Overlaying Asbestos Cement Roofs

Typical life of cement asbestos roofing.

Overlaying asbestos cement 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. The cement sheet is a building material made from asbestos fibres. The overcladding of an asbestos roof is a cost effective roof refurbishment process that minimises the disruption at site. In the early 1920s american roofing material manufacturers johns mansville carey eternit and century were all offering at least one asbestos cement roofing shingle to their customers.

Since the cement sheets were fireproof manufacturers initially considered them safer as compared to wood. It is mainly important as a roofing material. Roof cladding requires bolts to be drilled into the asbestos roof. With roofs of asbestos cement.

However many asbestos roofs are built with concrete portals meaning the roof is supported by a small number of concrete arches. Typical roof wear or failure patterns are either failure of the shingle fasteners or broken and falling shingles. Further the cement sheet contains asbestos fibres and cement. When overcladding an asbestos cement roof it will also be necessary in most cases to include a layer of insulation to meet current day building regulations.

We consider asbestos cement roof shingles a durable and fire resistant roof and an asset to the building provided that the roof is in good condition. At that time the minerals were the most common added ingredients in a group of construction materials known as fiber cement composites. This means the new roof cannot get enough stability on top of the old one a common risk of over cladding. One idea is to overlay the roof with insulation and steel sheets.

Historians from the portland cement association report that the use of asbestos fibers in concrete mixes reached its peak in the early 1900s. The overcladding process also reduces the costly disposal of the existing asbestos roof sheeting that must be sent to licensed landfill. The typical life expectancy of an cement asbestos shingle roof was given as 30 years but we have seen these roofs that were now 50 years old in good condition. Adding asbestos to the cement made the corrugated roofing sheets more heat resistant weatherproof and durable.

Then if you wish you can add insulation. The list of products made from these composites included. In the production of cement sheet thin rigid cement is reinforced using asbestos to form cement sheets. Corrugated roofing sheets made of asbestos is common in uk homes constructed prior to 2000.

Many of these built in the 1950 s and 60 s and are now beginning to leak. 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. The use of asbestos cement roof shingles was growing at a steady rate in the united states.