Friend of mine is doing some inside work at a new house under construction. Some prelim trim work.
The owner, who is self-GCing this thing, got plans drawn by some goof who knew enough to do pretty pics with Chief, but nothing about structure. No engineer was hired, and where it is being built, the AHJ did not look (nor was capable) at structure, either.
Built almost on a mountaintop, the road is so rugged that I’ll take your 4×4 there, but not mine. The last thousand feet of drive was blasted across a ledge, and it’s one way, period. You gotta either back in or back out; there’s no turnaround. As a consequence, there’s been no inspection. Fabulous view.
Here is the shape of the 8-pitch roof. The shed dormer thing is a 5-pitch. Framed using 2x10s with a pair of 2x12s for a ridge, it is all-cathedral underneath. All. One collar tie was scabbed into place by the framer, just about 6 feet in from the near end in the pic. One.
There is nowhere any opportunity to post down from the ridge to something, and get a load path down through. Consequently, the 36 feet of ridge is a single span. Ground snow load is 90 psf.
What would you do?
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I just did a rough workup of load. The 90 psf of ground snow load, run all through the ASCE 7-02 calcs, comes in at somewhere in the high 60 psf range. Let's use 75, and just do a simple trib area calc, say 14 feet per foot times the 75.
I get 1050 lbs/ft uniform loading. The gable gums things up a little, but let's just see what 1050 looks like if trying to go with some lumber products.
TrusJoist's ILevel spec guide for LVL, LSL, and PL has a table for LVLs used in roof structures when snow loading is in play.
Going to only a 30 foot span at max, the table shows an LVL triple-ply 20-incher (total 5.25 x 20 in section) as good for only about 500 plf, when L/240 deflection is controlling. L/240 for a 36 foot span is a little more than 1-3/4". I would want less deflection.
So, hmmmmmm, let's see. The framer used a paired-up 2x12 sandwich for a ridge, and ILevel says a triple 20" LVL is way inadequate.
What to do? What to do?
My friend says that this house got doodled to the max, while it was being built. Walls got moved, openings got changed everywhere, yadda, yadda, yadda. What is all "cathedral" may not have been at all, up front. Who knows. There may have even been opportunities for good loadpaths down, to sectionalize that ridge span.
It is quite apparent, with what we have now, that steel should have been used at the ridge, with LVL coming into play for the ridge and valleys of the intersecting gabled section, and maybe even LVLs as sidekings where the shedroof jumps out. But it's just plain old 2x12 spruce everywhere, and all foamed up with spray urethane.
What to do?Place a bet with the local bookie how long befoe it falls in.
Start a pool based on how many inches of snow it will take before it caves?Buy life insurance on teh owner
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"What would you do?"
Ahhhh,,,,skip the Xmas party if its snowin?
Spheramid Enterprises Architectural Woodworks
"If you want something you've never had, do something you've never done"
The Xmas party?
We can ski on the mountain by then, and to get to this place that time of year, your 4x4 will get you to within a mile or so, your snowshoes with carbide-tipped teeth in the shoe bindings will get you a lot of the rest of the way (puff, puff), and then you'll put on these, for the final assault.
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Good. Then nobody will be there when it collapses.
If your view never changes you're following the wrong leader
Buy stock in the skyhook company..
.
A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Yeah, What Dan just said. No one there when she all falls down.
Or, do him a favor and nudge it real hard when y'all are outside shooting the breeze, and if it stays up say ponderingly " Hey? did you feel that?" And then BOTH of you lean into it and have camera ready..Spheramid Enterprises Architectural Woodworks
"If you want something you've never had, do something you've never done"
What would you do?
Punt! ;-)
The only answer I see is to make trusses out of some, if not all, of the rafter pairs, depending on their spacing. Truss every four feet, would be my guess. Maybe they could all be trussed at the mid point in the rafter run, just to keep the high ceiling in play. Definitely needs some engineering.
I'd also like to see a bracing wall, parallel to the ridge, somewhere in that space. I'd sheath it with plywood on one side, before the dry wall. It could be one partition for a corner room.
Grow a tree in the middle - right to the ridge.
Add branches as collar/rafter ties at random levels.
Make it look real.
Years ago there was poster asking for ideas to get a full tree trunk into position, just because the customer wanted it there. I think he succeeded.
Great conversation piece and maybe a building saver in your situation. I'm sure someone could develop the calcs to put it in.
Gene,
Can you glue and bolt two together and put them underneath the existing 2x12 ridge? Or glue nail and bolt (6) 1-3/4" x 20" lvl's. With a 2x10 assuming 9-1/2", you'll have a 11-7/16" plumbcut. That will get you flush to the bottom of the double 2x12 ridge.
You would have to nail 2-2x4's on the bottom of the 2-2x12 ridge so that the outside of the lvl's don't hit the bottom of the rafters because you'll have 10-1/4" - 10-1/2" in width by the time glue and bolt everything together.
Built almost on a mountaintop, the road is so rugged that I'll take your 4x4 there, but not mine. The last thousand feet of drive was blasted across a ledge, and it's one way, period. You gotta either back in or back out; there's no turnaround. As a consequence, there's been no inspection. Fabulous view.
What to do? That's a tough one.
If they are ah,er, "hard-headed" er, 'willfull' enough to not even properly plan road access in advance, I'm guess your concerns about "a little snow" will fall on deaf ears (especially since anything curative you suggest will likely cost as much as the enitre structure--including engineering--has so far.
