Hi all:
I’m going to see my building official tomorrow about a barn I want to build and I have an issue I need help with.
The barn is designed as a 1 1/2 story balloon frame–2×6 walls, 2×10 rafters on 24 inch centers. The 2×10 rafters meet the IRC 2006 code for horizontal span (12 feet actual, 16.1 allowed) but… In the code book there is a multiplier/adjustment factor for rafters when the ceiling joists are not located at the bottom of the rafters or when rafter ties are not within X amount from the walls.
Here’s the problem. The code table 802.5.1(3) addresses platform framing, not balloon framing. This multiplier/adjustment factor is designed to beef up the rafters when there is insufficient connection to resist lateral thrust. However, in my balloon frame, the ceiling joists three feet below the top of the wall plates are connected to the opposite wall and serve to resist the outward thrust of rafters. For the hell of it, I even added rafter ties on every rafter. My code official thinks I must apply the adjustment factor, which would mean moving to 16 inch centers. I think the adjustment factor doesn’t apply to balloon framing because there is no hinge point. The trouble is–I can’t find anything but a passing reference in the code book and I can’t find any in depth coverage of this issue in any other place.
Anyone here know who is right, and where I might find the information?
John Painter
Replies
You can find the information from a structural engineer....
Where are you located? (Hint--fill out yer profile!)
I assume you don't have a structural ridge?
Here in snow country a roof built as you describe won't fall down, but the rafters will take on a significant bow. Engineers will call the rafters "overstressed." The eave wall above the floor will bow outward.
I'm working on a very similar project right now (existing building, for our structural engineer no less!)
Figuring out what size/spacing the rafters need to be, as well as the connections required, is fairly simple engineering but too complex for prescriptive code.
I'd spend a couple hundred bucks to run it past a local structural engineer or let your local LVL sales guy's engineer spec you a load bearing ridge beam.
------------------
"You cannot work hard enough to make up for a sloppy estimate."
I agree with the BI.
There is no hinge point, but the walls are still doing the job of resisting the outward thrust and at 24" OC that is a bit weak. I don't know what sort of snow load/live load your area falls under but by instinct, I think the 24" OC is a stretch.
Also, you mention you have added ties, but they would be only 5-6 feet off the floor to qualify as rafter ties, based on the info I read here so far
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Piffin (and others)
Interesting thoughts. I guess what I'll probably do to get around this problem is go to 19.2 or 16 centers for the rafters and use a triple top plate, since the wall studs will still be 24 centers. I'm already WAY over budget and I don't have time to mess around with a engineer or architect. I'm already going to be framing in winter, never mind the roofing and siding.
I'm still not convinced that the balloon framed walls are not enough to resist the outward thrust, though. I found one minor reference in Rob Thallon's Graphic Guide to Frame Construction noting that balloon framing is useful when there are vaulted roofs in 1 1/2 story buiildings. I wish I knew of a reference with more detailed balloon frame details, but, of course, when these frames were commonly being built there wasn't a building code anyway. I've certainly seen many in person which were built this way, but that doesn't mean a hill of beans.
Thanks for your input--I'll see what tomorrow brings.
John
I was actually suggesting 16" OC for the walls too!But the ONLY way you are going to get around an officials interpretation of the code is to have an engineer's stamp on the design.For this small of a building, you might be right.
But you still have to prove it.And until you have a degfree or license that shows you to be more qualified than the BI, you can show him all the calculations you want - in his mind, you are like Sgt Schutze - you know not-tink.
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Piffin:
16 centers on the walls would really screw up the rest of the barn design and I think 2x6 walls on 24 centers should be plenty. You are so right about not being able to make headway with the BI. Especially this guy, who has the personality of a brick wall.
I've got nothing against architects or engineers, but I'm already so over budget that I'll be eating hotdogs for the rest of my life. The block foundation with slab is $17K. The materials for everything else--and me doing all the labor for free--I estimate will bring the total to about $50K. When I started this idea I was aiming for a max of $30K total. So much for my aim. Now I know why I get those sour looks from my customers!
