The Forestry Forum

General Forestry => Timber Framing/Log construction => Topic started by: theuniquey on March 30, 2011, 11:07:47 PM

Title: Timber Framing vs. Post and Beam
Post by: theuniquey on March 30, 2011, 11:07:47 PM
I have been reading a lot over the past couple of years and have seen references to both, timber framing and post and beam and always thought they were the same thing.  Most recently, I heard that they are different.  Timber framing refers to the old (original) style of joinery and post and beam refers to the method using steel plates and bolts.  Is this true?

The reason I ask, is I am planning on building a 20' x 22' post and beam (using the above context) addition onto my house.  I have the basement in and covered, ready for the next step.  I'm assuming most of the terms are the same but the joinery is completely different.  I lean towards the steel plates and bolts for a couple of reasons.  I like the heavy, overbuilt industrial look and it just seems like a lot less work in prep.

Has anyone done this? 
Title: Re: Timber Framing vs. Post and Beam
Post by: Brad_bb on March 31, 2011, 12:00:03 AM
Yippy!  I'm the first to answer this one.  We've talked about this here quite a bit in the past and the consensus is that it is not faster, easier, or cheaper.   People often discount what it takes to make the plate work, which often requires some custom pieces.  Alignment and understanding of framing principles is also needed.  IN the end of the day, if you compare the two, not leaving anything out, like the cost or time to make the plates, and fitting them to each joint.  It's going to be pretty close to the same.  I would choose one over the other based on the aesthetics you want.   Timber frame does have some advantages.  You don't have to make specialized brackets for one.  You can cut a joint in the same time it would take to make and properly install the bracket.  The craftsmanship of timberframe is appreciated and beautiful.  It's not rocket science either.  If you have some level of aptitude, you can learn it.  One disadvantage of post and beam is that steel and wood interact over time to rust the steel, and rot the wood.  Have you ever pulled a nail out of old wood and the nail was corroded and the nail hole was blackened around it?  Eventually the hole would rot enough to make the nail loose.  This may happen only over a very long period of time, but will go even quicker if any of it is ever exposed to water- like a roof leak.  It's often a misconception that post and beam would be easier, but you still have to select your wood carefully, orient it properly in the frame with respect to crown and reference faces, and fit and install the bracketry. 
Title: Re: Timber Framing vs. Post and Beam
Post by: Jim_Rogers on March 31, 2011, 08:52:37 AM
Most recently, I heard that they are different.  Timber framing refers to the old (original) style of joinery and post and beam refers to the method using steel plates and bolts.  Is this true?

Yes this is true.

Title: Re: Timber Framing vs. Post and Beam
Post by: witterbound on March 31, 2011, 10:32:14 AM
There are also now nifty steel connectors that some use that are hidden in the timbers, and the holes are filled with pegs to make it look like a timber frame.  I don't remember what they are called, though.  But you've still got to square up everything, and make sure it will fit tight, just like a traditional timber frame.  I suppose you'd need to do that using angle iron too.
Title: Re: Timber Framing vs. Post and Beam
Post by: Jim_Rogers on March 31, 2011, 11:20:50 AM
it just seems like a lot less work in prep.


This maybe true, however, the bolts and plates have to be sized correctly to hold the load. The spacing of the bolt holes has to be right in order to not split the beam or the post. Bolt size, location and spacing is very important in this type of construction. And they have to meet code to be right.
I don't have enough experience in this type of construction to advise you other than to tell you to have your design review by a structural engineer for specific bolt sizing and spacing.

If done wrong it is very bad.

If done right it could last a long time, as most of the large industrial building have.

Good luck with your project.
Title: Re: Timber Framing vs. Post and Beam
Post by: pep on April 02, 2011, 08:08:53 PM
   check out www.timberlinx.com
   



    Cheers

    pep
Title: Re: Timber Framing vs. Post and Beam
Post by: Piston on April 03, 2011, 04:36:10 AM
Assuming you are not interested in getting into timberframing and want to do the work yourself, I think you could learn how to install brackets, install them, and put up your frame a lot quicker than learning how to cut proper joints and fit them correctly, and raise your frame. 
If you take into account making the brackets then its a different story.  I would take the time to timberframe it only because of personal reasons, but I do know that I personally could drill and bolt the brackets quicker than I could cut the joinery. 
Just as Jim said there are a lot more structural considerations to take into account, you can't just pick up the brackets at Home Depot and go to town. 

Either way you will have a great time building your frame and post some pics of your progress, If you like the look of the brackets better then you should go that route.  Good luck and happy post-and-beaming  ;D
Title: Re: Timber Framing vs. Post and Beam
Post by: Brad_bb on April 03, 2011, 08:09:58 PM
Timberframing is a great thing to learn.  Take one of the 5 day workshops.  You learn skills that you can apply to more than just timberframing, but to woodworking and more.  People always think things are harder until they actually get into and start learning.
Title: Re: Timber Framing vs. Post and Beam
Post by: Jim_Rogers on April 04, 2011, 12:08:56 PM
One thing I learned early on in life was to "learn by mistakes".......

One thing I learned early on in my timber framing life, was "learn by other people's mistakes"..... it cost a lost less.

