I realize codes vary all over the country, but I would be interested to know what people have found to be true in the following situation.
If one were to desire to use logs (round timbers?) to cantilever out from a building to support a three foot extension for a balcony, there would likely be codes to define how far back into the floor structure teh logs would have to go. But what are the requirements for the logs themselves? Obviously framing materials are graded but logs would typically not be graded.
What does code say about such things?
Just intuitively, say 12 inche diameter logs extending three feet out from a structure would easily support a balcony, but code often has noting to do with reality, likelihoods, etc. SO?
Replies
What does code say about such things?
We have some smart people here, so I hope they have an answer, as my quick (very quick) through IBC 2000 & 2003 did not offer up anything on log construction.
"Logs" are kind of tough to define in engineering terms. They are "inelegant" in the engineering sense, in not being uniform. Sure, if it's a barked doug fir log, we can use some of the fibre strength tables for DF off of the ATA tables. "Some of" is the important bit--many of those tables are for heartwood only. If we have a fast-growing DF log, and a 1/3 of the diameter is sapwood, it's not as strong as one with only 1/4. So, "logs" are hard to define to rigid specifications.
Now, for a framing rule-of-thumb, you could cantilever, generally, 50/50--that's "in" as far "out." But, that's putting a bunch of the load on whatever "header" is picking up the inside portion of the cantilever. Which is why 1/3:2/3 might be better. Might, could, perhaps, etc.--I'm just some dude on the internet. I've slaughtered my share of trees, but we burnt down what we made them into every year I did that.
"I've slaughtered my share of trees, but we burnt down what we made them into every year I did that."
Curious what you mean. Do you mean you were clearing bush and young trees adn just burning them up?
As for construction with logs. I hope you realize that I am not talking about a log home or anything close to it. I was thinking more in terms of a standard framed house in what might be called mock/timber style (beam elements, fake or otherwise). But I was thinking of using short logs to cantilever a balcony. The load on the balcony woulb be limited to the decking and two or three people, say five. And only extend say three feet. REally a decrotive element rather than of much function.
I can understand the problem here as codes have to spell EVERYTHINHG OUT. They can't just say "well use GOOD SOLID logs". SO I wondered how any of this could be handled. Perhaps there are sources where you can go and buy logs which are graded. Perhaps some log home outfit, or beam manufacturer. I don't know.
I think for the appliction I have in mind, I should be able to go and cut the 12 inch tree of my chosing and be just fine, but . . . .
Curious what you mean. Do you mean you were clearing bush and young trees adn just burning them up?
No, more of a ritualistic or cult-like behavior carried to an extreme <g>
From this:
View Image
To this:
View Image
In just under 82 days. Every year for five straight, too (1978-1983). Went to watch them burn every year after that, until 1999.
Occupational hazard of my occupation not being around (sorry Bubba)
Edited 3/13/2006 6:18 pm by CapnMac
OOOOOKKKKK . . .
I have seen pictures like those before. Where did you get teh trees?
Where did you get teh trees?
Well, the students running the operation (used to) spend most of their Spring Semester finding a site that was going to be clear cut for an Electrical or similar ROW; or some similar field of trees. In addition they went (begging) for donations of bailing wire, fuel, cash, all sorts of things.
The various student groups would go out on weekends and denuded the area of the mightiest (the first year <g>, second year you take the most convenient <g>) oaks. These were hauled off (manual labor, no less) to flat bed trailers to be hauled off back to campus. By tradition, all trees are felled with axes, too. Only on the "stack" site were student leaders allowed to "butt out" logs with chainsaws.
Record above-ground height (Guiness listed) was 110'; tallest I scaled was about 65'. Longest-burning (that I built) was 1980, lit about 2011, centerpole collapsed about 0022, ember pile finally went out about 5 days later.Occupational hazard of my occupation not being around (sorry Bubba)
An Aggie Huh? I'm sure you've mentioned that before but I never picked up on it.
Terrible accident in '99'.... How many students killed? 10-12? I hear rumor that the bonfire tradition is going to be brought back--- any truth to that? How bout the 12th man?
Back to the subect of the OP...... I too used some logs to cantlever a deck over the water. 12"-14"D X 15' used for a 6' cantelever. No egineering no inspection ... just over built and it looks good.
Will post a pic if I can find one
Excellent! Where did you build it.
Nobody mentioned rot yet.
