Replies

1. 
   andybuildz | Nov 27, 2003 05:33pm | #1

   post this in "construction techniques" here not in Breaktime fests.

   you'll be sure to get plenty of responses specifically from the expertise of Boss Hog who does truss design

   Be well

            andy

   My life is my practice!

   http://CLIFFORDRENOVATIONS.COM

2. 
   dIrishInMe | Nov 27, 2003 06:41pm | #2

   You said: "Here's my problem, someone gave me these 32 ft. steel bar trusses(20" deep) if I space them 36" on center I could get a 48 ft long building... "  Can you post a pic of those trusses?  I'd be interested to see what they look like.  Are they for the 2nd floor floor system or what?  That 36" OC spacing won't work too well with 4'x8'  plywood, etc.  I'm having a little trouble visualizing the whole thing...  Is this building going to be inspected?  Sorry, no answers... just questions...

3. 
   VaTom | Nov 29, 2003 01:26am | #3

   Would a shiplap type joint over each post ( 8' centers ), either laid sideways or up and down work.

   I too am generally confused by your description.  The above, for making a beam joint over a post, if that's correct, will work better if you make a Z or half-dovetail joint connecting the two beams.  A shoulder of each beam sitting on the post will work fine.

   What this has to do with steel bar joists I'm not sure.  I hope you aren't planning on resting the ends of a 32' bar joist on that wood beam, unless it's really short.  You mention snow, what's your roof design load? 

   If there's still a tag on those joists, and it's a K-Series, I can look up the load rating for you.  It's preferable to start there and then determine just how far you can stretch them.

   Do you know that your decking can handle 36" OC ?  The B22 decking we use goes perpendicular to the joists.  What're you putting on top?

   PAHS Designer/Builder- Bury it!

1. 
   rich539 | Dec 01, 2003 03:44am | #4

   hi, Thanks for reply. I found a tag on these trusses, 314 70 j11 Cisco Joist Co. Garee, S.C. My plan is to space 32" o-c and then run 2x4 joist 16" o-c across the trusses, then plywood as normal. My other question was what type of simple beam joint to make over 6x8" posts. Thanks again.  Sometimes I might be abit too frugel (cheap) on my own stuff.  rich d.

1. 
   fdampier5 | Dec 01, 2003 04:09am | #5

   Now you are in my territory..

            First what kind of wood are you going to use for your posts and top plates..

     but to answer your question a half lap will work and then you could either make a metal   "T" bracket to hold it all together*.  (I assume that you're planning on putting the half laps over the posts) or if you want to you could dove a dovetail and then mortice and tenion the posts onto the top plate..

     You might also be able to use triangle shaped plywood and nail everything to gether..

      

     *My timberframing buddies will hate me for that suggestion but you aren't building a piece of furniture just a shed..  

     I'll do a quick and dirty load check for you. 

1. 
   rich539 | Dec 03, 2003 04:24am | #7

   Hey thanks for the reply. I never thought of the T brace idea, simpson should have something. I plan on using native hemlock for post + beams, 8' o-c with diagaonal braces (3x6) about 2-6" in from posts. These bar trusses I have seem like they could be spaced 32" o-c with 2x4 joist 16"o-c across the trusses. 32' span is what they where made for, I'm just using the space for attic storage. thanks again for the help. Boss.

2. 
   VaTom | Dec 01, 2003 07:41am | #6

   314 70 j11

   Unfortunately that's not a K-Series, the only chart I have.  In K-Series, a 20" x 32' joist will have a total load rating from 199 to 468 lbs./lin ft and weighing 6.7 to 12.2 lbs/ft.  That's a huge range.  You need more information.  Call a steel company.

   Once you take the total weight of the steel, wood, decking, roofing and add your live load, 50-75 psf for here, you can determine your spacing.  For instance, on the low end of the K-Series, 20K3, you'd be restricted to 74 psf at 32" oc.  Doesn't work.

   Another factor that the steel company probably won't talk about is deformation.  I've bought a lot of used joists and always have found some deformed.  Nobody I know is going to predict how much strength loss occurs.  I use them, straightened with the cross-bracing, and narrow my oc spacing.

   The beam joint I use is a half dovetail between the two beams, tenoned to the post. 

   Get that load rating and good luck.  PAHS Designer/Builder- Bury it!