Laying New Roof Over Asbestos

Also heavily corrugated or textured vertical seam products might do well.

Laying new roof over asbestos.

This is a cost effective approach with an aesthetically pleasing and watertight result. The first stage is to fix a framework to hold the metal sheets in place directly to the purlins underneath the asbestos cement roof sheets. However the ability to install over old asbestos roofing requires that several factors be met and it sounds like your roof has not done this. Some people attempt to solve the problem of deteriorating asbestos siding by installing vinyl siding over top of it.

This practice is not recommended for a number of reasons. If the job is done correctly with the new layer of shingles laid flat over the existing shingles the old roof cushions the new one and serves as a secondary barrier should wind or water ever break through the new shingles. This is especially true when it comes to asbestos cement roof coverings. First the siding installation process itself nailing into the existing boards or tiles is enough to disturb the existing material and create a dangerous condition.

Roof cladding requires bolts to be drilled into the asbestos roof. The problem with coating old asbestos sheets is that the surface is likely to be a bit soft and friable due to age and so the coating does not stick for a long time its generally a temporary repair for a couple of years or so it is possible to replace just your sheets and lap the new sheets to the adjacent roofs. The insulation is then installed into the framework often an ashgrid system so named after the original manufacturer ash lacy construction and the metal weather sheet is the fixed to a bar. Asbestos over cladding in some cases asbestos containing materials need not be removed and can instead be over clad.

Once again thickness can be a consideration as is the amount of maintenance that natural stone requires such as sealing and cleaning with stone cleaners. If you are using an epoxy based thin set mortar and are willing to seal the tiles after installation natural stone tiles such as marble or granite can also be used over asbestos. My guess is that the asbestos is broken up enough at this point that if the metal panels are removed the asbestos will need to be removed as well. Next most of the modular shingle shake tile style products can be installed over asbestos.

However many asbestos roofs are built with concrete portals meaning the roof is supported by a small number of concrete arches. All shingle manufacturers honor the warranty whether their products are used for a reroof or a new roof.