John
I'll have to agree with piffen.
Manny years ago we did a great room addition with 16' balloon frame wall and a vaulted ceiling. Most of the load bearing walls were capture between two single story roof that butted the walls at about a 10' height. We set the rafters one day and check the span at the top plate the next morning. 1 1/2" pushed out in the 6' above the adjacent roof lines areas, 3" in unrestricted areas. A structural ridge solved the problem.
BTW I was working for an architect at the time. I had to prove to him that those walls were going to spread. He just couldn't believe a 2x6 @ 16" o.c. balloon frame wall would spread that much in 6'.
Dave
What I think is weird is that it sounds like code or people think that going to 16 OC from 24 OC for teh rafter in some way reduces the totat outward thrust against the wall. That is very odd.
Do:
Yeah, it is odd. But the reason this is being put forward is that the inspector is applying code meant for platform framing to my balloon framing. It still doesn't answer the question about outward thrust and all it does is add weight and expense to the roof. Actually, I think he could have called the code council (as a member) and asked for an expert opinion, but obviously that didn't happen. Oh, and the building department called a few minutes ago. After more than five weeks my permit is ready--$1001. I haven't even talked to them about electric yet! I'm sure that will be more.
John
I don't understand the BIs thing about the 16oc for rafters either, but I can gaurantee you that 2x6 @16oc for the walls will help resist that thrust.Here is a thought for you.
After looking again at the sketch, I wonder - is there a reason you need that entire upper loft open? if not you can post to support a ridge beam and cut it's bearing length in half or by thirds to reduce the size of a structural ridge. You already have a beam and posts in the first floor centered.
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Piffin;
Well, that upstairs space is open for storage. It wouldn't be the end of the world if I had to put in columns, but I'd prefer not to.
After considering everyone's thoughts here, I have decided to be very careful about connections and to bolt wherever possible. Plus, strapping the tops of the rafters over the ridge will allow me to easily retrofit a structural ridge if it ever becomes an issue. The 16 centers on the studs I'm not opposed to, but it would mean changing the floor design on the second floor since those joists lap the studs. By the time I added another 20 2x6 studs and another 20 2x10 joists (never mind the extra 10 2x10 rafters I'm already adding) I'm into quite a bit more money. In fact, this whole thing is ending up to be damned near what it would have been to do a post and beam design, except that I would have had to have an architect sign off on that!
The saltbox design certainly must help, too, since I have the extra wall on one side and that extra wall will have triangulation against the inside wall. (Other drawings would show that there is an enclosed area of abut 20 feet on the low side and an open area of about 16 feet. The two walls are about six feet apart.) I have no doubt that a structural ridge would remove any doubt, but, again, cost and difficulty of one-man installation are factors. $50K is a lot of dough for a storage barn that I have to build myself.
Truthfully, I wasn't that concerned about the possibility of walls bowing out until I saw the comments here! My building inspector wasn't concerned about it either, I gather, but only that the adjustment factor be (blindly) applied to the rafters. Nonetheless, I'm not one to cut corners to save a few pennies. It's just that I have to be able to pay for all of this somehow.
John
...structural ridge would remove any doubt, but, again, cost and difficulty of one-man installation are factors.
Would it be possible to build up the structural ridge beam out of several members (three 2x12s, for example)? That way, the size and weight could be kept down to something you might be able to handle.
Rag:
Yes, if it came down to it that is what I would do. Since I'm doing this for myself I have the freedom to play a little bit and not worry about scaring a client! I'll pay close attention when I frame this thing. If I see the slightest indication that the walls may spread with the weight of the roof, I'll drop to plan "B" and build a structural ridge with columns. I can take some measurements before and after the roof goes on and see what happens. If the measurments increase, I'll jack up the existing ridge, the straps I'll have put over the top will bring the rafters with it, and then I'll build up a structural ridge. Seat of the pants design--an American tradition!
