Does anyone have any general engineering experience with queen post barns. What I am looking at is a basic New York style barn 26' x 36'(14'-8'-14' bays). Much of the roof load is transferred to the purlin plates,queen post bents and and then to the tie beams. The tie beams have one support in the middle(with braces) and the queen posts go into the tie beam about 6' 6" from side wall.
My question is how would you calculate the actual amount of load on these tie beams? Additionally, when there is also a floor framed into them, would you have to add both the floor load and the point loads together, in order to size the beam? It seems if you did this,you would need a beam like 12"x24" to support it. However I have taken part in the building of and have seen enough of these frames, that had much smaller beams and have done just fine. Is there something I am missing?
I am new to the engineering aspects of building but I would like to know a little bit more than just floor joist sizing. If anyone has any experience with these frames please share some insights. Thanks tb

Just one post in the middle? Side entry or gable end entry? If it is a gable end entry I would see two post under the tie, running the length of the barn, not one post, it would get in the way. But with the 14-8-14 bay layout it appears to be side entry, in the 8' bay. Is there any sign of other members supporting the ties, as example, stall framing, walls, ladders, dividers of some kind?

What is the size of the typical tie beams seen in the old barns?

Hi TB,

The loads applied to the tie beam would need to include constant dead loads such as the self weight of the various roof and floor members and coverings (tiles, sarking boards, etc.). Then add to this the variable loads like those imposed by the typical items stored in the barn (hay, etc.) and most importantly don't forget the snow, wind & earthquake loads applied to the tie beam by the roof, side wall & foundations.

All of these loads are applied to the tie beam via the various connecting members such as main posts, queen posts, principal rafters, wall plates, sills, braces, intermediate studs, posts, etc.

The effect of all of these loads can be calculated using simple hand cranked approximations but it is much more easily done using a plane frame analysis program where different case study analysis can be made. These case studies will provide you with more than one answer for each of the conditions needing to be checked such as tension, compression, bending, shear & deflection and so you should take the worst values encountered from each of the case studies to size your beam.

Regards

Ken Hume

The short answer is hire an engineer to do this for you. This is what they do.

The guild resource book has a list. Also there is a list on the TFEC site (Timber Framing Engineering Council).

Jim Rogers

When will engineers be replace by apps on the ipad?

Not anytime soon, I'll wager.

Why is that, Joel?

What would it take to add on to Sketchup, a program to size timber?

Not enough demand?

Would it threaten the engineers work?

For what it's worth I believe you are right, not anytime soon.

Hi Tim,

How long have you got ? You might well be looking for an exactitude where this does not exist.

I spent Sunday examining the Abbingdon Long Gallery - a very large 10 bay jettied building which likely dates from 1430 or so and using the miracle of CAD I did a quick timber count and found that the original building had about 1600 or so individual timbers with almost half of these timbers now cut out and removed. Stuff happens over 600 years. The building has slowly yielded and deformed to the point that some of the joints have failed and are now coming apart and some members have fractured but still the building continues to stand.

Poor Design or Ravages of Time ?

I think that I have expressed my views on this forum many times before about the dangers of designing leggy empty buildings that could easily be subject to large deformations leading to disproportionate collapse typically for the reasons outlined above and so one must recognise that "time now" is only an approximation as to the final building configuration that is likely to exist before decay, deformation and loss results in collapse.

After a while it becomes perfectly possible to believe that because someone has examined and calculated how a timber or collection of timbers will perform that this means that everything will be OK but hopefully we have now advanced beyond that point. It's probably more important to examine existing buildings to see what works and what isn't such a good idea. This empirical approach to building is an equally valid approach when compared with calculations. Where calculations really come into their own is when something quite radical or rare is being undertaken i.e. where there is no experience base from which to draw or alternatively where the commercial, technical or risk to life and limb is such that a better understanding of the undertaking is required.

One must recognise in the USA that apart from New England there is probably very little in the way of a historic building experience base from which timber frame engineers and carpenters can draw upon and so an informed engineering partnership between carpenters and engineers might well provide a better result than over reliance on just the carpenter or just the engineer.

I feel a Rumsfeldian moment coming on again - time to adopt the recovery position !

