It’s estimated that 1.5 million UK buildings still contain asbestos, including homes, schools and workplaces. While most people know asbestos was used in insulation, flooring, ceiling tiles, and roofing, fewer realise it can also be found in bricks, mortar and cinder blocks.
Because asbestos fibres are microscopic and invisible to the naked eye, you cannot rely on appearance alone. We uncover why asbestos was added to masonry, where it may be found, the signs to watch for, and why only professional testing can confirm it’s presence.
Why was asbestos added to bricks & mortar?
From the late 1800s through to the 1980s, asbestos was widely added to masonry products because it was cheap, strong, and heat-resistant. Builders valued it for:
- Heat and Fire Resistant: asbestos fibres can withstand extreme temperatures, making them ideal for fireplaces, furnaces and chimneys.
- Insulation: excellent thermal performance, keeping heat in and cold out.
- Strength and Durability: asbestos increased the lifespan of mortar and cement.
- Lightweight: made blocks lighter and easier to handle without weakening the structure.
- Cost-Effective: asbestos was a low-cost material compared to alternatives.
It wasn’t until the severe health risks became clear that asbestos was gradually banned in the UK, first blue and brown asbestos in 1985, and finally white asbestos in 1999.
Where Can Asbestos Be Found in Masonry?
Asbestos-containing materials (ACMs) still exist in many pre-2000 buildings. Within masonry, we commonly find it’s presence in:
Cement Products
Many legacy cement products contain asbestos, most commonly found in:
– Corrugated or flat roof sheets or tiles
– Soffits, fascia and downpipes
– Ceiling, garage or wall partition boards
– Pipe linings or chimney flues
Mortar and Firebricks
Asbestos was used in a wide range of mortar and firebricks, due to it’s inherent ability to withstand high temperatures.
– Industrial or specialist masonry
– Kiln, boiler room, furnace refractory bricks
– Chimneys, fireplaces or stoves (usually in older buildings)
Insulation or Backing Materials within Masonry
Asbestos’ strength, heat resistance, durability and low-cost made it an ideal backing material.
– Steel or brick asbestos coatings inside a building’s walls
– Asbestos-containing boards behind brick walls or under cladding
SIGNS THAT YOUR BRICKS, CINDER BLOCKS AND MORTAR MAY CONTAIN ASBESTOS
Asbestos fibres are usually not, if barely, visible to the naked eye. In fact, some fibres are 0.02-0.3 micrometres wide. For context, this is two hundred times thinner than a human hair.
This means that only an asbestos survey, completed by fully-trained, experienced professionals, will categorically tell you that any bricks, cinder blocks and mortar contain the harmful material.
That said, there are some warning signs that may suggest asbestos is present in masonry.
- Building Age: Properties built between 1950 and 1999 have a high likelihood of asbestos-containing materials such as cement boards, flue liners and blocks.
- Weight: Asbestos cement is lighter than standard bricks or mortar, especially when moulded into thin panels or sheets.
- Unusual Locations: Commonly found in soffits, boiler rooms, service ducts, chimneys, or other fire-resistant structures.
- Heat-Resistant Structures: Firebricks, kilns, stoves and furnaces in older properties often used asbestos for insulation.
What Does Asbestos in Bricks, Mortar or Cinder Blocks Look Like?
Visually, asbestos cement can appear almost identical to standard mortar or blocks, that’s what makes it so difficult to detect. However, there are some subtle differences.
- Appearance: Typically smooth and uniform, light grey to white in colour, compared to the rougher, grainier finish of standard mortar.
- Texture: Damaged pieces may show fibrous or frayed edges, while standard bricks crumble into dust or grains.
- Surface Finish: Fine, dense and less porous than traditional cement.
The key differences between standard masonry and asbestos cement
To the naked eye, asbestos cement looks almost identical to standard cement or mortar. That’s what makes it so dangerous, most people can’t tell the difference without professional testing. Still, there are a few key differences and warning signs that may indicate asbestos is present.
Composition
- Standard cement: natural mix of clay (bricks), sand, lime, cement, concrete. No added fibres.
- Asbestos cement: standard mix plus 10–15% asbestos fibres (commonly chrysotile/white asbestos).
Appearance & Texture
- Standard cement: grainy, sandy finish; mortar joints rough and porous; bricks heavy and dense.
- Asbestos cement: smoother, finer finish; typically light or dark grey; fibrous edges when broken.
Weight & Use
- Standard cement: used in load-bearing structural walls and traditional housebuilding.
- Asbestos cement: lighter, often moulded into sheets, boards, soffits, flues, garage panels and other non-structural elements.
