F.A.Q.

Asbestos Roof FAQs

Important

The content on this page is for information only.

If you need definitive answers to asbestos questions or working safely at height, please refer to the HSE web site.

If anything on this web site contradicts official HSE guidance, please assume that the HSE is correct!

Domestic
Roofs

Is it safe to have an asbestos roof?

The asbestos content in a typical asbestos cement roof is between 2 and 8% and this is encapsulated within the cement matrix.

As long as the condition of the roof sheets is good, then there is little risk of asbestos contamination.

If the roof is in poor condition, with bits breaking off, then there is a chance of asbestos contamination.

The real risk with an asbestos roof however, comes from the fact that it is fragile.

Walking on this type of roof is extremely dangerous and should never be attempted, no matter how confident you might be.

Looked at in this context, an asbestos roof is not safe!

 

 

 

Can I remove an asbestos roof myself?

Domestic asbestos cement roof sheets can be removed by anybody, as long as precautions are taken AND the sheets are not breaking up and creating dust.

Suitable Personal Protective Equipment will be needed to avoid unneccessary exposure to asbestos fibres.

If you are not familiar with the safe procedures for doing this type or work, refer to a lcoal roofing contractor.

Removal of an asbestos roof can in some cases, be classified as Notifiable non-licensed work (NNLW).

See the HSE web site for guidance on how to carry this type of work safely.

 

 

How much does it cost to replace a garage roof?

Prices to replace an asbestos cement roof vary considerably.

For small domestic premises, the cost will depend on what you are replacing the asbestos cement sheets with.

Generally speaking, to replace with a fibre cement or metal profiled sheet will in the region of £50 per sq metre, but this varies depending on geographical location.

How do I dispose of old asbestos roof sheets?

The only legal method of disposing of asbestos cement roof sheets is via a licensed disposal contractor.

Ideally, you should have an asbestos skip or bin delivered to your site to facilitate this, because unless you have a contaminated waste carriers licence, you are not allowed to transport the material yourself.

What type of asbestos is present in roof sheets?

Crysotile (white) Asbestos is most typically found in asbestos roof sheets, but Amosite (brown) and Crocidolite (blue) asbestos can also be present in some profiles.

The only way to know for certain is to get the material tested, but this won’t make any difference to the cost of removal or disposal of the roof sheets.

Can you reuse old asbestos cement roof sheets?

Asbestos cement products were finally banned in the UK in 1999.

It is illegal to sell new or second-hand products containing asbestos.

If you need to replace an existing sheet with a spare one that you have, you can do this of course.

Changing an asbestos roof sheet can prove to be difficult though, because you’re likely to break adjoining or overlapping roof sheets when you replace the sheet.

Should I get my corrugated roof sheets tested for asbestos?

If you really want to know if your corrugated roof sheets contain asbestos, then you can get them tested by an asbestos laboratory.

However, we know of several cases where people have tested roof sheets and confirmed that they do not contain asbestos, only for the disposal company to have them re-checked and say that they do!

A skip company will always check corrugated fibre cement sheets, even if you have a laboratory certificate.

This is because you might have tested a replacement sheet, rather than an asbestos sheet and they can’t afford to dispose of asbestos contaminated waste as normal waste, since the fines can be enormous.

If all of your sheets carry a designated N or  CE mark, then they are clearly not asbestos and you should be okay.

I have asbestos roof tiles. Are they dangerous?

Generally speaking, asbestos roof tiles are even less dangerous to health than asbestos cement roof sheets, simply because they are usually installed on top of a sarking felt or other protective membrane.

As with sheets, the tiles still need to be handled with care if removing them or repairing them.

How common are asbestos roof tiles?

Asbestos roof tiles are usually found on domestic dwellings. 

They can be laid just like ordinary slate roofs and from a distance, often look very similar.

If the “slates” appear to be faded and have noticeable white parts, they are most likely to be asbestos cement.

Others are laid in a diamond pattern and will often be red or green.

They are less common than they used to be, because most are at the end of their life expectancy.

