Map of life expectancy at birth from Global Education Project.

Sunday, September 11, 2005

Raise high the roofbeam . . .

Even for the secular, Sunday is good to have as a day of rest and reflection, so I'm going to take it easy and reflect. (I'll have to use some vocabulary not all readers will understand. I'll explain in comments if anybody asks.)

Yesterday I went to O.L. Willard & Company in Willimantic and bought two 2X10" pieces of straight, flat douglas fir, one 12 feet long and one 14 feet. These are the ridgepole of my house. At the building site, Mark had looked up the rafter specifications for a 9 pitch roof and the span of my house, carefully laid out and cut a pattern rafter, then used it to produce a twin. He had also constructed a staging platform a little less than 9' high out of scrap.

My brother Tom arrived. We erected a 16' pole dead center and vertical at the south gable end, and used it to simulate the ridgepole as we temporarily placed the prototype rafters and clamped them to the top plate of the gable wall, which we had deliberately left a bit long. We confirmed that the rafter pattern was accurate, we scribed the plate for cutting and took down the rafters and the pole, then cut the plate as scribed. Mark laid out the rafter locations on the top plates of the side walls and the ridgepole, then started cutting rafters from the pattern, which Tom and I hauled up to the second floor. Once we had a good supply, Mark and I got up on the staging while Tom stayed below. Tom passed up the 12' section of ridgepole, then laid a rafter approximately where it would go, across the top of the east wall with the head on the staging. I supported the ridge pole as Mark nailed it to the rafter head with 12 penny cement coated nails. We attached a second rafter on the same side about 8' down, then Mark and I picked up the ridgepole with both rafters attached and lifted till the birdsmouths seated properly on the plate. Tom located both rafters on the marks and toenailed them to the plate, then he moved around to the other side and passed up a rafter at about the midpoint of the section of ridgepole. I supported the entire assembly on my shoulder (I think I may be a couple of inches shorter today) while Mark nailed on the third rafter and Tom toenailed it to the plate.

That was it. With three points of support, the ridgepole was now in the air, and I could get out from under. We installed the second gable rafter, and nailed both gable rafters to the gable plate. We installed plywood sheating to tie the roof to the gable wall and stabilize it, then we just started installing rafters. I had to shoulder the pole a couple of times more to tighten the birdmouths against the plates, but what the heck, I can take a compression load. Next week, we'll erect a pole on the north gable wall as a temporary support for the second section of ridgepole, gusset it to the section already installed, and place the rest of the rafters. We'll install the remaining gable studs, sheath the roof, and the house will be structurally complete.

This is a commonplace achievement. There is no saying how many tens of millions of houses have been built around the world using similar techniques. Mark is highly skilled, of course, but his profession is not considered highly prestigious. Carpenters make a living, but they don't get rich.

Now just stop for a moment and think how clever is our species. Over thousands of years of civilization we have learned methods for building with wood. We know exactly how to make warm, dry houses that can stand for hundreds of years. We understand footings and foundations; how to nail together a stiff, strong structure to withstand compression load and wind shear; insulation and ventilation, solar gain and the need to vent the attic -- all of it inside the heads of people like Mark who didn't learn any of it in school or see it written down, who just absorbed it from their predecessors. To be sure, it is written down and you can learn it in school if you want to, but most people don't.

We're still improving on our methods. My house incorporates a lot of manufactured wood products, starting with plywood of course which replaces the boards used to sheath my parents' old farmhouse, but also microlaminated beams and manufactured floor joists. Most roofs today are not built using our stick framing technique, but with factory built trusses lifted into place by a crane. The windows I eventually install will have double panes of glass with argon gas between them. Unlike us primitives, professional builders seldom use hammers any more. They drive nails with compressed air.

We know more than we did last century, last year, last week, and we know how to do things better. In many respects, my house will be better than my parents' house, which was built in 1835. It will be much better insulated, in fact it's a passive solar design that will hardly need to be heated at all. It was certainly much easier to build, using power tools and modern materials. Then again it won't have the same charm, at least not until 135 years from now.

But here's the bad news. My parents' house is better than the homes of at least 95% of the world's population -- much, much better than most of them. So will mine be. Even though we know more and more all the time, and we know how to do things better, in some of the most important ways, we don't. Are we making progress? Is our ever accumulating knowledge making our human society better, our planet happier? I'm not sure. Lots of people say no. So what are we not learning that we need to?

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