Let Me Breathe! A traditional approach to damp proofing

One of the mains causes of dampness problems in period buildings is due to the introduction of cement based renders and modern paint systems

 

Premier heritage's work on a grade 2 listed building

 

This large two storey Grade II Listed brick built house, with rendered elevations beneath a slate roof, is believed to date back to the 17th & 18th century, with the front elevation being added in the 19th century.

Traditionally period building were constructed using lime which allowed the walls to breathe, however when this is replaced with cement pointing or render or covered with modern paint systems then dampness can become trapped within the fabric of the wall and this generally results in the spoiling of internal decorations and plasterwork.

The rear elevations of the property (south-west facing) suffered from patchy internal dampness due to rising damp and rain penetration, resulting from cracked, hollow and delaminating render externally, which was aggravated by the application of numerous layers of modern paintwork. The render to the later front section of the house was in much better condition as this was less exposed.

Our initial investigation of the rendering revealed that it was made up in a two coat lime mortar averaging around 25-30mm in thickness. This had been subjected to extensive patching and repair using modern cement mortars and as a direct result of the application of modern paint systems was no longer meeting its designed requirement. Therefore it was now trapping moisture within the fabric of the wall and slowing down the evaporation process. This in turn was also causing other defects such as damp ingress to chimneys, lintel decay and contributing to the decay of window joinery.

Premier Heritage working with the clients appointed Chartered Surveyor undertook an extensive survey of the property, followed by the preparation of a specification of remedial works and then supervised the appointed contractors. The remedial works included the stripping and re-rendering of the external walls and chimneys with a lime based mortar, using a two-coat, weak hydraulic lime and sharp washed sand mortar incorporating an animal hair in the base coat.

Once the rendering had been completed the walls were redecorated using the Keim conservation specialist paint system, the walls now “breathe” and the dampness problems have been resolved.

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