Unless you live in Tuscon or such, forget extending logs past the roof line unless you get creosoted piles or similar.
Logs crack, cracks collect moaisture, moisture rots.
I had these extended 4 ft out for 20 years, had to cut the outside off before the rot started to extend into the house. The outside was penta treated, tarred on top, and covered with aluminum flashing, still got wet and rotted. D. FIr, pine or hemlock would be even worse.
Sorry, but did not bother to downsize the pix, just snapped overhead and posted.
Very good point.
I figured one could do as you did tar the tops, cover with tin, plus the deck itself (build deck as a unit and lag bolt it in say only four points). Plus I was thinking of a full roof over hang as well.
I figured it would be pretty safe. Maybe not.
On the other hand people have all kinds of decks extended with timbers and they crack as well.
I don't know. I suppose it depends on the risks you want to take.
What speice?
The logs/timbers I used were 12'-16' pile butts that we cut off some 50' piles---- all CCA treated -- we only used Aprox. 35' of the original piles. All our pilings or rough cut lumber is still CCA treated.
I still have 35 of these pile butts that I'm looking for a project for, most will probably be more ornamental than structural.
Good advise/method to hot tar the tops of vertical piles or logs regardless of other treatment. I always do that for bulkheads or at least advise owner to do same if I'm not completing the dock. - good barrier for termites also.
One bad thing about creosote is the smell that permeates inside the dwelling, not to mention the burns you get working with it.
Using creosoted wood in a living space is a BAD idea. Pre 1988 creosote was heavy with Pentachlorophenal, among other things....not something you want yourself or loved ones exposed to.
Using creosoted wood in a living space is a BAD idea. Pre 1988 creosote was heavy with Pentachlorophenal, among other things....not something you want yourself or loved ones exposed to.>>
Agreed! They still build a lot of camps around here using creosote pilings and sills. While the creosote is not in the living space, the smell still permeates into the dwelling from below--- especially when the camp has'nt been occupied for a while--no ventilation.
When you walk in the door after about 3 weeks of vacancy, the smell hits you hard. Takes about 2 days and 3 cases of beer for it to go away.
What speices did you use?
Terrible accident in '99'.... How many students killed? 10-12?
It was a bad day all around. 12 total died, another 27 with major injuries. At least two 'first responders' with PTS-related problems, too.
I hear rumor that the bonfire tradition is going to be brought back--- any truth to that?
Nope. The Campus Bonfire is dead and gone. There have been other bonfires; but there will never again be Bonfire. (The "off campus" bonfire had some major problems this year, like being 131% in the red; they used all green pine this year, which did not light; they tried to light under a Burn Ban, and got fined; green pine makes a bad bonfire when it won't light--it's still standing, since November.)
The Univ's "rules" are rigged just right to never permit another Bonfire. Construction requires a wet-stamped set of building plans at better than 100% safe construction. Construction insurance supplied only has to be to $2.5 mill; but the burn insurance policy requires a $50 mill policy.
It's not happening.
How bout the 12th man?
That, is still quite alive and well (despite the season Coach Fran had). Surprisingly, 2nd season coach Gillespie has the men's basketball teamm in the NCAA for the first time in 19 years (to the joy of the ever growing "6th man"); the women scored a 6th seed, breaking their 10 year drought. Get the baseball team to stop commiting errors, and it could be an exciting Spring.Occupational hazard of my occupation not being around (sorry Bubba)
I was thinking more in terms of a standard framed house in what might be called mock/timber style (beam elements, fake or otherwise). But I was thinking of using short logs to cantilever a balcony.
Now, to this, it's almost easier to do standard framing to whatever load you are going to need (which can be very high, even when small). Then, rip into some logs to dress the framing that's actally doing the work.
Why bother then?
Well, not having to notch a log to top plates (or cipher up a saddle header--a "U" 'punch-out' in the wall framing) to carry "logs." Which then gets you to the "how to fasten" the inside end (without needed drop beams, inconvenient bearing walls, etc.
Let's say you have 14-1/4" from finish ceiling to finish floor. Let's say you want a 3' x 6' deck. We could probably cobble together some numbers for a 6'x6' frame of, oh, 4" tube steel, which we can then tie to the existing wall structure with off-the-shelf fasteners. From the frame we could then add on some, oh, 3" wide, 6-9" long steel plates to which we could discreetly lag 12" "logs" right on to.
