Any practical way to frame a 24' span cathedral ceiling?

[Beavers]

Anyone have a close of photo of where the beam sits on the rake wall?  I'm still trying to figure out how that all ties together. 

Also what kind of column does the beam have to sit on...can't really tell from jr1318's pic.

One last question...

Doing a 12x16 with a loft.  I've got to have a cathedral ceiling to have any kind of head room in the loft.  I didn't think far enough ahead when doing my foundation, and I have no supports under the gable walls to take the weight of the ridge beam.  I did use 2x12 24" oc floor joists, so I'm over built there.  Am I screwed? 

[Beavers]

I crunched the numbers and this is what I came up with...

I have a snow load of 25 psf add in the 10 psf dead load, and I end up with 1680 lbs. under each end of the ridge beam. 
Something tells me that even though I used 2x12's for the floor joists they cant' take that kind of load. 

Any ideas on how I can get some of the weight transferred out to the sides and over my piers? 

[PEG688]

Any ideas on how I can get some of the weight transferred out to the sides and over my piers? 

  Other than stuffing a beam under the floor / beside the rim joists you mean, that beam would have to extend to your outer piers. Could you get one in there? Have you already built the floor system? I'm not up to speed on your build , guess I could go check , but I've already typed most of this so if your beyond , or yet to start take this for whats it's worth / or what parts apply.



I'd add solid blocking directly under the post , beside the rim joist and add a pier,  with a substantial footing , you'd then have direct bearing to ground under those two point loads.

   Your wall would , in ways, maybe considered  a box beam    , you'd have to nail it like a shear wall , and that MIGHT work as well , but that would be engineers work to see IF that wall could be considered a box beam. AND be substantial enought to take a big snow load.

 

 



   

[Beavers]

Thanks Peg,

I've got the subfloor down, and have one wall framed.  I haven't even thought about the roof up until this point when I've started trying to figure out the rake walls. 

I could knock the blocking out on the end joists and slide in a couple of 2x12's laminated together that would sit on top of the beam. 
The loft is going to be 10' long with 2x8 joists.  I was thinking I could add a horizontal beam at the end of the loft, and have a post going up to the ridge beam to reduce the weight at the end of the ridge beam.

I know that this should all be egineered, but that ain't going to happen with my budget. 
I would rather get suggestions from all the folks here and work out the problem on my own and come up with a solution.  It's not like an engineer has any magical powers...they have to work through a problem just like the rest of us.    I'm not in an inspected area so I don't need their magical stamp anyway.       

[PEG688]

#1: Thanks Peg,

  #2: I would rather get suggestions from all the folks here and work out the problem on my own and come up with a solution.  It's not like an engineer has any magical powers...they have to work through a problem just like the rest of us.    I'm not in an inspected area so I don't need their magical stamp anyway.     

 

  #1: Yer welcome!

  #2: Good idea , more than one way to skin a cat of support a point load.
  Most engineering solutions are way over kill , they seldom look for the simplest solution and they factor in many things that may be beyond thier control. I talked to Jack ( the same engineer John Raab has mentioned here before, we live on the same rock / island so we know some of the same folks ) and he asked me about how I'd sheath a bow front gable end  wall , I said I'd use my sheathing as gussets , to tie the windows and other openings together in a logical way. He was all for that , but said or alluded to the fact that a engineer can NOT count on every builder doing that sort of thinking . Which made me think he'd draw a plan that spec'ed lots of Simpson stuff that would insure positive ties , so engineer's are factoring in poor building practises when they spec'ed what they spec for where.

  It's on the plan and it fits the ##'s that they crunch.

       

[Don_P]

For the LVL comparison you guys are talking about be careful comparing anecdotes, there are many variables, load, trib area, span, strength or rather stiffness of lvl, make sure you compare all the apples  .

checking up on you Beavers,
12x16, lets add 2' overhang all around to be safe, 16x20=320 sf. Ridge bears half so 160sf x 35 psf=5600 lbs. Each end supports half of that so 2800 lbs. Haven't added floor loads but it fails. If the stacked depth of the double 2x12s is called one beam it passes by a mile. In order to do that the sheathing would need to cover both and be nailed VERY well. contrary to what you might think, near the piers is the most important for that shear restraint. This is getting into what PEG didn't want to do but we have basically stacked joists there that he is unaware of also. It is a judgement call, obviously there is nothing like doing it right and I don't want anyone thinking this is the right way, it ain't, but on this little shack, built the way it is, at that light load, I think you can get away with it. Lotta qualifiers.

Ridge beam itself is 16' clear span bearing a 6' wide trib width=96 sf. 96x35= 3360 lbs load on the beam
http://www.windyhilllogworks.com/Calcs/beamcalc.htm
inputs
load-3360
span 185...I assumed 16' less 2-2x4 walls
width-3
depth-11.25
Fb-1289... this is good SYP or Dougfir, carefully selected #2
E-1.6
Fv-175

a triple beam wouldn't hurt a thing, notice you are close in bending.

That was a quick run through, double check and think about it 

[PEG688]

This is getting into what PEG didn't want to do but we have basically stacked joists there that he is unaware of also.

  It is a judgement call, obviously there is nothing like doing it right and I don't want anyone thinking this is the right way, it ain't, but on this little shack, built the way it is, at that light load, I think you can get away with it. Lotta qualifiers.

I don't think I was leading in any direction other than "build it stout with something you know about". The reason for a couple of different ways to get there was I wasn't sure what he could get under the place , or IF he could get under the place with a beam and or joist long enought.

 Yes, it's small building and seldom to buildings get max load / max bad conditions all at once.


I really think the easiest /  safest "fix" , as this seems to be a bit of , ' build as you go',  would be the pressure blocking directly under , small blocks easy to install under a building and then hand dig a couple of pier pad holes , throw in some rebar and maybe even just use a PT 6x6 from the pad to the joist bottoms , and Bob's yer uncle.

  YMMV.

  G/L PEG






 

[Beavers]

Thanks alot guys...I really appreciate the help.

PEG,

I tried to get some more 2x12's underneath.  Can't get them in, just not enough room.  If I cut a strip of the subfloor off the end, I could drop them in from the top.  If I go that route it wouldn't be too tough to add pier at the same time.


Don,

I know this is far from the right way to do things.  I'm just glad I'm learning this stuff while building the 12x16 instead the larger house.  Gonna have to add a couple more piers so I don't run into this problem again!  Once you run the numbers it's hard to believe at how much weight a roof has to support.  Without doing the math I never would of believed that a roof that small could have to support 5000 lbs. !


I'm going to go sit in a lawn chair drink a couple of beers and just stare at the house.  If I sit there and stare at it long enough I should be able to figure it out. 


Thanks again for the help guys!

[Don_P]

That's important work, been known to take hours of intense cogitatin, make mine a brandy and coke 

I got some stories on way overly optimistic engineers but I ain't sayin nuthin. There's all kinds, that's why I learned to check up on em  .

[PEG688]

I may be missing something here but IF you have a ridge beam and no windows or doors ,  directly under it,  you could pick up that ridge load with a  direct path,  thru the house /  in the walls of course ,via posts , ,,,,,, to blocks directly under the floor,,,,   to the new pier. Maybe I've got a to simple solution OR you have windows or a door in that direct path to bearing, which of course changes that direct path to a slightly different solution.


G/L enjoy your beer , PEG