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.
Overlaying asbestos cement roofs.
The overcladding of an asbestos roof is a cost effective roof refurbishment process that minimises the disruption at site.
With roofs of asbestos cement.
The cement sheet is a building material made from asbestos fibres.
However many asbestos roofs are built with concrete portals meaning the roof is supported by a small number of concrete arches.
Corrugated roofing sheets made of asbestos is common in uk homes constructed prior to 2000.
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.
The benefits of asbestos overcladding.
The overcladding process also reduces the costly disposal of the existing asbestos roof sheeting that must be sent to licensed landfill.
But because asbestos cement roofing is easily damaged by a heavy footed worker unfamiliar with the materials involved asbestos cement roofs have to be repaired and maintained with the same care.
In the production of cement sheet thin rigid cement is reinforced using asbestos to form cement sheets.
First you must fit the spacer bars.
Historians from the portland cement association report that the use of asbestos fibers in concrete mixes reached its peak in the early 1900s.
Typical life of cement asbestos roofing.
Further the cement sheet contains asbestos fibres and cement.
Typical roof wear or failure patterns are either failure of the shingle fasteners or broken and falling shingles.
The list of products made from these composites included.
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.
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.
Many of these built in the 1950 s and 60 s and are now beginning to leak.
It is mainly important as a roofing material.
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.
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.
Since the cement sheets were fireproof manufacturers initially considered them safer as compared to wood.
The use of asbestos cement roof shingles was growing at a steady rate in the united states.
Roof cladding requires bolts to be drilled into the asbestos roof.
Adding asbestos to the cement made the corrugated roofing sheets more heat resistant weatherproof and durable.
