Common types of asbestos In Building Materials
Common ACMs (Asbestos Containing Materials)
Textures and/or plaster
It is rare to find asbestos in plaster. In most cases, asbestos is found on the surfaces of the plaster on its decorative patterns. These pattern-like surfacing materials are called textures and were added to give a pleasing aesthetic appearance to surfaces such as ceilings. Asbestos was used to provide textures with fire resistance, thermal insulation and acoustic isolation.
Not all textures contain asbestos. The only way of being sure of the presence of asbestos in texture is by taking a sample for analysis by an accredited lab. It is never safe to deny the presence of asbestos without microscopic analysis, though in some cases some will forego sampling and analysis costs by assuming an area contains. For enormous projects, usually involving a large area of texture, it’s best to have the texture sample(s) analyzed as the abatement or removal may get costly. If you’re not certain on sampling protocols and safety procedures for your textured area, have it tested by a qualified, independent, environmental consultant to be on the safe side. The consultant will recommend sampling density, volume and location within AHERA (Asbestos Hazard Emergency Response Act) building inspector guidelines. They may even suggest, should you have future renovation or demolition planned, to collect an extra sample from that corresponding area to assist with project planning. This will inevitably solve future concerns and can be an added bonus to the property owner if they are living in an aging structure with no asbestos management plan in place.
Fireproof spray coatings
Because asbestos is known to be fire-resistant, it was used to make fire resistance sprays. These sprays could be applied to walls and other structures in houses and buildings to increase their fire resistance. Identifiable by the characteristic fluffy appearance, these sprays can deteriorate in condition rapidly and are highly friable. They are usually sprayed on ceilings of warehouses, parking garages or other commercial buildings. The ceiling is usually left open to air as well so work in the area can result in exposure should the material not be tested before work commences.
If you decide on completely removing ACM from a building it is best to have a fireproofing backup plan as most buildings depend on the ACM for fire resistance. This is a requirement of most building codes and to pass a building inspection, a replacement fire retardant would need to be applied.
Asbestos duct tape and fibreboard
ACM Duct tape and fibreboard have been used often in houses to provide fire resistance and insulation. Usually, these materials have a high asbestos content. For example, the content of duct tape and fibreboard is sometimes composed of about 80 – 90% chrysotile. In spite of the high asbestos content, they are generally regarded as moderate risk ACM. Deterioration can occur over time though, and dislodging of the ductwork can easily disturb the material. When in good condition, they are remarkably sticky and will easily grab hold of any asbestos fibres.
To protect yourself from the ACM duct tape and fibreboard on or surrounding ductwork, use a wide commercial grade metallic duct tape and cover it over the ACM. If you take this route, be sure to inform future building occupants of the asbestos tape beneath, or label the area with a warning tag to prevent disturbance.
Because of the insulative properties of asbestos, it was used as loose fill material in masonry works of many homes, commercial, and industrial buildings before 1990. This distribution of the insulating material within a difficult to access masonry (cinder block wall, most often) can leave unsuspecting occupants or workers at high risk of exposure. Vermiculite, or Zonolite as the brand name it was often sold by, was most commonly used as this loose fill insulation. In Australia, Mr. Fluffy brand ACM loose fill insulation was added to the attics of many homes as a thermal system insulation. This loose fill was also placed in voids around chimneys, ductwork and wall cavities. Loose fill is a highly friable material, therefore sampling and analysis is crucial to prevent exposure.
Asbestos Insulation Boards (AIB’s) or backerboard
Asbestos containing insulation boards have a variety of applications from electrical to heating. They provide insulation, fire resistance, and are commonly seen as mounting material for electrical components or panels. These boards were sometimes made of the amphibole amosite, brown asbestos. Because amphiboles are friable, the AIB’s were amongst the first ACMs to be banned. More recent types of backerboard were made of cementitious materials and chrysotile. They have incredible durability when installed in areas protected from the elements of weather. The modern versions of backboard were made to stand the test of time but depending on location, they are still prone to degradation and over time may become friable.
Pipes and pipe insulations
Usually chrysotile was mixed with cement to produce these durable thermal resistant pipes, widely sold under the Transite product name. It is sometimes common to find these asbestos pipes or drainage tiles in residential applications as perimeter drains for homes. Do not be alarmed if you see one since this asbestos piping is often inaccessible, it poses little risk when not chipped or cracked. It is only ACMs located in places that receive a lot of traffic or exposure to the elements that can easily get damaged or pulverized and release their fibres. Usually there is no need to have piping tested and removed unless they are badly damaged. It’s important to conduct a thorough visual examination of the pipes.
