Author Topic: DIY Floor Joist Truss Help Needed  (Read 14488 times)

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Offline Joe Mann

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DIY Floor Joist Truss Help Needed
« on: June 19, 2007, 10:44:17 AM »
Anybody have any specs on any kind of do-it-yourself truss FLOOR joist? I'm trying to fabricate for remote site cabin.  ANY will be appreciated. Spent the day searching and have nothing so far. Thanks, Joe :-/

Offline glenn kangiser

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Re: DIY Floor Joist Truss Help Needed
« Reply #1 on: June 19, 2007, 05:30:58 PM »
Did you check out the links I posted in your other request.

http://www.countryplans.com/cgi-bin/yabb2/YaBB.pl?num=1182231372

Any relatives in Oregon, Joe :-? --- My grandmother was a Mann. :)
"Always work from the general to the specific." J. Raabe

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Offline Joe Mann

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Re: DIY Floor Joist Truss Help Needed
« Reply #2 on: June 19, 2007, 07:48:15 PM »
No relatives in Oregon, Glenn.  I spent a nice chunk of the day at the sites you recommended in the Owner/Bldr forum but found nothing on floor joist truss as yet, so I thought I'd reach a different audience in this Forum.  Thanks. Joe

Offline glenn kangiser

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Re: DIY Floor Joist Truss Help Needed
« Reply #3 on: June 19, 2007, 07:52:57 PM »
Most members go through most of the posts.  Possibly someone will come up with something else.
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

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Offline John Raabe

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Re: DIY Floor Joist Truss Help Needed
« Reply #4 on: June 21, 2007, 10:47:32 AM »
Joe:

A true open web floor truss will likely be overkill for a 20' or 24' wide span. And, for most places in the U.S. will need to be engineered for a permit.

You have expressed interest in a truss frame house. This idea has been around for at least 60 years and can work in large scale production of simple buildings. (The wall stud, floor and roof are made up as a single large frame or truss - usually assembled on a foundation at 24" o/c and sheathed.)



This system will not prove to be economical (compared to stick frame construction designed for small scale owner-builders) unless you have two things:
• No code requirements and a large flat area to assemble the jigs and build and store the frames out of the weather.
• The equipment needed to move, assemble, secure and brace these frames as they are sheathed and make structurally sound.

Barring these fortunate conditions you should look at either an interior beam or girder for standard floor joists (or use full span I-joists), stick frame tilt-up walls and then use standard trusses from a local supplier who can deliver to the wall plates.
« Last Edit: June 21, 2007, 11:25:25 AM by jraabe »
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Offline Joe Mann

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Re: DIY Floor Joist Truss Help Needed
« Reply #5 on: June 23, 2007, 10:51:51 AM »
John, What are your thoughts on this: modify the Truss Framed House so that the floor truss is replaced by 2x12 (code required for 22' span), the lower stud ends nailed/glued/screwed on the flat to the 2x12 joists and insteadof incorporating the top of each stud into the design structure of the roof truss, using 2 pieces of lumber, same dimension lumber as stud (or maybe using stud-width 3/4 ply gusset) overlap/sandwich the roof truss from top chord upper edge straight down and overlap/sandwich upper part of each stud same way.  The roof truss is in essence resting on the top of the exterior wall studs but roof truss, studs and joist are structurally intergrated with the overlap sandwich studs to roof and the overlap of studs to joist.  It strikes me  just as sound as the Truss Framed House (freepatentsonline.com shows substituting plywood for some elements), but cheaper for the DIY builder and easier to transport, build, etc.  I'd use the first truss as the pattern or jig for building the others. I've been a big fan of the ancient Rigid Frame Cabin concept (several of which I've seen "in the wild") and the Truss Framed House for many years.

Offline John Raabe

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Re: DIY Floor Joist Truss Help Needed
« Reply #6 on: June 24, 2007, 12:26:27 PM »
I don't think you would be happy with 2x12s spanning 22' feet, even if allowed locally. To make a frame system efficient you would want everything to be on 24" centers.

20' 2x12 select structural @ 16" o/c is about the limit for my comfort. You have to set deflection at 1/480 for these long spans or you will get "bounce" that will cause complaints. Strengthwise these 2x12s could probably span 22' at 24" o/c but [highlight]folks will get seasick[/highlight]. :-X

This 20' span limit is what I show in the 2 story Universal cottage. Even then I also give folks the option of engineered I-joists which have less problems with crowning, squeaks, etc.

Once you consider things like fire blocking, I don't know why anyone would give up the simplicity of platform framing and the wonderful big work table it gives you for layout of the walls.

Especially for new builders, it is best to break the project into manageable sections. Getting the foundation built and then completing a flat, square and solid platform is a very good start and a place to sit and plan the next steps. Also, should there be problems and small discrepancies, they can be adjusted for in the next stage (walls).
« Last Edit: June 24, 2007, 12:31:53 PM by jraabe »
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Offline Joe Mann

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Re: DIY Floor Joist Truss Help Needed
« Reply #7 on: June 24, 2007, 04:14:34 PM »
Thanks, John, I can keep it to 20' wide...and even add some support midway down the length under the center of the floor ;), but I'd like to try the modified truss framed house as I described.  What do you think of the "sandwiching" of the roof truss to wall stud tops and the joining of the studs to the joist as I described above strictly as a means of achieving the same result of the truss framed house without compromising its reliability. I see no reason why this cost cutting approach (and shipping advantage) would compromise the truss frame's reliability.   Apart from your personal preferences, do you see issues of structural integrity in either of these methods?  :o

 

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