Decontamination of drywall, panelling, plasterboard or gypsum board and joint compound

Nowadays, modern drywall and sealants do not contain asbestos. However, this has not always been the case.

Use of asbestos in building materials

In the case of a drywall system, references to asbestos focus primarily on asbestos that was in the jointed compound or in certain paints or spray products that would have been applied to the drywall ceiling.

It is important to remember that the asbestos-containing joint compound may have been applied not only over drywall joints up to 18 inches wide, but also in repairs, around penetrations or fixtures and in some buildings as a thin layer over an entire surface of the ceiling or wall.

Drywall systems that may contain asbestos, at least in finishes, sealed compounds, topcoats or gypsum systems, date back from around 1910 to the early 1980s in North America (1982 in Canada).

Asbestos content in building materials

In the jointed compound, the asbestos content varied, but was generally between 3 and 6%. Even if the gypsum boards themselves did not contain asbestos, this means that by weight, the asbestos content of the wall system was about 0.25%.

Beware that while the asbestos content of (uncommon) or (common) plasterboard or joints (common) can be relatively low, some aerosol sealant or textured ceiling treatments may be very high in asbestos, up to 40% or even higher.

How to cover or remove drywall or joints containing asbestos in building materials

It is important not to touch plasterboard materials suspected of containing asbestos; it is generally safer to leave these materials intact or cover them. If demolition or removal is necessary, the additional steps described in this document are important.

Testing plasterboard panels containing asbestos

If, in an older building (built before 1980 in North America), you are not sure whether the drywall, gypsum board or joint compounds used in your building contain asbestos, you should have representative samples of both materials (usually asbestos-free), the compound of the joints and plasterboard (which often contains the largest amount of asbestos) tested in a laboratory approved for analysis of asbestos.

Remember that even without asbestos, dust from compounds with joints and gypsum board creates ultrafine particles that can pose a serious respiratory hazard.

Do not attempt to remove gypsum board yourself if it contains asbestos

Since the dust from the plasterboard panels and the dust from the joint compound are easily airborne and friable (by sanding, cutting, sawing or other demolition operations), it is advisable not to engage in asbestos removal of plasterboard walls yourself, the same for cleaning.

Nevertheless, if you live in a place where the removal or repair of gypsum boards containing asbestos is permitted and you stubbornly do it yourself, take appropriate measures to control dust and adequately protect yourself, such as using a full wetting and wet sweep to clean the house and wipe the wet floor for work.

Turn off and protect all air handlers (air conditioners, heaters, humidifiers, dehumidifiers, fans) before handling asbestos-containing materials. Do not use a standard vacuum cleaner because it will activate the aeration of asbestos particles. Some HEPA-approved vacuum cleaners may also not treat asbestos and thus increase airborne asbestos levels.

Typical procedure for removing gypsum board in the case of small jobs

A “small job” should be limited to touching or removing less than one square metre of plasterboard when a joint compound containing asbestos has been used. The use of a respirator with new or used P100 filter cartridges and a disposable wetsuit is optional for small removal jobs. Then, follow these steps:

  • Install a sheet of polyethylene under the work area using canvas tape.

  • Spray the gypsum board to be removed, focusing on the corners and places where joints are visible or presumed to be present.

  • Continue spraying any suspicious material as the work progresses.

  • Dispose of all waste such as ordinary construction debris (asbestos waste disposal may be necessary depending on where you live).

  • Prepare a modified water solution by adding a cup of dishwasher detergent to 20 liters of water. This wetting agent will serve to reduce the surface tension of the water, thus improving its wetting and penetration properties.

Typical procedure for the removal and demolition of gypsum board in the case of larger works

For work of greater importance, do the following:

  • Shut down the HVAC system that affects the work area. Cover all HVAC vents and diffusers.

  • Wear a manufacturer-approved respirator (with new or used P100 filter cartridges) and a disposable coveralls.

  • Spray the gypsum board to be removed, focusing on corners and places where joints are visible or suspected of being present.

  • Continue spraying any suspicious material as the work progresses.

  • Control the dust in the area by spraying the fallen debris.

  • Dispose of all waste such as ordinary construction debris (asbestos waste disposal is mandatory or not, depending on where you live and applicable regulations.

Note: Special waste disposal or air monitoring may be required for this type of work, or a duly authorized asbestos work permit is required, depending on where you live and current standards.