35,000+ Sq Ft of Deficiencies on One Landmark: How RDH Building Science Inspected a Historic Hospital with Drones & Hammer Missions' AI

Inspecting a large, historic hospital is one of the hardest assignments in facade and structural engineering. The buildings are tall, sprawling, and often decades old — which makes traditional access slow, expensive, and disruptive. When engineering firm RDH Building Science took on the assessment of a landmark hospital, they turned to drones and AI to bring the entire building envelope to the desktop.

The result was a comprehensive condition assessment that surfaced a striking finding: over 2,000 individual spalls, covering more than 30,000 square feet of the structure — a volume that would have been nearly impossible to catalogue reliably by hand.

This case study walks through how the inspection was planned, captured, analysed, and reported using the Hammer Missions platform.

The Challenge: A Landmark Building at Scale

The hospital is a 19-storey landmark that first opened in the 1930s, part of a site spanning more than 1.2 million square feet. The traditional approach to a facade and structural assessment would be rope-access drops and hands-on inspection across the full envelope. But due to the structure's scale and age, this quickly becomes non-viable. Reaching every elevation and roof area by physical access would be slow, cost-prohibitive, and disruptive, and the sheer surface area makes it easy for defects to be missed or recorded inconsistently.

The inspection was led by senior forensic engineer, Clay Harman of RDH Building Science, and for this instance, drones and Hammer Missions’ AI were the natural solution to that access problem. They bring the entire building envelope to the desktop, letting RDH assess roofs and facades in detail without scaffolding or rope access. But solving access introduced a second challenge: capturing a building this size comprehensively meant collecting over 4,000 images — far more than any team could realistically review by eye, defect by defect. That volume is exactly where AI and a purpose-built platform like Hammer Missions become essential.

Planning the Flight for Complete Coverage

Using Hammer Missions' automated flight planning, RDH designed flight paths that captured the data in the right places. The drone followed predefined waypoints around the structure, with each waypoint documenting an exact photo location across the facades and roof.

The key to a clean, gap-free model is overlap and camera angle: top-down passes capture the roof, angled passes capture facade detail, and vertical overlap between the two ensures a seamless 3D reconstruction with no blind spots. For a footprint of this scale, that disciplined, automated flight design is what makes complete coverage achievable in a repeatable, standardised mission plan — rather than a patchwork of ad-hoc captures.

The team at Hammer Missions worked closely with the RDH team to ensure an effective flight plan was created, mapping out waypoints to cover every face of the building, accounting for tight angles, obstructions, and areas where defects were most likely to hide. The data was captured in accordance with the GOLD principle of capture, ensuring that every image met the overlap, orientation, lighting, and detail standards required for a complete and accurate reconstruction.

From Imagery to a Digital Twin

Once captured, the 4,154 images were uploaded to Hammer Hub, the platform's web-based environment, where they were transformed into 2D maps and a detailed 3D model — a high-resolution digital twin of the hospital that RDH could explore in full from the desktop.

A model alone, however, only sets the stage. To work through the envelope at scale, RDH applied Hammer Missions' AI defect detection to the dataset, training the analysis to automatically identify and tag cracks and spalls across the imagery. Instead of an engineer manually opening and assessing thousands of photos one by one, the AI surfaced candidate defects everywhere they appeared, including subtle ones that are easy to overlook in manual review.

Cross-Verifying More Than 35,000 Square Feet of AI-Detected Structural Defects

AI detection is powerful, but it is only half the story — engineering judgement confirms it. With the candidate defects flagged across all 4,000+ images, RDH's engineers cross-verified them against the high-resolution source imagery and the 3D model, distinguishing genuine deterioration from surface noise and assigning severity.

The confirmed result: over 2,000 individual spalls, spanning more than 30,000 square feet, and nearly 5,000 square feet of cracks across the building envelope. Each was anchored to its precise location on the 3D model, so similar-looking areas could be told apart and every observation stayed organised and traceable.

Just as important as what was found is how quickly. Reviewing 4,000+ images by hand and cataloguing deficiencies at this volume would have taken multiple weeks of engineering time. With AI-assisted detection and cross-verification inside Hammer Missions, RDH compressed that effort into a fraction of the time — without sacrificing the rigour of an engineer-reviewed inventory.

Quantifying and Reporting a Drone & AI Inspection

A defect inventory is only useful once it is quantified and communicated. The inspection produced two core deliverables:

• RDH's professional inspection report, with deficiencies quantified — counted by type and measured for affected area using in-model measurement tools — and presented with severity ratings so the most urgent repairs surface first. The report is exportable to PDF, and the underlying data to CSV, giving engineers and downstream contractors clean figures for repair estimation, budgeting, and capital planning.

• An interactive 3D model with every deficiency tagged in its correct location. Stakeholders can open it in a browser — no account required on the receiving end — and jump straight to any defect, turning a static report into a navigable record of the building's condition.

Together, these give owners a defensible, prioritised picture of the building's condition, and give the engineering team a deliverable clients can explore for themselves.

Conclusion: Turning a Landmark's Complexity into Clear, Actionable Data

The inspection shows what is possible when drones, AI, and a purpose-built platform come together on a genuinely demanding structure. RDH Building Science was able to capture a 19-storey, 1.2M+ sq ft landmark safely and non-intrusively, process 4,000+ images without weeks of manual review, and convert the data into a quantified, location-anchored inventory of 2,000+ spalls across 30,000+ square feet — complete with severity ratings and a shareable, interactive model.

For property owners and managers, that means a defensible, prioritised basis for repair budgets and capital planning. For engineering firms, it means catching defects at a scale and consistency that manual methods can't match — and delivering results clients can navigate themselves.

“Manually documenting and quantifying the facade deficiencies would've been nearly impossible without Hammer Missions. These tools, combined with engineering principles and careful review, have provided a baseline for saving and repurposing this landmark building” — Clay Harman, Associate, Senior Engineer RDH Building Science Inc.

This inspection was carried out by RDH Building Science using the Hammer Missions platform. See a project like this for yourself — book a demo

Interested in learning more about drone-based facade inspections or seeing how AI can enhance your workflows? Reach out to the Hammer Missions team — we’d love to show you how to bring this process to your next project.

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About Us

Hammer Missions is a software AI firm helping companies in the built environment leverage drones and AI for assessing existing conditions. Having seen 5000+ projects, we're pleased to be working with leading firms in AEC to streamline and scale the process of facade inspections. If you're looking to learn more about how AI can automate and accelerate your building assessment projects, please get in touch with us below. We look forward to hearing from you.