has a shine to it. Tar-containing material also has a pungent, often 'sweet' smell. Because these substances can be harmful to your health and in some cases even carcinogenic, they have not been allowed since the 1980s. When you're going to carry out demolition work, it's wise to use a PAH marker. A liquid is sprayed onto a sample to check whether PAHs are present and to what extent, so that you aren't exposed to more than the permitted 300 nanogram/m3.

Roofing waste can't simply go into a mixed skip for construction and demolition waste. Roofing gravel, roofing felt (bitumen) and material with tar or bitumen stuck to it must be collected separately in a roofing waste skip. Up to 10% of the total contents of the skip may be wood and other demolition waste. Asbestos, asbestos-containing or asbestos-like material must never go in the waste skip. Plastic, corrugated sheets, metal, rubble and glass are also not allowed in the roofing waste skip. Not sure what can go where? Feel free to contact us, or download our handy overview.

Around 100,000 tonnes of roofing waste are produced in the Netherlands every year. After collection, the roofing waste is first separated and sorted by type. Roofing gravel, for example, can be reused straight away as roofing gravel after washing and sieving. Tar-containing waste (contaminated bituminous waste) cannot be reused because of the harmful substances it contains. All recyclable materials, such as wood and stone, are filtered out. The contaminated waste is incinerated or used as auxiliary fuel in thermal incineration plants. Bitumen waste that doesn't contain tar is shredded. The resulting bitumen granulate can be used, among other things, as a sustainable raw material for producing asphalt. When bitumen is old, its quality may have deteriorated. For example, it may have developed small cracks and been damaged by long exposure to UV radiation. During processing, this bitumen can be 'rejuvenated'. Its viscosity is lowered, after which it can be processed again as a new raw material.