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I don?t know about you, but I absolutely hate spending my precious free time hacking out rotten wood, scraping peeling paint, and trying to preserve my biggest ever investment. Any time I see fancy painted wood fascias I don?t think that looks nice, I think I?d hate to own that house.
I?m still reading Stuart Brand?s book "How Buildings Work" which kinda sums the issue up for me:
?As for wood, redolent with tradition, it is the best of materials from the standpoint of adaptability and one of the worst in terms of maintenance. It is fairly cheap, made of a renewable resource, easy to work, and it can be extortionately beautiful. But it wants to absorb moisture, and wherever the water content gets over 21 per cent, the wood turns into habitat and food for fungus, termites, ants, beetles, bees, borers and other wildlife. "What holds up that house?" one cynical carpenter asked me rhetorically, gesturing at a nearby standard stick build home. "Faith, habit, and the dead bodies of termites, same as all the houses around here." Who builds in wood builds a shack, adaptable now, gone soon.
The exception is timber framed buildings, because the wood structure is protected from the weather, it is massive, and it is exposed. Air and eyeballs can get at it to keep it dry and inspected. "According to government statistics," reports Gene Logsdon, "the average life of a conventionally built stud house is about 75 years. The life of a timber frame house is at least 300 years, and some over 1000 years survive."
The principals for longevity are very simple:
1. design, design, design - the best Architects understand the materials they are using
2. material selection - fast grown softwood is a very cheap building material, but not in the long term
3. whatever you use, keeping it dry or allowing it to dry out easily is the key
More blogs by Scott Fotheringham
We were looking at a frame last week (not one of ours I hasten to add), where a considerable number of posts and studs had twisted, and we got to discussing why this was.
Trees are both geotropic and phototropic - that is, they generally grow straight down by default, but also grow to the light. While this might imply that the obvious way for a tree to grow is straight up, and that therefore the grain in it should be straight, in reality this is rarely true.
To a greater or lesser extent, all trees have tension built in. As soon as we cut a tree down, the tension will try to dissipate. This means that spiralled grain will try to straighten out, causing twisting along its length. (It is this same principle that makes boards of timber distort and cup - the rings are effectively straightening out with nothing restrain it.) None of this affects the structural strength of the timber, but can, of course look unsightly.
For the purposes of timber framing, our specification does not allow for markedly sloping or spiralling grain, so problematic pieces will be rejected. However, even a small twist can become relevant over a long period, so that a beam of good quality which is perfectly square when it comes off the sawmill, is unlikely to be perfectly square by the time the joints are cut in it.
This twisting effect is why we use the manufacturing methods that we do. We physically lay out the timbers and mark them up in relation to the others so we can take this movement into account, rather than assume the whole beam is square and take the edges or centres at the separate end as datum points.
So, like shrinkage, which we seem so keen to keep talking about, twisting shouldn't be an issue provided that the milling process and the manufacturing process take it into account.
More blogs by Tim Burrell
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