John
If this is storage only a set of 22" deep by 30" tall shelves/cupboards on the two exterior walls would hide a very effective bracing system made from 1/6 pieces of ply. If the BI would take it, you could make the system 14"x30" and use 1/9 cuts.SamT
A boxed soffit would help, using 2x6 lookouts bolted level from stud to tail/fascia. Using 3/4 ply for the soffit at 24" wide would also stiffen things up a bit, and allow for less deflection at the tails because of the triangle created there. You could also add some diagonal cross bracing between these lookouts, like a floor truss laid flat for the box soffit.John
John,Do the walls have to be balloon framed? You can frame the walls so that the ceiling joists sit on top of them and then frame kneewalls above them and brace the kneewalls. I frame like this all the time. If you wanted to sheetock, you just put kneewalls in front of the braces. Sometimes you have to put the kneewalls in anyway.Here's a link from a thread here four years ago with a drawing I made. http://forums.taunton.com/tp-breaktime/messages?msg=37395.3Joe Carola
Sounds like a good idea here, too, putting in those braces. That last two foot of floor space is a pain to deal with when the knee walls are 3' tall anyway. If you store something there you'll be on your hands and knees and bump your head all the time.JK
John,Thanks for the response. I guess you can read my posts here. I don't get the whole balloon framing thing here when it can be framed with the joists sitting on top of the walls top plates and then adding a kneewall, with braces. The joists alone spanning the with of the top plates and nailed into the top plates holds everything together without being on a ledger or whatever way he will tie them in.Joe Carola
A knee wall needs to be braced to prevent spreading and resist wind loading.SamT
>> A knee wall needs to be braced to prevent spreading and resist wind loading. <<I know Sam, read my other posts and look at my drawing.Joe Carola
I swear to gawd, when I read your post, it stopped at "then adding a kneewall."I dunno wah hoppen!?!?!?SamT
Sam,I should add that the kneewalls sit on the top plate and get nailed into the joists once the kneewall is lined and straightened. After that they get nailed into the joists and the joists hold them in place also. We then nail angled braces in. It's dead space anyway and there's usually a kneewall in front of them.Joe Carola
I should add that the kneewalls sit on the top plate and get nailed into the joists once the kneewall is lined and straightened.
Joe,
So what's the proper terminology for the top three feet of the (exterior) ballon wall as the OP has sketched?
So what's the proper terminology for the top three feet of the (exterior) ballon wall as the OP has sketched?
Ragnar,
I don't know because I always frame them the way I've described and drawn. We always frame the walls first and sit the ceiling joists on top of them and then the kneewalls go on top of the plates and along side the joists.
Joe Carola
John,
Here's another link to a thread.
http://forums.taunton.com/tp-breaktime/messages?msg=83810.4
Joe Carola
Edited 9/22/2007 7:08 am ET by Framer
I don't understand the BIs thing about the 16oc for rafters either, but I can gaurantee you that 2x6 @16oc for the walls will help resist that thrust.
There are two halves to this equation -- the walls and the rafters.
As you stated, beefing up the walls will help resist the thrust.
On the other hand, increasing the depth and density of the rafters will help reduce deflection at the low end of the rafters, which in turn decreases wall spread.
Think of how a two-story structure (i.e. not a 1-1/2 story structure) without a structural ridge is framed. The ceiling joists keep the rafters from spreading, of course. The joists and rafters are always nailed to the top plates, but imagine if they weren't -- there would be no lateral loading because there would be no deflection at the low end of the rafters. The rafters and joists create a triangular, rigid structure.
Stiffening the rafters approaches the above scenario. If the rafters can't significantly deflect, the system is essentially a rigid structure.
Edited 9/22/2007 3:29 am ET by Ragnar17
you and i need to get together and start a bussiness,note my sign on name. we'll write the quotes and then half way through decide that we'll make it up on the next job. just don't feel alone,i've learned if you buy hot dogs in the 20lb package they are cheap enough you can buy some day old buns,thats a meal...larrywhy pay someone to screw it up,i can do it for free....
"I guess what I'll probably do to get around this problem is go to 19.2 or 16 centers for the rafters..."
That won't help with the thrust at all. It will only add weight and make the problem worse.