How to identify asbestos cement roof tiles

asbestos cement roof tiles in diamond formationAsbestos cement roof tiles are relatively easy to identify.

Many are laid in a diamond pattern, rather than in rectangular shaped straight lines.

These soert of asbestos cement tiles will often be coloured red or green.

The asbestos cement roof tiles that look more like slates will often be faded with age and have noticeable white patches, particularly at the edges.

In some cases, where the asbestos roof tiles are degraded, they will curl at the edges. 

If you see this, they are at the end of their life and will require replacement.

 

How do I know if my asbestos roof needs replacing?

If in doubt, ask a building surveyor because a roofing contractor is unlikely to provide you with unbiased advice.

For commercial or industriual property, please call 0121 711 7110 where one of our experienced asbestos and roofing surveyors will be able to assist you further, without obligation.

Alternatively, see our independent asbestos roof survey page.

Where can I buy new asbestos cement roof sheets?

Asbestos containing materials, including asbestos roof sheets were banned in the UK in 1999.

It is now illegal to sell them, even second-hand, so it is highly unlikely that you will be able to buy them, unless from dubious sources.

However, you can buy non-asbestos replacement sheets in the same profile from some roofing merchants.

These sheets will be stamped with an identifying mark, which will be either a CE mark or  letter N for non-asbestos.

Commercial 
Roofs

 

How much does it cost to replace an industrial asbestos roof?

 

For commercial or industrial property, allow £100 – £110 per square metre due to the stringent health and safety requirements and the requirement to increase insulation, structural calculations etc.

What does it cost to overclad an asbestos roof?

Over-cladding is a popular choice when considering asbestos roofing options.

It involves using an Ash Grid system, which is essentially a framework installed onto the asbestos cement roof sheets.

A layer of insulation of 200-240mm is then laid into the grid, before it is topped with a metal profile sheet.

Done properly, by a competent industrial roofing contractor, you should budget around £65 per sq metre.

What is the cost of coating an asbestos roof?

BBA asbestos roof coating - AsbestosealThis will depend on the coating.

Asbestoseal is a BBA Approved asbestos roof coating, the only one on the market that has been tested for use on this type of roof.

The costs for cleaning and coating, including all safe access can be as low as £30 per sq metre for large projects.

For small projects, up to say 1500 sq metres, allow £5-40 per sq metre.

For more details on Asbestoseal, click here.

What is the cost of cleaning an asbestos roof?

There are specialist asbestos roof cleaning companies that will be able to provide you with a quotation for this work.

For budget costs, allow £10 per sq metre on roofs more than 1000 sq metres or up to £15 for smaller roofs.

The reason for the higher cost on a smaller roof is simply because the costs of mobilisation is about the same for a small roof as it is for a larger one.

Can you pressure wash an asbestos roof?

The HSE advise against using pressure wash lances to clean asbestos roofs.

The cement sheets are very fragile and in some cases, pressure washers have been known to destroy them, causing considerable contamination to the building beneath.

A clsoed box pressure washer is an approved method of cleaning. This is a box rather like a patio cleaning attachment, that is lowered down the roof slope, cleaning as it goes.

How is heavy moss removed from an asbestos roof

Heavy moss growth on an asbestos roof can be problematic and we’ve seen several instances where the moss has grown through the roof, to the inside.

The way to remove the moss is to make sure it is wet and then scrape it off using profiled scrapers or trowels on poles.

During cleaning, it is imperative that you do not step onto the fragile asbestos cement roof sheets.

For commercial / industrial roofs, this is a job best left to the experts.

All moss and vegetation removed from the roof must be considered to be contaminated waste and placed into double asbestos waste bags, for disposal by a licensed disposal contractor.

What is the weight of an asbestos roof sheet?

Typically, the weight of an asbestos cement roof sheet is 15kg per sq metre, but this can vary.

How do I know if my asbestos roof needs replacing?

delaminating asbestos roof sheetIf in doubt, ask a building surveyor because a roofing contractor is unlikely to provide you with unbiased advice.

