Derelict building inspection, Wexford

Understanding what you're dealing with when you can't safely look

An established client approached Engineers With Drones to assess the feasibility of restoring a historic hospital building in Wexford. This would have been the main hospital building, but it has since been overtaken by a new hospital building and left to ruin.

But it is a very beautiful building. It could still become a functional building again, and the client needed to understand its current condition and restoration potential.

The problem: "it's incredibly dangerous to go inside because it's collapsing" - all the roofs are collapsing. The walls are beautiful old stone walls, but the roof is just falling in.

The client needed to know what they were dealing with at a fundamental level. "Is there still walls inside? Is there a roof inside? What is the story with this building?" All anyone could see was dense bush and a building behind it, with a fence preventing access to even understand the extent or layout of the building.

There were no drawings for a building like this - it was built years and years and years ago. The building was completely inaccessible for conventional assessment.

So the client asked Engineers With Drones to provide a solution.

The two-technology approach

To give the client a complete understanding of what exactly they were dealing with, Engineers With Drones deployed two different drone technologies: an external photogrammetric drone and an internal confined space drone.

The external photogrammetric drone created a full 3D scan of the entire structure from the outside. This allowed the client to understand the overall condition, the extent of the building, features like chimneys and roof condition, and areas that weren't even visible from ground level.

The internal confined space drone went inside through open windows and documented the interior spaces with high-quality 4K video. This showed what the inside looked like - the condition of floors, ceilings, beams, walls, and crucially, where it was safe to approach and where it was not.

Together, these two approaches gave the client everything they needed to assess the feasibility of the restoration project and make informed decisions about how to proceed.

External 3D photogrammetric scan - seeing what nobody else can see

One of the best solutions Engineers With Drones could provide was a full photogrammetric 3D scan of the entire structure. "That way anybody associated with the project at all with a single internet link could suddenly get extremely well orientated with exactly what they were dealing with."

The photogrammetric scan is quite lifelike and quite useful. You can clearly see the condition of the roof slates and tiles. You can see the condition of the brickwork in chimneys - whether there are major cracks or not.

"An awful lot of things can be understood at an intuitive level very very fast by anybody looking at this 3D model." Whereas most people who would approach this building without the 3D model would only see it from the road, with the model they can see everything.

Video: Interactive 3D model

See the 3D photogrammetric model in action. The video shows how users can zoom in and out, rotate the view, and examine any part of the building from their office:

Discovering what wasn't visible from the ground

The 3D model revealed features the client had no idea existed. "They had no idea that there was some form of courtyard here" where all these trees are growing. All the gaps, the tall chimney - everything becomes clear in the model.

Understanding the limitations and strengths of photogrammetry

The photogrammetric process is not good at processing thin objects like fences, wires, or tree branches. "But monolithic objects like buildings, it's extremely good at processing" - which is why the boarded up sections almost look exactly like a photograph. It's very easy to understand and intuitive. You can get an idea of size, scale, shape, and condition very quickly.

A permanent heritage record

At some point somebody in the demolition business will come in and strip out all these roofs. "But they will have a record of what it was" - they'll know there was a little bell tower where a bell could go, chimneys, air vents. "So there is a record of how they found it before they broke it all down and rebuilt it."

Internal confined space drone survey - walking through without walking through

Once the external scan was complete, Engineers With Drones "fired up our internal confined space drone" to show the client what the inside looks like.

The video quality is extremely high - shot in 4K at 30 frames per second "so that the client could pause it at any point" and examine details.

How the confined space drone accesses the building

"Any open, clean access at all is usable." The drone starts broadly to orientate viewers to the location - accessing about halfway down the building, first floor. "You never want to start just right in the thing because then nobody knows where you are."

Then the drone carefully accesses the window, looking up and down to make sure everything is checked and visible. There's a nice big open span that the drone can easily fly through.

