TF design opinions/critic

[Dieskyver]

Hi All,
 
  I'm working on the design of my first timber frame.  Its a 30x30 SYP cabin with three bents. There are no code compliance requirements.

Im located in central AL
roof decking will be 1.5" t&g
The rafters will be 4x8s @ 44" centers.  I would like to use two running from the plate to the ridge and let the principle purlin carry the middle ends.
The principle purlins will be a 6x8s.
The straining beams are drawn as a 6x8s
I have two schemes. A king post one and a queen post... they are 8x8.

The queen will make for a more solid roof system but it will put extra stress on a free span beam(8x12) carrying the loft floor joists(6x8)(my next concern).
With the beam bearing the weight of a portion of the roof, the joints for the loft floor joists are my big question mark.  I've heard/seen alap joints or I can even put the Jsts over the Bm and eliminate the joints.  This would however kill my head room so I would have to raise the knee wall height.

Oh yeah, there will be 2x4 stud walls on the exterior placed so the frame will be visible from the exterior, a wall under the other beam in the center bent, and a wall creating a room underneath the half the loft section.

I have concerns about the roof loads pushing the exterior walls out but i was thinking the purlins would help that out.  I thought this would be easier but I'm having my doubts.

Also,  as far as involving an engineer, can anyone give me an estimate?  I don't know if $500 or$5000 for this scope of work.  I know they are all different.  The Timber Framers Engineering council has members in NC I will probably talk to.  I just wanted to get a heads up from the gurus here so I would know what to expect when.


Here are the pics of what I have so far:

The king post design


 




 

And the Queen


 




 

[Jim_Rogers]

You might want to consider uploading one or both of the plans to the sketchup plans section of this forum so that others can download it to review it closely.

Jim Rogers

[Jay C. White Cloud]

Welcome to the Forestry Forum.

Hi Dieskyver,

I will let others chime in on this over me, for now.  I am trying to limit my feedback to frames that follow a more non-european style (no oblique braces) and leave the Anglo European designs to others, as this is a style I least often pursue other that folk styles.  Your design should be looked at by a PE since you do not have much time under your belt as a timber wright.

Most of the feed back I could give now is on aesthetics, and functional design, which is not what you requested.  Go with queen post design over your king post design, as you have them, it is better of your two designs. What books have you read, and/or what traditions are you following?

Regards,

jay

[Dieskyver]

     I hoped to have more completed in the sketchup file so that functionality could be discussed.  I still haven't figured out a stair/ladder config for the loft area.  I have read Ted Bensons book.  The biggest reason I chose the oblique bracing was I figured it would be stronger.  I'm really not following any particular style...that I'm aware of. I can distinguish between the Asian style and the non Asian style I guess but there are many characteristics such as joinery that I have to learn about before I really choose a style to follow.  I do plan to do more frames and wish that some of the schools/classes where more convenient to my location.  I figure I would build a gazebo or two and learn different styles.  Necessity is pushing me toward a cabin.  Not my first choice of projects.  I appreciate your imagination while sticking to traditional style so any input you give will be valued highly.  But like you said, Jay, this is my first one and I thought I was keeping it simple.  An engineer will allow me to sleep better on stormy nights.
    BTW, I will be using an LT40 to do the milling.  My PC access is limited so my time on sketchup and uploads to the forum are very valuable.  I have attached the sketchup file into the depository and can respond to any comments via my phone most anytime during the day.  Try to cut me some slack on the organization of the drawing. The layers are crazy and I will have to sort it out but the you should be able to activate/deactivate layers provided in the post to access the two different roof schemes.
  I was also having trouble find out how/where to donate to the forum.  As I was uploading my file I did feel like I was contributing to future users but it just wasn't enough for all the blood, sweat, tears and splinter that others have donated.   

[Jay C. White Cloud]

Hello Dieskyver,

Ted's books are more "coffee table" and "look at books" that instructional.  Good information, but without a solid foundation, you are hard pressed to cut a frame from them.  Jack Sobon's are much more informative, but in the English style of framing.  James Mitchell and I work in very similar styles, and his books are very informative and instructional.

