Urban A-Salt !

Is the council destroying your building?

Road salt is one of the most damaging substances when it comes to stone buildings.

When salt dissolves in water, and splashes against a wall, it soaks into the structure of the stone, deeper and deeper into the microscopic pores. Once it is in the stone, it is almost impossible to remove. Year on year, the quantity of salt within the stone builds up.


Salt damage to stonework MAAC studio conservation architect


We often talk about the impact of frost damage on saturated stone, but salt gives a double whammy. In freezing weather frost crystals grow within a saturated wall shattering the microscopic structure of the stone, when the weather warms and the walls starts to dry out, salt crystals begin to grow. Not only do you a white stain and unsightly tide mark appearing on the stone, at a microscopic level, the salt crystals are extremely sharp, cutting through the stone as they grow like mini scalpel blades.

This is particularly damaging to sandstone and in particular the soft red tarradale sandstone that is so predominant around inverness. The surface of the stone becomes so friable that is just turns to sand, disintegrating as you brush your hand across it. Eventually you will have no option but to replace the stone.


Salt staining and efloresence MAAC Studio conservation architect


Are there treatments available ?

Water repellents and surface coating all have their problems. Some will prevent the stone from breathing increasing the problem. Some will protect the outer face, but will not penetrate deep into the stone with the result that eventually the face of the stone will split off. There are specialist mortar repairs available, but these will only ever last 10 years and then they will begin to fail. These treatments require a great deal of specialist knowledge and skill and should only be undertaken on the advice of a conservation architect.

The problem is, once the salt is in the stone, its too late ?


Salt damage and repairs MAAC Studio conservation archtect


Is the council going to compensate you for the damage, unlikely, they will argue that it is a safety issue.

If you property is right beside a public road or pavement there are some measures you can take. First stop using salt or any mixture of grit and salt around your building. Use unsalted grit and spread it on paths early, before the frost forms rather than as an after treatment and don’t allow snow to build up on paths.

It may sound like a chore, but you will save yourself thousands of pounds in stone repairs.


MAAC studio are accredited conservation architects and principal designers working with traditional buildings throughout Scotland. 

If you need independent advice give us a call ?