What the video reveals

Once inside, "you get an idea. We're fundamentally inside an old ward or something like that. You can see the old tiles that used to be on the wall there. That sort of 70s green." Old shelving, old corridors, door frames, old stud partitions - all clearly visible.

All of this is extremely useful for the client in terms of deciding how best to approach the project. You can see where the floor is completely collapsed, the roof above almost completely gone. "Remember if you were walking through here normally any of those tiles could come down at any moment on top of your head."

"Whereas the drone here if a tile comes down, yeah the drone might get hit but that's all we got to worry about, nothing else."

The drone flies at almost head height, "just walk through the building, step through various doors, windows, whatnot" and gives a very good impression of exactly what the structure looks like.

Video: Confined space drone footage

Watch the confined space drone navigate through the interior of the derelict building, capturing 4K footage at head height as it moves through wards, corridors, and around structural elements:

What the survey revealed - understanding condition and safe approach

The purpose of this survey was not to create a defect classification report, but to give the client an understanding of what they were dealing with so they could assess feasibility and plan a safe approach. Here's what the survey documented.

Complete floor collapse in multiple areas

In several areas, "the floor is completely gone, all the joists are completely gone." But anybody can look at this and understand the condition of the building.

Staircase in good condition - a safe approach point

One of the most useful findings was identifying safe access points. An old staircase was found to be in reasonably good condition. "There's no debris. There's no overgrowth. There's no falling object dangers." The team could at least get up the staircase to make further analysis. "That'd be a good point of approach."

Unstable upper floors with hanging materials

In contrast, a first or second floor area was identified where "that floor there looks incredibly unstable and the roof above it and the materials above it hanging down look incredibly unstable." This told the client where not to approach.

Critical beam assessment - water damage and rot

The drone paid particular attention to the heavy duty beams "because those will tell the client overall whether it's safe to access or whether they have to attack the problem from a different angle."

One wooden beam was found to have significant issues: "that beam is not in good conditions. Rotten could be dangerous. The plaster could be dangerous. There's a lot of water damage on the end of that wooden beam."

Steel work condition visible throughout

Throughout the survey, the condition of the steel work was documented and captured in the imagery "so that the client can then make a much more detailed assessment of how they want to access this building and where the danger points are."

Conservation context - what stays, what goes

An important consideration for this project was heritage protection. Not all of the building has the same status.

"All of the stonework is fully conserved. You wouldn't be allowed to touch that." The beautiful old stone walls that form the core structure of the hospital are protected and must be preserved.

But sections that were built later don't have that protection. Newer sections built in 1960 have no heritage value - "we'll just knock all that right now because it's easier to knock it and build something else there than to try and renovate that."

The client could make decisions like that based on the imagery at the very start "as opposed to waiting and then looking and going actually this is not worth it." They could immediately see what needed to be preserved and what could be replaced.

Everything needed for feasibility assessment

Engineers With Drones presented "a whole set of video deliverables and a whole set of 3D photogrammetric data to the client. And that was what they wanted. That was their scope."

Informed decisions without dangerous site visits

Once the client had the deliverables, "they seemed very happy. They were able to make an awful lot of decisions based on the imagery in those videos."

Feasibility assessment without personnel risk

The entire feasibility assessment could be conducted without requiring anyone to enter the dangerous structure. The project team was able to understand what they were dealing with - the extent of the building, which areas were collapsed, which areas were stable, where heritage stonework existed, where 1960s additions could be demolished and replaced.

Team orientation from a single link

Anybody associated with the project could access the 3D model through a single internet link and immediately understand the building. There was no need to bring multiple team members out to the dangerous site for orientation. They could access the model remotely and fully understand what they were looking at.

Restoration timeline and planning

The building itself is significant. As Bob Foley notes: "I don't see anybody tearing it down anytime soon. I see it more as a building that will be restored in time."

The survey data will support that restoration project by providing complete baseline documentation, safe approach planning, and a permanent record of the building's condition before work begins.