Plenty of possibilities there, too. Mount some beadboard to the bottom of the frame, and you get that traditional porch roof "look." The deck floor soes on top, and there's no "fussing" with the edges, either: trim the edge and you're done. (if using logs for beams, you then need joists, then the deck thickness--could be another 8-10" over the tops of the logs).
It can be done, it just deserves doing it right. Which is often a bit more work.Occupational hazard of my occupation not being around (sorry Bubba)
CapnMAc:
I must thank you for your detailed response. It sounds like you must work on some pretty interesting projects. However, I must also say that I am not sure you have a picture of what I am thinking about and I am certain I did not follow your plan (at least could not marry it to my idea). LOL! A picture is worth a thousand words adn I don't have one.
In this area, if an engineer stamps the plans, the building official will pass it. I recommend you talk to an engineer. My engineer had tables or a computer program for rough cut timber, which I used (in some areas) and the inspector passed.
>>"Obviously framing materials are graded but logs would typically not be graded."
Don't you watch the Sopranos? This question was actually answered in the season premiere. ;-)
Ok, yes the code does answer this (at least the code where I am -- IRC 2003 -- I assume this is a residence). Lumber used for framing has to be graded if you want to use the prescriptive method. Beyond that, there is no prescriptive method for logs.
No prescriptive method available -- Time for the engineer.
"A job well done is its own reward. Now would you prefer to make the final payment by cash, check or Master Card?"
Prescriptive method? Please explain.
>>"Prescriptive method? Please explain."
DoRight:
Presciptive method means the way already sanctioned or authorized in the code. The code contains a "cookbook" way to meet the universal requirements for how to put a residential building together (requirement #1 -- it shall not collapse; actually paying permit fees comes before that in the code -- seriously -- but that's another issue). Everything from foundation to roof.
If you submit plans for and build something in a way that's already "prescribed" by the code (which has pre-cooked tables to allow you to determine joist species, spacing, size, grade, and even allowable cantilever, etc., for your balcony for example), you don't need to "prove" that the structure will meet the code's structural design criteria.
Once you move off the pre-approved charts and tables, you are no longer building something tried and true. You've got a one-off. Now you need the engineer's stamp to prove to your local plan review dept. and building inspector that, for example, your balcony can resist, say, 10 psf (pounds per square foot) of dead load (what it weighs) plus 50 psf live load (you, your guests and your furniture), if those are the numbers required in your area (those are the desisgn criteria used where I live for a floor).
All this is moot if your locality isn't strict with the code, but your original post asked about how the code would handle this. Made me scratch my head for a while, but that's how the code would handle it (at least the code where I live).
Anyway, best of luck with it.
"A job well done is its own reward. Now would you prefer to make the final payment by cash, check or Master Card?"
Your post regards to code is nuts on with what I would expect.
Was curious as to whether there are easy ways to get data to support the use of logs in such applications. ie can you get "approved" logs from some manufactures to "meet" code. etc.
I have some ideas from some posters here. Thanks.
This is one of those places where someone with a smart stamp will help your project fly through the building department.
In absense of that, think of the log as a number of low grade dimentional boards and throw that at the inspector. While a log is not graded as structual lumber, you'll at least have a somewhat inteligent place to start the discussion.
Better, would be digging up load tables from timber framing. It seems I've seen those floating around the internet somewhere. Check the timber framing association websites.
The portion of the log burried in the house does not have to remain round if it's accounted for in the design and it can be helpful to square it off so it's then easily handled like a beam in the framing.
Working with logs is kinda fun if you like messing with them. If you don't have one, get a Veritas double bubble scribe for $75 and it will pay for itself the first day you need it.
If there are any log home builders in your area they may be able to give you some specs from a log building load chart of some kind. Probably cheaper than an engineer.
Cheers
Best of luck.
troout: Thank you for another great post.
I suppose a lot of this depends on the inspectors. It sounds like you have had experience being logical with inspectors in the absence of complete documentation, hence your suggestion of offering structural tables for low grade lumber as a substitue for details for logs. Worth a shot. I am sure that whether the application in question were truely an issue of holding a house up verse just a balcony would make a difference in the view of the inspector.
Also your idea of running the idea past a log home builder was great. I had already thought about sourcing the logs through them as they would likely already have a system for gettign there jobs through inspection.
I can understand that you might want to use polynomials, but why on the earth logs??
What? Oh, yeah!
Sorry, wrong thread.
happy?
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