Murano Condo, Toronto, Where the Glass is Falling off Balconies. Image credit Allan Windows
Glass balcony panels are raining down on the streets of Toronto from the shiny new condominiums, building envelope expert John Straube was interviewed on Ontario Morning to discuss the problem. He didn't say a whole lot about why the panels are falling, but did a great explanation of the problems that come from building condos out of glass. There is a big difference between the glass on office buildings and on condos; the former is usually curtain wall, that runs continuously on the exterior, the latter is window wall, really a modified store-front wall redesigned for condos, supported by each floor and running from slab to slab. It is a lot cheaper. Straube does a good interview; some bon mots:
Murano Condo under construction, image credit Loozrboy
- Glass and aluminum are great for cookware but not for buildings.
- With floor to ceiling glass, you have nowhere to hang a picture, place your furniture or change your underwear.
- Energy efficiency is five times lower than a conventional wood framed house.
- The glass area is so large that it is difficult to control temperature, it's too hot or too cold.
- If we care about the long term, we should go for a balance, no more than 30 or 40 percent glass.
Straube noted that while aluminum and glass are easy to clean and durable, the sealants and gaskets are not, and will need maintenance and replacement down the road. This is not cheap or easy, and the burden falls on the condominium association and the owners. (Glass and aluminum have very different coefficients of expansion, and the sealants are exposed to sun, wind and rain for years.)
Straube suggests that the reason architects choose to build like this is about style and not cost, but I disagree, having worked with the architect and window manufacturer for the project with the falling glass (which was from the balconies, not the windows, and from a different manufacturer) on some of the earliest all-glass projects in Toronto in the 90s. It's a lot cheaper and a lot easier for a developer to work with one trade, the window wall supplier, than to coordinate among trades when mixing precast or brick with glass.
The building code encourages it too, by regulating the R-value of wall constructions, like saying all solid walls have to have an R-Value of R20, but not regulating the overall heat loss through a wall, so a builder can put up a glass tower with an R Value of R4 and comply with the code.
If the authorities in Ontario said, for example, that a total wall area must have an average R-value of 10, then designers would have to figure out a mix of solid wall and glass, and if they wanted more glass they would need to buy better windows, and stop building radiator fin balconies.
But that would raise costs and prices and might kill the golden goose that is the Canadian condo boom, so they will just let the condo purchasers worry about it a decade from now.