Guidance for Heritage Property Owners
Maintenance increases the life of all old buildings. Regular maintenance will reduce the cost of repairs substantially, as causes of deterioration of heritage structures are often preventable. Most damage can be traced to a few factors, such as neglect, leakages, rising damp, growth of vegetation and termites.
The building should be inspected on a regular basis so that inaction does not convert a minor problem into a major one. For example, replacement of roof tiles is a very minor cost but if not undertaken in time, leaks could result in damage to the false ceiling, interior and roof structure thus necessitating more expensive repairs.
All heritage buildings must create their own in-house maintenance programmes.
Long Term : 3/5 years or longer
Medium Term : 1-3 years
Short Term: This includes immediate repairs.
The inspections should be timed as per the climatic cycle. For example inspections of the terraces and roofs should taken place before the monsoon in sufficient time to undertake repairs in order to prevent leakages. Repairs should be undertaken in materials and techniques as close as possible to the original.
Sometimes new elements used in a building can damage the building such as the metal screen shown in the photograph, which has rusted and stained the stone. The stains will be more difficult to remove and damage the stone.
Causes of decay
The cause for the deterioration should be identified before any repairs are undertaken. The following are the most common causes for the decay of heritage structures.
Maximum damage is done to old buildings due to leakages. If water leakage is prevented a lot of money can be saved. The following checks should always be maintained:
- Roof tiles should be checked regularly and broken ones replaced.
- The terrace should be properly waterproofed.
- The terrace should be cleared of all debris and gutters should be cleaned before monsoon.
- All vegetation growing in part of the building should be removed immediately and not allowed to take root.
- New water tanks should be placed after careful consideration. Arrangements should be taken for diversion of overflow. The overflow should not be allowed to fall on the building.
- The origin of the leak and its cause should be traced before any repairs are undertaken. Treating the leakage at the end will result in the dampness transferring itself to a new location.
- Leaking pipes should be repaired.
Rising damp is a serious problem and difficult to tackle. Before trying insertion of any layer in the walls, professional help should be sought.
- Ensure that the building has plinth protection.
- Prevent water collection around the building. Water must be drained away from the building.
- Remove all vegetation close to the building walls.
- Allow the walls to breathe by allowing proper ventilation and by using lime washes and not cement and oil paints on the surface.
- In many cases these solutions won’t work and lead sheeting can be inserted as a damp proof layer.
Plant growth in old buildings can cause severe damage, particularly when the plant is a large tree like a banyan or peepal. Pulling out plants will not solve the problem as the roots may remain in place. To remove woody plants, cut off the plant, retaining the stump. Add a solution of asafoetida to the stump and cover with a plastic bag. This is best done in summer as the plant will dry up quickly in the heat and the roots can be removed easily. In case of a large tree which has caused cracks in the structure, take professional advice, as sudden removal could also lead to a collapse. It is always better to remove all plants on a regular basis and ensure that there are no water leaks which will promote their growth.
As a rule, trees or plants should not be planted adjoining a heritage structure. While planting large trees, sufficient distance should be maintained.
Birds can damage a building with their droppings as well as create a lot of rubbish when they nest and should be discouraged from nesting. Nets can be used to keep birds out of the buildings.
Algae and moss:
Algae and moss can be removed by simple brushing with a bristle brush.
All the buildings must be inspected regularly for termite infestation. In case termites are found, anti termite treatment must be undertaken without delay.
Care of Building Materials
Building materials will last longer if they are maintained regularly.
Iron or steel:
All surfaces should be clean of rust, paint, etc before any preservative is applied. On exterior surfaces, three coats of boiled linseed oil applied every 24 hours can be applied after letting each coat dry.
Wood deteriorates rapidly when exposed to rain or with termite infestation. To preserve old wood, ensure that it is not exposed to rain or water leaks and check regularly for termite infestation. Applications of boiled linseed oil will help preserve it. Wood should be painted only if there is historical evidence that it was painted.