Asbestos pipe insulation (lagging) has fair durability and without disturbance in the area, it’s unlikely to degrade, so these ACMs are regarded as low risk when in good condition. However, it’s important to take the time to clear the pipes labelled as containing asbestos and warn plumbers and heating contractors that may be unaware of the asbestos.
Mastic is the adhesive material used to attach floor tiles to the floor. It was common for old houses, that is those before 1990, to have mastic that contained asbestos. This helped with fireproofing, adhesion and insulation.
Black mastic is a relatively safe ACM. The reason being due to its adhesive nature, to some extent it is organically bound material where some asbestos fibres attach. Also, because mastic is located between the floor and tiles it is unlikely for asbestos fibres from black mastic to find their way to the tile surface or, even worse, into the occupied space. The mastic only becomes problematic when the flooring is damaged and the mastic is exposed. Mitigation of this problem is simply placing new tile or duct tape over the damaged area. Removal of the mastic is a possible option although it can be a very expensive, labour intensive process.
Before you can begin any work with mastic, have it tested for asbestos in an accredited asbestos testing laboratory that meets the testing requirements of your area. If the tests prove to be positive you can either build a layer over the mastic or opt to have it scraped off.
Before removing tiles, to remove the mastic you need to wear a p100 half respirator mask and other safety clothing such as gloves and disposable coveralls. Once you have the safety gear on, you will have to liberally moisturize the tiles you plan on removing so you can have access to the asbestos mastic below. This will prevent any asbestos fibres from becoming airborne. Once you have the mastic exposed, you can then liberally spray fibre lock asbestos encapsulant (essentially spray glue); this will trap any fibres in the mastic. With the mastic evenly covered and once the encapsulant dries, you can then place a fresh layer of tiling.
Placing new tiles over asbestos mastic is much more cost effective than scraping the adhesive off. Removing mastic is an extremely laborious and rather costly undertaking. In most cases even after grinding and scraping the layer below the mastic not all of it is removed. It is tolerable in most abatement projects to allow some stubborn mastic to be left as this would no longer be deemed asbestos containing material by the 0.5- 1% asbestos content criteria. To cut down on costs, you are better off layering over black mastic or, if a plywood subfloor that has the mastic applied can be cut out as a whole, scraping can be avoided all together.
Drywall Joint Compound (DJC)
DJC is a filler used to attach, seamlessly, two drywall boards together. Drywall joint compound has an appearance similar to that of plaster. The most common type of board that is attached using DJC, as the name implies, is drywall. However, they are used in joining a wide variety of boards and other applications to fill in small voids and seams. In most cases, drywall joint compound consists of less than 6% asbestos; in most cases, white asbestos or chrysotile. I should stress that the only way of confirming the presence of asbestos in the drywall joint compound is through having a sample of the material tested in a locally certified laboratory.
During the era when asbestos was used in tile manufacturing, it was common practice for the tiles to be 9 x 9 inches. Tiles also came in 12 x 12 inch although 9 x 9 was the most prevalent. The thickness of the tiles unlike their fixed sizes varied. Tiles may be thick, whilst others were thin vinyl tiles.
Another important characteristic of the asbestos tiles is that they usually appear oily and/or stained with patches of discolouration. This misalignment of colour is as a result of the degradation of asphalt, a major ingredient in asbestos tiles.
The stains caused by the deterioration of the asphalt in these tiles cannot be mistaken for ordinary dirt, because in spite of scrubbing the tiles, this colouration won’t vanish. But the only way to be certain of the presence of asbestos is through having it tested in an accredited laboratory.
Usually, it is best to layer over an asbestos tile as it is cheaper than removing the tiles and is just as safe. Make sure to inform future property owners that asbestos tiles have been layered over. Informing future owners about the presence of asbestos will help them plan renovations but most importantly keep all future occupants safe from exposure. Moreover, it protects you from any legal action the new owners may take. All of this information can be released in a property disclosure before sale. This would be the opportunity for the property seller to disclose all known defects to a potential buyer.
