A composite roof is the most expensive and generally, the most common type of replacement for an old asbestos roof.
It is manufactured as a twin skin panel, bonded to a layer of high density foam insulation that keeps the building cool in summer and reduces heat loss through the roof in the winter months.
Prices vary depending on the manufacturer chosen. The important thing to remember is that the new roof must comply with current building regulations, which determine the amount of insulation (and therefore thickness) of the sheet required.
A key consideration when opting for a composite roof, is the issue of maintenance following installation.
Whilst most will be problem-free, sometimes the later addition of flues or vents could mean that you have to replace panels, which can be quite a complicated and expensive affair, given how the sheets are locked and fastened together.
A built-up roof is similar to the composite roof, in that it includes an insulation layer.
However, the insulation is generally in the form of a quilt that sits between the inner and other metal sheets. The roof will be higher than a composite, because quilts are thicker than their foam equivalent.
Once the roof is removed, the internal liner is fixed to the purlins and a spacer bar installed to hold the insulation in place and allow the external sheet to be fixed into position.
Ideally, the spacer bars will incorporate plastic pads to act as thermal breaks and prevent thermal bridging which can create cold spots and condensation within the roof.
It is important to determine that the frame of the building can support the additional weight that can be involved with this type of roof.
What Is The Weight Of An Asbestos Roof Sheet?
This is one of the most common questions we are asked by callers and visitors to this web site, but because there are different types and sizes of asbestos cement roof sheet, there’s no standard answer.
That said, a pretty good rule of thumb would be to allow 15kg per sq metre for a typical sheet in the UK.
It is an important consideration because when you’re replacing an asbestos roof, the old one needs to be disposed of by a licensed asbestos disposal company and they charge by the kilogram!
What To Do Next
Whether you are unsure what to do with your asbestos roof, or if you’ve decided that a new roof is your preferred option, it is best that you receive impartial advice.
To speak with one of our qualified and experienced building surveyors, please call 0121 711 7110.
We’ll be happy to discuss your options without any obligation to use our services.
Commercial Property Surveys Ltd
Unit 3 Radway Industrial Estate
Tel: 0121 711 7110
Unit 8 Radway Industrial Estate
Tel: 0121 709 5352