Building Salt Deterioration
What is Salt Deterioration?
Over the last 10 years, there have been many buildings that have been in the news with either collapsed brick walls, shop front awnings, concrete patios and in part excessively sagged roofs. Many of these are caused by salt deterioration and the effects on a building are of a structural concern, particularly those located close to the sea with these buildings approaching the age where the prolonged exposure to salt has now caused significant deterioration to the building.
Due to an incident at Manly of a shop awning collapsing due to salt deterioration, Council now requires that all shop owners in the area provide a Structural Engineer’s certification that the shop awnings and brickwork are structurally adequate.
Most of these problems are related to salt deterioration of the mortar to the brickwork, particularly in exposed location. This does not preclude that some buildings located 1 to 5 kilometres from the sea can also be affected by salt deterioration over a longer period.
What happens with Salt Deterioration?
The salt will cause disintegration of the soft lime mortar and can cause some dislodgement of brickwork. The problem is further aggravated by the wall ties which secure external brickwork to the internal skin of the brickwork. As the external bricks are wet and affected by salt, this will accelerate the rusting of the ties and can result in the ties being completely rusted through.
This leaves the external skin of brickwork unrestrained to the building and can be subject to excessive structural bowing. In extreme cases this will result in the wall physically collapsing and can cause death or significant injuries. There are some situations where soft callow bricks are deteriorated due to the salt environment. Further, many of the bricks used during the 1960’s, 70’s and 80’s is not salt tolerant and particularly in exposed locations can be subject to surface disintegration.
Terracotta roof tiles are not salt tolerant, particularly those constructed after 1950. The degree of deterioration is not evident from the external side but can be readily viewed from the underneath. In some extreme cases the tiles can be affected by excessive salt deterioration and require replacement within 20 years from the date of installation. Failure to replace the affected tiles will result in excessive water entry to the building.
Many of the structural timbers, particularly to Oregon, can be affected by delignification due to the salt environment. Delignification is a breakdown of the cells of the timber which does result in a substantial varied look to the timbers. The early stages of this are not a problem but in an advanced condition it can cause significant loss of structural strength of timbers and can result in the collapse of the roof.
If you have any questions about possible salt deterioration problems in your property or a property you are thinking of buying, then please get in touch with us below. With over 30 years’ experience inspecting buildings, our expert consultants will be able to help you understand the condition and potential issues of a building you own or are considering.