Durability & Risk
- Standard cement: safe, durable, no long-term health hazards.
- Asbestos cement: durable but dangerous when cut, drilled, or damaged, as fibres can be released into the air.
Why Is It Difficult to Identify Asbestos in Masonry?
Asbestos was widely mixed into cement, mortar and plaster products throughout the 20th century. Once set, these materials look almost identical to standard masonry, which makes asbestos very hard to spot.
- Microscopic fibres: asbestos fibres are invisible to the naked eye, often hidden within sand and concrete mixes.
- Ageing materials: as bricks and mortar wear down, asbestos may become airborne without showing clear visual signs.
- Mixed use: asbestos was added to a wide range of products (cement boards, artex, insulation), all of which resemble ordinary, non-asbestos containing products.
Lab Testing
To ascertain the presence of asbestos in masonry materials, you’ll need to conduct an asbestos survey and complete laboratory testing.
This means that sample mortar, cinder blocks or brickwork will need to be taken and analysed under a microscope using specialist techniques like polarised light microscopy (PLM) or transmission electron microscopy (TEM).
What Are the Risks of Drilling, Cutting or Demolishing Brickwork with Asbestos?
Drilling, cutting or demolishing brickwork with asbestos carries serious health and safety risks and should only be performed by fully-trained professionals, like Fibre Safe. Below is an overview of the health and safety risks associated with drilling, cutting or demolishing brickwork.
Release of Airbourne Asbestos Fibres
Drilling, cutting or breaking asbestos masonry materials, like brickwork, disturbs the materials composition, releasing microscopic fibres into the air. These fibres can stay suspended for hours and can be easily inhaled.
Inhalation of Health Hazards
Inhaling asbestos in homes, or any public or commercial building, can lead to a range of serious health complications. We’ve listed these below for you to be aware of.
Health Condition
|
Description |
Asbestosis | Scarring of lung tissue which can lead to chronic breathing issues |
Mesothelioma | A rare, aggressive cancer of the lungs or abdomen which is almost exclusively caused by asbestos |
Lung cancer | Asbestos exposure significantly increases lung cancer risk, especially amongst smokers |
Pleural thickening | Thickening or stiffening of the lung lining which can impair breathing |
Hidden or Friable Asbestos
In some masonry, asbestos can be present in friable form (i.e., it’s easily crumbled by hand). This includes asbestos-containing render, plaster or mortar which crumbles during demolition and cement bricks which shed fibres if dry cut with power tools. Friable asbestos is even more dangerous because fibres can be more easily released.
The Risk to People
Drilling or disturbing brickwork with asbestos poses a significant risk to anyone within the building. Asbestos in homes poses a risk to homeowners. Asbestos in schools poses a risk to students and teaching professionals. Asbestos in public or commercial buildings poses a risk to short or long-term employees and other occupants.
Don’t also forget that asbestos fibres can easily stick to clothes, hair or personal belongings, like tools, and transported home, increasing the risk.
FAQs
Can I identify asbestos in bricks, cinder blocks and mortar, just by looking at them?
No. Without sufficient training and experience, it’s difficult for anyone to reliably identify asbestos in bricks, cinder blocks and mortar. Asbestos fibres are so small that they’re virtually invisible, and they’re often woven into the fabric of the material.
Is asbestos in bricks, cinder blocks and mortar safe if left undisturbed?
Yes. Asbestos in bricks, cinder blocks and mortar is safe if left undisturbed. However, if the material starts to deteriorate or crumble, releasing fibres into the air, the area will become hazardous.
Why is asbestos in masonry a hidden risk?
Asbestos was mixed directly into cement and mortar, making it indistinguishable from standard building materials without laboratory analysis.
What should I do if I suspect asbestos in bricks, cinder blocks and mortar?
If you suspect the presence of asbestos in a building’s brickwork, cinder blocks or mortar, you should contact professionals, like Fibre Safe, who can conduct an asbestos survey to comprehensively determine if asbestos is indeed present. If you’re drilling, cutting or demolishing, immediately stop any work. Releasing microscopic asbestos fibres into the air is hazardous.
How Fibre Safe can Help
With over 20 years of experience, Fibre Safe are trusted specialists in asbestos surveys, testing and removal. We’ve worked with homeowners, landlords, schools, housing associations and commercial clients across the North West and nationwide.
- UKAS-accredited asbestos testing
- Fully HSE-compliant surveys and removal
- Safe disposal of hazardous waste
- Fast response and clear, practical advice
If you need any help with asbestos in homes anywhere in the North West, call 0800 458 4136 or email sales@fibresafe.com.
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