Asbestos cement roof damaged by washing:

This article warns about un-supervised or un-trained environmental cleanup companies or work crews handling asbestos, lead, mold, and similar indoor contaminants, including identification of amateur or improper asbestos "abatement" projects that failed to properly remove materials or that left abandoned asbestos materials in place.

We also discuss certification & training for asbestos abatement, cleanup, or removal workers & companies, warnings about un-trained asbestos cleanup workers lack of training or job supervision result in improper asbestos, lead, mold and similar contamination removal efforts.

These warnings about using a power washer on an asbestos-cement roof also pertain to asbestos cement siding as well.

Asbestos Cement Roof Washing Troubles - "... they power-washed my asbestos cement roof ..."

Question: Is power-washed asbestos-cement roof runoff an environmental hazard?

I live in Brantford Ontario and a building in my neighbourhood has was I think is a corrugated asbestos roof.

Last weekend some workmen power washed it. The run off, when dried, looked like grey powder and lifted from the pavement in "sheets" almost like parchment paper.

I've attached a couple of photos [shown at page top and just above].

My second photo shows the white stuff from the roof, now a powdery deposit on the paved parking area.

Does this present any danger or give cause for health concerns? - D.F., Brantford ONT

Reply: Asbestos hazards are probably present, asbestos regulation violations may have occurred, and further steps are needed

OPINION:

Most likely the debris that was washed off of the roof contains road and other environmental dust that had settled on the roof surface over time, and possibly algae, mold, or lichens that were staining the surface (as in our file photo of corrugated asbestos roofing below) leading to the desire to wash the roof in the first place.

But because power washing is a strong approach to cleaning a surface it is likely to also have dislodged asbestos and cement particles from the asbestos-cement corrugated roof itself.

While wetting the material, something that would naturally occur during the power-washing of the cement-asbestos roof surface, would be expected to reduce the airborne level of asbestos during the actual washing process, although when properly performed, wetting to control asbestos particle release includes the addition of a wetting agent to the spray before it is applied.

Power-washing a cement asbestos roof could indeed leave substantial materials on the ground after the cleaning procedure. As the on-ground material dries asbestos fiber and particle risks are likely to be present.

So it would be no surprise if the debris on the ground around the building in your photos contains a high level of asbestos fibers and particles. The material therefore may form an airborne asbestos hazard in the neighborhood, or as it washes into local storm drains, it may constitute an illegal and improper disposal of asbestos dust and debris.

If the added cost to properly clean up this mess is going to be high (which we would guess is the case), it would be appropriate and inexpensive to collect a debris sample for testing by a local, certified asbestos testing lab to confirm that the contents are indeed contaminated at a level requiring professional cleaning.

Photo above: corrugated asbestos-cement roofing on a building in Herefordshire, England, photographed by the author.

In addition, power-washing the roof surface risks increasing the friable nature of the material that remains on the building, as the cementious binding has been removed from the uppermost roof surface, first by normal weathering and second, and much more aggressively, by the power washing process.

The building owners should address these questions immediately in order to reduce the spread and thus possible costs of a proper asbestos dust cleanup.

Asbestos regulations for Ontario [PDF] are published under the Occupational Health and Safety Act and are in Ontario Regulation 278/05 [PDF] and provide a clearly-written and comprehensive guide to cleaning up and disposing of asbestos containing materials in or on buildings. Discussing [Type 1] asbestos operations that regulation states:

1. Before beginning work, visible dust shall be removed with a damp cloth or a vacuum equipped with a HEPA filter from any surface in the work area, including the thing to be worked on, if the dust on that surface is likely to be disturbed.

2. The spread of dust from the work area shall be controlled by measures appropriate to the work to be done including the use of drop sheets of polyethylene or other suitable material that is impervious to asbestos.

3. In the case of an operation mentioned in paragraph 4 of subsection 12 (2), the material shall be wetted before and kept wet during the work to control the spread of dust or fibres, unless wetting would create a hazard or cause damage.

4. A wetting agent shall be added to water that is to be used to control the spread of dust and fibres.

5. Frequently and at regular intervals during the doing of the work and immediately on completion of the work,

i. dust and waste shall be cleaned up and removed using a vacuum equipped with a HEPA filter, or by damp mopping or wet sweeping, and placed in a container as described in paragraph 5 of section 15, and

ii. drop sheets shall be wetted and placed in a container as described in paragraph 5 of section 15, as soon as practicable after subparagraph i has been complied with.

6. Drop sheets shall not be reused.

7. After the work is completed, polyethylene sheeting and similar materials used for barriers and enclosures shall not be reused, but shall be wetted and placed in a container as described in paragraph 5 of section 15 as soon as practicable after paragraph 5 of this section has been complied with.

Watch out: in 2010 The New York Times reported that 65 to 80 percent of those receiving certification as qualified asbestos removal experts had not received the necessary training.

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Neighbor putting up asbestos cement roofing that was "jet washed" - will that continue to release asbestos?

Hi please advise the guy next door is putting up asbestos cement roof sheets that have been jetwashed, previous to construction, will they continue to release fibres in the wind if they are not sealed. worried that they will be in my lawn and hedge that I need to cut. Please advise. - On 2022-06-03 by Chris -

Reply by InspectApedia-911 (mod)

@Chris,

Thanks, that's an interesting and reasonable question. I think that any cement-asbestos product exposed to the weather will shed at least some detectable asbestos particles and fibres that might be detected on the ground around and close to the building.