In many heritage buildings stone shows signs of deterioration. The cause needs to be identified. There are a number of reasons for the deterioration, from the quality of the stone to the workmanship. Stone can deteriorate if it is not laid correctly at construction or due to the weakness of the stone. It can also be damaged due to plant growth, painting of surface which does not allow it to breathe.
Repairs should not be undertaken without the expert advice of conservation experts. Historical integrity of the building fabric needs to be maintained and during repairs care must be taken to retain as much of the original material as possible is retained.
While undertaking repairs the materials used should be as close as possible to the original. For eg., if lime is replaced by cement, the behaviour of the structure will change. The life of cement is much shorter than lime, and it does not allow the building to breathe and traps moisture, which can weaken the structure.
To prevent roof leaks it may be necessary to introduce GI sheets in cases where the original structure had a tiled roof with a false ceiling. The tiles can be replaced on the GI sheets with the addition of wooden battens.
In case the plaster has failed, replastering can be undertaken using material similar to the original construction. Lime plaster should not be replaced. Cement plaster should not be used to replace lime plaster as cement does not allow the walls to breathe and will not allow the evaporation of moisture and may lead to further problems.
When cutting out and cleaning joints for pointing in stone, care should be taken that the stone is not damaged. When the mortar has completely failed, the cleaning of the joints should be done as far as the tools will allow, without the use of a hammer. Material similar to the original must be used, including the colour so that it harmonises with the old work.
Any damaged wood structural members should be repaired as far as possible and not replaced. In case replacement is essential a wood member should be used. If this is not possible, the member can be replaced by a steel rectangular sections of the same size.
Replacement of stone: Decaying stone should be replaced only when it adversely affects the stability of the building. The new stone should match the old stone as closely as possible. Dowels to be used should be of stainless steel, copper, and gunmetal. If iron dowels are used, they should be galvanised and laid in cement. The stone should be laid on its proper bed.
While renovating interiors, care should be taken that the interior design is in the same style as the building. Original panelling fixtures and fittings should be preserved. In case of restoration of any mouldings or decorative features, the material should be the same as the original.
Introduction of new services:
When new services are added in heritage buildings, it must be done with utmost care so as not to damage the structure and should be invisible as far as possible. Electrical and plumbing installations and fixtures should be fitted sensitively and in harmony with the building.
New Fixtures & Fittings
Fixtures should harmonise with the buildings and should be carefully selected so that they do not damage the building during installation.
Removal of paint can damage the surface and should be undertaken only on expert advice. Historically, when surfaces such as brick and stone were painted, lime washes or water colours were used. Today oil paints, toxic chemicals and cement based paints are used which can trap moisture within the walls and cause degeneration.
Brick & Stone surfaces:
Removal of paint from either surface will normally damage the surface and therefore it is best if it is left to weather and disintegrate naturally. In the intervening period, a lime wash could be used.
Lime wash, distemper can be removed with warm water.
Solvent strippers can be used to remove oil paints, tar and some emulsions. After stripping the paint, the residue should be washed down with white spirit as water can raise the grain and darken the timber. Sanding should always be done in the direction of the grain.
Unless absolutely necessary damaged elements should not be replaced, they should be repaired. Original elements such as cast iron railings, wooden railings, jallis add value to heritage buildings. In case some elements are missing such as cornices or chhajas which need to be restored to protect the fabric of the building, they should be in the same material as the original.
Recycling Old Material:
Many heritage buildings have removed or discarded original material. Many of the materials used in heritage building are not available today and restoration is difficult. It would be a good idea to create an old material store which could make such material available for heritage buildings.
Rust stains caused due to a metal screen
Damage from leaking roof.
Plant growth can damage the structure
Bird droppings can stain the structure
Moss growth on walls
Deterioration of stone blocks in the Mohite Gateway
Repairs with cement has caused grey streaks on the stone surface
Cement mortar for pointing used in a building with lime mortar.
Leaking pipes can cause serious damage