Increased Buildability

  • Building Design Expert
  • 9 years ago

There has always been a problem with the ‘standard design detail’. That problem being, what is ‘standard’ about anything in building construction? A standard brick comes in a variety of sizes. Similarly, standard timber sections are from an inconsistent material that continues to move, expand and contract, throughout it’s installed life; as do all materials to one degree or another.

So building design professionals are aware and acknowledge a wide palette of differing construction tolerances when putting together their building jigsaw. If it’s done with thought, care and methodology, the outcome can sometimes belie the visual intention. But if the original sketch design is not practically resolvable, then pragmatism wins in the end. Or does it?

An outside of the box design detail in inexperienced hands may tick all the right boxes in the drawing office, then give it to the building site manager, or engineer – “I’m calling to let you know that I can’t build this detail” – “What do you mean, you can’t build it? I’ve spent days drawing it!!”

Anyone who has tried will know that spending too long on a detail, can have the same consequences as spending too little time. ‘Wood for trees” is the phrase that tends to kick in. But there is often other stuff too.

In an earlier life I recall going to site to see a suspended timber floor being installed. I asked the joiner why he was packing what seemed to be endless amounts of slate under the bearing ends of each joist. (We didn’t do ‘timber regularisation’ back then), he patiently explained that it was okay for you people ‘on the board’, drawing nice straight lines in our perfect worlds, but we find out all your dead straight lines on site – he cast his arm around a semi-circle – in all this dust and grime. He explained that the subtle variations in the bed course of the inner leaf were then magnified by the fact that all the joist sections were of slightly different sizes. The result being that a level floor was much harder to come by. Well you live and learn don’t you? In fact you live, learn and never forget those sort of lessons.

So a sharp lesson in translation from the computer screen (drawing board) to reality. The buildability of my perfect floor was brought into sharp focus. Fortunately for me, my joiner with infinite patience was quite used to adapting our ‘cartoon details’, virtually without thinking about it. If only to fulfil the base requirements of his own trade. Unfortunately it’s an all too common problem in general. What’s works perfectly on the CAD screen, can and is often found out once on site.

I learned a great deal from what was an unscheduled visit to site that day. Both the obvious resolution of the floor construction, and just as important, the between the lines stuff that influenced the completion of so many other details thereafter.

So what’s the secret? No secret. No silver bullet. If I had not been to site to see things built, there would have been no realisation that we needed to consider not only resolving the technical design such that it will remain structurally stable, and do things like keep the water on the outside. Despite any contractors claims, I know this cannot successfully be achieved by designing on site; consistently anyway, so it’s best not to take the chance. But lose sight of practical execution, and you will turn a great design detail into a caricature of the original and you will find out how ugly caricatures can be.

A successful design will not only use all the right thickness lines, and all the right hatches in all the right places; but the author will understand how all the constituent parts will go together under the less clinical conditions of a building site, taking into account dusty, grimy, cold and wet conditions, and even the bad tempered joiner who didn’t get his bacon butty that morning. Flippant points that lead to the sometimes indefinable that is Increased Buildability.

Just think if it’s easier to build, you might just get a better quality of build. – ‘Quality’, now that’s worth holding out for.