I haven't found objective data or studies reporting on wind-blown asbestos dust from asbestos-cement roofing onto neighbouring properties, though I expect that it's below the limits of detection except if the roofing is being demolished or disturbed,
OR
if the roof was power-washed and the power-washing debris was left on the ground nearby.

In the case you describe, the fellow putting up asbestos cement roofing next-door the dust hazard would arise from grinding, chopping, sanding, sawing the sheets in their current (new) location.

Are you really sure that the product is asbestos-cement roofing? In most countries that material has not been sold for decades now.

So if it's new material it's fibre-cement roofing but not asbestos-fibre-cement.

Post a photo of the work in process.

Followup by Chris

@InspectApedia-911, Hi Thanks for your reply. I have spoken to this person next door and he admitted that it was asbestos roofing sheets he was putting up. After speaking to him he knows nothing about asbestos or wants to. He was on the roof drilling it to fix it , no mask or ppe. I just could not get through to him. Thanks .

Reply by InspectApedia-911 (mod)

@Chris,

Even if there's no asbestos, if one is drilling into fiber cement material you should not be breathing the dust.

Where do you think someone found asbestos cement roofing materials so long after its use has been banned?

Followup by Chris

@InspectApedia-911, Hi I remember about 20 years ago he removed it from a shed that he demolished and it's been in his yard till now. Do you think I should wear ppe when cutting my lawn or hedge Thanks.

Reply by InspectApedia-911 (mod)

@Chris,

If you see actual white sludge, debris, or dust in or at your property you might take a sample to an asbestos test lab.

Without that objective data any guess would be so speculative as to be of little value.

Followup by Chris

@InspectApedia-911, Hi Thanks for your advice. Can't see any asbestos debris around my garden, but the good news is that the person next door has changed the roof sheets for new cement ones. I must of got through to him. But I'm still worried about my garden? Thanks for your advice and a great service.

Reply byInspectApedia-911 (mod) - neighbor installing asbestos cement sheets on roof

@Chris,

If you want to have objective data in order to force some appropriate response or action, it might be a smart move to collect a sample of the material in your yard and have it tested by certified asbestos test lab.

If you do that, do keep us informed there may be able to comment further.

On 2020-08-27 by pressure washer - Says asbestos from pressure washing is safe.

Wet asbestos does not fly. if you see "dust" its water fog 99,9%. car brake pads have had asbestos in them so it is most likely that asbestos can be found from the roadsides all around the world.

Reply by (mod) - we disagree

Thanks for the commenbt Pressure Washer person.

Unfortunately, the debris and particles that pressure washing blows off of asbestos-cement roofing or siding doesn't stay wet. And when it dries we've got a fine powder that may easily become airborne and thus may be a hazard.

Pointing out, as you did, that asbestos dust from vehicle brakes is hardous is fair but not quite: the research on that topic points principally to asbestos exposure risks for workers in garages or shops where brakework was performed, not along roadsides. With respect, pointing out that brake dust can be hazardous doesn't mean that asbestos roof or siding dust is safe any more than raising chickens tells us that nobody is raising sheep.

 

Is it dangerous for me to walk past a building with corrugated asbestos cement roofing and siding?

I regular walk to work and on my route is a building with a corrugated asbestos cement roof and siding. It seems a small part of the siding has been cleaned at some point in the past. I looked on Google Street view and it has been cleaned for at least two years.

I walk on the opposite side of the road to the building, probably around 40-50 metres away.

Do you think there would be a health risk from this building? I don't know what method was used to clean the siding but power washing is a possibility.
- Anonymous 2019/01/11

Reply:

We just can't bet your health on making an environmental risk assessment by a brief e-text. There are just too many variables.

Actual roof composition, age, condition, method of cleaning, debris removed by cleaning asbestos content in debris, control of or disposition of roof wash-off debris, debris remaining in the area, conditions causing it to be airborne, distances, exposure level and duration, health vulnerability of people, etc.

But in general, just walking past asbestos-containing materials would not, alone, be considered dangerous.

Reader follow-up

Thank you for the response.

From looking at Google streetview, it would seem the siding must have been cleaned at least 10 years ago. The images show that the appearance has remained 'clean' since then.

I am guessing they must have used a sealer after cleaning it which allays my fears a bit.

Reply:

The measurable hazard (if there is one) would not be the roof it would be powdery residue or debris or dust containing asbestos in the roof wash-off.

Neighbor blew asbestos from roof all over our garden

Our neighbour has just power washed his garage roof sending asbestos all over our house and Garden.

We are worried about our health and the cat we feel has long hair and should go into quarantine as she's been playing in it.

Help!

I've searched the Internet and can't find anyone in the same position. We are upset and also angry but don't know what action to take or how to approach the neighbour. Help! - On 2016-11-12 by Anonymous -

Reply by (mod)

No one can measure the actual hazard from your neighbor's roof by text, but you could certainly ask for help from a local environmental inspection and test consultant.

Ask her to sample your garden soil and plants for asbestos contamination.

Then if the asbestos test report shows that there is indeed a hazard you'll need help from your local building department and, perhaps, an attorney to decide what cleanup is needed and who pays for it.

Keep in mind that if your neighbor's asbestos dust is present and hazardous on your property, it's likely that there's a hazard for the occupants of their own property too. Be sure they know about your concern.

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Continue reading at ASBESTOS ROOFING / SIDING DUST or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

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