I still haven't figured out a stair/ladder config for the loft area. 

Get the rough frame done, then we will help you deal with the stairs.

The biggest reason I chose the oblique bracing was I figured it would be stronger. 

No, they are far from stronger, they only make a frame stiffer.  Under the correct, (or bad) wind or seismic events, if they are not designed correctly and put in strategic locations, they can actually weaken a frame by acting as a fulcrum.  That is why they fell out of favor in Japanese architecture, replaced by horizontal bracing methods, as did other parts of Asia, which suffer horrible earthquakes, (some areas, on a daily basis.)  These methods provide stability and flexibility, a must for any event that causes harmonic loads, then rapid horizontal release.
If you read a little bit more from varied sources, you will, I am sure develop a style that speaks to you.  I have loves in each in every one.  Overall, I specialize in folk traditions (common house styles of the indigenous people of an area.)  Their since of need, space, and aesthetic, matches me more than other more refined styles.  In folk traditions of Europe, I prefer log and cruck folk styles, but my passion is Native American, Middle Eastern and Asian folk styles.

I do plan to do more frames and wish that some of the schools/classes where more convenient to my location.

At this point you would have to travel, or find someone like me that you can jump on a job and pick up some valuable OJT.  Most timberwrights, have to travel to some extent, especially in the beginning of their career's as wrights.  The Holder Brothers are in your "neck of the woods," reach out to them, and see if you could pay a visit.  I also think they are teaching.  If I teach this fall or next summer, I will post the course work here on the forum.

Necessity is pushing me toward a cabin.  Not my first choice of projects.

A cabin is perfect, did my first solo frame for my mother, and I, on a small farm when I was 19.  I had been apprenticing on and off for five years, and was ready to try it by myself.  You are going to do fine, but the frame you have presented for consideration is rather large for a cabin, isn't it?

I appreciate your imagination while sticking to traditional style so any input you give will be valued highly.  But like you said, Jay, this is my first one and I thought I was keeping it simple.

Check out my gallery and the links I have posted, (that is under my name, just hit the "earth symbol."  Asian folk is really simple to do, far easier than most European designs.  A cruck is more of a challenge, but a beautiful frame for a cabin.

An engineer will allow me to sleep better on stormy nights.

They are a wonderful thing to have around those PE types.  I talk to them on a regular basis.

BTW,I will be using an LT40 to do the milling. 

Do you own one?  If so, you are off to a good start, as you will learn from the tree more than many new timberwrights get to.  Seeing the trees standing is also very important, if you can get to at all.  In time you can read them like old friends.  You should be able to glance at a timber and tell crown from root, species and potential behavior, of the timber in your frame.

My PC access is limited so my time on sketchup and uploads to the forum are very valuable.  I have attached the sketchup file into the depository and can respond to any comments via my phone most anytime during the day.

I will do the best I can responding, as the busy season is upon us.

Try to cut me some slack on the organization of the drawing.

No worries, you will get better with time, I'm still improving myself, as I am an old school draftsman, and still would rather draw it then use a computer.

I was also having trouble find out how/where to donate to the forum.

An administrator, or Jeff will be glad to help you with that.

Regards,

jay

[Rooster]

Hello,

My initial advice is to read some of the previous build/design threads like this one:
https://forestryforum.com/board/index.php/topic,63364.0.html

You can learn a lot from past projects.

And get your hands on some beginner books.

"Experience is not the best teacher...someone else's experience, is the best teacher."

We all learn as we go...

Rooster

[Dieskyver]

I agree with the Benson comment. Good info but I've learned more through this site.
 
   My brother owns the lt40. I talked him into buying it about a a year ago. And recently acquired a lap siding attachment. I've had the good fortune to cut some cedar and black walnut already. I didn't know wood could look that good. We have a pile of logs (mainly syp but some oak and poplar) behind my folks house after a bad tornado last year.  I already look at trees differently than I did.
   I've been followed johns progress (amount others on the forum) and saw they and Jim broke down the process. I work with dressed commercial material on a regular basis so I'm familiar with the ways of wood and framing in that aspect. The joinery is what reduces the efficiency of the timber in a frame. 

