Salt Damp - Hygroscopic Salt Contamination

Salt contamination is not only caused by Rising dampness.

Other sources of salt contamination of masonry and plaster are:

• Combustion gases in chimney flues contain traces of acids which form chlorides, nitrates and sulphates in the masonry. This is a common source of contamination at the surface of chimney breasts and reveals at all levels (upper floors as well as ground floor level).
• Prolonged leakage of tap water or central heating water.
• Leakage of soil water or contamination with urine. (Salts from animal urine are often responsible for salt damp problems in barn conversions/stables etc.
• Direct rain penetration

As these salts are often hygroscopic (Moisture Attracting), patches of dampness may appear and disappear depending on the weather. This can sometimes be confused with a leak occurring. This is why it is important to have a qualified surveyor investigate.

We have a range of specifications designed to deal with salt contamination. These will result in a dry and protected surface.

Vertical Damp Proofing Membrane Method

Here is an example of a vertical damp proofing membrane (Drybase Flex Membrance) being used to isolate the masonry from the new plaster finishes.

Plasterboards or wet plasters such as Thistle Hardwall and Bonding plaster can be applied directly on top of the membrane. A finish plaster (Thistle Board or Multi Finish) is then applied to a smooth finish.

Redecoration can then take place after 1 week where plasterboards have been used or 6 weeks after wet plaster finishes have been applied.

Ultimately, this vertical damp proofing system will prevent the movement of moisture and salts from the masonry background (wall structure) into the new wall finishes (plaster etc). This will give a guaranteed dry decorative surface.