If the roof surface is delaminating (like in the picture) and breaking up, or looks white and patchy all over, then it probably needs replacing.

For commercial or industriual property, please call 0121 711 7110 where one of our experienced asbestos and roofing surveyors will be able to assist you further, without obligation.

Alternatively, see our independent asbestos roof survey page.

Can I patch repair an asbestos roof?

Unless you have easy access to the area that’s leaking, we don’t recommend patch repairs.

The reason is simply that the cost of safe access is better spent on wholesale repair of the roof.

It’s always going to be expensive to access an asbestos roof and small patch repairs rarely solve the problem in any case.

How long do asbestos roofs last?

According to the Royal Insitution of Chartered Surveyors (RICS), the life expectancy of an asbestos roof is 25 to 40 years.

We have seen some roofs that require replacement with this time frame and we have also seen roofs that were installed in the 1920s that are still in decent condition.

A lot depends on timely maintenance, for example, keeping the roof sheets free of heavy moss and other fungal growth.

Is Sprayed Polyurethane Foam (SPF) suitable for asbestos roofs?

SPF was used a lot in the 1980’s and 1990’s, to provide waterproofing and increased insulation on asbestos roofs.

It fell out of favour as steel became cheaper and made overcladding a viable alternative.

SPF isn’t pretty, because it’s applied wet and then expands, so a uniform finish is very difficult to achieve. It requires an extremely skilled spray operative to get a decent looking finish.

SPF is not UV stable, so in sunlight, the product begins to degrade almost as soon as it is applied.

In severe cases, where the SPF is left exposed to sunlight, it goes brown and powdery and will continue break down with time. If the degrading material is scraped off, it can be reapplied and coated with a UV stable coating such as Liquasil’s Asbestoseal, which is 100% UV stable.

We aren’t fans of SPF on asbestos roofs, since the product expands so much that the finished aesthetic will almost certainly be poor.

The advantage of SPF is that it covers every defect and has excellent insulation qualities, but in our opinion, these advantages are far outweighed by the disadvantages.

How do you repair an asbestos gutter?

asbestos gutter lined with Liquasil's liquid gutter lining systemLiquasil has an asbestos gutter lining system that is ideal for the purpose.

It is a liquid silicone system that provides a seamless finish that will last many years.

When installed by a Liquasil approved installer, larger gutters will benefit from their unique 10 year guarantee.

The product is available for order direct by calling 0121 709 5352.

Safe
Access

Why is accessing an asbestos roof so expensive?

 

An asbestos cement roof is fragile. 

If you walk on on an asbestos roof sheet, it can give way without warning, leading to serious injury or even death.

Consequently, safe access systems must be in place before any work commences, to both prevent and arrest falls from height.

It is the fall from height more than anything else, that makes asbestos roofs dangerous. 

What is internal netting?

internal netting on an asbestos roofInternally netting an asbestos roof is essential if it’s posisble to do so.

The netting is fixed to the underside of the roof, so that in the event of somebody falling through the roof, they will be caught in the netting, preventing serious injury.

Double-netting is where two nets are installed, one within the other. The inner net is finer and is often referred to as a “debris net” designed to catch any falling debris or tools that might be accidentally  dropped from the roof.

Double netting is only usually employed in occupied premises, to prevent people from being injured by falling objects.

In environments where dust control is required, double netting would be employed along with a polythene liner, sprayed with PVA adhesive that remains tacky and catches any dust and debris within.

 

 

Why use double hand-railed platforms?

asbestos roof access - double hand-railed platformThe concept of using double hand-railed working plaforms on an asbestos cement roof is to form a physical barrier to help prevent a worker accidentally stepping onto the fragile roof surface.

Do I need to scaffold an asbestos roof to work on it?

permieter edgescaffold during asbestos roof worksNot always. Some asbestos roof works can be completed safely from a cherry picker, or other means of safe access.

Where large scale works are being undertaken, then it is a reasonable expectation to see  perimeter edge scaffold employed.

For any other questions, please contact us.