jopezu |
bread-train
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Reged: 09/21/03
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Posts: 5500
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Loc: georgia
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Re: More garage talk, rafter edition part 1.
01/16/11 03:40 AM
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> Finally finished enough of the little things on the ground to start thinking about a > roof. For those following along with their own adventure in mind, the type of roof > you are putting up should have been decided already. It's not too late to change > things if you must. I priced both prefab truss and "stick frame" (cut everythig > yourself). I'll elaborate on the pluses and minuses a bit in this post. > > Prefab truss: > Easy as pie to install, lightweight, and fairly sturdy. You can get them with an > actual "room" preformed in them as well. They typically call these attic trusses. > They are considerably more expensive too. They aren't going to hold as much weight as > a majority of stick framed roofs. I'd say prefab is the way to go for low sloped > roofs, or if you are dead set on quick and easy. For my garage, attic trusses at the > pitch I wanted (10/12) would cost me $1400-$1600. > > What a prefab truss looks like > > > Stick Framing: > This route is not as easy as prefab. It takes a little more math, and a step up in > carpentry skill. Those negatives aside it's sturdy as all heck, Leaves you with a > nice open attic space, and just looks cooler. I chose this method for my garage as it > was $500-$700 cheaper, for an attic that would hold 3x the weight. > > What stick framing looks like > > > Now on to the big question, how the hell do I build it? The first thing to do is draw > a mock up of what you have in your head. It can be as simple as a triangle on a piece > of paper with some basic measurements. For a square building, you are pretty much > going to build this triangle over, and over, and over, and over.... > > > Once you have your triangle, look up your local codes for how much weight this thing > needs to hold. This will be your bare minimum spec, build up from here if you want. I > found a ton of nice calculators online that figure things like dead and live load, > span charts, snow load charts, pitch charts, and just about every other chart you > could imagine. Your head is going to spin, and probably hurt. After a few days of > reading you should have a decent understanding of what you need to do and how to tie > all the numbers together. You could also farm this part out to a carpenter buddy, or > an engineer of you are dealing with something tricky. > > For my garage I decided on 2'x12'-18' rafter ties. This is quite a bit of overkill > for a rafter tie, yes. The bonus in using such thick wood is two fold. > > 1. 2x12's made the 18' span fine for the weight I wanted to support. > 2. Thick rafter ties double as excellent floor/ceiling joists. > > I chose 2x8's for the actual rafters as that seemed a pretty common size to use. It > also met the load requirements for my village (and then some) for the span it needed > to make. > > > So I have my roof planned and again the question comes up, "How the hell do I build > it?" If you aren't familiar with cutting rafters, read. Read a ton. Plan on wasting a > board or two practicing as well. It's not hard to do, but it is repetitive. You'll > need a good framing square, a pencil, and a saw. > > Now before you begin cutting, a little note. The more perfect your cuts are, the > stronger your roof will be. On that note, it realllyyyy sucks to have pre-cut all > your rafters and find out they are wrong when you try to place them. It also really > sucks to have to cut each rafter on the fly, and makes for a long day (an even longer > day if the temperature outside is 20F). How do you do both then? Great question. One > I asked to a few people. The best answer I got back was "Build a jig." > > My fist thought on the matter was "A jig! Why didn't I think of that!" > > My second thought was "WTF is a jig?". > > To be honest I'm still not entirely solid on the definition of "Jig" myself. It seems > to me that carpenters use it to describe anything they don't have a proper name for. > Loosely ~I'd~ describe it as anything that helps you make something else. So a jig > building I will go.... > > My jig was more for "quality checking" than cutting as shown below. It did help me > see that my plumb cuts were off a tiny bit, which was well worth the 20 minutes and > scrap wood it took to build it. > > A quick tidbit of advice on making "templates" for your rafters. This is fine to do > and will save you a lot of time. The only important thing to note is that you should > use the SAME template for every rafter. This prevents "wandering" of your marks. If > you used the rafter you just cut to make your next rafter and so on, the last rafter > you cut will be nowhere close to the first. I guarantee it. It's the carpentry > version of that telephone game you played in school. > > > To be continued...
you should compile all of this on a webpage. very good reference
i learned everything i know from KC
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