Many materials have been used to layer over asbestos. I have seen tiles, hardwood, and laminate over asbestos tiles. The most common type of asbestos tile is vinyl asbestos tiles (VAT). They are comprised of very strong material and are resilient to damage during layering or other renovation operations. In order for your layering to look flawless, you need to make sure that the VAT is well levelled. If all the tiles are in good condition, there is almost no need for levelling. If, however, some VAT’s are broken, you’ll have to do some work with the tiles. The first thing you should do is wear protective gear, this should consist of a half mask respirator (p100 removable cartridge), a Tyvek suit and gloves. Once you have the protective clothing on, spray glue over the tiles which acts as an encapsulant and once the glue dries, remove your safety clothes and dispose of them according to the regulations of your area. With the tiles encapsulated you can then apply levelling compound and a fresh layer of tiles.
In cases where the crumbled pieces of VAT make levelling a challenge, you’ll have to remove the crumbled pieces (please mist the area with water first), wearing protective gear, and have them disposed of according to your asbestos disposal laws. Then apply an encapsulant over the remaining tiles. Once the encapsulant is dry, use levelling compound to have the surface level and lay new flooring.
Sheet vinyl flooring (SVF) is another common type of flooring that can possibly contain asbestos. Remember, the only way to be certain that it has asbestos is through laboratory tests by certified firms. SVF, unlike vinyl flooring tiles (VFT) like VAT, has a high asbestos content, from 10 – 70% chrysotile. This means that handling of SVF is done under much more care than VFT’s. Operations such as removal of SVF can release asbestos fibres making them airborne, where they can remain suspended for up to 48 hours. If you intend on having asbestos SVF completely removed, it would be a good idea to receive removal quotes from up to three abatement companies to ensure all asbestos is removed. An asbestos abatement company would need to do the removal with full containment including a three-stage decontamination facility and negative air machine.
If the flooring layer underneath the SVF is plywood, it is possible for the SVF to be removed with the plywood attached. This method minimizes damage to the ACM and is generally less risky than removing the sheet vinyl flooring alone.
Transite was the name given to products made primarily from asbestos and cement by an American company called Johns Manville. The name “transite” isn’t exclusive to the products of Johns Manville, it was used for many asbestos-cement products not only those produced by Johns Manville. In fact, the name has become so generic, it is at times used to call fireproof, hard composite materials, or backerboard used in the construction of residential, commercial and industrial properties.
Transite has found a wide variety of applications; the common ones being fluid piping, siding, cement wallboards, and roof tiles/gutters. In most cases, we see transite being used where durability is required. This is because transite is an incredibly strong material. It is common to see transite being used in making siding tiles, backerboard and drainage pipes. Usually, transite materials last for 30 – 75 years. Though impact can destroy it after exposure to the elements for a shorter period of time.
The use of asbestos in the production of transite diminished after the 1980s in most countries. Asbestos in cementitious building materials has now been replaced by a material called crystalline silica. Transite was usually composed of 15 – 25% asbestos fibre. This high fibre content greatly increased its tensile strength and durability. This is very similar to how rebar strengthens reinforced concrete. Because of the impressive strength of asbestos transite, it is far from friable, meaning it is actually one of the safest ACMs.
Asbestos transite only poses a risk when it is broken or processed during construction work through cutting, machining and trimming.
As mentioned earlier, transite is incredibly durable and acts as an impressive insulator; however, the material gradually degrades in the presence of sunlight. It takes a very long time for transite to degrade to a noticeable state. Usually, it will take about 30 years to notice any degradation in transite.
Vermiculite is a type of clay mineral that is commonly mined in Russia, South Africa, Australia, and Japan, as well as in the United States; specifically in Libby, Montana and the Carolinas. Vermiculite has a similar composition to asbestos and shares a similar geological origin when it comes to formation, and it is therefore not rare for you to find vermiculite deposits mixed with or near asbestos. This combination of vermiculite with asbestos was most common in one of the earliest large- scale vermiculite mines, owned by W.R Grace and Company in Libby, Montana, where the mined vermiculite was mixed with asbestos and mica. At this time, the health impacts of vermiculite were poorly known, meaning the presence of asbestos in the Montana mine was of no concern to the company.
Vermiculite has the special ability to expand rapidly when heated. And if heated to the right temperature, vermiculite breaks up into worm-like structures. This process is called the exfoliation of vermiculite.
Vermiculite’s strange ability to break up into these worm-shaped fibres is what gave it its name. The name vermiculite originated from the Latin word ‘vermiculare’, which means to breed worms. The fibres formed from exfoliated vermiculite have many uses. In Fact, most of the uses of vermiculite functions only come when vermiculite has been exfoliated.