Professional Builder Column by Jeff Howell.
How long do building materials last? Well, that depends on the way they are used, of course, and the amount or wear-and-tear they get. As well as the effects of “weathering”, which includes sunlight, rain, wind, frost, and the constant expansion-and-contraction that comes with changes in temperature.
But some materials have a defined lifetime no matter how carefully they are chosen, installed, and maintained. One good example of that is polymeric materials, or “plastics”.
Let me tell you an interesting story. When the Millennium Dome was first designed in the mid-1990s, the planned canopy was to be made of PVC-coated polyester. This was opposed by environmental campaign group Greenpeace, who thought that PVC had a short life and was bad for the planet.
When Tony Blair took over as Prime Minister in 1997, he gave the Dome the go-ahead on the condition that the canopy would instead be made of PTFE-coated fibreglass, which would have a projected lifespan of 25 years.
So it should really have been no surprise in February this year, when the canopy of the Millennium Dome – now known as the O2 Arena – was partially ripped off in the gale known as Storm Eunice. After all, it had reached its 25-year lifespan, exactly.
Funnily enough, the day after the Dome’s canopy was ripped to shreds, I was retrieving a plastic garden chair from the hedge where Storm Eunice had deposited it. As I tossed the chair back onto the lawn, there was a cracking sound, and one of the legs fell off. When I picked the remains up, another leg came away in my hand. I know just how long I’ve had those chairs, because I bought them when I moved into the house – exactly 25 years ago!
PVC guttering is probably the plastic material that’s been around the longest, and it does seem to last well, although you lean a ladder against it at your peril. And the clips can get brittle quite quickly.
Most of the storm damage around my way was from dislodged hip tiles. One neighbour was especially disappointed because his roof was only three years old. I explained that his roofer didn’t seem to know the rules, because hip tiles were supposed to be mechanically fixed down these days, not just plonked on dabs of mortar like his had been.
The neighbour asked how the mechanical fixing worked, so I invited him round to see my recent back addition. It’s easy I said, there’s no mortar involved, just these plastic clips between the tiles and a plastic washer on top, that you screw down to a batten.
Er . . . did I just say plastic? Well, I wonder how these dry fixing systems will be performing after 25 years?
