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Problems with brick slips aren’t always obvious immediately after installation. Once the project is wrapped up, they may look aesthetically perfect, just as you intended at the design stage.
But that doesn’t mean they’re going to last.
There’s a lot beneath the visual surface, from substrate compatibility to post-install finishes, that affects the longevity of that beautiful new brick slip wall. Some you may already be aware of, some you may not.
To help you future-proof your project, we’ll run through common problems and the specification checks needed to avoid them.
It may seem obvious, but the step of inspecting a brick slip delivery on arrival can easily slip the mind, especially when a project is on a tight timeline and the installer is ready to get going.
Though suppliers carefully check and pack orders, occasionally damages can happen during transit. Before installation begins, brick slips should be checked for any damage such as cracking, excessive chipping or breakages.
It’s recommended to add an additional 5-10% on to the quantity you need, to account for on-site offcuts and minor damages. If there’s more than this in the delivery, make sure you inform the supplier before beginning an install.
If it becomes apparent half way through installing that there’s an excessive amount of damage, there may be no slips left from that exact batch to replace them with, risking a mismatch of slips in the finished wall.
This is especially important if you’re using traditional slips, or the order is bespoke.
With our traditional brick slips for example, many feature natural shade variations produced during the firing process. Because clay is a natural resource, shades can vary slightly between batches, which is sometimes noticeable when slips from different batches are placed directly next to each other. Add in custom finishes such as weathering, which can react slightly differently to varied shades, and matching slips from different batches becomes an impossible task.
Tip: Don’t immediately discard slips with minor cracks or chips that fall within your wastage allowance. Keep them to one side – they can be usable for cuts around reveals, cills or internal corners.
A huge issue with potentially catastrophic safety concerns is brick slips falling off.
There are a few reasons they may become dislodged and fall, but it’s often down to improper usage or application, rather than the product itself.
Knowing these potential issues in advance can save a lot of stress later down the line.
Choosing the wrong type of adhesive for direct adhesion and EWI cladding systems can cause brick slips to fall off a wall.
There are generally three types of tile adhesives:
For most brick slip applications, a high-quality, exterior grade polymer-modified cement adhesive is needed. It provides flexible adhesion required to withstand thermal changes and freeze-thaw cycles endured externally.
An obvious point, but you cannot use an internal adhesive for external application. However, you can absolutely use an external (or ‘dual’) adhesive for internal fixing.
Failure to choose an appropriate adhesive can result in brick slip slippage and detachment from the wall later on. Along with being expensive to put right compared to the minor cost uplift of buying the correct adhesive, slips falling from height is a severe safety issue.
Any competent contractor or installer will know what adhesive and application technique is required for the job. Furthermore, if using an EWI system, the manufacturer will mandate a specific adhesive to ensure their system’s warranty and fire certification. For peace of mind, though, it’s always advantageous to state the adhesive requirement in your design specification.
When considering a cladding system for brick slip installation, there are three main types to choose from: EWI, mechanical and precast, all of which have different brick slip compatibility requirements.
Selecting the right type of slips is essential to ensuring long-term performance and a secure fix within the chosen cladding system.
Slips Required:
Consequence of Incorrect Slips:
Slips Required:
Consequence of Incorrect Slips:
Slips Required:
Consequence of Incorrect Slips:
For all cladding systems, the manufacturer will specify the type of brick slips and adhesive (if applicable) required to adhere to building safety regulations and their warranties, so if you’re unsure, always check your choice of brick slip with them.
From the outside, all brick slips look the same – a thin slice of brick used to create the look of an authentic masonry wall.
However, there are key technical differences you need to be aware of when selecting slips for external applications.
As a general specification guide:
| Internal Slips | External Slips | |
| Thickness | 7-20mm (approx.) | EWI: 15 – 20mm
Mechanical: 20 – 28mm Precast: Manufacturer’s specification |
| Frost Resistance Rating | Any (F1 acceptable) | F2 rated (severe exposure) |
| Water Absorption Rating | Any | EWI: Typically <7%
Mechanical/Precast: Varies by system manufacturer |
For general internal use, thinner slips (usually 7-20mm thick) are preferable to avoid excessive protrusion from the wall, particularly around doorways and skirting boards. Interior walls aren’t subjected to rain or freezing temperatures, so you don’t need to worry about frost resistance or water absorption ratings.
However, slips intended only for indoor use should not be used externally.
Brick slips applied externally must:
If internal or inappropriate grade brick slips are used externally, they are highly likely to fail.
