Under One Roof: Repairs to traditional tenement buildings

Repairing traditional tenement buildings is an essential part of ensuring that Scotland’s built heritage stays standing strong. Due to their age and the materials that they are made of, there are certain things to look out for when it comes to repairing these buildings and extra care needs to be taken to ensure the repairs are adequate and will not cause further damage.

When repairing listed buildings or those in conservation areas, additional care may be required, such as obtaining planning permission for repairs or changes to the building, or using materials that match the original. It’s possible to find out if a building is listed or in a conservation area through the local council’s planning department, online maps, or using the Historic Environment Scotland online register.

Taking care of stone

Repairing older tenements with the correct materials is important for their long-term health. Traditional tenements were often built using different types of stone, such as sandstone, granite, and whinstone, which naturally absorbs water and then dries. This process is usually referred to as ‘breathing’. It’s important to keep this characteristic of stone in mind when carrying out repairs to parts of traditional tenement buildings, such as the external stone walls. In the past, cement mortar was often used to repair stone, known as ‘plastic repairs’. However, now most of these repairs are cracking and need to be replaced. This is because the cement affects the breathability of the stone, allowing water to be trapped where it can then freeze and expand, damaging both the stone and the cement mortar.

If you notice cracks in the external stone walls or lintels on a traditional tenement building, it’s important to seek advice from a structural engineer with knowledge of these types of buildings and the material used to build them to assess the condition of the building and ensure the repair will not cause further damage.

Keeping chimneys in check

Many tenement buildings have chimneys, and although they may no longer be in use, maintenance of them is still necessary. Chimneys are exposed to the weather and need to be properly maintained to reduce the risk of collapse or dislodgement. Look out for leaning or cracked chimneys and leaning chimney pots, which are especially dangerous and require immediate attention.

Additionally, plant growth on a chimney indicates that there may be a damp problem. Plant growth can cause further damage as cracks and roots can force stones apart. Moreover, moss and plant growth can speed up the decay of the chimney. When organising repairs to chimneyheads or pots, it’s necessary to hire a roofing contractor.

Caring for external cast iron downpipes

Original downpipes, also known as drainpipes, are made of cast iron. This material is more durable than plastic but still requires regular maintenance. For example, a lack of painting to the rear of the downpipe can lead to corrosion and leaks. Keep an eye out for staining or plant growth behind the downpipes on external walls as they may be a sign of leaks. To prevent this from happening, it’s recommended to remove rust and paint external cast iron downpipes every five years. If a downpipe needs replacing, using cast iron may be required in conservation areas and listed buildings.

Bouncy floors and rotten joists

In older stone buildings, the floors between flats are usually made from timber joists, which extend across the front and back walls, with secondary support beams and internal load-bearing walls in between. If the floor in a tenement flat feels uneven or bouncy, this could be a sign of rot in the joist ends. Left untreated, rot can cause structural damage to the building, such as bulges in the front or back external walls. It’s crucial to replace any rotten joists and deal with the cause of the rot to ensure it does not return. When it comes to structural repairs in a tenement building, seek help from a structural engineer to assess the problem and deal with it swiftly and accurately.

Sash and case windows

Traditional sash and case windows first came about during the late 1600s and started being installed across Scotland in the 1680s. They are a common sight in traditional tenement buildings. To keep windows in good condition, it’s recommended to repaint timber sills and the bottom rail every five years, or more regularly if the windows are in exposed locations, as these can decay first. If sills are badly decayed, this can allow water in and lead to rot.

Alongside repainting, check the mastic around windows. Mastic is a filling material which is used to seal the join between a window frame and the glass. If it needs replacing, consider using traditional burnt sand and boiled linseed oil mastic as it lasts longer and retains its flexibility better than ordinary, trowel-applied builders’ mastic. It is not recommended to use polysulphide mastics applied with a gun as these are unlikely to effectively fill the gaps.

If sash and case windows need replacing, it is better to retain existing timber windows from a sustainability and conservation perspective. Seek specialist information on sash windows to ensure they are repaired properly.

Visit the Under One Roof Website to find other articles on tenement maintenance and repair management.