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Reinforced Timber Framing / Mock Timber Framing?

Started by Stuart Caruk, January 07, 2015, 06:17:54 PM

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Stuart Caruk

Now that I have my own mill, and access to lots of trees, I'd like to design a timber framed structure. I'm not terribly interested in cutting all the joints (Unless I take the time to build a CNC machine that will whip them out automatically), rather I have a CNC plasma cutter and for years I've been burning out supporting brackets for large log home companies.

They essentially miter the ends of the logs to fit the shape of a truss, then I cut a pair of steel reinforcing plates that get through bolted and attached to each side of the log. I'd like to do the same thing, but make some artistically shaped plates to do the same job with milled beams. I've ordered up and read a half dozen books on timber framing, yet none of them even mention this option. Is there any reason not to go this route? It would seem to me that since you're not reducing the timber size at the joints that it should actually be stronger. I can also make any intersection I want by cutting brackets and welding them together as needed.

Curiously,

Stu
Stuart Caruk
Wood-Mizer LX450 Diesel w/ debarker and home brewed extension, live log deck and outfeed rolls. Woodmizer twin blade edger, Barko 450 log loader, Clark 666 Grapple Skidder w/ 200' of mainline. Bobcats and forklifts.

Brian_Weekley

Quote from: Stuart Caruk on January 07, 2015, 06:17:54 PM
I'd like to design a timber framed structure. I'm not terribly interested in cutting all the joints...

But that's the fun part!   :)

Quote from: Stuart Caruk on January 07, 2015, 06:17:54 PM
I've ordered up and read a half dozen books on timber framing, yet none of them even mention this option.

Because metal is not timber (hence the term "timber framing").     :P

Quote from: Stuart Caruk on January 07, 2015, 06:17:54 PM
Is there any reason not to go this route?

Because it's not nearly as beautiful as a wooden timber frame (in my humble opinion).   ;)
e aho laula

Roger Nair

Hey Stu, I am certain, if you shake the trees, a large number of builders, engineers and architects in the Pac NW will show a preference for steel gusseted frames given a seismic design concerns.  You should get up to date standards from the American Wood Council's National Design Specification.

http://www.awc.org/standards/nds/2015.php
An optimist believes this is the best of all possible worlds, the pessimist fears that the optimist is correct.--James Branch Cabell

Jim1611

It seems easier to put the timbers together with the steel plates. Miters are not hard to cut either. My trade is in metal fabrication and I am always interested in how metal structures are made. Take a look at bridges. Much of that structure is held together with plates and rivets. Bolts work too, as I assume that's what you'll use. The problem I see with wood and steel plates is the wood will shrink and unless you plan to tighten all of those bolts afterwards the structure isn't going to be as strong as it should. Those bolts being tight cause pressure on the plates and that makes for a good joint. If they're loose all that's holding things together are the bolts through the plates and timbers. You've lost the best part of that system if that happens. You'll also have to make sure the timbers are the same width where they meet so there's equal pressure on them both. I'm not trying to say one way is better than the other, I'm just thinking with words.
"Let every man be swift to hear, slow to speak, slow to wrath."

Stuart Caruk

Go figure... I've been plasma cutting, welding, and fabbing parts for years, and I actually prefer the look of a nice powder coated steel tie plate securing the timbers with bolts. I figure I can easily tighten them up as the wood shrinks. This just might let me overcome the design challenge on a structure I've wanted to put up for a couple years.

Surely there has to be a name for this method of construction, I just don't know what it is. If you look around my shops and motley collection of buildings you'll see all kinds of unique features. I have some serious reinforcing plates welding things together from those times when I'm cutting up an 8' x 20' hunk of 1" thick plate and I need a couple small brackets. Too much time and effort to move the plate, load some 1/4" plate and get back to work, so the gussets are an inch or thicker...

ON the plus side, I found I need a logging arch to get some big logs out of the woods, and I have some plate on the table right now...
Stuart Caruk
Wood-Mizer LX450 Diesel w/ debarker and home brewed extension, live log deck and outfeed rolls. Woodmizer twin blade edger, Barko 450 log loader, Clark 666 Grapple Skidder w/ 200' of mainline. Bobcats and forklifts.

Ljohnsaw

Stuart,

I can't believe no one has said it.  You are NOT talking about Timber Frame Construction, you are talking about Post and Beam Construction.  That is exactly what your are doing.  It was one of the main construction methods used during the industrial revolution.  Fast and strong.  I read up about the fire safety as well - a big timber chars but does not burn - oxygen has a hard time getting to it.