Regards

Ken Hume

Too many variables for a simple solution. The basic calcs are easy, but the infinite number of configurations means that there is no formula that can handle all circumstances. The closest thing might be Finite Element Analysis, but that's a bear to configure even in 2D from what I've been told. CB.

I have heard that excuse before. Infinite number? What is the poor human to do?
http://www.youtube.com/watch?v=MlyTq-xVkQE

I'm pretty sure Clark is suggesting that a human should drive the decision / engineering process. Tim, are you suggesting that a computer should do the work?

Setting up a 2d FEA can be difficult for the novice, but it will likely not tell you how to set up te joinery, just what forces up need to contain with the joinery. Which then needs its own analysis.

Also, I envision your iPad sitting next to your boring machine.

I really have no idea how sketchup works. No ipad, and I only use my cell phone for calls and as a clock, I read the rare text and I take forever to send one so I don't bother. So, I am not much for a techie.

I do see a lot of people posting sketchup drawings on the Forestry Forum and wonder what their background in Timber Framing really is. How are they making the decisions on what joinery to use, tenon size, peg location, etc.. By no means do I want a computer to make those decisions for me, it would take the fun out of that half of the game. Someone else may not think that part attractive and wish to have it done by a computer, or they don't have the experience to make the correct choice. Does sketchup provide any assistance in this department?

The OP, did not inquire about joinery decisions but loads. There are calculators out there that can answer simple load problems Where is the bigger version that can take in a few more inputs and size the tie beam? I can chase out a reasonable picture in my head of where the loads are coming from, it is not that big of an issue to be handled by a computer. So I will reiterate, is it job security? Demand? Or is it as some have suggested it is too big a task? If some Dr. computer nerd can solve sodoko problems, no menial task, this surely should not be an issue, after all it is just numbers.

I believe it has been said before, we all use calculators to punch out not so simple equation to gain lengths or other such inputs in our framing so, yes I am suggesting computers can do some of this work. I myself and always looking for way around the calculator. The compass works very well for this at times. And don't tell me it is just another computer, there is a big difference.

Quote,"I do see a lot of people posting sketchup drawings on the Forestry Forum and wonder what their background in Timber Framing really is. How are they making the decisions on what joinery to use, tenon size, peg location, etc.."

TIMBEAL,
I would like to shed some light on your curiosity. Most people who post Sketchup drawings on the Forestry Forum have done a reasonable amount of research which includes learning from some of the more popular timber framing books, have taken classes on TFing, or have had "on the job training" working on existing buildings. Yes, there are people who are using the postings to get feed back on their design choices, from those who have experience and are willing to share their knowledge, and to help them learn how to design, draw and build timber frames for themselves. We don't see alot of professional TFers posting their designs for everone to copy...most are DIYers who feel that they can have a once in a life time experience building their own frame. Sketchup is a drawing program, not an engineering program...it is the modern day equivalent of paper, pencil, straight edge, and a scale rule. The advantage is that it is done in 3D, which can help the flow of ideas when designing, and make changes without having to re-draw everything over. I myself am "old school" and resisted using the computer to do my drawings. I have found the benefits to far outweigh the learning curve.

I feel that the Forestry Forum has helped produce and encouraged any number of new timber-framers, who will in turn, assist the next generation in learning. You have to give the site credit...it gets a lot of traffic!

I hope that helps.

Rooster
(Timber-Framer and Barn Restorer)

I personally think along the lines of what I think Ken is suggesting, that adhering to traditional systems is better than relying on an engineer's calculations. We have at our disposal the collective knowledge of thousands of years of carpenters, they have through trial and error figured out what works and what doesnt, and so forth.
As much as is possible, I think we should rely on the traditional wisdom of the carpenters of the past, which is more freely available to us today than ever it was before.
In a way, this system replaces the engineer.
And in another way, the compass replaces the engineer if you know how to use it.

DLB

I agree DL, that the traditional forms have an immense value to we modern framers. But I'd speculate that 90% of the frames that are cut today have remarkably little in common with the old forms. The companies that are cranking out frames, and represent the industry in North America (through the magazines and the TFBC), are certainly not present on this forum. And they're not Guild members (I'm referring to the minion workers). That's not to say that I dislike all modern frames--I'm a big fan of what may be termed Brungraberism at some point in the future.