A structural ridge beam will solve the problem easily.
Men don't care what's on TV. They only care what ELSE is on TV. [Jerry Seinfeld]
BH:
I agree with you--it will just add extra weight and accomplish little. I've found numerous references now about balloon framing being used to resist the outward thrust of rafters, but no concrete design criteria. I'm having trouble understanding how a 2x6 wall stud could bow out significantly under the weight of a rafter above given that the stud is restrained by the floor joist three feet below the rafter. In other words, a three foot long section of 2x6 is going to bend or snap under the load?
A structural ridge would certainly solve the problem, and the only reason I'm resisting that method is that I am framing this entire building alone and I'm not sure I could handle that very well. The ridge is 36 feet long, which would mean one hell of a heavy piece of engineered lumber or else columns. I have also been trying to avoid modern looking materials which will be exposed in the barn.
Oh well, maybe I'm a dreamer and maybe I should have waited until I have enough money to do the post and beam I wanted to do. We'll see what the building guy says in about an hour.
John
What you propose MIGHT work. But you can't make it work just by thinking it will or wanting to believe that it will. The loading, width of the building, and pitch of the roof would all affect the forces that are involved. Someone would have to figure those forces and then determine what it would take to make it work. The connections will be the critical thing. You have to transfer all the forces from the rafters to the plates, then down to the studs. That's likely going to take more than a couple of 16D nais. Adding a triple top plate would only make those connectins more difficult.
The trouble with being the best man at a wedding is that you never get to prove it.
"Someone would have to figure those forces and then determine what it would take to make it work."Someone like an engineer that he does not want to pay for?;)
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"Someone like an engineer that he does not want to pay for?"
I was trying to avoid saying that...
One half of the world cannot understand the pleasures of the other. [Jane Austen]
Ceiling, rafter tie, and rafters?
View Image
SamT
Sam;
No, the "rafter ties" (I know this term gets used differently in diffefent areas) are located higher in the rafters. Picture the floor joists of the second floor lapping the studs and leaving about 3 feet of stud exposed in the second story. The rafters sit atop the wall plate, and about eight feet above the floor (5 feet above the wall plate) are the rafter ties.
John
Those would be rafter ties only if the ridge is 10' above them.
How about a pony wall and internal braces?
View Image
SamT
In order to fit the structural needs and description of "rafter ties" to be able to do away with a structural ridge, the ties MUST be in the lowest third of the rafter space, which is why I stated earlier that with such a small building, they would only be 5-6 feet above that upper floor.
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Hi all:
Here's the update. I just got back from the building department. He thinks that 2x10 rafters on 16 centers and 2x6 walls on 24 centers is okay, with a double top plate. That looks like what he'll approve. One drawing is attached.
That said, I'm going to keep investigating. I think, like boss hog said, that this will just add weight with little else. The outward thrust is still being held by the same number of studs held in check by the same number of floor joists on the second floor. I'm not so stubborn that I won't change something if I'm wrong or even marginal. I just wish I had a better reference for balloon framing.
I thought I'd need a triple top plate if the rafters don't line up with the studs (over 5 inches) but the BI says a double top plate is fine.
Anyway, thanks for everyone's 2 cents. Before I actually start framing I'll keep plugging away at this to make sure I'm not making a mistake.
John
I'm building a house with a very similar situation. Balloon framing extending 3'6" above the second floor. Although I haven't had the framing inspection yet, I did ask the BI during the permitting process what he thought about it, he said as long as that floor system is in there (and that room has a ceiling at 8 or 9 feet, (not cathedral)) to tie the walls together it will be fine. Like yourself I haven't found much info regarding that type of situation. Another thing you may want to consider is a truss system. I considered that option.. but I never did like what they came up with.. and of course they do cost a bit more than rafters...
Edited 9/21/2007 11:47 am ET by Doobz26
That's interesting--what is the spacing for the rafters and studs?