I guess that's my biggest concern dealing with the live load bearing beam. I didn't know if the load of the joist + roof load of the queen post on it would be too much after the joints were cut.  I'm not against using oak for that one beam or if there are other design solutions. If there is even a problem.

I didn't want to spend the time drawing all the joint only to have to revise my whole plan. I'm sure an engineer will want to see the joints though(what is the P in PE?)
   
Yes, my shack has turned into a cabin and I guess I should start calling it a house. The little camper I have on my property doesn't accommodate visitors very well and I wanted to make sure I had plenty of space for guests. I thought the 30x30 was a good size.  possible too big but I will probably be staying here a while.  I could settle for a 30x28 if it would make that big of a difference. I'm satisfied with the design but I'd rather satisfy physics.

[WmFritz]

I'm sure an engineer will want to see the joints though(what is the P in PE?)

P is for Professional. It means the Engineer is state licensed and can stamp blueprints.

[Jay C. White Cloud]

I guess that's my biggest concern dealing with the live load bearing beam. I didn't know if the load of the joist + roof load of the queen post on it would be too much after the joints were cut.  I'm not against using oak for that one beam or if there are other design solutions. If there is even a problem.

We'll worry about those things later.  First we need to get you up to speed on a good design, and understanding basic layout and joinery principles.

I didn't want to spend the time drawing all the joint only to have to revise my whole plan. I'm sure an engineer will want to see the joints though(what is the P in PE?)

You correct about not adding joints at this time, just focus on the big picture.  When it comes time for a PE, shop for one that has timber framing experience.  Many try there best to get you to do what they know, not what you want to do.  I routinely (60% of the time) have to get our own PE for a job, because the one the architect wants/is using has no timber frame experience, and starts the conversation with:

"why do you want to do it that way..." or " that won't work..." which translated from PE language, means I don't know, understand or trust timber framing so I don't want to use it. 

Yes, my shack has turned into a cabin and I guess I should start calling it a house. The little camper I have on my property doesn't accommodate visitors very well and I wanted to make sure I had plenty of space for guests. I thought the 30x30 was a good size.  possible too big but I will probably be staying here a while.  I could settle for a 30x28 if it would make that big of a difference. I'm satisfied with the design but I'd rather satisfy physics.

Often folks will worry about physics first, and not aesthetics, but it is just as important.  Aesthetics are very important to understand, and often effect physics.  The "golden mean" is found throughout nature, and when you achieve it, things look good, when you ignore it things look bad and often are weaker for it.  It (the golden mean) is also called euphemistically, the "God Rule."  It is in every single natural systems you look at, from the stars in the heavens as the swirl in the galaxy to the way a flower or seashell is formed.  The "God Rule," of balance and symmetry is everywhere, learning to understand it is vital to good design.

I meet folks on a regular basis that are in the building trades that know they can't do the engineering work for a design the way they would like to be able to for the structure to be safe, so they ask for help...which is good!  Then they go on and ask why they need a designer or architect, often feeling they can easily do that on their own.  Many buildings I see are border lining on ugly, have no balance or symmetry, and could have been do much better with just a little adjusting.  Design is just as demanding as engineer, and can even be more so, as it isn't always easily quantifiable. 

I'm often asked, "isn't it an opinion, when we talk about what looks good?"  No, not really.  You know you may not like a style or color of something, but generally thinks it looks good, while something else just like it looks really bad for some reason.  That is design.

[Dieskyver]

I've been told by an architect that form follows function. I guess that was my primary design principle. I've heard of the golden section and proportioning systems such as the Romans used. I see the value in it no doubt. I just don't know how/where to apply it. 
  I have sacrificed some aesthetic values on my frame.  I figured it being a TF was pleasing enough for me and I'm sooo ready to start cutting wood...