For whatever reason, this forum is full of traditionalist framers. We all know what happens when someone puts up a picture of a frame without top plates. But Tim's right, the reaction is a little different on the Forestry Forum.

There's also the enormous issue of building codes. If you live in an area where there's an enforced code, you may have to compromise a bit on your strict historic interpretation. I don't think that's implying old frame forms are weak, so much as the safety factors in the wood strength values, the required loads, and that that modern models aren't modeling what's really going on (particularly at the joints). Tim, didn't Maine adopt a statewide code? Has it crept up to your neck of the woods?

To get back to the original point, I like queen post barns a lot. I've never understood why there's only a center post though--I think the double posts look better, and it's certainly stronger.

Hi Brad, I haven't seen any hard enforced code work down this way. There was the lead paint issue. It's coming I can hear it. Which is kind of why I feel the way I do about this engineering thing. If we are going to be required to bring things to a specific level of "safety" give the people the tools to assist them in getting there. Don't hold back and say "tah tah, no you have to have a professional do this for you".

I used to post a fair amount on the FF but have stopped. I am glad to see Craig, Jim and a few others continue to post there.

I remember back to the first few building I planned out and cut. It felt like I was back in high school taking a test I was not prepared for. Compared to today, I just did a whole plan, cut list, timber size, joinery decisions, a full estimate all on one sheet of paper 8x11 and can saw the timber and cut the frame with no other input and feel very comfortable with how it will work and will probably make few change as it progresses, the finer details. And I am sure it would pass any engineers scrutiny. All with hand tool and up hill in a snow storm, well it turned to rain.

I have on occasion use an engineer to chase out some of the more questionable items.

Where is the OP, I have questions that aren't answered? How about a canted queen post? wouldn't this push the loads out nearer the center post and exterior post via the strut?

Thank you all for your input. I do use engineers but I would like to be able figure these frames on my own and then just get assurance. This is what we do with floor joists , why not with this fairly simple barn plan. I do believe this queen post barn to be a superior design in many ways. It helps greatly deal with thrust on the exterior top plates and posts, it cuts the rafter loads in half by the mid span with the purlin plates, the clear spans on the beams are generally not that long with the interior post, there is a prevalence of these barns that still stand strong today.
I believe these are primary reasons that this barn type prevailed in my region and probably many other areas as well. It is a simple design and there is no reason someone like myself could not figure the loads on the tie beams and adjust accordingly especially when referring to extant barns that have almost the same joinery , wood species, dimensions, snow loads, and probably did not have the sheathing strength that we have now.
I am not trying to be or replace engineers, I am merely trying to empower myself with some of the tools that engineers use related to specific work that I am engaged in.
I thought maybe someone had already been down this road on queen post barns or the like, and could share some formulas or general guidelines for sizing these beams.
All that being said. I do really like canted posts, but I find they are more difficult for people to navigate. I also believe engineers generally dont like them as they have trouble figuring where the loads are going.
On top of that I am already positive that the load issues are solved by having two interior posts directly under the queen posts and then support directly under these to the foundation. However many times you dont want interior post getting in the way, in this case every 8 feet. A primary reason I use timber is to have clearer spans , less intermediate posts. tb

Last time I tried to configure FEA floppy discs were involved.

Now I am told that it is fully integrated into CadWorks, at least.

Oh Tim. Sorry I missed your first post. It is side entry in the 8' bays. I m not concerned about intermediate posts on gable ends and also side walls with intermediate support under top plates. It is the interior two bents that I need the figuring for. I dont mind beefing up the beams to take the extra load. I figure they are each taking half of the 14 bay floor load, half of the 8' bay floor load. I'm not sure how much if not most of the roof from these portions of the bays.
I would say the tie beams I see are mostly 8"-10" x 10"-14" range. Which is still attainable especially if I dont mind scarfing two pieces.
To add , I like sketchup a lot and use it often and it is a interesting idea that engineering could be incorporated into it. However its a bit off topic and would fare better on its own post. tb

Ken, do you have an idea of how much proportion of the roof load transfers to the purlin plate-queen post bents and how much goes to the top plates. Support is just about mid span on a 15+' rafter and 8/12 pitch.
Also have you used these plane frame analysis programs and do have suggestions how to get attain the programming? However, Tim was right ,I know the frame design, joinery ,species,sizing works fine by looking at the extant barns. I did really want to more calculate the loads to the beams to show they can handle the floor and the roof loads. tb

can you post up some drawings or sketches? or images?