Sorry, you bought the wrong books...

However, IMHO, not as pretty as timber frame ;)
John Sawicky

Just North-East of Sacramento...

SkyTrak 9038, Ford 545D FEL, Davis Little Monster backhoe, Case 16+4 Trencher, Home Built 42" capacity/36" cut Bandmill up to 54' long - using it all to build a timber frame cabin.

Stuart Caruk

Ah, that makes sense, although the timber framing books gave me some really good insights onto how to saw my beams. I used to think for example that the center of the log was the strongest, and figured boxed heart beams were ideal... a fallacy I picked up years ago at a manufactured log home seminar. Now I have a strong preference for quarter sawn clear heart beams... and I happen to love to read almost anything technical. So it's all good. Now off to find Post and Beam books. Thanks.
Stuart Caruk
Wood-Mizer LX450 Diesel w/ debarker and home brewed extension, live log deck and outfeed rolls. Woodmizer twin blade edger, Barko 450 log loader, Clark 666 Grapple Skidder w/ 200' of mainline. Bobcats and forklifts.

Jim1611

I was thinking about your project again. This idea is most likely an overkill but look at the way those metal stamped parts are made for fabricated trusses. They are punched out so that the side that faces the wood has teeth to bite into the wood's surface. Now do that with some 1/4" thick plate and just imagine how well it'd hold.

I'm with Stuart though and to me the traditional timber frame looks more appealing. What you end up with will still be far better than a stick built structure.
"Let every man be swift to hear, slow to speak, slow to wrath."

Brian_Weekley

With my previous kidding aside, construction with metal plates has certainly been around for a while.  When properly designed and sized, wooden mortise–tenon joints are more than adequate; a proven design that have been used for many centuries.  As a kid, I was always fascinated looking at the insides of old barns.  There was something magical looking up at the wooden joints held together with wooden trunnels.  Construction with metal plates, bolts, and washers has more of an industrial feel that I expect to see in factories and commercial buildings.  To me, they just seem out of place in smaller, family farms and residential houses.
e aho laula

Jim_Rogers

Quote from: Jim1611 on January 08, 2015, 08:51:46 AM
look at the way those metal stamped parts are made for fabricated trusses. They are punched out so that the side that faces the wood has teeth to bite into the wood's surface.

Any building made with trusses and stamped out plates not nailed to the truss usually has warning label on the outside of the building. Most fire departments will not enter the burning building made with those types of trusses as the metal heats up and expands the plate drops off the truss and there is no strength to hold the building together. Larger version of the same thing will have the same effect.

I have cautioned may who have posted here that they want to do "post and beam" construction on their own that boring holes and putting in bolts in the wrong location or size or pattern can weaken the timber more than strengthen the joint. Each frame design should be reviewed by a qualified structural engineer to determine the correct size and location of these bolts and plates so that the structure is strong.

Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

Jim1611

Quote from: Jim_Rogers on January 08, 2015, 10:53:48 AM
Quote from: Jim1611 on January 08, 2015, 08:51:46 AM
look at the way those metal stamped parts are made for fabricated trusses. They are punched out so that the side that faces the wood has teeth to bite into the wood's surface.

Any building made with trusses and stamped out plates not nailed to the truss usually has warning label on the outside of the building. Most fire departments will not enter the burning building made with those types of trusses as the metal heats up and expands the plate drops off the truss and there is no strength to hold the building together. Larger version of the same thing will have the same effect.

I have cautioned may who have posted here that they want to do "post and beam" construction on their own that boring holes and putting in bolts in the wrong location or size or pattern can weaken the timber more than strengthen the joint. Each frame design should be reviewed by a qualified structural engineer to determine the correct size and location of these bolts and plates so that the structure is strong.

Jim Rogers

I didn't mention that with the intentions of not using the bolts too and they'd still be the same thickness as he would normally cut. Sorry I wasn't more clear.
"Let every man be swift to hear, slow to speak, slow to wrath."

woodworker9

Jim

Since you posted this, I just want to add a quick story from very personal experience.

25 years ago, I worked in a building that was post and beam construction.  It was older, built in the 1940's, and having an engineering background from college days, I always was concerned about how some of the trusses looked out in the shop area.  One Monday morning, we all arrived to work to discover that after a bad, bad snow storm, one of the trusses snapped right where all the holes/bolts were located, in the middle of the metal plate sandwich.

