Hornsby Construction Site Mould Remediation: Structural Frame Mould Removal During Build

By Michael Nguyen

IICRC Certified Mould Remediation Specialist

Connect on LinkedIn | Learn more about Michael

🏗️ Project Overview

A large two-storey construction site in Hornsby, Sydney experienced significant mould contamination during the framing stage. Recent heavy storms struck before the roof was installed, leaving the timber frame exposed and saturated.

With the project on tight construction deadlines, AAA Mould Removal was engaged to perform an urgent mould inspection and remediation plan that complied with IICRC S500 and S520 standards. We designed a comprehensive scope of works tailored for an active building site with elevated moisture and widespread mould growth.

🧪 Site Assessment & Conditions

• Inspection Date: 4 weeks prior to remediation - June 202

• Completed : Mid July 2025

• Building Type : Class 1 Building - Brick Venner

• Location: Hornsby, Sydney

• Building Stage : Framing and Roof constructed

• Site Type: Active construction site

• Building Size: 280 sqm across 2 levels

• Contamination Issues:

  • Prolonged moisture due to open roof

  • Mould visible on framing throughout the site

  • Elevated timber moisture levels in select frame sections

    
    
    
    

✅ Scope of Works & Methodology

The following steps were completed over a 2-week period, balancing remediation with ongoing construction activities:

1. Containment Setup

• Full containment to prevent cross-contamination to other areas on-site.

2. Air Filtration

• Installation of HEPA-filtered air scrubbers to continuously capture airborne mould spores. Click here to learn more about our Hepa Air Filtration Devices (AFD) during mould remediation work.

3. Initial Cleaning

• HEPA vacuuming to remove surface contamination and loose particulates.

4. Mechanical Abrasion

• Sanding of timber surfaces to remove ingrained mould colonies from joists and base plates.

5. Detail HEPA Vacuum

• A second pass of HEPA vacuuming post-sanding to eliminate remaining debris. Click here to learn more about HEPA Vacuum equipement and processes.

6. Targeted Chemical Treatment

• Low-pressure chemical washing and flushing of butt joints and base plates.

• High-pressure chemical wash on severely affected framing sections.

7. Flash Drying (Structural Drying)

• Deployment of rapid drying equipment to lower moisture levels in damp framing members and prepare for post-remediation verification. Click here to learn more about our processes in structural drying for water damage buildings.

8. PRV (Post-Remediation Verification)

• Independent clearance testing confirmed the site passed IICRC-compliant standards for moisture and mould levels.

🧾 Project Details

• Total Cost: $10,500

• Project Timeline: 2 weeks (including drying phase)

• Outcome: Full clearance achieved with PRV passed

• Standards Followed: IICRC S500 (Water Damage) & S520 (Mould Remediation)

Videos from this project

a video compile of all the stages of our mold remediation project at Hornsby site.

second level floor joist affeted with mould from the result of water damage during construction at the Hornsby site

💡 Why It Matters

Timely mould remediation in early-stage construction is critical. Left untreated, embedded mould in framing timber can cause:

• Structural degradation over time

• Health hazards for future occupants

• Delays in construction schedules due to necessary rework

AAA Mould Removal’s proactive, standards-based approach ensured this Hornsby site remained on track and safe for future progress.

📍 Related Services

• Mould Remediation Process

• Book a Mould Inspection

• Mould Monitoring & Moisture Logging

• Inner West & Greater Sydney Services

💬 Testimonial / Builder Review Block

“We were under pressure to keep the construction schedule on track, but the mould across the frame was a huge concern. Michael and the AAA Mould Removal team were incredibly professional, fast, and knowledgeable. They not only remediated the mould but gave us confidence moving forward with the build. Highly recommend them for any site-wide mould issues.” — Site Supervisor, Hornsby Construction Project

❓ Frequently Asked Questions (FAQ)

1. Can mould really grow during the construction phase?

Yes, absolutely. If framing timbers or structural elements are exposed to water—such as during storms or plumbing leaks—mould can begin to grow within 24–48 hours, especially if drying is delayed.

2. Is it safe to continue construction when mould is present on the frame?

No. Continuing to build over contaminated materials risks sealing mould inside walls and ceilings. This can lead to long-term indoor air quality issues and costly structural remediation later on.

3. What’s involved in removing mould from a building frame?

We follow a certified protocol involving containment, HEPA-filtered air scrubbing, sanding, vacuuming, chemical treatment, and rapid drying. Every step follows IICRC S500/S520 standards for health and safety.

4. What is PRV and why is it important?

PRV stands for Post-Remediation Verification. It’s an independent clearance test that confirms all mould contamination has been properly removed, and the site is safe to proceed with construction.

5. Can you remove mould even if parts of the timber are still wet?

Yes. We use advanced drying equipment and moisture meters to ensure we remove both visible mould and underlying dampness. Flash drying and ongoing monitoring are key to preventing regrowth.

6. How do you price construction mould remediation jobs?

Pricing depends on the size of the area, the severity of contamination, access challenges, and equipment required. For this Hornsby project, the total cost was $10,500 for 280 sqm over 2 levels.

7. Do you work with builders and developers?

Absolutely. We frequently partner with builders, developers, and site supervisors across Sydney to manage active site mould issues quickly and professionally—with minimal project disruption.

About the Author

Michael Nguyen is the founder of AAA Mould Removal and a leading expert in mould remediation and building science. His mission is to help Sydney residents maintain healthy indoor environments through scientifically-backed, professional remediation services.

With a unique combination of hands-on and academic expertise, Michael's qualifications are extensive:

• IICRC Certified: Water Damage Restoration, Applied Microbial Remediation & Applied Structural Drying.

• Microbiology: Completed specialised study in Microbiology at RMIT University.

• Licensed Builder & Carpenter with a Diploma in Building & Construction.

• Current University Studies: Double Bachelor’s degree in Medical Science and Environmental Science at Macquarie University.

  
  

This deep understanding of building structures, environmental science, and microbiology allows Michael to diagnose the root cause of mould problems, not just treat the symptoms. He specialises in residential and commercial mould removal, black mould treatment, and water damage restoration.

Need a true expert to assess your property? Contact AAA Mould Removal today for a comprehensive inspection