AsbestosRoofing.co.uk

With age, the surface of an asbestos roof is likely to be discoloured and, unless it’s been regularly maintained, also covered in moss, algae and lichen.

Typical asbestos cement roof with moss and lichen growth

Although some people are of the opinion that this aged look adds character, lichen in partcular, can cause severe damage if it grows through to the underside of the roof, when asbestos contamination to the space below can occur.

For this reason, it is recommended that roofs affected by moss and lichen are cleaned off and sealed with a proprietary sealer.

There are several methods of cleaning an asbestos roof and in all cases, the correct health and safety procedures have to be followed, not only in terms of the asbestos, but also with regard to working at height.

Dry Scraping
Often carried with a wire brush, this method should be avoided, as it can result in high fibre release.

High Pressure Water Jetting

This used to be a common method for cleaning asbestos roofs but it has several problems including:

•  breaking down the cement matrix, causing fibre release
• asbestos fibres cannot absorb water
• it creates a large amount of virtually unmanageable slurry, containing unbound asbestos fibres, leading to contamination of surrounding areas – subsequent cleanup can be very expensive!

Remote Cleaning

 There are remote controlled cleaning units available with enclosed rotary cleaning heads that use high pressure jets and brushes to clean asbestos cement roofing sheets. The operator is remote from the cleaning area, but provision still needs to be made to collect the resultant slurry.

This work is usually carried out by specialist contractors who have not only the correct equipment, but also the necessary filtration plant necessary to collect the slurry and prevent asbestos fibres from entering the drainage system of the building.

We are able to recommend contractors for asbestos roof cleaning work on industrial and commercial properties.

Once cleaned in this way, an asbestos cement roof should be re-sealed, with particular attention paid to fixings which will often be rusty and failing.

Surface Biocides

There is a wide range of approved pesticides available to kill plant material growing on asbestos cement surfaces and these will generally cause no damage to asbestos cement if used in the recommended concentrations in non-frosty conditions.

They should be applied as a low pressure spray or a wash.

Once the moss and algae is dead, they can be safely removed with water using gentle brushing.

Dead lichen crusts are more difficult to remove and should be left in place. Roots of dead mosses may hold loosened asbestos fibres.

Asbestos Roof Cleaning Costs

The cost of cleaning an asbestos roof is never going to be inexpensive, as it must be carried out by competent roofers using specialist materials and safety equipment.

Often, it’s the safety equipment that increases the cost – things like scaffolding, safety netting and cherry pickers need to be factored in.

For this reason, it’s often wise to consider cleaning an asbestos roof when you’re also looking at re-coating or overcladding, as the safety equipment will be required anyway.

Costs of cleaning vary from company to company, but in our experience, somewhere in the region of £15-£20 per square metre should be allowed.

As independent and unbiased asbestos and building surveyors, we can prepare a full specification of works and tender the job on your behalf.

Our fees for running such a project are 10% of the contract value, but this will repay itself with the other savings that we can make on your behalf.

Alternatively, we may be able to provide you with details of specialist asbestos roofing contractors who will be pleased to provide direct quotations to you.

Please note that we cannot assist domestic customers. 

For advice on cleaning industrial or commercial asbestos roofs anywhere in the UK,
please call David Carter on 01564 824554 or 07800 790427.