Roofing materials, and in particular corrugated sheets, constituted the majority of asbestos-cement products sold until their ban. Other asbestos-cement products have been widely used in construction: cladding and cladding products, partitioning or interior lining products, pipes, ducts, composite elements assembled by gluing. For the Asbestos Siding this is important.
Most of these materials are fixed to support by hooks, lag screws, bolts, staples or screws; they are sometimes sealed together (pipes) or to masonry supports. These materials are made up of a homogeneous mixture of cement and fibers and, although strongly linked, are likely to release asbestos fibers either:
- by brutal mechanical degradation (breakage, drilling),
- by high-speed cutting (cutting) machining operation,
- by falling and scattering of dry plants (lichens, mosses), which have colonized and degraded the surfaces of the plates. Unless technical impossibility, the removal of asbestos-cement materials must be done by deconstruction and must be accompanied by rules aimed at protecting operators and the environment against the risk linked to asbestos fibers.
The company must determine the dust expected at workstations based on its feedback from measurements made on construction sites carried out under similar conditions. The preventive measures envisaged will follow from this and will be validated by new dust control. Depending on the age of the products, the dust values may be very different for the same operation. Wet cutting does not allow a significant reduction in exposure, any cutting should be avoided.
Removal of asbestos-cement roofing sheets
In the case of removing roofs, it should be remembered that any work at height is inherently dangerous. This risk is aggravated when there are materials recognized as not very resistant, in particular asbestos-cement roofing sheets. Except in the event of technical impossibility to justify, the depositing of this type of materials must be carried out as a priority from below, using a work station adapted against the risks of falls from height (decking or scissor lift for example).
In the event of justified technical impossibility (battles, etc.), the risk assessment and the prevention measures which result from it, must imperatively integrate the respect of the rules of access, circulation on the roofs in fragile materials and the installation of collective protection on the underside and perimeter ( example: safety net, railing, foot scaffolding) or any protection of equivalent effectiveness. A seal is put in place so as to:
- prevent pollution of materials on the underside of the roof (insulation materials, framework, false ceiling, etc.),
- maintain human activity or occupation of the building.
Procedure and preventive measures to be implemented The preventive measures to be implemented will be adapted to each case, after the risk analysis phase:
- the general configuration of the place,
- the nature of the building,
- the presence of technical or industrial activity near the withdrawal area,
- the occupation of other premises in the building,
- the surface to be treated,
- any other parameter that could affect the health of operators or other occupants of the premises, during and after the site. It is essential to validate in the field the adequacy of the technical solution chosen. It is necessary to isolate the occupied area from the work area.
Depending on the configuration of the premises, a horizontal or vertical separation must be implemented, whether the intervention takes place from inside or from outside the building.