When it comes to maintaining the structural integrity and appearance of your property, masonry mortar repair and lime rendering are essential. Over time, issues such as crumbling mortar joints, spalling brickwork, algae growth, and damp ingress can affect even the strongest walls. If not addressed promptly, these problems can escalate, damaging both the fabric of your building and its character.
At Marshels, we provide expert masonry repair and restoration services, using a blend of traditional techniques and modern solutions such as mineral stone paints. In this blog, we’ll explore the most common problems found in old brickwork and lime render, explain how we fix them, and highlight why our approach delivers long-lasting results.
Common Mortar and Lime Render Issues
How to Fix Crumbling Mortar Joints
Crumbling or deteriorating mortar joints occur when the material binding bricks together begins to erode due to weather exposure or age. This weakens walls, allowing moisture to penetrate and potentially damage the structure.
The best solution to fixing mortar joints is through professional repointing. At Marshels, we carefully remove failing mortar and repair the affected area using lime-based mixes suited to your property. This not only strengthens the wall but also improves breathability, making it the best choice for masonry restoration on heritage and period buildings.
Also identifying when the wrong materials have been used instead of period materials when making repairs is essential. Modern cement-based mortars used on lime-built properties/ structures can cause further damage to brickwork, resulting in damp and black mould growth as Portland cement mortars prevent the breathability of buildings and walls.
How to Fix Cracked or Spalling Brickwork
Cracked or spalling brickwork is when bricks start to chip, flake, or fracture – often due to frost damage or trapped moisture. Left untreated, brick spalling can compromise the stability and appearance of your walls.
To fix cracked brickwork, our approach involves removing damaged bricks and replacing them with matching materials. Where appropriate, we apply lime render to protect the surface, preventing further brick spalling and preserving the look of your old brickwork.
Removing Moss on Brickwork and Algae Growth
One of the most common cosmetic issues with external masonry is the growth of algae, lichen, or moss on brickwork. While often dismissed as purely visual, moss retains moisture against the wall, accelerating deterioration.
We remove these growths through DOFF Steam Cleaning, a safe and highly effective method for heritage buildings. You can learn more about the science behind this process in our article on DOFF Steam Cleaning and How it Works. Once clean, we carry out any necessary masonry repair and apply breathable finishes to help prevent regrowth. We can also use masonry creams to add a first line of protection to masonry to further prevent water ingress/algae growth.
Dealing with White Salt Deposits on Masonry
If you notice a chalky, white staining on your brickwork, it’s likely efflorescence – salt deposits caused by moisture movement. While generally not harmful, it’s a clear indication that water is travelling through your wall, which can lead to more serious damp problems.
To treat this, we carefully clean away the deposits and carry out targeted masonry mortar repair to address the underlying issue. This might involve repointing, repairing render, or applying coatings of protective, breathable paint.
Damp and Moisture Ingress in Masonry
Perhaps the most damaging issue for any building is damp ingress, often caused by cracked mortar joints, faulty render, or poor drainage. Damp not only harms ageing brickwork but can also lead to mould and health problems indoors.
At Marshels, our solution combines masonry restoration with preventative treatments. We repair mortar and render, improve water run-off, and finish walls with mineral stone paint to provide a breathable yet protective barrier. This ensures moisture can escape while preventing new water penetration. We will also advise on drainage solutions if ground level walls are soaking up water. Solutions may include Akko drains or traditional French drain systems which divert water away from the masonry, giving a level of protection from rising damp or total brick saturation.
Commercial Restoration Case Study
Our expertise is demonstrated in our Period Commercial Building Renovation in Farnham. This large-scale project included extensive masonry mortar repair and lime rendering to restore the building’s heritage façade.
We carefully repointed the walls, fixed damaged render, and applied a breathable mineral paint system, leaving the property not only visually enhanced but also fully protected against the elements.
What is Mineral Paint and Why Do We Use It?
Unlike conventional masonry paints that simply sit on the surface, mineral paints are made using natural silicate minerals that chemically bond with the masonry substrate. This process, known as silicification, creates an exceptionally durable finish that becomes part of the wall itself rather than just forming a layer on top.
Because of this, mineral paint is both water-repellent and vapour-permeable. In practice, this means it keeps rainwater out while still allowing trapped moisture within the wall to escape. For traditional properties with lime render or old brickwork, this breathability is essential to prevent damp, peeling, or damage to the masonry beneath.
When considering how to use mineral paint, preparation is key. Surfaces must be clean, dry, and free from loose material. Often, a primer designed to work with mineral paint is applied first to aid the bonding process. The paint itself is then brushed or rolled on much like standard masonry paint, but the results are far superior in terms of longevity and protection.
At Marshels, we frequently use Keim paint, a leading brand of mineral stone paint trusted worldwide for its eco-friendly, non-toxic, and colourfast qualities. It’s particularly well-suited for masonry restoration and heritage projects, as it preserves the building’s character while providing decades of protection. By choosing mineral paint over conventional alternatives, we ensure our clients benefit from a finish that resists blistering, cracking, and weather damage — keeping buildings both beautiful and structurally sound for the long term.
Why Choose Marshels?
We’re more than just painters and decorators here at Marshels. Alongside our painting and decorating services, we specialise residential and commercial refurbishment for interiors and exteriors, wallpaper hanging, spray painting, and gilding amongst other specialist services.
Our services for exterior masonry repair and restoration for both residential and commercial clients include:
- Masonry mortar repair and repointing
- Traditional lime rendering and lime work
- Fixing cracked and spalling brickwork
- Chimney refurbishment and restoration
- Patio installation and hard landscaping
- Roofing, fascia, soffit, and gutter replacement
- Exterior painting and decorating
Our skilled craftsmen understand the unique challenges of working with old brickwork and period properties, delivering results that combine structural strength with authentic finishes.
Summary
From crumbling mortar joints to spalling brickwork, algae growth, salt deposits, and damp ingress, masonry can face a wide range of issues over time. At Marshels, we provide tailored solutions – from brick mortar repair to the application of breathable Keim mineral paint – ensuring your property remains strong, beautiful, and protected for years to come.
If you’re looking for trusted experts in masonry repair and restoration, contact us today to discuss how we can help bring your property back to life.
