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About this event

This webinar is jointly hosted by ClearCalcs and PYTHON Fixings Australia. 

In this Australia-specific session, join PYTHON Fixings Australia's Business Development and Sales Engineer, Kieran Bisacre-Peters on Thursday, August 14th, 2025, from 12 pm to 1 pm (AEST) to discuss remediation and retrofit techniques for existing masonry structures, with an emphasis on cost-effective, code-aligned solutions that improve safety and constructability.

Drawing on real-world observations and dynamic testing, this session offers actionable design recommendations to help engineers assess existing masonry conditions, select appropriate remediation methods, and deliver more resilient outcomes.

All registered attendees will receive a recording of the webinar after the event.

In this webinar, we will cover:

• Common structural issues found in Australian masonry construction
• How to assess and diagnose deterioration or vulnerability in existing walls
• Retrofit and remediation strategies for various masonry systems
• Results and insights from full-scale shake table testing of modern retrofit techniques

This content is ideal for engineers, building consultants, and asset managers working across commercial, residential, and heritage sectors in Australia.

Summary

This webinar, hosted by ClearCalcs in partnership with Python Fixings Australia, explored remedial and retrofit strategies for masonry structures with a focus on seismic performance, life safety, and durability. The session was designed for structural engineers and building designers working with existing masonry buildings in Australia and other regions with similar building stock.

The presentation began with a background on the origins of Python Fixings, which was founded following the Christchurch earthquakes in New Zealand, where many seismically retrofitted masonry buildings performed worse than expected. The inquiry revealed that anchorage systems into existing masonry were a critical failure point, setting the foundation for the company’s focus.

Kieran provided a high-level overview of common retrofit systems, highlighting veneer tie replacement, parapet bracing, chimney strengthening, and out-of-plane wall reinforcement. Case studies from Christchurch and Newcastle earthquakes illustrated both failures and successful interventions. Several retrofit solutions were discussed in detail:

• Veneer and cavity ties: corrosion issues with original ties, differences between helical ties and screw anchors, and inspection challenges in lime mortar construction.
• Parapets and chimneys: performance of steel bracing versus timber bracing, use of long mechanical anchors, and post-tensioning systems for chimneys to increase overburden load.
• Out-of-plane walls: effectiveness of timber strongbacks, shake table evidence demonstrating threefold improvements in capacity, and scaled model testing validating system redundancy.
• In-plane strengthening: comparison of reinforced concrete overlays with alternative plywood and CLT panels, alongside cost and constructability considerations.

Anchor performance was another major focus. Epoxy anchors, while widely used, were shown to be highly dependent on workmanship and prone to failure when holes were not properly cleaned or adhesives inadequately cured. Concrete screw anchors tended to underperform due to short embedment and large diameters causing brick splitting, whereas long, thin mechanical anchors achieved more reliable engagement. Other lessons included avoiding angled epoxy anchors, limiting anchor diameters to 16 mm in clay brick, and ensuring proper drilling techniques to prevent radial cracking in softer masonry units.

The session emphasized that no single retrofit method is universally applicable. Instead, engineers should approach retrofits as an “engineering toolkit,” matching techniques to building conditions, heritage considerations, and project constraints.

Questions and Answers

1. How can cracked masonry from soil subsidence be stabilized?

Answer: Stitching with wire and epoxy can redistribute stresses, but the underlying soil movement must be addressed through foundation strengthening to prevent recurring damage.

2. What is the best way to inspect rusted cavity ties hidden under brickwork?

Answer: Extract sample bricks across different locations—especially in lime mortar walls where moisture accelerates deterioration—to inspect tie condition directly.

3. For timber strongbacks, should engineers ignore masonry contribution?

Answer: Both approaches exist. Designs may assume timber carries full wall mass or composite action, with research papers supporting either method.

4. Can Python Fixings provide solutions for masonry stitching similar to Helifix products?

Answer: Yes. Python offers systems for both crack stitching and veneer tie remediation, with screw anchors often performing better than helical ties for long-term restraint.

5. What are the maximum spacings for veneer retrofit anchors?

Answer: Typically aligned with AS 3700 requirements (around 600 mm x 600 mm), though closer spacing may be needed when designing for composite action between wythes.

6. Will Australia eventually mandate cavity tie inspections like the US?

Answer: It is possible, given the prevalence of corrosion issues. Currently, inspections occur mainly as part of building upgrades or retrofits.

7. What is the maximum chimney height for post-tensioned retrofit systems?

Answer: Research shows successful applications up to ~8 m, though geometry and anchorage capacity dictate project-specific limits.

8. How can bowed masonry walls be strengthened?

Answer: Options include propping walls back into place and installing ties for composite action. In severe cases, full reconstruction may be required.

9. How should minimum edge distances be handled when wall geometry is unknown?

Answer: Either apply statistical allowances (installing additional anchors) or conduct site-specific testing to validate anchor performance near joints or edges.

10. What criteria determine when to retrofit versus reconstruct a wall?

Answer: Decisions hinge on structural role, extent of deterioration, and project budget. Retrofits are often more economical, but severe displacement or loss of strength may necessitate rebuilding.

11. Do Python anchors corrode over time like traditional ties?

Answer: Python anchors are high-strength steel with zinc-nickel galvanic coatings, significantly more durable than untreated ties. They can also be easily unscrewed for inspection and replacement.

12. How are lintels under suspended masonry repaired without removing brickwork?

Answer: Options include anchoring into brickwork before recasting concrete, or using crack stitching wires across lintels to act as reinforcement.

13. What’s the recommended fixing method for post-tensioned chimney plates?

Answer: Plates may simply sit in compression, but additional small mechanical anchors can be used for positive fixing.

14. How should cantilevered awnings be attached to masonry?

Answer: Plates with multiple mechanical anchors can suffice. If concentrated loads are high, through-bolts with backing plates are often the most reliable option.

15. How can engineers verify epoxy anchors are correctly installed?

Answer: QA testing is essential. Specs typically require 2–5% of anchors to be proof tested on site after installation.

16. What’s the longest anchor available and are angled installations allowed?

Answer: Python supplies long anchors designed for multiple masonry courses. Angled installations are feasible but must account for combined shear and tension forces.

17. Are Python anchors stainless steel? Do they have seismic ETA ratings?

Answer: Anchors are high-strength carbon steel with zinc-nickel coatings, not stainless. ETA C2 ratings apply to concrete, not masonry, so they are not required for retrofit applications.

18. What about masonry retaining walls and multi-wythe crack stitching?

Answer: Retaining walls may use plates or timber/steel bracing. For three-wythe walls, stitching wires can be embedded half-depth with multiple wires to provide robust reinforcement.

19. How durable is the coating under repeated installation/removal?

Answer: Testing under salt spray exposure confirmed performance remains intact even after multiple installation cycles, due to its galvanic protection mechanism.

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