CAUSES / SOURCES OF

DETERIORATION AND DEFECTS

DETERIORATION:

DETERIORATION:

• Deterioration is the process of becoming worse and in the context of building materials and components it can be said to be transition from fulfilling to not fulfilling their intended function.

• It is a natural process which can only be minimized, slowed down or abated by taking the correct action at the appropriate time.

• Durability is the rate at which deterioration take place.

WHEN IT STARTS?

• It starts when the molecular bond of the building material is broken.

• Molecular bond of different materials is broken by different agents.

Mud brick and mud mortar WaterBurnt brick Salt Lime stone Chemical

Sand stone ChemicalMarble Air Pollution, Bird DroppingsWood FireIron Heat, Water

SYMPTOMS OF DETERIORATION

Historic Buildings and Remains of Buildings show signs of Material Decay and Structural Distress.

MATERIAL DECAY:

• Crumbling and spalling of brick.

• Spalling, splitting, powdering, staining and pitting of stone.

• Weathering, loosening, powdering and cracking of mortar joint.

• Weathering, cracking and detachment of rendering.

• Glaze cracking (crazing) and spalling and detachment of architectural glazed terracotta.

• Blustering, peeling and detachment of fresco painting.

• Corrosion of iron cramps and dowels.

• Decay of timber.

There are only three basic causes of deterioration: 1. Dampness2. Movements(i.e. physical changes)3. Chemical / Biological changes The above three causes of deterioration of historic buildings can have many sources and some of them are interactive.

CAUSES / SOURCES OF DETERIORATION

Structural Distress:

Leans, Bulges, Displacement & Fractures

POSSIBLE SOURCES OF THE THREE CAUSES OF DETERIORATION

I. Dampness:

1. Rain2. Ground3. Atmosphere (Condensation notable)4. Faulty services5. Faulty mortar joints; damaged parapets; cracks in

the masonry; defective gutters, down spouts and flashing; copings with leaks; Ivy growth; damaged surface such as sand blasted brick

6. Poor maintenance7. Incorrect usage

POSSIBLE SOURCES OF THE THREE CAUSES OF DETERIORATIONII.Movements:

1. Faulty construction2. Faulty material3. Inadequate design4. Material movement5. Wall movement6. Change in the original pattern of loading, thrust and counter thrust – active

through history and derived from the building’s own structural form due to alterations

7. Foundation failures or ground movements, overloading of foundations, differential settlement of foundation, undermining of foundations, consolidation of soil below foundations, movement of soil below foundation

8. Wind9. Vibration10. Changes in temperature11. Changes in moisture (some of the sources for dampness relevant, but the

atmosphere notably)12. Other physical changes (such as crystalline salt formation, weeds, shrubs and

ivy growing in the joints of masonry)13. Chemical changes (most of the sources of dampness, atmospheric pollution

relevant e.g. corrosion of iron cramps and dowels)

II.Chemical / biological changes:

1. Dampness (corrosion, wood decay)2. Fire3. Solar radiation (fading and/or decomposition of

paints)4. Atmospheric pollution5. Biological agents such as dry and wet rot,

moulds, algae etc6. Incompatibility of materials adjacent to one

another (e.g. laying of lime stone above sand stone)

POSSIBLE SOURCES OF THE THREE CAUSES OF DETERIORATION

STANDARD CATEGORIES FOR CONSERVATION WORK

IMMEDIATE Any work needed to prevent imminent collapse or danger to persons.

URGENT Work which must be done within 3 months to prevent rapid decay such as fungal attack, rainwater penetration.

NECESSARY Work which should be completed in 2-5 years. The bulk of conservation work lies in this category. Two years give sufficient time for funds to be made available.

DESIRABLE This is variable quantity and depends on the standard of maintenance required. It generally includes internal redecoration and may include rehabilitation schemes. Unfortunately, this item often gets postponed due to shortage of funds. If work affects the life of the historic building, it should be classified as necessary.

MONITOR This category includes any item which needs further investigation. Typical examples are the movement of cracks or the deterioration in roof covering.

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