wider story and a half?

Started by FrankInWI, August 01, 2007, 09:33:56 PM

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FrankInWI

have there been any discussion here about how much I might have to modify the trusses is I go from 20 to 24 wide on the story and a half?  I'm already increasing the joists to double 12's.  Wonder if I can beef up the trusses with bigger lumber and bigger gussets to increase the span to 24?  
god helps those who help them selves

John_C

#1
Frank you're confusing me again.  First you said trusses, then I thought we you were talking about rafters and now you are back to trusses.  Which is it?  

If you are building it yourself you can do the rafters with one or two people.  A 24' truss with 12/12 pitch is HEAVY.  You would probably want a crane to set those.  Windy day =  :-[

If they are rafter you can look them up in a span table ...  here is one for yellow pine
http://www.southernpine.com/spantables.shtml   Most good carpentry books will have a table as well.

There are some tables for designing your own trusses but I don't have a link.  You might want to get a quote from a local truss manufacturer.  They will also be able to design the trusses for your local wind loads.

You might need to be concerned about the foundation & floor joist loads.  The second floor joists will need a bearing wall unless you want the to be very large $$$$$.


glenn kangiser

What John C. said.  Widening a house plan increases loading on all the members under the roof load as well as floor members etc.

Lengthening on the other hand is basically just more of the same. :)

"Always work from the general to the specific." J. Raabe

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

Please put your area in your sig line so we can assist with location specific answers.

FrankInWI

Thanks for the replies.  There sure is someting to be said for building with the plan as is.  I'm sorry about using terminology carelessly.  Since the township inspector is screwing with my plans for a "shelter", I may have to go the garage route first, then do the 1 1/2 when I retire in a couple years, sell our primary home, split it with the wife, and get out of Dodge!  
The garage plans are 24 X 24 with no bearing wall downstairs.  12 / 12 roof too.  There is a room upstairs, that could be made much better with a couple of feet of walls up there.  I know I better be careful about changing without understanding the engineering issues.  I'm  pretty much from the build it with common sense side of the fence, but I'm finding out I can get in over my head easy when it comes to changing full fledged building plans....especially when wanting to push the envelope on spans and loads.
Your comment about the 24ft 12 / 12 site built trusses weight being a challange got my attention too.  It's me and two strong teenages, and I'd hate to have to rent something to hoist them....but things are slow up there now, I may be able to get a good price on some lifting.  Wonder if half day is enough?  
thanks as always....
Frank
god helps those who help them selves

John_C

What type of truss is it that would allow usable upstairs room in a 24' wide building and make any sense to build on site?

I think it would have to be some sort of Fink truss.  They look like a pain to build & set.  I'd figure out a way to have a centerline beam and regular joists.  It would not be difficult to make that work.  


FrankInWI

http://www.cadnw.com/images/FreeGarage.pdf   this is the one without the beam support for 24'span of 2X12s (or wood I beams).  just so tempted to give it two feet of side wall upstairs.
god helps those who help them selves

FrankInWI

sorry about metioning other plan here.  I really really really own and bought John's 1 and 1/2. I like it more than ever now...but for the need to start out with a "storage" building right now.  

my email addy is krosspen@yahoo.com

Bye the way Jim C.  I think your 1 1/2 story is the nicest I have seen.  Wonderful work!!
god helps those who help them selves

glenn kangiser

No problem on the other plan.  We talk about them a bit here - but no Plans Support.
"Always work from the general to the specific." J. Raabe

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

Please put your area in your sig line so we can assist with location specific answers.