How technology is changing heritage restoration

Oh, I wish I had these tools when I was an architect!

Trade shows at heritage conferences are usually full of heritage stuff, like stonemasons, metalworkers and restoration companies. However, while touring the show at the APT/ National Trust conference in Montreal, I was amazed at some of the new tools and technologies that have changed the industry since I was a young architect doing heritage restorations forty (!) years ago. If only these had been around then, I could have put them to good use. Here is a story of how one project might have turned out differently:

In 1984, a major development company hired me to restore some historic houses on the fringes of one of their land assemblies. One was the James Crowther mansion on Bloor Street West in Toronto; this was a big, impressive, important home smack in the middle of prime Bloor frontage.

The plan was to bring in an experienced American house mover, pick it up, and roll it 76 meters (including a 90-degree right turn) onto a parking lot over the subway on St. George. However, when I went through the house with my engineers, I was surprised at how shoddy the structure was. It seemed to be just stuff leaning on stuff. I wondered how it was standing at all, let alone whether it would survive being lifted and moved.

I told my client that moving the house was a bad idea. I proposed a different plan: rent a cherry picker and photograph every square inch of it, carefully dismantle it, cut out all the difficult brick detailing, clean up the rest of the bricks, and rebuild it on the St. George site.

The client didn’t think much of my idea and I was fired. Another architect took over and the move commenced; you can see a great Getty Image of it up on its steel beams here. As soon as they started to move the house, it collapsed into a pile of bricks and sticks, and that was the end of the Crowther Mansion. A sort of post-modern allusion to it was built instead.

When I wanted to document the Crowther Mansion, I was going to use a lot of film and a cherry picker as a platform so that there would be no perspective distortion. Now, I would call in iSCAN. Nathalie Garceau explained how they use 3D scanners and photogrammetry to produce detailed drawings and models of existing buildings in far greater detail than I could ever have achieved with film, and in 3 dimensions.

The detail is amazing and precise; they can measure deformation in millimetres. They can “digitize the exterior and or interior of the building using a laser scanning device. It is also possible to identify more precisely particular details, objects, furniture, monuments, statues, and combine them with photogrammetry for photorealistic digital clones.” More at iscan3d.ca

One of the problems I would have faced with the Crowther building is cleaning all the bricks, a slow, expensive and labour-intensive process. Unless you have the Brique Recyc machine; Olivier Da Costa says it can clean two to eight bricks per minute. You just feed them in and it saws off the mortar. So many old bricks are sent off to landfills; now they can be reused.

It’s a small machine that can be purchased or leased for a job. It’s also light enough to be used on a scaffold. You can watch a video of it in action here. (The audio is in French.) More at Brique Recyc

I had planned to put new windows in the reconstructed Crowther mansion because the existing single-glazed windows had such low insulating values. But windows were such an important part of its character, with a turret and bay windows on the second floor.

Today, we have vacuum glass! It has the thermal resistance of double or even triple-glazed windows. Giovanna Fernandes of Pilkington is showing Spacia vacuum glass in panels only 6mm thick; they can replace panes in existing glazing or be used in new windows. You can barely see the little black spacers that keep the panes apart.

“A vacuum provides excellent thermal efficiency and if the pressure is low enough, it will eliminate the conductive and convective heat exchange between the two panes of glass. In a standard double glazed unit with a low-e coating, the conduction/ convection component can result in 70% of the heat lost and so eliminating this loss is significant. The vacuum space provided between the two panes with Pilkington Spacia™ significantly reduces thermal conduction and convection, and a low-e coating reduces thermal radiation.”

Let me conclude by noting that dismantling and reconstructing buildings is generally not good practice, especially in Toronto, where, today, façades and buildings are moved around like chess pieces to make room for condos. We are left with a pastiche, what Bob Allsopp calls “urban taxidermy;” as he noted in Now Magazine:

“Is it worth keeping these buildings? Yes, of course, but do we have to kill, stuff and mount them for them to survive? They are more than historical artifacts, bricks-and-mortar facades with finely detailed sills and cornices. They are part of an economic, social and cultural ecology that cannot be disassembled.”

With the Crowther mansion, I got fired, it didn’t happen, and my conscience is clear. But I am still so impressed with the technologies that would have made it possible.