I kid you not, the truss crashed down right through my office, smashing my desk and computer and crushing the adjacent wall to smithereens.  It happened on a Sunday night when we were closed for business.  I have always felt extremely lucky after that incident.

We were closed for a short time after as the owner of the business/building had to have major support posts installed everywhere before occupancy by the city was permitted again.

Sorry about posting this, but your warning sent me to an instant flashback.

Jeff
03' LT40HD25 Kohler hydraulic w/ accuset
MS 441, MS 290, New Holland L185

Jim_Rogers

Jeff:
I'm sure there was a complete investigation of the collapse.

Several years ago, I was talking to the WM dealer out of NY. They had their shop where the resharp service are roof trusses collapse on them due to snow, in the middle of the night.
The truss manufacturers were right on the spot and figured out what went wrong.
Sometimes it's not the correct design load used.
Sometimes it's that they weren't installed properly, and what I mean by that is they need to be tied to each other so that the combined mass has strength. If they aren't tied together with supporting lumber correctly then they can fail.
I asked him how he new that the roof had collapsed in the middle of the night? He said he had one of those things that calls you when the temperature gets too low. And he got a call in the middle of the night from this system telling him that the temp was down. He drove over there to see why and found the snow had crushed his roof.
I think they had to crane in a bobcat to scoop the snow out so that the could repair the roof, and get the machines back to work sharpening blades. Set their schedule back a couple of weeks.

It can happen and in order to sleep at night you need to cover all your bases.

Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

beenthere

QuoteAny building made with trusses and stamped out plates not nailed to the truss usually has warning label on the outside of the building.

Never have heard of this warning label. What more can you add?  Just curious.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

jueston

Quote from: beenthere on January 08, 2015, 12:19:55 PM
QuoteAny building made with trusses and stamped out plates not nailed to the truss usually has warning label on the outside of the building.

Never have heard of this warning label. What more can you add?  Just curious.

i too am curious about this, manufactured trusses(the kind with metal plates and no nails) are the only way residential buildings are built around me, in order to frame a roof in any other way you would have to have engineered drawings and a rider on our insurance. 

the developments around here use manufactured trusses for all of the floors and roofs and even headers and load bearing beams in some instances.

i know when the trusses are used for floors there is additional fireproofing required(ussually just more drywall), but I've never heard anything about warning signs or firefighters not entering these houses.


Jim_Rogers

I'll have to do an internet search but it was a big deal when they first came out.
The fire departments or national codes tried to get them banned as they were very bad for fire fighters. The truss makes fought it so due to "free enterprise" and you can't ban someone's product.
So the fire departments came up with this notice that is, I believe, required on all building, (and this may be only commercial buildings), have this notice on the outside of the building.
I've seen pictures of the notice somewhere.
I'll have to try and find it but if someone else finds it first please post it for all to see.

Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

Jim_Rogers

Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

Brian_Weekley

Quote from: ljohnsaw on January 08, 2015, 12:29:43 AM
You are NOT talking about Timber Frame Construction, you are talking about Post and Beam Construction.  That is exactly what your are doing. 

Timber frames also consist of "posts" and "beams".   However, the term "timber frame" is "generally" reserved for the traditional, all-wood, mortise and tenon method of joinery.  It's a subset of the overall "post and beam construction" which includes other methods of joinery such as metal plates.  My understanding anyway...
e aho laula

jdtuttle

NY will soon be requiring Placards on residential structures built with truss construction. It is now required for commercial.
Have a great day

beenthere

I'd suggest more over-reaction to media hype (IMO).

Here is some third party take on the controversy and comparing some of the "facts" that get presented where things do go awry.

http://www.trussway.com/pdf/wtca/firebro.pdf

Airs the claims and presents some "facts" to consider with respect to those claims.
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

schakey

Good morning Mr. Caruk
Have you read "Timber Framing for the rest of us "by Rob Roy?
Think-Dream-Plan-Do

Stuart Caruk

Stuart Caruk
Wood-Mizer LX450 Diesel w/ debarker and home brewed extension, live log deck and outfeed rolls. Woodmizer twin blade edger, Barko 450 log loader, Clark 666 Grapple Skidder w/ 200' of mainline. Bobcats and forklifts.

Gumneck


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