cellini's Diaryland Diary ----------------------------------------------------------------------------------------- Carpentry Geekery Somehow I seem to have spent the entire weekend building a roof for Trish's father's new pole barn. This was a truss roof as opposed to having to cut and fit a million rafters by hand, which was a nice change of pace from the last roof I built. I had not done any serious framing work since over a year ago on account of my horrible, dual cases of tennis elbow in both arms that resulted from excessive use of a hammer. My right arm held up pretty well and I am hoping that I can keep building with it through the summer if I don't push it too much on any one day. I really like framing buildings and if I could do that every day for a living then I would be quite happy. This is a big enough project that he had 4 other people come over to help, non of who I'd met before. All of them were his neighbors, including a state police office named Chuck who owns a huge bulldozer, a kid named Ian who just got back from Iraq whom we are pretty sure was dishonorably discharged for some reason, Ian's older brother, Sean, and Bob's brother Tom (a field biology professor). I got there a little late and they'd already hoisted up the first few trusses. Over the course of the next 2 hours a funny thing happened. I started out assuming that they were all competant carpenters and knew what they were doing, while they assumed that I had no clue about anything since I was the last to arrive and didn't say much while we were pulling up the trusses. But it gradually became clear that aside from Bob I was the only one there who had any idea about how to build a roof. And while Bob is a technically competant framing carpenter, he doesn't know a damned thing about building code or comparative means of building something for different uses and to withstand different types of loads. I am not a professional carpenter, but I have framed a small house working completely solo and built a bunch of decks and re-read the same framing books over and over again until I memorized most of the techniques, specifications and load considerations. I'm no expert and I can't work nearly as fast as a professional, but I can build something just as sturdy and code-conforming as a pro. These dipshits were doing retarded things like trying to put on a gable-end extension by attaching the lookout rafters with blocking that was face-nailed on to the last truss THROUGH THE END GRAIN, rather than cutting slots for outriggers. Even Bob didn't understand why this was a bad thing until I asked him if he was willing to lay over the extension with all of his weight while nailing sheathing over it. Basic self-preservation forced him to acknowledge the fact that this pair of rafters could literally be pulled out of the blocking by hand. So pretty much the first major wind storm is going to tear that gable end open. Chuck argued that the OSB sheathing will make it strong enough. No, Chuck. It won't. OSB is not meant to support 2x4 framing. Its the other way around. The sheathing is just going to act as a big sail that the wind pushes against to rip the blocking out and tear the whole end of thr roof open like a can opener. Ok, that last paragraph makes no sense to anyone who isn't a carpenter. Sorry. They were nailing sheathing down by the corners only, saying that they would come back later to fill in the rest of the nails. Two problems there: 1. No they won't. The brownish nail heads are practically invisible in the OSB and they won't be able to tell at a glance what is properly nailed and what isn't. If they are in a hurry for no reason now, they will be in a hurry for no reason when the felt is ready to go down and they will skip most of that nailing. The way to do it is to put the nails you need where you need them right when you are putting that wood in place. 2. An 8 foot long section of OSB has slack in the middle if you tack all 4 corners down first. When you go back and try to fill in the other nails, you get a bulge somewhere in the middle. This bulge will then telegraph through the felt and asphalt shingle, which looks bad and will eventially cause a leak at that spot. This was one of the few things that they finally understood and managed to stop doing. Other things they sort of understood but pride prevented them from actually implementing. Like hammering a fucking nail. Nobody wants to be told that they are hammering nails wrong. These guys kept trying to bang 8 and 12d nails into framing members less than half an inch from the end. About half of those would split and significantly weaken the structure. So what you do there is either pre-drill the hole, or turn the nail upside down and use the hammer to blunt the tip. Then drive the nail. By blunting the tip, the nail will penetrate by crushing the wood fibers rather than splitting through them, which takes more force but will not split the end of the piece of wood. None of them could manage to implment this. Nor could any of them except Tom and Bob figure out how to toe-nail properly. Which would have been fine if they'd have admitted it. 10:57 a.m. - 2010-04-19 ----------------------------------------------------------------------------------------- |
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