Friday, 27 October 2017

How to build a house in Japan part 3.14159265... How much do you need to know?

Disclaimer: you're going to have to wait for the next post if you want some ideas about exactly what you need to know.

If you buy a car, you don't usually start making suggestions about where to put the seats, where the filler for the fuel tank should go, or the timing of the spark plugs. But when you build a house it's possible to make all kinds of request and suggestions. You may also have noticed that almost all cars are built in factories, where standard parts are assembled in quality-assured processes. Although cars were all bespoke in the beginning, to build a car by hand now you would need a lot of expertise, time, money, or perhaps all three.

It's tempting to think that the same economic forces will push all houses to be factory-built, leading to higher quality and lower cost. But that happened to the automobile industry well within a hundred years, while house building is perhaps a hundred times older, and many houses are still built by hand. So some other factors are at play. Of course there are logistical issues with actually building houses in factories: wall and roof structures can be factory-produced and assembled on site, and sometimes are, but it would be very difficult to transport whole buildings over inevitably large distances from these huge factories. Cars, on the other hand, could be literally driven off assembly lines.

Another conclusion is that building a house is much easier than building a car, and it is within the capability of many more people. So one question you may want to ask is: how much do you need to know to build a house yourself? The short answer is that if you can ask that question, you probably know enough, or at least will find out enough in the process, which you should appreciate will take at least a couple of years.

But before you start thinking about doing everything yourself, how much do you need to know before you start commissioning others, and looking at part 4, which is paying for the project.

High-volume, low-cost builders are likely to give fewer options, but as the scale comes down and the price goes up, so do the choices you can make. Building professionals should probably be giving clients simple choices between limited options or within small ranges, with the kind of user friendliness that Steve Jobs brought to Macintosh. But people do have opinions about the way a house should be, and it may not be on the menu. These ideas may be based on things you have in your existing house, things you saw in someone else's house, things you read about somewhere, or something from your fertile imagination. Whatever ideas you have, if you are paying for your own house, it's reasonable to request it to be your ideal house.

But be careful of what you wish for, as you might just get it. Indeed your imagination may be playing around with what some of those things in other people's houses and in magazines actually are or do. And if you have a great idea for your house, but have never seen another house that uses that idea, then it's possible it's not actually a great idea, and there are very good reasons for not doing it. It's also possible that you have just invented something. 

And it's also possible that it is a great idea and has been used in several other houses, but you just haven't seen them. If the architect or builders tell you it's impossible it may just be beyond their experience. I remember in the early stages of our project suggesting to the architect that we could take heat out of the air leaving the house and use that for generating hot water. The architect laughed at me. Later I was talking about the same thing to the passive house lady, and she said, "Oh yeah, that's what they do in Sweden."

So visit as many houses as possible. You can also look at houses in magazines, but beware that they may be idealised houses that are lived in very differently, and any of the features may have lost their sparkle a couple of years, or even a couple of weeks after the paint dried. Or the features may still be there but are invisible under layers of magazines, homework the kids didn't do, bits of clothing that you're not sure who left behind, and jars filled with pens that mostly don't work.

The internet is a great source of information and you may often be in a position where you know more about a topic than the professionals. Materials and techniques around the world are developing all the time, and what your architect learnt at college twenty years ago may have changed, been superseded or debunked. Watch this you tube video for some brilliant tips for doing it yourself. I particularly liked the idea of putting a rubber band over the head of a worn-out screw to get some purchase on it. But also remember that a lot of professional builders now make a living from correcting projects by people who watched one youtube video and thought they knew what to do.

Stick some foam in, she'll be right! (not)
But beware of the Dunning-Kruger effect. This means that your ability to know how good you are at something depends on how good you are at doing it, because the skills needed to judge an ability are similar to the skills needed to have that ability. This should make you humble about your ability to specify the building you want, choose contractors, or take on a project management role. It may also apply to the architect or builder if you are expecting them to do something new. They may have no relevant experience with insulation, airtightness, installing high performance windows, ventilation systems or any other features essential to low energy buildings.

So when talking to professionals, while they probably know more than you know, remember:

  • they probably know less than they think they know 
  • you probably know more than they think you know
  • you may know less than you think you know

People say that a little knowledge is a dangerous thing, but in fact any amount of knowledge can be dangerous.


1. For most calculations, pi is a bit over three. The precision in the title would give you the length of a piece of string around the equator to within 40 centimetres, if the earth was perfectly round, which it is not, and you knew the diameter to within a few centimetres.

2. How long is a piece of string?