Replies

1. 
   nathan_wegemer | Feb 01, 2002 11:13am | #1

   *
   Your I-joist supplier will have skewable hangers for commons and jacks. The one's I've installed by Simpson were a significant labor burden. The ones that make you work are the skewed hangers at the jacks. I might look at pre-assembly of the hangers on skewed and common hangers after making the plumb cuts. The web stiffener could then be inserted and c-clamped together (it's a sandwich). A jig in a vise or clamp could be made to bend the hanger flanges to 45º if needed, then attach to the rafter. Doing this in place consumes time, and it takes some time to do well.

   I don't recall the plate connection... it may have been a squash block with 2x, or web stiffened. The joist manufacturer will provide instructions for connections.

   I think they make a fine rafter. If I were to put them into my house, I'd use a plywood web truss over osb, and I'd try to hit them with a preservative of some sort before assembly.

1. 
   George_Roberts | Feb 01, 2002 01:34pm | #2

   *You might follow the directions. It is very easy to mess up and have the joists fail.

1. 
   Boss_Hog | Feb 01, 2002 03:56pm | #3

   *Nathan and George are right - Follow the directions that come with the I-joists you're getting. Whomever is supplying them will have enough literature to cure insomnia for about a year. Since that info varies from manufacturer to manufacturer, there's no way we can tell you what's best here. The literature will have at least a couple of different options for tying the I-joists into the ridge beam, and attaching them to the walls. Keep in mind that youi musthave a ridge beam, not just a ridge board. Nathan is right in saying that it's labor intensive. I'll bet I've quoted 50 roofs of I-joists for every one I've sold due to this. One final point - Check the flange width of the I-joists you're getting, then make sure you have a saw that will cut through it in one pass. You might consider putting them on 2' centers rather than 16". Even if you have to go to a deeper joist to make it work, you'll have a lot less pieces and a lot less labor.

1. 
   Mongo_ | Feb 01, 2002 04:45pm | #4

   *If you need I-joists because standard framing timber can't handle a long roof span for a cathedral-type ceiling, then they're worth the trouble to use as rafters.Otherwise, a much as I like I-joists, I dislike them for rafters.Pure personal preference and opinion.Here's a link that may help you out:http://www.jlconline.com/jlc/archive/framing/i_joist/index.html

1. 
   Joe_Hennessey | Feb 01, 2002 06:44pm | #5

   *I think Eddie mentioned he's building an A frame type house, so the attachment angles shouldn't be a problem. And didn't he also mention earlier something about the size of lumber availabe being a problem? Joe H

2. 
   Bob_Walker | Feb 02, 2002 05:14pm | #6

   *Boss:"Keep in mind that you must have a ridge beam, not just a ridge board."Do you mean a structural beam which is, itself supported independently of the rafters and from which the rafters hang?

3. 
   jim_"crazy_legs"_blodg | Feb 02, 2002 06:40pm | #7

   *We used them for rafters on a house we're remodeling right now and I like them a lot - straight, strong, light. We added 3/4" web stiffeners and cut a horizontal seat, like the flat cut in a bird's mouth of a regular rafter, toe nailed them right to the plate, and blocked between them. We'll have to add hurricane clips, but it was a lot faster than messing with those ajustable angle clips from Simpson Nathan might be talking about. We also could have used dimensional lumber ripped to the appropriate angle between the top plate and the rafters.There are several ways we could have done the ridge, depending on pitch and bearing points beneath. Our's was pretty unusual, more like a shed dormer situation, but you can hang them directly on the side of a beam with hangers made for that, or they can run across the top of a beam or bearing wall with blocking and gussets fastening them to the rafter opposite.Overhangs were a piece of cake - 6' 2x4s sistered so they cantaliever 2' with a vertical block between the top of the plate and bottom of the overhang 2x4. All per manufacturer's specs. We put them 19.2 o.c. because we sheathed the roof with 1/2" osb, but Boss is right, check the span tables in manufacturer's specs for span/spacing.Man, sheathing is a dream on those things, nice wide flange, and stiff, I'll be using them again. I just wish I could buy 8 inchers for short floor joists.