I purchased a 4-flat apartment that I have occupied one of the upper floors as a tenant. I love this apartment because the internal finishings looked good. Though the compound was about the same level with the "unpaved" road, the compound was never water-logged until recently when all the roads on the estate were paved except ours. The problem we face today is multi-faceted.

1) The compound now is below road level due to regular intervention on the road (pouring of rubbles).

2) A barrier has been built to stop water encroachment from the street but that means that the compound becomes "perpetually water-logged".

3) Last rainy season sacked the tenants on the ground floor due to rising damp from the wall and completely destroyed the painting and skirting as water seeps in from the floor-wall junction and forms ponds on the floor. The damp is so bad that the Chinese doors and even the ward-ropes have been destroyed.

4) The integrity of the structure is being compromised.

Please who is an expert in this subject? Can this building be salvaged from imminent collapse?


I am a geologist so I have started pulling some articles to understand the real cause of this problem and possible answers. I will be posting these articles as I wait anxiously to hear from the professionals.



Rising Damp

Tim Hutton



Rising damp is widely misdiagnosed in existing buildings, based on the incorrect interpretation of visual evidence and the readings of moisture meters. Because of a highly successful sales campaign for over 30 years by specialist remedial contractors installing injected 'chemical dampproof courses', this misdiagnosis of rising damp has also become synonymous with a diagnosis of a lack of an 'injected chemical damp-proof course'. Although this has been very good for business, it has often resulted in a waste of the clients' money and resources; original plasters and finishes have been destroyed in the process of installation, and unnecessary damage has been caused to original structures by the drilling of irrigation holes. In addition, money that might have been spent on more cost-effective maintenance or repair works has been wasted.

Whilst injected chemical damp-proof courses may provide some protection for certain types of structure if properly specified, their general application is rarely the most cost-effective way of controlling damp problems in buildings, and may be wrongly specified and ineffective. In particular the more generally available water based products may only form an effective ‘hydrophobic band’ if applied to a dry wall after it has dried out. This can prevent their effective installation in damp walls.

CAUSE AND EFFECT

Rising damp actually describes the movement of moisture upward through permeable building materials by capillary action. It becomes a problem if the moisture penetrates vulnerable materials or finishes, particularly in the occupied parts of a building. This moisture will dissolve soluble salts from the building materials such as calcium sulphate, and may also carry soluble salts from its source. If the moisture evaporates through a permeable surface, these salts will be left behind and form deposits on or within the evaporative surface. Where there is a large evaporative surface, salt crystals are deposited as a harmless flour-like dusting on the surface. If evaporation is restricted to localised areas such as defects in an impermeable paint finish, then salt deposition is concentrated, forming thick crystalline deposits with the appearance of small flowers; hence the term 'efflorescence'. When evaporation occurs within the material, salts can be deposited within the pores. The expanding salt crystals in these locations may result in fractures forming in the material and spalling of the surface. This type of decay may be seen in porous brickwork or masonry.

When there has been a long-term problem with moisture penetration, evaporation at the edge of the damp area leads to a distinctive 'tide mark' as a result of salt deposition. Where this occurs at the base of a wall, the tide mark is often taken as a typical diagnostic feature of 'rising damp'. However, these salt accumulations may remain even when the water penetration that originally caused them has long gone. Similarly, water penetration may have occurred from causes other than 'rising damp'.

The most common source of moisture in the base of the walls of buildings is from defective ground and surface drainage. This is present to some degree in almost every building in the country, due to a combination of such factors as rising ground levels, the failure of ground drainage systems, and the increased use of concrete or finishes around buildings without consideration of drainage slopes.

Damp masonry at the base of walls may lead to a number of problems:

•The moisture content of the structure may rise to a level at which decay organisms may grow, or the materials themselves may be adversely affected. For example, timber skirting boards or built-in bonding timbers along the base of walls may become infected and decayed by dry rot, wet rot, weevils or woodworm.


•In very damp conditions, the inorganic materials themselves may lose their structural strength. This occurs most spectacularly with walls made of cob (earth) soaked with water.


•Damp conditions on the surface of walls, particularly in conjunction with condensation, allow the growth of moulds both on the surface and within porous or fibrous materials, such as wallpapers or carpets fitted against the base of the wall. Not only is this aesthetically unacceptable and damaging to finishes, but it can be a significant health hazard to occupants.


•Where evaporation takes place, the deposition of soluble salts on the surface or within the pores of materials can cause aesthetic and structural damage.

TREATMENT OPTIONS

As described above, 'rising damp' is only one of many mechanisms resulting in high moisture levels in the base of walls, and even when it is a significant factor, it is rarely the primary source of moisture. The management of problems due to high moisture levels requires the proper identification of the moisture source and the defect responsible, before the most cost-effective solution to the problem can be determined.

Damp and its effects may then be controlled by adopting one or more of the following measures:

•The provision of suitable moisture sinks to dissipate the moisture at its source without causing problems to the structure or occupants, and the repair of any contributing defects acting as moisture sources, such as broken pipes.


•The introduction of either physical barriers using damp-proof membranes or materials to form a 'damp-proof course' or hydrophobic (water-repellent) materials as in 'chemical damp proof courses'.


•The isolation of vulnerable materials such as timber and interior finishes from damp fabric.

READ SOURCE BELOW FOR FULL ARTICLE

http://www.buildingconservation.com/articles/risingdamp/risingdamp.htm

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