Brickwork

Dampness is the most common cause of problems with historic brickwork, causing damage.

Walls can become damp in three main ways:

1. water can get into brickwork from outside or
2. from inside or
3. or from the ground

Water coming into the building from outside can be caused by the rain, unsuitable rainwater goods, bad weathering details, or mortar missing between bricks.

Inside, brickwork walls can get damp from condensation. Solid brickwork retains heat well, and when there is poor airflow, damp patches can appear on the walls. This can often be seen behind furniture or inside built-in cupboards where the air is very still.

Water from the ground, known as rising damp, can also affect walls. Sealing the outside of a wall with waterproof coatings or waterproof plasters inside can trap moisture, causing it to rise higher. In severe cases, this can lead to damp rotting out a timber first floor if this is the only place moisture can escape.

Ventilation and heating

Ventilating and heating a building are key. These simple jobs should be carried out over several month so that the amount of damp can be monitored. Only after doing this and seeing no improvement should more invasive works be considered.

Maintenance

Maintaining the building in a good condition is also very important. The rainwater goods should be regularly checked so that the rain is able to get carried away from the building quickly and not seep into the fabric.

French drain

The installation of a French drain around the outside edge of a building can help water drain away from the fabric more quickly. This means it doesn’t sit against the brickwork walls and travel up the fabric. French drains do not need Listed Building Consent to be installed, but care should be given so that any shallow foundations are not disturbed.

Injected chemical DPC

An injected chemical DPC is sometimes the only option for a damp brick wall. Removing the internal plaster by 1 meter is often not needed and should be avoided where there is lime plaster present. A chemical DPC should be injected into the mortar beds only and not the brick face. Injecting into the face can be damaging to the brick and results in an ugly appearance. If injecting into the mortar bed only and no other works are proposed, this can often be carried out without the need for Listed Building Consent.

Lead or slate damp proof course

From the later Victorian period onwards, a horizontal damp proof course at low level was inserted using either lead or slate. This is difficult to insert after the wall has already been built so often can’t be used in modern repairs. 

Frost can damage damp brick walls as the moisture inside freezes, causing the brick surface to crack or flake. Sealing the bricks with a silicon treatment should be avoided, as it traps moisture leading to larger chunks breaking off and can alter the bricks colour and texture.

Frost damage is worse when cement mortar is used. This is hard and doesn’t let water evaporate, forcing moisture through the bricks and increasing damage to the bricks. Traditional lime-based mortars are more absorbent and porous, allowing water to evaporate fast and move more freely.

Cement can also harm brickwork because it sticks firmly to soft, traditional bricks, while lime mortar allows for slight movement without causing damage. When stressed, cement will damage the brick before giving way itself. Bricks are less likely to fail in lime mortar walls, but if they do, repairs are easier, as bricks can often be reused, making small repairs possible without needing to rebuild entire walls.

Small scale patch repairs can usually be carried out without Listed Building Consent if they match the existing materials and detailing.

Larger repairs or structural changes may require consent and a formal application for Listed Building Consent.

Brickwork may look damaged by pollution and dirt, but using sandblasting or abrasive materials can harm the bricks. It removes their outer face, which makes them more vulnerable to damp and dirt.

If cleaning is needed (such as to address damp from nearby foliage) it's best to use water jets, or to gently scrub the bricks with a bristle brush.

For more thorough cleaning - with a diluted, non-alkaline chemical cleaner, by a specialist - you may need Listed Building Consent, as it can change the building’s appearance. It is wise to test the cleaning method on a small, hidden area first.

Over time, the lime mortar in historic brickwork wears away and will eventually need repointing. This involves raking out the loose or missing mortar to about an inch depth and replacing it. Only loose mortar should be removed - including any easily removable lumps of cement mortar - but mechanical tools like chisels or grinders shouldn’t be used as they can damage and cut into the bricks.

Repointing is rarely needed for an entire wall at once. Damp areas at ground level, or high corners exposed to the weather, often need attention first. Occasionally, masonry bees can cause minor problems with lime mortar which makes repointing necessary. These bees can live in a group, in a wall or a chimney, and dig tunnels in the mortar to raise their young.

Repointing should be done carefully, matching the colour, texture and profile of the original lime mortar to blend seamlessly.

Small-scale patch repairs can be done without Listed Building Consent. However larger-scale repointing (like an entire elevation) may need Listed Building Consent, due to the significant change in appearance. 

Generally, a 1:3 ratio of lime to sharp sand mortar mix is best.

For a precise match, mortar can be professionally tested to analyse its composition. Traditionally, additives such as crushed chalk or limestone were sometimes used to create a lighter colour, while ash or soot were added to make a darker tone. Some additives can also have a ‘pozzolanic’ effect which helps a lime-based mortar to set more rapidly.

It’s a good idea to consult a lime mortar and render expert for specific, tailored advice.

Whether Listed Building Consent is required will depend on the type and extent of the repairs. Small-scale patch repairs using matching materials usually don’t need a formal application - but it's best to consult with our Heritage team for clarification.

Complete demolition and rebuilding of a brick wall or chimney is rarely necessary. A structural engineer can assess the condition and help create a repair schedule. If dismantling and rebuilding are needed, Listed Building Consent will be required.

Individual damaged bricks (spalled bricks) can be replaced without consent in walls built in lime mortar. Turning a brick around to show a better face if done in a small area can often be carried out without Listed Building Consent.

However, painting or rendering exposed brickwork, some repointing, and other larger repairs do need Listed Building Consent.

Historic and traditional brickwork contributes to the character of a listed building or heritage asset. It often reflects local materials, craftsmanship, and the building’s original use. The appearance adds visual appeal, and can indicate the building’s status - with finely detailed brickwork often signifying wealth or high status, while simpler designs may suggest more functional buildings like farmsteads.

In Suffolk, brickwork is especially characteristic and, when well-maintained, enhances the charm and identity of traditional buildings, as well as the surrounding area. It plays a key role in preserving the architectural heritage and local history.

If you need further advice, please contact our Heritage team.

Email heritage@baberghmidsuffolk.gov.uk

Phone 0300 123 4000 (Option 5, then Option 3)

Write to us:

Heritage Team

Babergh and Mid Suffolk District Councils

8 Russell Road

Ipswich

IP1 2BX

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