Older asbestos roofs are often covered in moss that retains water during rainfall and encourages lichen growth that can, if left, permeate the roof causing failure of the cement base and ultimately, asbestos fibre release into the building.
Asbestos roofs can be cleaned and resealed in certain circumstances and as part of a planned maintenance programme, this is recommended as it will prolong the life of the roof.
Attention should also be paid to roof lights, rainwater goods and fixings, as this is where many leakage problems originate.
Cleaning an asbestos roof on a commercial property is a specialist job and in addition to the cost of cleaning , there will also be scaffolding and other health and safety considerations, depending on the cleaning method employed.
Costs do vary and as qualified asbestos surveyors and chartered building surveyors, we offer a feasibility study to tenants and landlords of commercial property throughout England and Wales, since cleaning and sealing is not always a viable option.
Asbestos Roof Cleaning
Presently, there are only two HSE approved methods for asbestos roof cleaning. These are:
1. Closed Box Method – this is essentially an industrial sized patio cleaner that is placed on the roof ridge and then slowly run down the roof slope, cleaning the roof sheets as it goes.
This method produces excellent results in a relatively short time scale. Asbestos fibre release and disbursement is minimised due to the amount of water used.
However, it does have some disadvantages, especially in terms of the volume of water used, which can often flood the gutters and disburse waste material down the sides and sometimes, the inside of the building.
All waste water must be filtered to prevent asbestos fibres entering the water system.
2. Scraping – Asbestos cement should never be aggressively scraped, as fibres can be released and roof sheets can be damaged as a consequence.
When using this method, the roof must be kept wet at all times to reduce fibre release and all waste must be collected and disposed of as contaminated waste.
Unfortunately, cleaning a roof by scraping is only likely to remove heavy moss. The roof will generally not be suitably clean to accept a coating afterwards and will need further cleaning using chemicals and brushes or a more thorough closed box clean.
Non-HSE Approved Asbestos Roof Cleaning Method
Just because a method isn’t HSE approved, it doesn’t necessarily mean that it can’t be used – though care must be taken to ensure that risks of falls and asbestos contamination are correctly identified and managed.
As one of the UK’s leading experts on asbestos roof issues, we are currently investigating and studying the use of steam for cleaning asbestos roofs. This has many advantages over the closed box pressure wash method, but special precautions need to be in place before the cleaning project starts.
Therefore, a two-stage cleaning regime should be employed which first involves manually scraping the previously wetted roof surface to remove larger clumps of moss and other vegetation that might be present,
Steam cleaning uses a lance to deliver the steam and because of this, extra care needs to be taken to ensure that asbestos fibres are not released into the atmosphere. This can be controlled with the use of specially adapted filters designed to catch flying debris that could contain asbestos.
Although the water run-off is vastly reduced when steam is used for asbestos roof cleaning, this water still needs to be filtered to reduce the risk of asbestos fibres being carried into the drainage system.
For more information about the various methods, please see this dedicated asbestos roof cleaning web site.
How The Roof Feasibility Study Works:
We will attend site and inspect the roof externally using whatever method of access is most appropriate. This could involve hiring access equipment at extra cost, though lower roofs can often be accessed with ladders in certain cases.
A thorough photographic schedule of the roof is provided, highlighting specific areas requiring attention.
A report is compiled explaining the issues and potential solutions, along with budget costs for each option.
You are then free to either get the works completed yourself using your preferred contractor or we can, for a fee based on a percentage of the contract value, manage the project and perform the following duties:
- Produce a specification for the works
- Produce Health and Safety specification
- Tender the works
- Appoint a suitably qualified contractor
- Manage stage payments on your behalf
- Inspect the works
- Issue warranties and guarantees
- Handle any asbestos removal certification required
The managed route is one that many companies choose simply because of the extra peace of mind this offers.
Because the work is tendered against a pre-specified schedule of works, the savings often exceed the cost of our management fees.
Please note that we do not provide a specification for works unless we are instructed to act on your behalf.
The cost of the initial site survey is £750 – £950 per building (depending on location) plus access hire if necessary.
Access charges are additional and beyond our control, but somewhere in the region of £450 should be allowed.
Want to see what you get for the money? No problem. You may download an example roof report by clicking here. As chartered building surveyors, you can rest assured that our report will be impartial and the advice you receive will be completely independent.
Note that this report is a large pdf document and will open in a new window (which could take some time), or you may right-click and save the report to your computer.
Please call David Carter on 0121 711 7110 if you need more information about asbestos roofing issues.