Water hazard: The soggy blight on old buildings

Maria Endah Hulupi, Contributor/Jakarta

Restoring an old, damaged building to its former glory requires careful planning, handling and, of course, considerable financing.

Shining examples of properly conserved ones include the National Archives building and Fatahillah Museum in West Jakarta, but more pressing funding priorities and ignorance of the significance of cultural heritage are among the main reasons why old buildings in the country are often abandoned.

A common problem affecting old buildings is dampness, causing damage ranging from the decay of timber, termites, corrosion of metal structure, mold and mildew to structural failure of concrete, masonry and renders.

Dampness most frequently happens here due to leaking pipes and roofs, flooding, rain (falling damp) and rising damp. The latter, if not anticipated and managed properly, is a source of serious deterioration, threatening the stability of structures and destroying early, fragile building materials.

Rising damp-related damage occurs when salt-laden ground moisture rises to building materials through capillary action. It dries up near the surface of the wall and causes salt crystals to form. The latter pushes out from a very small hole, creating a bigger and bigger hole.

"It grows like a cancer and can be harmful when inhaled in a confined area," said the principal heritage architect of the New South Wales Government Architect's office, Bruce Pettman, during a recent seminar on rising damp in heritage buildings.

Other possible damage comes from staining of wall surfaces, increasing loss of mortar joints, renders and plasters, cracking, loss of larger areas of wall surfaces and, occasionally, floor finishing too.

The type of damage can be differentiated into efflorescence (white powder seen on the wall where the crystallization begins); exfoliation (when the wall surface breaks away); fretting (when timber material breaks away) and erosion, which eats away at the building.

Rising damp is controlled by installing damp rising courses (dpc) or a barrier -- usually made of slate bitumen, glass, terra cotta, fly ash, granite, hard-fired bricks or composite mortar -- in the bottom of walls to stop the moisture from rising. When old buildings are not equipped with sufficient damp proof courses, they are prone to develop such damage.

Besides failure of the original dpc, poor under floor ventilation and inefficient disposal of rain water at the base of the building, Pettman also mentioned that rising damp could also be caused by breaching the original dpc through applying coatings or render repairs over dpc joints.

Changing floor materials and under floor spaces also aggravate the problem.

"Old traditional buildings in Indonesia have tile floors which sit on sand, where the moisture can evaporate through the joints and so the floor can breathe. When you put concrete (on top), the floor cannot breathe so the moisture kept down and rises to the walls."

He added that having a garden bed against a wall of a building also helped bridge the ground moisture from rising up.

Rising damp is also facilitated by failure of building services -- such as leaking pipes and blocked drains -- and inappropriate repairs that range from using a hard cement base for renders and plaster (which smother the wall and cause cracking) and for repointing of brickwork and stonework (which make the joints harder and cause damage to the original bricks or stones, instead) to blocking of floor vents.

When rising damp-related damage affects heritage buildings, Pettman said conservation efforts should be made based on through investigation of the possible causes. The building's original and current materials and their condition must also be taken into account before making any decisions.

It is also important to study the in-place protective measures, such as the building's drainage and ventilation systems, to determine if they have been damaged or disturbed. Knowing the location and types of early and existing services, like drainage, storage tanks and water supply, is also necessary.

In general, the wisest thing to do is to do as much as is necessary but as little as possible, Pettman said.

"Old buildings are fragile, they are sometimes made from porous materials, so you cannot stop the moisture completely. What you need is to eliminate as much as possible and do it in a sensitive way."

He added that most old buildings used limestone rather than cement, and it was important to replace it with the same sort of material whenever possible.

Uninformed decisions are often made regarding repairs, ranging from covering the wall with paneling (which does not solve the problem), applying coatings to the affected wall (only serving to hide the problem) to other work that causes even more serious damage and ruins the original appearance of the building.

"There is no cure-all for all forms of rising damp, and a combination of treatments is often required," Pettman said.

In the restoration effort to safeguard the country's rich cultural heritage, it's a race against time to prevent worsening damage.

And it's up to the public to help out.

"You are the stewards of the past for the future," the architect said.