2x6 walls at 16" o.c., 2x12 rafters at 16" o.c. 12:12 roof slope. ceiling joist at 9' above the second floor. (I won't call it a "rafter tie"... don't want to get into that discussion).. but that ceiling joist is doing something to hold the walls together as well as the floor system. I also have collar ties up at the ridge... not sure what they add to the system but they were easy enough to put in...
Edited 9/21/2007 11:40 am ET by Doobz26
Hm. Sounds pretty similar to my barn, except for the spacing. Then again, I'm building a barn not a house.
I looked up an old college buddy of mine who is an architect in another state and talked to him this morning. After explaining the situation to him, he couldn't come up with a solid answer either, except to say that my idea sounded reasonable but he would have to consult an engineer.
I have pawed through the yellow pages locally to see if I could find an engineer in my area of NJ, but they all seem to be big-time outfits with no interest in a piddly little problem like mine. Plus, I'm broke.
Well, if nothing else I'll make sure all the connections are bolted and strengthened with metal connectors. That way it will have to be a total catastophic failure of the framing members to take down the roof, and hopefully I won't know what hit me when it falls! ;-)
John
Those are collar ties he is showing in the drawing. They are too high up to count for much of anything as rafter ties, but the balloon walls certainly do a fair amt.I have worked on several older farmhouses, vernacular style, that are balloon framed with 2x4Full sized rough cut at 16" OC with about a 4-5 foot upper height and a 1x6 let in ledger for the floor joists.Every single one of them has an outward bending demonstrating that after 80-100 years, they show themselves under designed to resist the thrust of the rafters, and some of them are only 20-22 feet wide.
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View ImageSamT
I think, like boss hog said, that this will just add weight with little else. The outward thrust is still being held by the same number of studs held in check by the same number of floor joists on the second floor.
John,
I'm not a structural expert on balloon-framed 1-1/2 story houses either. But I have done a lot of investigating myself, since it's the way my house was framed back in 1911.
One thing that the 2x10s will do for you is to resist bending -- much more so than 2x6s (a 2x10 is 4.76x stiffer than a 2x6, to be exact).
The thrust problem at the knee walls can be solved with two approaches: (1) a ridge beam, or (2) very stiff rafters. The ridge beam prevents the rafters from slouching down, which completely eliminates the thrust problem. The stiff rafters (in conjunction with the ceiling joist/collar ties) minimize rafter tail deflection, which in turn minimizes deflection at the plates of the knee wall.
When I was working on a similar problem for a client, the engineer called for (if I remember correctly) doubled 2x10s at 24" centers. Additionally, each rafter pair was bolted to the ceiling joist. With that in mind, I think the 2x10s at 16" centers are close, but I'd be putting in ceiling joists every 16 inches, too.
PS: Another consideration is that this balloon-framed approach can cause problems when you try to cut out for windows in the eave walls of the main floor. A window RO in the main floor drastically reduces the length of the balloon stud. In effect, the balloon stud becomes more like a platform-framed stud, and has little ability to resist rafter thrust. If you're going to have some large openings in the main floor eave walls, this might be a factor to consider.
Edited 9/21/2007 2:07 pm ET by Ragnar17
R:
You make some excellent points. As I was thinking about this today, I thought of an idea as a bit of an insurance plan. When I frame the rafters I'll put metal straps across the ridge and connected to each rafter top and that way if I ever do see evidence of the walls spreading I can retrofit a ridge beam without too much effort. There will be a center girder to hold the second floor up, so I could put in second floor columns and a beam under the original ridge if it comes to it.
I really doubt I'll have an issue. This is a salt box design, so one side of the roof actually has two structural walls holding it up, and there will be some triangulation between those two walls themselves. I've been inside enough balloon frames from the turn of the century (the LAST century!) to see where problems are likely, it's just that there is no way to translate that experience into modern codes.
It's a shame that so much building experience is lost over the decades to the genericization of practice. Yes, platform framing is superior in many ways, but there is reason to use balloon or timber or hybrid or other systems from time to time. With modern building codes it is a real effort to resist being forced into the mold.
