What goes into maintaining the houses by architect greats such as Frank Lloyd Wright and Miles van der Rohe? Quite a lot actually. Curbed.com recently interviewed Gunny Harboe, an architect and preservation specialists who works to make sure that the iconic pieces of architecture are there for future victors and architect enthusiasts. Currently working on Lloyd’s Unity Temple, Harboe discusses the complexities of restoring reinforced concrete architecture from its early days.
One of the characteristics of this early concrete is that it's rather porous. It's not a solid mass like you think of when you look at the foundation of a house now. It's a very different type of material. It wasn't really consistent and had a lot of voids in it, meaning moisture and water could move through it very easily. We're not sure how early on it started to exhibit issues, but it was pretty early. By the 1970s, the concrete was at a point where they needed to do something about it and they made the choice to reface the building with Gunnite, which is Shotcrete, basically a spray-applied concrete. They resurfaced the whole building and applied the Shotcrete, it's shot on like a hose like when you're fixing a swimming pool. We're repairing the cracks, and the biggest challenge is getting it all to blend in so it doesn't look blotchy. We're going to great pains to do mock-ups and trials to match the appearance of the aggregate. There are little pebbles in it with different colors and different types.