Masonry cracking is a common occurrence in commercial stock across the UK. There’s a variety of factors when considering how cracks form – Subsidence, renovations, urban vibration, building settlement, and even the age of your property can all influence how cracks form and how prevalent and widespread they are.
Crack stitching is a recognised repair method used for structural cracking repairs. In this blog, we’ll cover what crack stitching is, what methods of crack stitching are available, and what you can do to tell the difference between a structural crack and a cosmetic crack.
What is Structural Cracking in Commercial Masonry?
Structural cracking is the process of splits forming in a building’s load bearing constructions, such as walls, floors, or foundations. Unlike thin cosmetic cracks that only appear on the surface of a wall, structural cracks are usually wider (at least 3mm) and longer. They are also capable of presenting in horizonal, vertical, stepped, or diagonal patterns, depending on the defect causing the damage.
Structural cracking indicates a defect or weakness in a building’s structural support. In commercial buildings, this likely cause is subsidence or settlement, where either the ground underneath a property or the property itself is shifting. However, it can also be caused by defective structural components like wall ties or lintels, or even urban vibration from nearby traffic or building sites. The age of your property is also a consideration, as older buildings are not constructed under the same stringent standards as modern buildings.
What is Crack Stitching?
Crack stitching is a structural repair method to repair cracked masonry, restoring its structural strength. It is achieved by inserting stainless steel helical bars into the wall itself, usually through the mortar joints. The area around the bars is then filled either with a resin of grout, which chemically bonds the bar to the masonry, stitching it to the wall.
Crack stitching is an ideal method for dormant cracks. This is because they are often easy to install, blend seamlessly with the masonry, and provide additional structural strength even in cases of cyclic movement. For live cracking, i.e. cracks where activity is still present, you should consult a structural repair specialist to diagnose the cause of cracking prior to repair.
How Does Crack Stitching Work?
Crack stitching often used the following method:
- The technician cuts slots into the mortar joints around a crack.
- Debris is cleared from the mortar joints to create a clean surface.
- The technician inserts the steel helical bars into the mortar joints.
- A specialist resin or grout is applied around the bar to bond it to the masonry.
- The wall is repointed to match the masonry, leaving the repair invisible once completed.
When is Crack Stitching Appropriate in Commercial Buildings?
Crack stitching can be an appropriate solution for repairing cracks in several scenarios.
Settlement Cracking
Settlement cracking occurs in new buildings or renovations as the structure settles on its new foundations, compacting the soil underneath. Structural cracking often forms as stepped cracks, following the mortar lines in the wall as different parts of the wall settle faster than others.
After Wall Tie Failure
Wall ties are used to hold the inner and outer skins of a cavity wall together. Failure is often the result of corrosion, causing the tie to weaken and allow either skin to bow or crack. Once replaced, crack stitching can be used to stabilise cracked masonry and provide additional support to the wall above.
After Lintel Failure
These cracks often radiate from windows or doorways where a concrete or timber lintel is installed. Crack stitching can be used alongside lintel replacement or repair.
When is Crack Stitching Not Suitable?
Crack stitching is ideal for use in historic cracks or older properties that have settled completely. However, they can only provide a temporary repair if used too soon after a building’s construction, or in cases of current subsidence or structural movement.
In cases where walls have bowed significantly or foundations have failed, it is often too late to use crack stitching methods, and instead more intensive repairs or rebuilding work may be required. You should request a survey to have your property assessed prior to beginning any repair work to ensure the correct solution is used.
What are the Benefits of Crack Stitching for Commercial Property Owners?
There are several benefits to crack stitching repairs:
- They’re often very cost-effective when compared to rebuilding work.
- They can be conducted on occupied buildings while being minimally disruptive to tenants or operations.
- They can be installed quickly and safely.
- They improve long-term structural integrity and expand the lifespan of masonry.
- They are visually discreet, blending in with the existing masonry.
Crack Stitching vs Rebuilding Brickwork
Here is a comparison of the differences between crack stitching and rebuilding work.
|
Crack Stitching |
Rebuilding |
|
Targeted repair |
Large scale work |
|
Faster |
Slower |
|
Lower cost |
High cost |
|
Minimal disruption |
Major disruption |
| Retains original fabric |
Removes original fabric |
How is Crack Stitching Specified in Structural Reports?
Upon identifying a crack, it is recommended that you have a specialised structural repair survey conducted to assess the property and diagnose the issues causing the cracking. Structural repair surveys can be requested for any type of building, across commercial, heritage, and residential building stock.
Once on site, a surveyor can identify the cause of cracking, the severity of the damage, and the correct remedial solution to prevent further damage and restore structural integrity within the wall.
Why Does Proper Diagnosis Matter Before Crack Stitching?
You should always have a crack diagnosed prior to repairs, as it is integral to ensuring a repair is conducted successfully first time. Repairing a defect without confirming the root cause may cause a repair to fail, leading to further repair work or even rebuilding if the damage returns more severely than before.
It is also true that not all cracks should be stitched. Crack stitching can be effective in the correct circumstances. However, it should not be the sole solution in all cases of cracking, as it can sometimes mask a greater issue rather than repair it entirely.
Related Structural Repairs
In cases of cracking, it may be necessary to conduct further repairs at the same time to completely remedy a structural issue. These could include:
- Concrete Crack Repairs, usually in large-scale building projects like apartments or skyscrapers.
- Lintel Repair & Replacement above door and window frames.
- Structural Repairs to the foundations or solid stone / brick walls within a building.
- Wall Tie Replacement in more recent cavity wall constructions.
Speak to a Structural Repair Specialist
If you are a commercial property owner, a facilities management company, or a managing agent for a property suffering from structural cracking, Timberwise can provide structural surveying and repairs to remediate any property concern.
You can book a survey to have one of our specialist surveyors attend your property to assess any damage prior to repairs to ensure the solution is both ideal for your unique situation and perfectly implemented to avoid future structural damage.
FAQs
How Strong is Crack Stitching?
Crack stitching restores the tensile strength to a wall, and redistributes a load through the masonry to prevent future cracking. It is also a flexible solution, moving in turn with differentia movement in a property to prevent future defects from forming.
Is Crack Stitching Permanent?
Yes, when the underlying cause has been addressed. Conducting crack stitching repairs prior to addressing an underlying cause can result in masking an issue, allowing it to reoccur in the future.
How Long does Crack Stitching Take?
Crack stitching repairs can often be completed within 1-2 days, depending on the extent of damage and the size of the treatment area.
Does Crack Stitching Affect Building Insurance?
Crack stitching is a recognised structural repair method, and is often recommended by surveyors and engineers in cases of structural cracking. Disclosing crack stitching repairs with your insurer can in some cases reduce premiums, and is also proof of compliance with some building regulations.
Is Crack Stitching Visible After Repair?
No. Once repointed, a crack stitching repair blends seamlessly into the existing brickwork without any visible signs of a repair having been applied.
