Let's talk about rising damp

The common reaction to moisture laden walls is Rising Damp. Is this possible, is water actually defeating gravity? There has been much discussion between architects and architectural associations as to whether this is possible for water to rise above the water table without any help. So lets take a look.

Rising damp as a phrase is common place and it is the most used phrase by many contractors when seeing moisture patches on walls. Yes we all agree that if a moisture meter is placed on a moisture laden wall it will activate. The meter registered water so what else can be causing it but rising damp, a damp course must be installed correct, sorry wrong.

For water to rise above the water table, it requires assistance, it cannot defeat gravity by itself. One very common problem is salt, this can come from the building materials and air quality within the property.

The salinity of the United Kingdom is uniformly high. Surface waters average about 38 parts per thousand except in the extreme western parts, and the salinity can approach 40 parts per thousand during the summer months.

The salt is hygroscopic, meaning it attracts water. And salt increases the ability of water to carry electrons, which get corrosive when a redox reaction occurs (reduction and oxidation). Most people will know that salt air is most prevalent in coastal zones.

Once salt settled on a wall, it will draw in moisture from the air and any localised nearby water source which will assist it to rise up the walls both internally and externally, usually to a height of .08 of a meter, from then on travel laterally.

So what about a damp course? A damp course will have zero effect in controlling the moisture and is likely to do more structural damage than help the situation. Pumping fluids into the mortar line can cause a separation between the mortar and granule bonding, therefore weakening the structure.

Another solution I very often come across is dry lining of the walls. Dry lining of walls is a very useful method to cover up untidy or uneven walls, or being used as insulation. But when used to cover up moisture laden walls, this is bad practise, as a damp wall can loose up to 50% of it load bearing ability.

So is there such a thing as unassisted rising damp coming up from the foundation, I am afraid not.

To correctly rectify high moisture levels in walls, the source reason for the problem must be found and repaired, for that you require a technical survey undertaken with the correct equipment, not a simple moisture or thermal meter. When a wall has been subject to high levels of moisture over a period of time, it will have certainly effected the indoor air quality, bacteria and mould will have started to develop, even if it's not visible on the walls, there is a very high possibility of infestation.

Structural damage may have developed and salt acids formed and surface wall coatings degenerated. If detected and rectified early, the cost of repair should be low, so make sure you employ qualified independent advice, not someone looking for a job to work on.

Be sure to employ a qualified technician in all structural matters. www.pureazone.com