No smoking here, dummy!

I'm retired now, but I can't help musing on certain things when I see them. One of those things I saw recently was on top of a partially built house in a new housing development near where my parents live. It was a chimney stack on top of a roof. Except the roof was as yet no more than flimsy timber trussed rafters. There was no actual chimney below the roofline to support the bricks-and-mortar chimney stack, nor any chimney breasts in the rooms further down. The stack, complete with earthenware chimney pot, appeared to balance unsupported above the uncompleted house as if hoisted wholesale into position. Which, I concluded, it probably was.

During my working life in architectural practice I came across fakes of various kinds, including plaster and glass-fibre pretending to be something else, and I've been against them on principle, despite many being such good fakes that without actual physical contact it wasn't possible to distinguish them from the real thing. My objection isn't based on how poorly they replicate the real thing, but on how well they do it. They do it so well that it's impossible, at a moderate distance, to tell that they are fakes.

But once you know such fakes exist, that knowledge devalues the genuine article. You see something that looks genuine, but is it? The existence of convincing counterfeits puts everything into question. Does this matter? In the grand scheme of things, probably not, but if you care about truth, it most certainly does.

So I now look at chimneys with a degree of suspicion. Nowadays of course, this also applies to news media.

From the Stormking website:

The Stormking GRP SmartStack dummy chimney applies the same principles of the Stormking GRP chimney that enhance the appearance of any building offering the builder virtually maintenance free product, with a traditional aesthetic look, but with the added bonus of incorporating a GRP lead effect plinth box and lead flashing detail, saving you time and money with installation. Whilst the chimney used to have a function to them in the past, today they are viewed as unnecessary features that add to the build cost but are required under planning restrictions.

Skepticism in the construction industry

Misunderstandings abound in everyday life, at home, at work, in education, in government. This is an example from my own field — construction.

Herringbone strutting is an arrangement of short lengths of timber nailed between timber floor or roof joists to reduce their likelihood of twisting as they dry out. But very few builders actually use herringbone strutting, preferring what they call solid strutting, which is usually short lengths of the same joist timber, nailed at right-angles between the joists. Strutting isn't usually needed between joists less than 2.4 metres long, but timbers that span farther than this can warp as their moisture content decreases.

Solid strutting, however, is next to useless. The short lengths of timber can be jammed in between the joists as hard as you like, but as the joists dry out they shrink, and if the solid strutting wasn't nailed in only the ceiling (usually plasterboard) would prevent it falling out. Herringbone strutting on the other hand exploits the cross section of the joists, which are deeper than they are thick, so as they dry out, the vertical shrinkage is greater than the horizontal shrinkage, and the strutting (which is fixed diagonally — with the top of each joist being strutted against the bottom of its neighbour — and vice versa) actually increases its action, applying greater pressure between the joists as the moisture content reduces.

It's only in fairly old books about construction techniques that I've seen this explanation of how herringbone strutting works. Modern instructions seem oblivious to its unique cleverness, stressing its use in spreading point loads to adjacent joists, and suggesting that solid strutting is an adequate alternative. It isn't. The only effective way of using solid strutting is to drill a hole through each joist next to the strutting and fit a tension rod with nuts at each end. The joists can then be cramped up by force to ensure they won't twist. Needless to say I've never seen this done, and when I suggest it the response is derisive laughter or plain astonishment. But then I point out that herringbone strutting would be a cheaper, easier and effective alternative.

When timber arrives on site green there's a chance it will be used in the construction while its moisture content is still above 18% — all the more reason, therefore, to insist on the proper job.

That's an example of misunderstanding how something works. I've also encountered magical thinking on building sites, in particular dowsing. Anecdotes — like misunderstandings — abound, but as far as I can tell that's all they are. Here's my anecdote.

My own encounter with a dowser was initially impressive as he accurately traced the route of drains. However, when I asked if there were drains elsewhere on the site, he confidently swept the area in question and pronounced it dry. But my own knowledge of how drains are laid led me to speculate that there were in fact drains in this area, and judicious examination of manholes, flushing of loos and turning on of taps revealed that to be the case. I concluded that the dowser was extremely good at detecting drains when he already knew where they were.

It was some time after this encounter that I learned that when dowsers are properly tested under controlled conditions, their results are no better than chance. Unlike the dowsers in the tests, I didn't find this surprising.