South Africa is rich in architectural history. From Cape Dutch farmsteads to early 20th – century municipal buildings , our
towns and cities are dotted with structures that reflect the passage of time and the evolution of style.
But time and weather take their toll as many of these buildings were constructed long before effective damp- proofing methods
existed.
Older buildings often lack modern damp – proofing systems. We find
Overtime , changes to building use or structure like blocked vents , sealed floors or modern extensions can exacerbate damp issues. What once worked , may now be failing.
Rising damp , penetrating damp and the slow decay of irreplaceable heritage.
The 60 – Year Rule
Under Section 34 of the National Heritage Resources Act , any building over 60 years old is protected by law.
You may not alter , demolish or apply treatments , even paint or plaster without a permit from the relevant heritage authority.
That means any damp treatment done must
Construction of these buildings are usually with stone or even clay bricks. Rising damp presents itself on the exterior of walls as a white fluffy powder – efflorescent salts whilst the interior wall surfaces may be of similar construction or even covered in a lime plaster which will start to delaminate and show signs of salts.
Under these circumstances it is possible to create a chemical damp – proof course following the lines of the mortar between the stone and bricks. Dry zone Cream is injected in to holes drilled into the mortar at regular intervals to create a moisture barrier using silanes and siloxanes. This barrier should be created as close to the top of the floors lab as possible. This prevents ground moisture rising above this level and enables treatment of any damaged plaster on the inner surfaces to be effected. It is sound practice to remove plaster 300 mm above floor level or above the highest visible plaster damage and to allow walls to dry out for several days before further treatment. New plaster , lime – based or conventional cement and sand should be mixed with Safeguard Chemicals Renderguard Gold ( a salt retardant ) to prevent the growth of any further salts in the new plaster.
Floor surfaces may also show signs of damp. Where there are floor tiles, signs of efflorescent salts may be seen in the grouting. Since these tiles may be part of the history of the building it may not be possible to remove the tiles to damp – proof the underlying substrate. Under such circumstances and provided that the tiles themselves are not showing signs of damp , the grouting should be raked out and re – placed with new grout mixed with bonding liquid. This should repel moisture for some considerable time.
If moisture starts penetrating the outer skin of the building , the stone /mud bricks and mortar will need to be treated with a water repellent.
In the past this has been achieved using a liquid – based product that had to be applied in 2 coats and repeated every 2 years due to UV attack.
Safeguard has introduced a cream – based water repellent – Storm Dry – that is applied by brush in one coat and penetrates the substrate to a depth of 2 – 3 cm making it totally resistant to UV attack. As a result it has a guaranteed life in excess of 10 years. Whilst the cream is white in colour , it is soon absorbed by the substrate and on curing does not change the appearance of the substrate in anyway.
Any damage to internal plaster should be treated in the same way as Rising Damp.
Rainwater penetration of the outer skin of a building is not only unsightly but can cause serious deterioration of the building substrate as well as causing considerable damage to interior surfaces. A wet wall is also something that will affect the thermal properties of a building. Simply put , a dry wall is a warm wall. When walls retain more heat , houses stay warmer for longer. This reduces the reliance on heating , which leads to lowered energy bills and reduced household carbon footprints.
In areas where there is considerable frost , water accumulating in the substrate will turn to ice and cause serious spalling of brickwork and concrete. Wet walls are also serious health hazards as they provide a perfect growing medium for fungus and mould.
For many years , exterior stone and brickwork surfaces have been treated with a variety of products to prevent water ingress . Some have sealed the exterior by blocking the pores – varnishes etc. But this can be counter – productive as it does not allow the building to “ breathe ” – releasing humidity build – up with in the building.
Various liquid – based products containing silanes and siloxanes have been used successfully for several decades . These have been either solvent or water – based products which have prevented moisture ingress whilst still allowing the escape of water vapour from the interior of the building. These products , however , simply lined the exterior building surface and were affected by UV attack requiring them to be re – applied every 2 – 3 years.