The good samaritiant thing that leaps first to my mind would be to drop trees across the access road in bulk. But, what might be better would be to go find the local emergency services coordinator and ask about what sorts of helos they have aon hand, and have they done any actual practice runs (since you have a canidate test location). Sure, once the place is built, the owners only hazzard themsleves. But, right now, while it's building, everyone on that site gets to do so 'at risk' that the FD, the EMTs will only get up the road as far as the equipment will go.
Maybe the roof can be re-engineered after the mandated fire sprinkler system goes in . . .
Good points. Makes one wonder how the crete got there. Had a buddy that built his bridge over a 30' wide creek, found him some precast cross beams and RR ties for decking, twin rails of 2 wide 2x12 for tires rolling over the ties..pretty dang stout.
Fixing to add an addition, the 8 yrd truck driver looked at the bridge and the drive way, and decided they had better get the Hoe down to the fording and bucket up the crete..he wouldn't try crossing the bridge or risk sinking in the ford.
Later the HO called the local FD and had them inspect the bridge ( no AHJ in that area) and they drove the tanker and the battle truck over no problems.Spheramid Enterprises Architectural Woodworks
"If you want something you've never had, do something you've never done"
Makes one wonder how the crete got there.
Well, I share, some, of Johnnie's opinion of ready-mix drivers (despite having been one myself, back in the dawn of time, like '80 or so . . . )
Something about "blasted out road" and "can't turn around" made a bad picture of all the labors' trucks perched willy-nilly in the verges, and that made a really, really bad mental image of what the VFD's driver would see bringing the ambulance out to the site.
Rant followed, far too easily, from that.
I like the idea of living out in the county. I like the idea of throwing off a few of the "fetters" modern municipalities (or the offites of the City Attorney) place upon us. But, maybe I'm backwards, in that, by wanting those things, I feel compelled to do more not less. That means over-engineering. That means more planning for emergency services. That means a bunch of things, that just don't seem very important to other folks out in the stix (but enough of those think little bells will keep bars an cougars from eatin'em, too--perhaps it all evens out).Occupational hazard of my occupation not being around (sorry Bubba)
The redimix barely got there. Three trips were made to the site by reps from the concrete outfit, the first two visitors saying they could absolutely not get their trucks up through the top two switchbacks. A little work was done to make the turns wider, and finally, somehow, rigs got through.
The pump-rig truck really doesn't have a wheelbase and turn radius bigger than a mixer, so if a mixer rig got there, I'm not surprised to hear the pump made it too. Which it did.
Lumber deliveries, too. Nothing came with a trailer. Everything 16-foot max, arrived via straightbed. If someone needs to get a 36-foot piece of wideflange up there, they are going to have to fly it up.
What has us all scratching our heads, though, is the crew that went there with a 1-ton 4x4 pulling one of those good sized trailers that is used to haul the sprayfoam mix barrels and pumping rig. God only knows how that worked, but it did.
Flying stuff into "camps" for building or maintenance is a regular thing, in the locale where this thing is being built. A number of places have been built around a remote lake, two valleys over, all by members of a very exclusive club, no road access whatsoever, and the annual propane fuel "jump" is a big helicopter event, with the staging all taking place on a small grass airstrip up the highway from the village.
Do some research into hammer-beam trusses.
or steel cabled rafter ties
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Yeah, I think about the only thing that would pull it out (short of a complete rebuild of the roof) is cable or rod rafter ties. Although if this one thing is so badly thought out you have to wonder about other issues.
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There was this arrangement in this church where we installed this organ...I think it was steel rods with couplings.
Ugly as sin IMO.
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"If you want something you've never had, do something you've never done"
Yep, seen a dozen of them. Definityely ugly, but when the idjits fail to plan, whatchagonna do?
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In the right circumstances they can be virtually invisible.Otherwise, to avoid columns I think you'd have to get a steel truss designed to carry the center cross, and of course that would require running pilasters down to a footing.Who designed this fiasco? I hope it wasn't a pro.
If your view never changes you're following the wrong leader
What would I do?
I'd contact movie producers and inquire if there's any wilderness setting films being made where they're looking for a house to blow up.
Runnerguy
A preliminary set of calcs I've run show that a steel beam (W16x40) will handle the load at the clear span of 35'-11".
Here is a concept sketch showing it packed out so the 2x12 rafters can head into it. It is all just wishful thinking now, that the place is all framed and sprayfoam insulated. Dreaming back at what should have been done at frame-up time.
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What would you do instead, to try to avoid so much lumber being used for the packout?
We will look at some options for posts somewhere along the span, in order to cut down the section size needed, and perhaps facilitate a way to do this with a string of timber beams, each simple span, running post to post. A custom glulam at 3" width might be able to socket right up in there under the pair of 2x12s that were used as the ridge.
Before a ridge beam is installed it would be wise to assure that there is sufficient bearing strength at both ends. [Especially since it seems likely that at least one of the end walls has been filled with windows.]
If your view never changes you're following the wrong leader
Edited 9/24/2007 10:27 am by DanH
You are preaching to the choir, Dan. Posting down under bearings, headers and reinforcement, everything needs to be reexamined. Worst case now is for end reactions in the 18 kip range.
At the very least, the nearest news crew with a chopper should be notified to be ready for some neat footage, after the first big snowfall.
If your view never changes you're following the wrong leader