And I can see how the oblique bracing can act as a fulcrum.  I remember reading a forum post about a mother/grandmother backing her car into a tf post and snapping it at the brace.

[Jay C. White Cloud]

I've been told by an architect that form follows function.  I guess that was my primary design principle.

Yes, that is part of the modernist movement from the 1930's, but there is more to it than just that part of the saying.  Also, it is only a formulation of "modernist" not architecture in it's entirety.  It has come to be very self serving for those that just what to drop a box on the ground that will contain the items it is suppose to, no more.

I've heard of the golden section and proportioning systems such as the Romans used.

It isn't just Roman, all the great cultures that mastered mathematics understood the principles of natural ratios.  It has even been applied to "form follows function," in nature, but there it follows these ratios, not just the "function" part.

I see the value in it no doubt. I just don't know how/where to apply it. I have sacrificed some aesthetic values on my frame.  I figured it being a TF was pleasing enough for me and I'm sooo ready to start cutting wood...

As a timber wright and facilitator of same, I try to get initiates to start this process in a logical progression.  Impatience with the craft, yourself, or the pending project will only lead to frustration down the line (and poor craftsmanship.)  So the first thing I could do, is say slow down.  I can appreciate the desire to cut a joint, but that is part of the problem with this modern timber framing that is taking off.  Corners are being cut, both in application and learning, and the, "lets get it done as soon and as quick as we can," has begun to take over.  You need a good solid, well understood, planned, and checked design before you cut your first joint of that design.  If you must do something now, make a model, or a smaller project, would be the only advice I could share.  You really need to think through this process, and make you mistakes on paper, (or computer) before you do any real world cutting.  Or, you can hire, and/or work with an establish crew to speed things up, if there is a need logistically.

[Jim_Rogers]

An old timer timber framer used to say at every guild raising that it's 80% planning and 20% execution.....

Plan it out right and it will go easier.....

Jim Rogers

[Jay C. White Cloud]

Amen, brother Amen!

This craft is all about planning, the cutting is fun, but accounts for little of work, when you consider the entire picture, and what goes into a frame.  We often pay by the joint, and planning and layout gets, at a minimum, 50% of the value for each joint.

[witterbound]

My engineer didn't want to see, nor did he seem to care about, my joints.

[Jay C. White Cloud]

My engineer didn't want to see, nor did he seem to care about, my joints.

Hey Witterbound,

Was that a good thing, or a bad???  I'm not sure how you meant that?  Did it turn out o.k. for you with them?

[witterbound]

Not bad or good.  My frame is great.  Just saying that for some engineers there is no need to show joinery.  I think my engineer calculated loads, thrust, etc., but joinery wasn't part of his review, nor were braces for that matter.  I've heard that it is common for engineers to rely on the outer skin for adding the necessary stiffness to the frame.  Again not saying whether that is wrong or right, just saying is that I think that is how some do it.

[Jay C. White Cloud]

Hi Witterbound,

I asked out of academic curiosity.  The PE like you found, turn out to be really open to timber framing, and don't project biased or preconceived notions about the building form.  They (the one's like yours,) make the logical assertion that the joinery has work for thousands of years, we know what we are doing with the joinery, and all they need concern themselves with is loads, shears, modulus of rupture, etc., as it could affect the framing members. 

He never asked about Peg size, housed joints vs. shear on tenons, or things of that nature?

[witterbound]

You're correct.  He correctly left all that to the timber framer who cut the frame. 

[jueston]

just because timber frames have stood for thousands of years does not mean that the joints should be not analyzed by the PE.... if the wrong joints are chosen then it doesn't matter how strong the beams are...

[Jay C. White Cloud]

Hey Justin,

You are absolutely correct about that.  They often do want to know spline size, peg dimension, how deep a framing member is housed into another, etc..  They do consider all of these.  If they have met a timber wright and looked at the drawings/examples of the frame(s) they cut, they will focus more on species and member size, but you are correct, all is considered and examined.

Regards,

jay