Repair and Maintenance

Information about Historic Environment Division and their role providing advice and guidance relating to historic buildings and energy efficiency.


The Department is responsible for supplying advice to owners on how best to look after their buildings. We are also happy to visit a building and offer on-site advice, and this can be arranged by contacting your Area Senior Conservation Architect.

If you are unsure, you can contact us;


The Division publishes a range of guidance documents and Technial Notes aimed at improving  the quality of work carried out to historic buildings and ensuring that their character is maintained.


Information on grants and funding for repair work to Listed Buildings can be found within the site topic;

A Guide to Maintenance

All buildings require maintenance and it is the best way to ensure the continued life of your building. It's importance can't be overemphasised as most of the damage that occurs to historic buildings can be avoided by small scale regular maintenance that can ensure an indefinite life for most building elements. Inevitably, defects start as a small problem and grow in scale if not fixed.

Regular maintenance requires a relatively small amount of time and very considerable savings will be gained in the long term as a result. Scanning a roof, for example, can reveal missing or loose slates, or noting broken guttering can pinpoint areas where serious decay will result if the problem is left unattended. Maintenance must be carried out regularly and systematically. Without it the aesthetic appearance and fabric of the building can deteriorate to an unacceptable level. If this is allowed to continue a more extensive restoration will be needed to guarantee the preservation of the historic building.

Maintenance checklist

The following checklist is not intended to be exhaustive, but to identify aspects of maintenance that if overlooked can lead to serious problems.

Leaves and silt

Blocked gutters, particularly secret gutters, can lead to water penetrating external walls and wet rot in structural timbers which can require very costly repairs. Leaves and silt should be removed from gutters, flat roofs, downpipes, gully traps etc. roughly every three months and more frequently during the autumn fall of leaves.

Plant growth

Most historic buildings are constructed using lime mortar which has many features that make it a superior material to modern cement based mortar. After a century or more, however, it can become susceptible to damage from the roots of vegetation. Vegetation should be removed at regular intervals before the roots penetrate the structure.


Moss can harbour damp and cause slate to delaminate and should be removed. The acid run-off from moss and lichens will gradually erode all metals. There is a particular danger to lead work, but copper, zinc and iron are all at risk where these growths exist.

Bird droppings

Bird droppings can cause timber decay and should not be allowed to accumulate.


Where treatment of woodworm, repairs, or alterations are planned in any building used by bats, advice must be sought from us to conform with Wildlife (NI) Order 1985. Also when bats are unwanted, advice will be given on how to evict or deter bats while avoiding any harm to them.

Insect or fungal attack

Regular checks should be made for signs of active attack in the building timbers, such as bore holes and sawdust. If this is suspected, seek advice from a professional consultant or specialist contractor.


Snow should be removed from valley and parapet gutters where there is a danger that it could build up above the level of the lead flashings and so allow water into the building.


Historic buildings achieve a balance between the uptake of moisture from internal as well as external sources, such as cooking, washing and rain, and its subsequent release. When released internally the water vapour must be allowed to escape through ventilation openings and chimneys; otherwise condensation will occur which can lead to fungal attack. Redundant chimneys should not be sealed for the same reason, but should be cleaned and weatherproofed as water accumulating in a disused flue can be very damaging.

Woodwork, metalwork and walls

Depending on the degree of exposure, external woodwork, render and metalwork should be repainted every three to five years. Lime render should be lime washed. A variety of colours are available and the washes, when properly constituted, will give a durable finish that will allow the wall to breathe. In windows pay attention to the state of the glazing, the glazing putty and the timberwork to ensure timber windows are in good order. Timber windows can be particularly vulnerable to rot attack so investigate any smells of rot or the mustiness of damp.

Slates and tiles

Slipped slates can lead to water penetration. Loose and slipped slates or tiles should be refixed as soon as possible, and broken slates or tiles replaced with matching ones.

Lead Flashings

Slipped lead flashings should be refixed, and damaged ones replaced, as soon as possible.

Lead roofs, valleys and gutters

Lead sheets should be inspected for holes or splits that can lead to water penetration. The internal sign of water penetration is often far removed from the defect, as water will often move horizontally through the structure before finding a vertical path. Small repairs may be made using lead patches or whole sheets may need to be replaced. Either way this is a job for a specialist contractor.


Thatched roofs need regular, usually minor, repairs as a result of natural decay, wind or animal damage, and this should be carried out in a matching material by an experienced thatcher using materials tested for its nitrate content. High nitrate concentrations in thatching materials have resulted in expensive premature decay.

Additonal Information 

Back to top