John
Enduringcharm: From looking at your section I think rafter ties will work. Parts of a coupla of dimensions on the left are missing so I'm assuming the dimension from eave to ridge is 12'. If so, this would place your rafter ties 5' above the eave and 7' below the ridge. Lot of other considerations of course but the rule of thumb for rafter ties is they need to be located in the bottom 2/3 of the rafter to be effective.
I'm not a structural engineer but I am an architect and I'd feel comfortable with the setup if all of the sizes and spacing where ok too. The 3' section could even be a cripple wall. It's been my experience that engineers and code enforcers tend to "be safe" and way overdesign.
As an aside, from looking at your sketch, it looks like the center beam is 12' from the exterior wall, directly below the ridge, and the ridge is 12' above the eave. If so this would equate to a 12/12 pitch not 10/12.
Runnerguy
Edited 9/22/2007 6:36 am ET by runnerguy
Runner:
Let's just say my carpentry is better than my drawing skills! Originally I had a 12/12 pitch and then changed it to a 10/12. The collar or rafter ties, or whatever we want to call them, are about five feet above the top of the wall plate. They are around eight feet from the floor, since there is three feet of wall exposed upstairs.
I take your point, though. I think the combination of the ties and the long balloon framed studs will be enough to resist any outward thrust, assuming that I am meticulous about all the connections and use metal and bolts wherever I can. The fact that there are two walls on one side and that I can install some triangulation in between there can only help, and the fact that I have a pretty steep pitch means that any snow loads will be short lived.
Someone else mentioned seeing older balloon frames bowing out after 80 years. Well, I won't live half that long! Sarcasm aside, I've taken apart some poorly built balloon (and other) frames which look like they are about to fall down, but it takes a surprising amount of effort to pry them apart. The over engineering today is real, I think, and not particularly justified in a storage barn. If I was building a house for my grandchildren I might feel differently.
John
end, sorry I don't have an answer for you, but I must say you did a great job laying your question out. Nicely done.
I've built a few ballooned framed buildings in my day(all 16oc) and after looking at your drawing, I know you will be just fine. The 16oc rafters on a 24oc wall layout is not something that makes much sense to me when building balloon(rafters should have a corresponding stud/joist tie. IMO, it's more work and a waste of wood given your choice for stud spacing.
You and your children will never live to see any significant bowing out due to thrust on the parapit walls given your design.
Some points of note
The last few structures we built(10+yrs ago):
required 2x6 stud walls 16oc min. with 1x6 letins not 1x4s. The BI and local PTB decreed it.
Joist to stud wall tie-ins required more than just a 3 nail sched of 16db nails. I don't remember the sched. but laggs or carriage bolts were required. BossHogg could probably remember what that was back in the day, I know I don't.
Enough of my 2cents,
good luck!
Lou,
I'm interested to hear that you have some experience in building balloon-framed houses.
My own house is very dimensionally similar to the sketch provided by the OP, with the exception that there is no "shed" roof extension on either side. Specifically, my house is roughly 24' wide, has a 10/12 pitch, 3' knee walls (2x4 @ 16" oc), and 2x4 ceiling joists @ 16" centers 8' above finish floor.
What would your experience/gut tell you about sizing the rafters for my own house? Assume 16" centers, of course. The house is in the Seattle area, so there is not much snow load to be of concern.
There are lots of things to consider and sight unseen I can only guess as to what your actual conditions are. But....
Well, just as Piffin mentioned, your knee walls and your rafters are bowed and sagging alot respectively. These distortions are there to stay, you cannot realisticlly true them up again.
Snow load or not, 2x4 studded knee walls by themselves will not cut it in todays world. You should not consider beefing up the rafters by themselves without addressing the knee walls. You are just adding more weight to the ....you get the picture. Also, most roofs on these types of structures have no ridge beams.
IMO, if you can bank role it, replace the roof structure entirely with a conventional roof structure with dormers to break up roof line that will let you utilize the entire footprint. Yes, this would be a second floor addition. Yes more extreme than you wanted to hear but you can't take a Yugo and drop in a Cummins turbo deisel and expect it to hold together.