Recently I watched a webinar where an engineer that I know was showing different things about "heavy timber engineering". I spent this past weekend at a conference and this engineer was there, along with other members of their firm.
I asked him to if he could share with me; so I could share with you, some examples of "failures" so that you can all "learn from other peoples mistakes".....

I emailed him this morning, he is one of the engineers at Fire Tower Engineering in RI. An engineering firm that I have used in my design business. A bunch of really nice guys.

He has just sent me several photos to share with you about the need to properly size and space bolts for "post and beam" construction. As doing it wrong is very dangerous.

Here are the photos:

(http://www.forestryforum.com/gallery/albums/userpics/10095/3416/Poor_Surface_Plate_Design_%281%29.JPG)

(http://www.forestryforum.com/gallery/albums/userpics/10095/3416/Poor_Surface_Plate_Design_%282%29.JPG)

(http://www.forestryforum.com/gallery/albums/userpics/10095/3416/Poor_Surface_Plate_Design_%283%29.JPG)

And here is a drawing of an awful connection or bad joint:

(http://www.forestryforum.com/gallery/albums/userpics/10095/3416/Awful_Joint-2.JPG)

(All the red "Bad Joint" was added by me to insure that someone else in the future doesn't see this and think it's an ok thing to do.)

I would like to thank Mack Magee for sharing these with us.

Jim Rogers

Title: Re: Timber Framing vs. Post and Beam
Post by: beenthere on April 04, 2011, 02:39:37 PM
One real obvious reason it is a bad joint is the fasteners (bolts here) are in line with the grain of the wood, and not staggered. That is a pretty basic woodworkers rule not to line up nails, screws of bolts along the same grain.
That is a pretty pathetic joint system shown. Good that you posted it Jim.
And we sometimes wonder why there are building codes. Unfortunately this is one example.
Title: Re: Timber Framing vs. Post and Beam
Post by: Jim_Rogers on April 04, 2011, 06:35:36 PM
Yes, and my point about showing these, is that you can't just pick up a plate, bore a few holes, bolt it on and call it done, and/or good.

The bolt spacing and location are important, as well as the bolt size. There are code rules as to what you can do and where you can do it.

Engineers look up these rules and follow them so that everyone is safe.

I'm just trying to educate everyone or anyone that it has to be done right.
Title: Re: Timber Framing vs. Post and Beam
Post by: theuniquey on April 05, 2011, 03:12:23 PM
Thank you all so much for your responses.  Jim, I have read a lot of things you have posted and enjoy your writing very much.

At best, I am a wood butcher with perfectionist tendancies.  I am also a steel fabricator and welder of similar capabilities...I don't think there's much I cannot do.  As I get "stage 2" underway, I will post pix and will look forward to everyone's input.  I fully intend to end up with a grossly overbuilt structure.

I think you could learn how to install brackets, install them, and put up your frame a lot quicker than learning how to cut proper joints and fit them correctly, and raise your frame. 
This is exactly my mentality.  Plus, like I said, I am shooting for the heavy industrial look.

Thanks again everybody.
Title: Re: Timber Framing vs. Post and Beam
Post by: Thehardway on April 05, 2011, 04:55:10 PM
"Overbuilding" does not always mean stronger or better.  A good example of this is the truss.  It uses smaller lighter members working in harmony to span great distances with great strength.  Larger, heavier members would never make the distance and would be unable to support their own weight.  Wood can be very strong and durable when used properly.  Steel can strengthen when used properly or weaken a structure when used improperly. 

Steel was used early on in many timberframe structures to "reinforce" joints.  Over time it was often found that the removal of wood for the accompanying throughbolts and plates actually caused premature failure and failed to improve performance.

In order for a bolted plate structure to match the strength of traditional joints, engineers must use the compression of the plates on the wooden members as well as the through bolts resisting tension and they must be tightened and inspected over time to accommodate the contiuous expansion and contraction of the wood and dissimilar materials.  Ever see a crew of maintenance workers go over the superstructure of a wooden roller coaster?  The best method of using steel in a wood structure is in the form of brackets rather than plates.  This is used in many industrial warehouses built in the mid 1800's-early 1900's and is very durable as the joints do not bear soley on the bolts or rely soley on compression bolts/washers and plates.  This also requires less engineering ability and is more intuitive.

An interesting study that is ongoing is how lightweight trusses which use steel splicing plates pressed into the wood perform in fires.  It is typically not pretty.  The thin metal plates lose their tensile strength rapidly as the heat rises and they fail allowing the roof structure to collapse on firemen and rescue personnel. 

Bowstring trusses were pretty much eliminated from use years ago because of this type of failure.

http://www.middletownfire1.com/History/Actual%20Incidents.htm

I like the look of both types of joinery when well done but would agree that traditional joinery requires much less technical ability to do properly and make it last than Post and Beam.  If you are a certified PE and a certified structural welder then you have nothing to lose going with steel plate joinery.  If you are not, expect a lot of delays at the permit office, a lot of money spent on PE fees and a few arguments with the LAHJ no matter how overbuilt it is.

The heavier it is, the more it hurts when it falls on you.  Don't ask me ehow I know :-[

Keep us posted...