Asbestos was widely used in building materials for much of the twentieth century because it is durable and resists heat. It is not usually a hazard when it is intact and undisturbed. The concern arises when materials containing asbestos are damaged, sanded, cut or demolished, which can release fibers into the air. That is why an inspection is so often the first step before renovation or demolition.
Why you cannot tell by looking
Many asbestos-containing materials look exactly like their asbestos-free counterparts. A floor tile, pipe wrap or ceiling texture gives no visual signal of what it contains. The only reliable way to know is to collect a sample and have it analyzed by a qualified laboratory — or to treat the material as if it contains asbestos.
Step 1: Identifying suspect materials
The inspector walks the areas of the building that are in scope — often the areas that will be disturbed by planned work — and identifies materials that could contain asbestos. Common examples include:
- Pipe, boiler and duct insulation
- Vinyl floor tiles, sheet flooring and the adhesive (mastic) beneath them
- Textured ceilings, ceiling tiles and plaster
- Drywall joint compound
- Roofing, siding and window caulking or glazing
Materials that look and behave alike are grouped together so that each distinct type can be sampled appropriately.
Step 2: Collecting bulk samples
For each suspect material, the inspector removes a small piece using procedures designed to limit fiber release — typically wetting the material, wearing appropriate protective equipment, and sealing the sample container immediately. The sampled spot is then patched or sealed. Each sample is labeled with its location and recorded on a chain-of-custody form.
Step 3: Laboratory analysis
Bulk samples are most commonly analyzed by polarized light microscopy (PLM), which identifies asbestos fibers and estimates their percentage in the material. Under the U.S. EPA definition, a material containing more than 1% asbestos is considered asbestos-containing. In some cases, additional methods are used for materials where fibers are very small or difficult to detect.
Step 4: The report
A useful asbestos report lists each material sampled, its location, its condition, the laboratory result and whether it is considered asbestos-containing. It should also note any areas that could not be accessed, since an inspection can only speak to the materials it actually evaluated.
An asbestos inspection is not about finding a problem. It is about knowing what is in the materials before anyone disturbs them.
When an inspection is needed
Federal rules require many commercial buildings and larger residential buildings to be inspected for asbestos before demolition or certain renovations, and state and local requirements may also apply. For single-family homes, an inspection before renovating older materials is a sensible precaution even where it is not required. If asbestos-containing materials will be disturbed, removal or other abatement work must be handled by appropriately licensed abatement professionals — separate from the independent inspection.