Alternate plan if you must;
Consider installing,
The rafters, long hypotenuse' for 2x4s, sister in 2x8s, place collar ties for every rafter(2x6s) at desired 8' height, 3/4" ply gussets at the peaks, if dormers are not in the picture---build new pony walls halfway from the collar ties to the originals. Now, for all your efforts, you will get a very much smaller footprint and you will not be happy v.s. the work put in, and you will have added an enormous amount of weight that might spring other "issues down the road. That new roof structure with dormers is sounding better all the time.
Joking aside, I think a building engineer or archet. can give you better realistic alternatives.
Good luck and enough of my 2cents
Big Lou:
It's good to hear from someone who has built similar structures. I certainly agree--I think we all agree--that the extra rafters will do nothing but add weight and cost. I do plan on through-bolting the joist-stud connections and maybe I'll go to a 1x6 band too. In spite of my skyrocketing costs I'm not going to let a few hundred dollars worth of fasteners stand in the way of a stronger building.
John
This mention of the floor joist connection has me wondering again....Since you seem adament NOT to go to 16"OC for the wall framing - where I think it is the most necessary upgrade - that means that your floor framing will be 24"OC so for safe storage, you then need to be upgrading the floor joists.That means spending money. At the same time you say you will not let a few hundred in hardware from making the building stronger, but you let that same few hundred for a few more studs keep you in the grey area????
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Piff:
In my defense... :-)
For brevity's sake I haven't shared all the design information earlier. As it stands I have 24 centers on the studs and 24 centers on the 2x10 floor joists which will lap the studs and each other. The floor itself is two inch thick T&G planks spanning the joists. Part of the point of this whole thing is to make the barn look old, within the limitations of my budget and the building code. I like that look and I live in a town with lots of old, red barns dotting the landscape. I can't afford the post and beam I would have liked, but I thought I could at least approximate some of the features, such as exposed floor planks, etc. Of course, the layout of windows and doors and the foundation was also planned around the 24 inch centers.
If I move to 16 inch centers for the walls I lose part of the look I was after because the closer spacing would also affect the floor joists and closer joists would obscure the exposed floor planks. The combination of extra joists, studs, hardware and the need to work around previously designed window and door openings and foundation layout is not an insignificant expense or amount of labor time. One could argue that I could go to 16 centers on the walls and 32 centers on the floor joists, I suppose, but that would mean a weaker floor/wall connection and less strength for the floor itself versus the 24 inch centers.
As far as the strength of 24 inch centers on the floor joints, the two inch T&G planks will easily span that and the things being stored on the second floor are not heavy. Look, I have no doubt that your point about 16 centers adding strength is correct. My point is that the 24 centers are perfectly adequate (based on some opinions here, anyway) and that it better suits the aims of this building. Hell, if I just wanted cheap strong storage I'd buy a prefab metal building and be over with it. However, I live in an upscale country-suburban neighborhood where this barn will be highly visable and, besides, I put a premium on good looks myself. I'm a wood-bigot. So, I guess I have champaign tastes and a beer budget and I'm doing the best I can with what I've got. My goal is not the srongest possible building, it is an adequately-strong building which maximizes beauty for the dollars I have to spend.
John
That all makes more sense from that POV. what I was getting at with my musings is that instead of 2x8 floor frame and 3/4" decking, you were making it necessary to have 2x10 and car decking which is all much more expensive.I have to constantly remind the people I design for that a building is an interwoven WHOLE and not a cafeteria meal where you can pick and choose as you go along - that changing anyu one thing can mean changing EVERYTHING!;)
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Piff:
LOL! That's actually a good analogy I'm going to steal. I don't do new construction, I focus on repair/restoration of older houses or small remodels and trim work. Even so, I get the same thing--people assume you can make one change without affecting six other things. Or, they want to know why changing one minor thing costs so much more, forgetting that those six other things are interrelated.
John
You know, I read threads like this and think I may just have to start brushing up on my old Civil Engineering texts and seriously...see about going after that P.E. one day. I'd like to contribute on BT more substantively than I have to date; and I note that you guys are pros at what you do but man, the BT collective seems way too willing to continuously SWAG thru civil engineering situations versus incorporate the cost of an engineered design up front - or as retrofit along the project way... (Not you of course PFN, you've grown older and WISER along the way!)