Without an F2 frost resistance rating, absorbed water can freeze and expand within the clay, causing cracking, spalling and even detachment from the substrate or cladding system.
Excessive water ingress can also occur, causing saturation to the backing system which can degrade its structural integrity.
Beyond selecting compatible brick slips and adhesives, using the wrong pointing mortar can cause significant problems.
Clay brick slips (just like full-size bricks) are naturally porous and require a pointing mortar with flexible and breathable (vapour permeable) properties.
Using standard tile grout isn’t an option – for internal or external application. It’s designed for rigid, non-porous tiles with narrow joints, and risks shrinking, cracking and trapping moisture if used for 10mm brick joints.
Specify an external-grade pointing mortar which offers flexibility, high vapour permeability, and long-term durability.
Most modern pointing mortars are cement-based, which is usually appropriate for machine-made slips.
If, however, you’re designing a traditional masonry aesthetic, working with a period property, or specifying handmade brick slips with a higher water absorption rate, consider using a traditional lime pointing mortar.
Lime is significantly more breathable and softer than cement, and has superior flexibility. This allows for better moisture management and breathability, while also offering a truly traditional aesthetic.
Once the brick slip install is complete, you may consider finishing it with a clear sealant.
It’s quite common for internal applications (such as kitchen splashbacks and high-traffic commercial areas), but less so externally. Many external brick slip facades are intentionally left unsealed. Either way, if using a sealant, you must ensure it is breathable.
Brick slips, like full-size bricks, are porous and designed to ‘breathe’. They naturally absorb and release moisture from the atmosphere – yes, even indoors.
Applying a non-breathable sealant covers the wall in an impermeable layer, trapping moisture behind the brick face. For internal walls, this can cause adhesive failure, damp and even mould within the substrate.
For external walls the consequences are more severe. Improperly managed moisture can accelerate frost damage, trigger efflorescence, cause spalling, and eventually lead to slips detaching from the wall.
Use this table as a quick checklist to ensure your brick slip specification mitigates any potential future problems:
| Specification Criteria | Internal Application | External Application |
| Thickness | Approx 15-20mm (standard)
Thinner slips as low as 7mm can be used for direct adhesion |
Generally 15mm+ for direct adhesion (only suitable under 18m in height), or align with cladding system manufacturer requirements |
| Frost Resistance | Not applicable indoors | Must be classified F2 for frost resistance |
| Water Absorption | Not critical indoors | EWI Systems: <7%
Mechanical/Precast: Varies by system manufacturer |
| Groove/Key Profile | Direct Adhesion & EWI Systems: Standard flat back
Mechanical & Precast Systems: Align with manufacturer requirements |
Direct Adhesion & EWI Systems: Standard flat back
Mechanical & Precast Systems: Align with manufacturer requirements |
| Adhesive | High-quality, flexible cement based | Exterior-grade, frost resistant, polymer-modified cement based |
| Pointing | Standard pointing mortar, or lime mortar for handmade slips and period properties | Standard pointing mortar, or lime mortar for handmade slips and period properties |
| Sealant | Optional, but must be breathable | Not generally recommended, but if used, must be breathable |
| Delivery & Quality | Inspect slips upon delivery for acceptable wastage levels before installation | Inspect slips upon delivery for acceptable wastage levels before installation |
Specifying the right type and grade of brick slips might seem a little complex initially, but getting it right is essential to prevent installation failures and longevity problems.
Design-wise, it’s natural to get excited about choosing the brick slips, but a decision on the application method needs to be made first. Whether it be direct adhesion, or via an EWI, mechanical or precast carrier system.
Once decided, your choice of compatible brick slips and other products, such as pointing mortar, adhesive, or sealant, all play a role in how well the finished brick facade will perform.
If you’re unsure what products are compatible with your chosen application method (especially for carrier systems), check with the system manufacturer. They will have readily available documentation and be able to advise on your specific project if needed.
Should you need any advice on compatible brick slips for your design or chosen cladding system, we’re here to help. Simply contact our team, and we’ll advise you on suitable options from our ranges, along with any technical data or guidance you need.
Alternatively, if you already know what you need, we offer brick slip ranges compatible with each type of carrier system.
We also offer a brick slip cutting service to match your system profiles (such as grooved slips), opening up a wider range of aesthetic options for your project.
Our aim is to provide you with brick slips that not only create the look of authentic masonry, but perform and last for decades to come.