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Why Resin Fixings Are the Safer Choice for Gallows Brackets in Old Masonry Walls

Tuesday 17th June 2025

Retrofitting gallows brackets into historic buildings presents a unique set of challenges. Many older masonry walls—particularly those constructed with lime mortar—simply aren’t suited to modern anchoring techniques that rely on force and expansion. In these cases, resin fixings provide a far more appropriate and structurally sympathetic solution. Here’s why resin anchors outperform traditional compression fixings when working with heritage structures.

1. Old Masonry Is Brittle, Soft, or Loosely Bonded
One of the most critical factors to consider is the condition of the masonry. Historic brick or stone walls often use lime-based mortar, which is far softer and more flexible than modern cement mortars. These materials:

- Don’t offer the compressive resistance needed for expansion fixings.
- Can crack, crumble, or "burst" under the radial pressure exerted by mechanical anchors like sleeve or through-bolts.
- May consist of a mix of materials (e.g., rubble infill), complicating the use of force-based fixings.

Resin fixings, by contrast, bond chemically rather than mechanically. This drastically reduces the risk of damage during installation, making them a more sympathetic option for older structures.

2. Resin Fixings Distribute Load More Gently and Evenly
Gallows brackets are tasked with resisting cantilever and shear forces—especially when supporting retained chimney breasts. To do this reliably, the fixings must remain secure under pull-out and torsional loads.

Resin anchors excel here:
- They bond the entire embedded length of the bolt, not just at a pressure point.
- This means better load distribution and higher resistance to pull-out—even in weak, mixed, or variable masonry substrates.

In contrast, expansion fixings concentrate force at specific points and rely heavily on the local integrity of the masonry, which can be unpredictable in heritage walls.

3. Greater Flexibility During Installation
Working with old walls often means dealing with irregularities, voids, and unknown substrate compositions—especially if the wall has a rubble-filled core or degraded sections.

Resin anchors offer flexibility:
- They can be installed in oversized or imperfect holes.
- They're forgiving of irregular shapes or partially collapsed cores.
- Failed holes can often be re-drilled and reused with resin, saving time and reducing the need for invasive repair work.

This flexibility is a major advantage during retrofits, where surprises behind the plaster or render are all too common.

4. Minimal Disturbance and Vibration During Setting
One overlooked risk of expansion fixings is the vibration and radial stress they introduce into the wall when tightened. In old masonry, even minor disturbances can trigger cracking or accelerate deterioration.

With resin:
- There's no mechanical expansion.
- The curing process is chemical, not physical, meaning less stress on the surrounding fabric.
- Installation is gentler, preserving structural integrity—especially vital when working on listed or sensitive historic buildings.

Conclusion: Resin Wins on Reliability and Respect for Historic Fabric
For structural applications like gallows brackets in old masonry, resin fixings are clearly the superior choice. They offer:

- A lower-risk, less invasive installation method.
- Better performance in weak or variable masonry.
- Greater long-term reliability under structural loads.

In contrast, traditional expansion fixings are often too aggressive, risking damage to fragile historic materials. If you're tasked with upgrading or stabilising chimney breasts in a heritage property, resin anchors should be your go-to solution for both performance and preservation.