Post Tension Cables: A Fictitious History & Serious Facts About
by KaraLee Foat
on Tuesday, December 5th, 2017 at 11:59am.
I'm not an engineer, evidenced by the fact that I have people skills.
Just kidding. My brother is an engineer and he is brilliant. For the most part, engineers get things right. But when they don't, it's really fun to mock them.
For years, issues keep popping up with post tension cables in condo buildings. Since I had no concept of what those are, I tried to get into the headspace of an engineer - I locked myself in the basement with multiple laptops and a single flavor Slurpee. Eventually, I developed a fictional story of the origin of post tension cables to explain some very relevant facts that have a huge impact on many condo owners in Calgary.
This is how I imagine post tension cables were created:
The boss, probably an architect with a keen eye for design, entered a room full of engineers. This was 1968ish so I'd like to think it looked like Madmen: with guys in slick suits, drinking scotch, huddled around a radio listening to Cream.
But they were engineers so it looked nothing like that. I can't picture it at all. Anyways, the architect explained to the dorks that people want bigger, more open spaces in their apartments; therefore, fewer structural walls. However, people hate falling through the floor. So figure out a way to reinforce floors to create larger rooms. 'And don't come out of this room until you've figured it out.'
The nerds made primitive spreadsheets with paper and pencil and punched numbers in massive calculators. They eventually came up with an idea: take a steel cable, cover it with grease, insert it into a plastic tube, run them through the floors of the building, and pull the cables tight.
The boss loved it. To celebrate they went for drinks at the new restaurant/single male engineer hangout called Hooters.
This is where the story gets real:
Years later, after the geeks had invested in Microsoft stock and owed small islands in the Caribbean, problems started to emerge. When the steel cables were exposed to water and oxygen, which are quite common on our planet, they begin to corrode. Taught corroded cables tend to snap like an engineer's stick arm in a UFC match.
Now you've got a giant cable secured inside plastic, in the middle of a huge span of floor, providing zero structural support. Again, I'm not an engineer, but this sounds like a disaster. An extremely costly disaster.
In Calgary, a significant number of apartment buildings were built in the 70s and 80s with post tension cables.
If you live in a building with post-tension cables it's imperative your condo board gets frequent engineering reports on the status of the cables. I recommend engineers with computers, not paper and pencil spreadsheets. Those guys tend to be quite expensive. And, I've been told, getting a clear indication of the state of a cable inside a plastic tube, covered in concrete, under the floor of where your couch sits can be difficult to do. Once again, I'm not an engineer, but I suppose that makes sense.
Here's the kicker for condo buyers: if you have less than a 20% down payment your mortgage needs to be insured (I wrote about that here). CMHC and Genworth are the two largest providers of this insurance. Currently, neither one are insuring buildings with post tension cables. (In some cases they will but I've never seen it happen). Without insurance, you can't get a mortgage. So your options are: A) have a big down payment and assume a huge risk, or B) not be able to get financing at all.
As a Realtor my advice is, avoiding these buildings all together is your safest bet. Always make a condo document reviewa condition when purchasing a condo. That way you'll know for sure if the building has post-tension cables and if they are being monitored properly.