Extreme Durability – Helping Buildings Last 100+ Years
Durability is often thought of in terms of how long a material will last, but buildings are more than the materials they’re made from. As John Straube discussed in his presentation on “Extreme Durability” at our January LAB Event, how long a building lasts depends on how materials are combined, what they are exposed to, and how they are maintained.
The definition in CSA S478-95 (R2007) – Guideline on Durability in Buildings covers a lot of important ground: “the ability of a building or any of its components to perform its required functions in its service environment over a period of time without unforeseen cost for maintenance or repair.” In particular, as John pointed out, this definition rightly highlights the service environment; a material that lasts well in Arizona might not do so well in Seattle or Alaska (and vice versa).
The CSA S478-95 definition also touches on the idea of different components having different deterioration rates. Theorists such as Stewart Brand and Bill MacClay have repeatedly pointed out that buildings are made up of different layers or components which each have different lifespans (if you’re curious, Brand’s “How Buildings Learn” series is available on youtube and recommended by Dr. Straube: www.youtube.com/watch?v=AvEqfg2sIH0). Decoupling components can allow them to be repaired or replaced on different schedules.
In general, deterioration mechanisms and likely environmental exposure need to be considered for each combination of materials in an enclosure. Materials never exist in isolation. John gave the example of stainless steel roofing chosen for its material durability that wound up suffering from “the Wolfgang Puck effect” – i.e. lots of mushrooms, in this case growing underneath the stainless steel after water leaked into the felt and OSB components below the surface of the assembly. Different materials will be more or less susceptible to water, solar radiation, temperature, etc. They might also be better or worse protectors of susceptible materials: stainless steel roofing won’t itself be damaged by water but is likely to leak. Material selection and arrangement should take all of this into account.
John also made the point that technical durability doesn’t mean much if a building gets torn down after 10 years for non-technical reasons. It’s worth asking questions like:
- Will the arrangement of space allow for multiple uses?
- Will the style of architecture go “out of fashion” quickly?
- Does the building have historical or other cultural significance that will motivate people to keep it standing?
Many old buildings that have lasted for 100+ years have done so in part because of their flexibility to accommodate new uses and tastes. Buildings of today should also consider how needs might change over the next 100 years.
Buildings that no longer suit local needs may be demolished long before their predicted lifespan.
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