Bricks may look similar at a glance, but not all are created equal. Choosing the wrong brick for your build can lead to a long list of problems. From failed inspections to frost damage, even a minor misjudgement can turn into a costly issue down the line.
At Lords, we know how important it is to get it right first time. Here are five tell-tale signs that the brick you’re using might not be suitable, and what steps you can take to fix or avoid the problem.
1. Cracking, flaking, or spalling appears on the brickwork
The problem: Visible damage like surface flaking, cracking, or pieces breaking away from the brick face is often a sign the brick has not been designed to handle the weather conditions on site.
What it means: You may be using a brick with an incorrect frost resistance rating. In exposed locations, bricks absorb moisture. When that moisture freezes and expands, it places pressure on the surface of the brick, which causes spalling.
How to avoid it: Always check the frost resistance grade. For most external applications, particularly those exposed to rain or freezing conditions, you should be using bricks classified as F2 under BS EN 771-1. These are designed to withstand regular freeze-thaw cycles without deteriorating.
Bricks rated F1 can be used externally but only in sheltered conditions such as covered patios or beneath eaves. Bricks rated F0 should only be used internally.
Top tip: Garden walls, gate piers, parapets and boundary walls all tend to be fully exposed. These jobs will almost always need an F2-rated brick to last.
2. Damp or salt deposits are appearing
The problem: You are seeing white powdery staining, damp patches, or bubbling paint on the surface of the wall. This could be inside or out.
What it means: You are likely dealing with efflorescence or early signs of moisture ingress. This is often caused by high water absorption rates in the bricks, which draw in water and bring salts to the surface. It can also indicate that the wrong brick type has been used below the damp-proof course (DPC), where water resistance is critical.
How to avoid it: Check the brick’s water absorption rate. Facing bricks used externally should generally have an absorption rate below 12 per cent. For bricks being used below DPC level or in damp environments, aim for bricks with water absorption below 7 per cent, or ideally under 4.5 per cent such as Class A engineering bricks.
Top tip: Always use engineering bricks or DPC-grade bricks for retaining walls, footings, and any areas in contact with soil or high moisture. These are denser and much more resistant to water penetration.
3. The brickwork fails inspection or delays a project
The problem: Your work is complete, but it is flagged up during inspection or holds up sign-off.
What it means: The brick does not meet the structural or performance standards required by current UK regulations, particularly BS EN 771-1. This can happen when lower-grade common bricks or decorative bricks are used where load-bearing or weather performance is needed.
How to avoid it: Always check the brick’s technical specifications, particularly the compressive strength rating, durability, and dimensional tolerances. For structural or load-bearing jobs, bricks must meet a minimum compressive strength, typically 7 N/mm², but ideally 20 N/mm² or higher for most external walls or multi-storey builds.
Top tip: If you are unsure, ask your supplier for the Declaration of Performance (DoP) or CE/UKCA certification for the brick. This will give you all the necessary ratings for strength, water absorption, and frost resistance.
4. The appearance doesn’t match the project
The problem: The finished wall looks out of place or inconsistent with the rest of the build. It might clash in colour, texture, or style.
What it means: The wrong brick has been chosen for a visual match or for a location with aesthetic requirements. This is especially important for extensions, refurbishments, or projects in conservation areas where planning approval may depend on using sympathetic materials.
How to avoid it: For any job where the bricks will remain visible, always use facing bricks rather than commons. These are manufactured to tighter standards for appearance and come in a wide variety of colours, textures, and formats.
Top tip: If you need to match existing brickwork, bring a sample to your nearest Lords branch. Our team can help you find the closest available match or recommend alternatives that will blend well once weathered.
5. The wall isn’t coping with the load
The problem: The wall is showing signs of structural stress such as bowing, cracking, or uneven movement.
What it means: The bricks in use may not have the compressive strength needed for the load they are carrying. This is especially risky in retaining walls, high-load foundations, or where heavy lintels or beams are being supported.
How to avoid it: Use engineering bricks or high-strength structural bricks in any application that will carry weight. Class A engineering bricks typically offer compressive strength of 125 N/mm² and are highly resistant to water and frost. Class B bricks provide 75 N/mm² strength, which is suitable for most retaining and foundation work.
Top tip: Even in smaller projects like garden walls or outdoor kitchens, if the structure is supporting weight or built to last, higher strength bricks will pay off in long-term durability.
Final advice: always ask if you’re unsure
Choosing the right brick is not just about meeting building regulations. It also protects your reputation, helps avoid costly rework, and ensures your projects stand the test of time. The good news is, you don’t have to figure it all out alone.
At Lords, our team of experts is always on hand to talk you through brick selection. We stock a full range of facing bricks, engineering bricks, DPC-grade bricks, and specialist masonry products for every kind of job.
If you need help understanding specifications, finding a close visual match, or selecting the right product for the job’s location and load, pop into your local branch or give us a call.
