Building materials often form layered assemblies. Beneath a tile there may be mortar, adhesive, filler or waterproofing. When a representative piece is removed, the layers belonging to that assembly are submitted together in one sample bag.
Why should layers not be sorted at home?
Asbestos content cannot be judged from a layer's colour or position. Separating every thin layer yourself can leave out part of the material and creates unnecessary handling.
A representative piece shows the laboratory what the assembly contains. A tile fragment with attached mortar and adhesive is packed as one sample. Label it by location and material, for example “bathroom wall, tile and underlying layers”.
When is another bag needed?
Use another sample for a different material assembly or clearly different location. Bathroom wall tile and floor vinyl flooring do not belong in the same bag. Materials installed during different renovations should also be kept separate when they differ from each other.
A useful rule of thumb
Keep layers that come from one structure together. Keep different structures, materials and clearly different locations in separate bags. This keeps the sample understandable and allows the result to be assigned to the exact place where it was taken.
If the technical material name is unknown, use a practical description. An exact location and understandable material description matter more than perfect construction terminology.