Asbestos in mortar: masonry mortar, render and grout

Mortar can contain asbestos, particularly old masonry mortar, render, chimney mortar and grout, as well as fire-stopping compounds. Asbestos in mortar cannot be seen with the naked eye, so it is identified with a sample before the mortar is chiselled, drilled or demolished. This applies to every building constructed before 1994 or whose mortar dates from before 1994.

Which mortars may contain asbestos?

Asbestos in mortar goes back to the fact that asbestos was added to cement-based products to improve strength, crack resistance and fire resistance. There is more mortar in a building than many people think, because it is often hidden under tiles, boards or paint. Typical mortars that are examined include:

• Masonry mortar in brick and block walls, partition walls and basement walls.
• Render on facades, plinths, in basements and on interior walls.
• Chimney and fireplace mortar in chimneys, masonry stoves and flue connections.
• Grout in tiling in bathrooms, saunas and kitchens.
• Fire-stopping compounds and fire seals at pipe and cable penetrations.
• Repair mortars and patches from earlier repairs.

Mortar is often linked to concrete structures, so see also asbestos in concrete. Not all old mortars contain asbestos, but you cannot tell by looking. The same building may have both asbestos-containing and asbestos-free mortar in different places.

Chimneys and fireplaces

In detached houses, asbestos in mortar often comes up during chimney and fireplace work. Heat-resistant mortars and compounds were used in the masonry of chimneys and stoves, at flue connections and around soot doors. Chimneys have also often been repaired at different times, so the same stack may contain original mortar and later patches. In old timber houses, such as post-war veterans’ houses, the chimney and fireplaces are often where even the original structures may contain asbestos.

Is there asbestos in grout?

Grout may contain asbestos, especially in tiling from the 1960s to 1980s. When tiling is removed, the tiles, grout, tile adhesive and often the filler beneath are all broken up together. That is why grout is usually tested at the same time as the tile adhesive, with separate samples where needed, because the layers may be different products. Read more about asbestos in tile adhesive.

Even simple regrouting breaks up the old grout. When old joints are opened with a grout rake or multi-tool, the grout comes away as dust. Renewing grout is therefore a job where the old grout should be tested first.

Which jobs break up mortar?

Intact mortar left in place does not usually release fibres. The risk arises when mortar is worked mechanically. Jobs like these include:

• Chiselling: removing tiling, stripping render and opening up walls.
• Drilling and fitting fixings in masonry and rendered walls.
• Chimney renovation: opening the flue, relining, repairing or rebuilding the stack.
• Dismantling or replacing a fireplace, which breaks masonry and fireplace mortar.
• Raking out and regrouting joints in tiling and masonry.
• Opening penetrations during plumbing, electrical and ventilation work.
• Repairing facade render, when old render is hacked off.

Many of these are small jobs, but chiselling and drilling produce fine dust that spreads easily. If the building or mortar dates from before 1994, a survey is required before renovation and demolition work under Finland’s Asbestos Act (684/2015) and the Government Decree on the safety of asbestos work (798/2015).

Can you identify asbestos-containing mortar yourself?

Not reliably. Asbestos fibres are so small that they blend invisibly into the mortar, and its colour, hardness or texture tells you nothing about asbestos. The year of construction and renovation history help you judge which mortars are worth testing, but the answer only comes from laboratory analysis. A surveyor can also tell where different mortars have been used, for example in the original masonry and in a later repair, and target the samples accordingly.

How is an asbestos sample taken from mortar?

A mortar sample is taken from a spot that represents the whole structure. A few points are worth keeping in mind:

1. A separate sample for each type of mortar. Masonry mortar, render, chimney mortar and grout are different products, so one sample tells you nothing about the others.
2. Consider the layers. Render may have several coats from different periods, and at repaired spots the patching mortar may differ from the original.
3. Wet it before removal. The mortar is wetted so no dust is produced, and the piece is removed with a hand tool without drilling or grinding.
4. Airtight packaging and labelling. The sample is sealed straight away in an airtight bag marked with where it was taken.

The samples are analysed in the laboratory with a JEOL SEM-EDS electron microscope. If you want to check a single mortar, for example before relining a flue, you can send a sample by post for 39,90 € + VAT per sample. For a larger renovation involving several mortars and other materials, a survey covers everything in one go.

How much does it cost to test mortar?

Depending on the city, an asbestos survey costs from 119 € incl. VAT. The price includes the survey, all samples, the laboratory analysis, travel and the report, so testing different types of mortar does not raise the price. If the whole building is being demolished, 100 € is added for a demolition project. The surveyor visits on site in Southern Finland. From elsewhere in Finland, a mortar sample can be sent by post. See the price for your city in the price list.

If the mortar contains asbestos, the chiselling and demolition work is carried out by an authorised asbestos removal contractor. If no asbestos is found, the renovation can go ahead as normal.