IMO, this OP is planning his structure to minimize deflection, address thrust, and handle weight of its structural components and yet I've not noted where he has addressed the LOAD impact of whatever it is he's planning on storing up there on that 2nd level. Perhaps I missed that piece of posted info along the way tho.
Anyhow - I wonder: is bartering for services (civil engineer PE and the OP/renovator) still a legal alternative with specific IRS rules that cover it...? and, IIRC, wasn't there a group online that used to collect and match up various professionals/consumers for just that purpose...?
Just my 2 cents. I'll go away now; gotta finish packing again anyway!
Only dead fish swim with the stream. Author Unknown
Actually I do my fair share of SWAGs here.
Based on previous experience with similar structures and sizes, both building them new and repairing what has failed from previous generations.( I can't answer your barter aside, BTW)I think the reason there is no one single answer to this guys position other than to hire a good engineer to pull it all together is that this is a combo plate deluxe, not a simple side order of fries.So the tables that might apply to any typical situation will not work accurately here.
There might or might not be a semi-structural ridge possibly with posting...
There will be some amt of resistance to deflection in the walls depending on just how tall they are, whether he uses 2x6 or 2x4 and whether they are 24" or 16" OC....and maybe with added bracing and or kneewall....
There can be some diaphragm action in the sheathing of the roof ply and in a structurally designed soffit to brace...And the right engineer can potentially find a way to wet stamp and reconfigure things for him for a couple hundred bucks and save him a thousand in materials and satisfy the BI all in one....But short of paying the pro, he is stuck with his own seat of the pants analysis and our SWAGs;)
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"And the right engineer can potentially find a way to wet stamp and reconfigure things for him for a couple hundred bucks and save him a thousand in materials and satisfy the BI all in one...."
I was having that EXACT same thought too but given he's already paid his permit fee and the time invested til now with the BI to get it, I figured the potential of the OP stepping back and taking that approach, was low.
I sure hope all works out well for him tho. I DO know what it is try and build something on a squeezed budget...BTDT. Not sure what is making this barn a pressing need for him (I'm sure there's lotsa reasons) but seems too bad he has to rush the project thru in this manner and under these circumstances. Sometimes renting storage space can be a good thing.
Only dead fish swim with the stream. Author Unknown
Figure YOU understood, but there are a hundred other DIYs reading this who need to know that professional advice is not a cost - it is an investment. I am currently dealing with a customer who over-analyzes every thing and has added a good five thousand bucks to his cost by his way of communicating and deciding issues better left to me but he hjas to feel like he is in control.The problem is that he is doing all this because his budget is limited and he is one of the least likely customers I have ever had to be able to afford to do things the way hew wants to do them. This OP reminds me of him. Low budget but still trying hard to avoid the pros on the assumption that he is saving money that way.
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Ayup.
Only dead fish swim with the stream. Author Unknown
"But short of paying the pro, he is stuck with his own seat of the pants analysis and our SWAGs"
LOL, yes, yes "swag", that's it! I like it. HA-HA....
Repying to message #47
Thats my thinking, now get out of my head!!
LOL
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I certainly agree--I think we all agree--that the extra rafters will do nothing but add weight and cost.
I, for one, disagree -- I think the extra rafters will act to stiffen the roof structure and minimize deflection at the knee walls. What I don't know is whether the extra rafters are actually necessary.
I think the extra rafters will act to stiffen the roof structure and minimize deflection at the knee walls. What I don't know is whether the extra rafters are actually necessary.
I agree. The OP's walls will bow out BECAUSE his rafters will bend with the rafter tie that far up. More rafters (or even better, wider rafters) means less bending of the rafters, which means less bowing out of the wall.
Need a pro to crunch the numbers though.
Just for thed record, a parapet wall is one that extends ABOVE the roof
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Yep, thats true.
John,
Does this have to be balloon framed?