Online Toolkit

Use our Online Toolkit to find out more about Northern Ireland’s historic environment and to learn about the processes which will you help you better understand, protect, conserve, regenerate, and highlight our significant historic buildings and monuments

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Maintain Historic Buildings

Proper maintenance of a historic building not only guarantees the preservation of its historic fabric but also has the potential to save you substantial money in the long run. Building materials naturally degrade over time and can deteriorate due to various factors, including exposure to the elements and human activities. However, the most prevalent cause of damage to a building is moisture and water penetration, which can infiltrate the structure through roofs, rainwater systems, exterior walls, and even rising groundwater. Neglecting these seemingly minor issues can result in the accumulation of more significant and often expensive problems. For instance, if left unattended, penetrating damp can lead to the growth of rot, exacerbating the damage and costs involved

Maintaining Roofs and Chimneys


Regular maintenance is crucial for the roof, which is the most exposed area of a building. Even minor leaks can lead to severe problems if neglected. To ensure the building remains wind and watertight, it is essential to conduct repairs and inspections through a trained professional.

Replace any missing or damaged slates, and repair any damage to lead flashings at junctions, valleys, chimneys, dormers, or walls. Carefully salvage and set aside original slates for future use. Introduce replacement slates in less noticeable areas, reserving the originals for prominent sections. The new slates should closely match the original building material in type, color, texture, size, and thickness. Remove noticeably corroded nails and replace them with high-quality stainless steel nails.

Consider a full re-slating of the roof only when the roofing materials have reached their natural end of life or repairs are no longer cost-effective. As a guideline, if one-fifth or more of the slates need renewal, re-roofing should be considered

Chimneys are often overlooked but require regular inspection, even when they are no longer in use. Open chimneys can accumulate water from above, leading to dampness in the flue, especially if the chimney is only used intermittently. Installing chimney cowls can help prevent water ingress while allowing continued use of the chimney. Factors such as plant growth, weather, and impact damage can contribute to deterioration and potential collapse. If plant growth is present on a chimney stack, it indicates failing mortar joints and requires further inspection to prevent structural failure, which could result in costly repairs.

Capped and permanently closed chimneys, as well as sealed and unvented fireplaces, can trap moisture within the structure, leading to instability and damp patches inside the building. Opening closed chimneys and fitting vented caps can prevent water entry from above and provide ventilation for the chimney stack. Closed fireplaces should be equipped with vented grilles to ensure proper airflow.


Check for defects such as:

Missing or damaged roof coverings/tiles/slates

Cracks in the chimney or surrounding render

Missing/damaged flashings

Movement

Maintaining Windows and Doors


Windows play a crucial role in the façade, providing balance and unity. Replacing original period features with modern alternatives can harm the building’s appearance. In many cases, the quality of original timber surpasses that of modern timber, allowing traditional windows to be repaired and outlast their contemporary counterparts. Regular maintenance involves inspecting external paintwork, cills, joints, and timber. Damaged areas that allow water penetration should be addressed as they indicate decay. Windows and doors facing prevailing winds are more susceptible to weathering.

To prevent timber decay, regular repainting is necessary. Prior to applying a new coat, remove any flaking paint to avoid excessive build up around the window panes and achieve a higher-quality finish. Take caution when removing lead paint from surfaces, as it can be harmful. Fill cracks or open joints to protect the timber from water and prevent decay. If needed, sections of rotten wood can be replaced with new wood through a process called “splicing.” Inspect sash cords and weights, and replace any missing putty with an appropriate type and profile. Old glass, such as crown or cylinder types, differs from modern glass and contributes significantly to the character of windows, including colour and texture. Preserve and retain original glass whenever possible.

Original doors are significant features of historic buildings. Replacing them with mass-produced substitutes dramatically alters the property’s character. Whenever feasible, retain, restore, and reinstate original door furniture such as knockers and letterboxes.


Check for defects such as:

Areas of wetting

Damp patches

Flaking and peeling paint

Missing putty or slips

Open joints

Broken/damaged lintels, cills and cords

Wet rot or soft wood

Maintaining Walls


Walls provide essential shelter, but they require regular protection and maintenance. Incorrect repairs to brick and stone can result in severe damage. Before undertaking any repointing work, it is crucial to seek professional advice. If you have concerns about the stability of a wall, consulting a structural engineer is recommended.

The integrity and flexibility of mortar play a vital role in keeping water out of a building. Missing mortar, failed or eroded pointing, as well as cracked and open joints, can all lead to water penetration, which becomes particularly destructive during frost. Be vigilant for signs of delamination and degradation in stone and brickwork.

When it comes to cleaning and repairing stone or brick, it is imperative to rely on the guidance of a qualified professional. Harsh chemical cleaners, abrasive cleaning methods, and inappropriate repairs have the potential to cause long-term or even permanent damage

Render serves as a protective finish for walls and was traditionally primarily lime-based. This allowed the wall to breathe and accommodated movement in the building materials. However, modern cement renders are harder and can trap moisture, causing damage to the building fabric. It is advisable to avoid using them. If the render sounds hollow when tapped, it indicates that it has separated from the underlying wall and requires repair or replacement.

When trees grow in close proximity to walls, or even from the base of the wall, they should be carefully cut down as close to the base as possible. The stump should be treated to prevent further growth. Removing the roots often results in significant damage and is therefore not recommended. While it is unlikely, it is essential to monitor the wall for any signs of long-term local subsidence


Check for defects such as:

Signs of movement, including cracks

Areas of staining

Material degradation

Damp patches

Mould, algae and vegetation growth

Cracks or erosion

Open joints, missing or crumbling pointing

Render detachment

Maintaining Rainwater Goods


Rainwater goods, including gutters, downpipes, valleys, and flashings, play a crucial role in directing excess water away from the roof and preventing water penetration. Regular inspections, especially during heavy rainfall, are essential to identify overflow issues and leaks easily.

To maintain the effectiveness of rainwater goods, ensure that gutters are kept clear to prevent water overflow onto the building’s face. Check where your gutters and downpipes drain to and keep the drains clear to direct water away from the building’s base and foundation. Avoid hard landscaped ground surfaces like concrete or tarmac adjacent to the building, as they may cause splashback; ground surfaces should be designed or sloped to guide water away from the base of the building. When trees are nearby, consider fitting drain covers and wire coverings on downpipes to prevent blockages from leaves. Regularly remove grass and plant growth.

Repairing cast iron rainwater goods is often possible, preserving original features and avoiding inappropriate replacements. Explore repair methods before considering the removal of any original features. Cast iron is readily available in traditional sizes and profiles, and skilled workers can easily install them if replacement is necessary. In cases where replacement is the only option, extruded aluminium may be acceptable, but any material changes should receive approval from the local planning department or the Department for Communities.