Helical bars are a hugely useful tool for masonry repair. A quick and simple brick reinforcement method, it’s the go-to solution for the majority of brick lintel repairs.
This article looks at how helical stitching bars work and how they are used when repairing a cracked brick lintel.
What is a Helical Masonry Stitching Kit?
The primary component of a masonry stitching kit is the helical stitching bars. These bars are often made of stainless steel and are twisted - helical refers to a spiral shape - to provide extra strength and flexibility.
You can buy helical stitching bars separately or as part of a helical masonry crack stitching kit, which usually includes:
- Helical stitching bars
- Masonry repair grout
- Grout applicator
- Mixer paddle
- Finger trowel
Do Helical Bars Work?
Helical stitching bars are a great way to add tensile strength to existing masonry which has started to crack. They work similarly to standard forms of bed joint reinforcement used during initial construction, such as brick reinforcement ladders and mesh.
A particular advantage of helical stitching kits is their ease of application. Helical bars can be inserted into existing masonry with minimal effort or disturbance, providing excellent strength while leaving no visible mark on the wall’s exterior.
Helical bars can be used in any areas of masonry that are experiencing subsidence. Sagging and cracking in masonry often occurs in areas with particular tension or weaknesses, such as lintels and arches. As a result, these locations are where masonry stitching kits are most commonly used.
What Causes a Cracked Brick Lintel?
Lintels and arches are particularly vulnerable because they rely on external forces - such as a door or window - for support. The most common cause of a cracked lintel is replacing the supporting window or door, which can shift the pressure or support on the lintel.
For example, replacing an older metal or wooden window frame with a UPVC frame can reduce the amount of support offered to the lintel. Eventually, a slight reduction in support will cause the lintel to sag and crack.
While replacing windows and doors is the most common reason, other things can cause a lintel to crack, such as subsidence or structural movement of the building as a whole.
Some lintel cracks can also be caused by excess moisture, but this rarely impacts masonry - it is more common for concrete or timber lintels, which cannot be repaired using helical stitching bars.
How Do You Use Helical Bars for Lintel Repair?
Installing helical stitching bars into masonry is straightforward so long as you have all the right tools. A helical masonry crack stitching kit will provide everything you need except for a blade for the first step.
- Cut two horizontal slots at 300mm to 900mm centres (around 4-12 brick courses), starting 500mm before the lintel’s opening and ending 500mm beyond the other side.
- Clean the incisions with water to ensure the spaces are clear and damp.
- Pump the specialist grout into the incision and fill between one-half and two-thirds full.
- Push a helical bar into the incision about three-quarters deep. Ensure the grout encapsulates it and compress any grout that has been displaced.
- Pump more specialist grout into the incisions, filling up to 15mm of the wall’s surface.
- Insert a second helical bar into the incision about halfway into the incision. Ensure a 10mm gap between the two bars.
- Use a trowel to ensure the second rod is also fully covered by the grout. Then, fill any cracks and point the disturbed joints to conceal evidence of the repair.
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