Hi TB,

You can download a trial version of EngiLab plane frame analysis from http://www.engilab.com/download.htm and this will enable you to play at inputting and visualising the effects of loads and restraints on different configurations of timber framed structures. The trial version is not time limited but instead limits the number of members that can be included in a frame. You will not be able to save your models until you contribute a little money to the struggling Greek economy. Other trial packages are available to download from the web.

I am sending you (offline) results of a queenpost frame analysis using another plane frame analysis programme so that you can see typical some of the loads, load cases and restraints that need to be input to the model to help determine the various outputs for beam sizing (axial, bending, shear, deflection).

You will need to have a basic understanding of structural mechanics in order to arive at a meaningful result.

Regards

Ken Hume

Hey Mike. I dont really have the ability to post up my pictures, I still have not figured that out yet.
Here is a link to a company that builds modern barns using very traditional techniques and design. the design is just about the same.



http://newenglandbarn.com/ridgefield-queenpost-barn.php



Most of the these queen post barns are pretty close in a lot of characteristics, perhaps there was some kind of code or system for joiners to adhere to at this time period.
I do have my own preferences though. I like to join my joists to the tie beams, not have them sleep on top. I like the look much better and dont want the extra height that sleepers add. I like to join them in a way Daiku had told me about a while ago, with 1.25" housing at half the depth of the tie beam and then screwed diagonally into the beam. I also prefer to use vertical intermediate support not horizontal struts , as I prefer to horizontal siding.
Oh yeah, and this example is 38'long(14'-10-14') and mine is 36' long( 14'-8'-14') tb

Just as a note worth considering.... The wall girt is now joined where the tie meets and this may be a week point in the post, and causes pegging problems. Being a principle purling roof your rafter thrust is reduced so it may not be an issue. Lodging the joist on top of the ties means you figure the full size of the timber but when you cut joist pocket out then you need to figure the smaller size remaining after the joist pocket is cut, requiring a larger beam, which I thought your were trying to avoid.

The other issue I see is in relation to Ken's reply dealing with "poor design or ravages of time" thing when setting joist into pocket as described. Better than 3/4" pockets. There are other solutions which come very close to your visual requirements and deal well with the problems as I see them.

Tim. that wall girt at the same level as the tie beam, has always been a puzzle. The way I see it ,you need not to have much thrust on that post or have a very beefy post to take that connection.
In this kind of design you have sill plates and then the top plates holding the frame together with the help of braces and good sheathing, not to mention the other longitudinal joining timbers like purlin plates and tying joists.
My solution is to join that girt the same as the joist with shoulder for bearing(1.25") and diagonally screw it to the post. I really dont see any structural advantage of cutting deep mortises and pegging this "joist" at a point where you really dont want to weaken the post. I would rather do a tying joists to the tie beams.
What did you mean"Better than 3/4" pockets"?
What other solutions do you like to use?
thanks for reply. tb

tb, I have seen joist housed into the tie using only a 3/4" pocket, after shrinkage there is not much left for support, 1-1/4" is a better number. Basically I got tired of cutting pockets in the side of the timbers and found lodging them on top a very efficient method. With the tooling I use in my shop I find a tusk or soffit tenon to be easier than a drop in pocket and it takes no wood out of the top surface of the beam like drop ins do. The peg needs consideration, though. So mortices in the face of the tie beam, I would use 22' long joist plugged into the mortices in bents 1 and 4 they are lodged on top of bents 2 and 3., spanning from bent 1-2-3 and a shorter joist covering the third bay. Alternating long short across the frame. Also the ties in bents 1 and 4 are raised higher than the two middle bents, so the tops are flush with the joist system, this fitting your visual requirements, almost. There is always a give and take, somewhere, here you get to have to two middle tie beam uncompromised with pockets and the end bents have stronger pocket where they are carrying far less load than the mid ties.

I hear you on the tie post connection.

I call them slide in joists as you slide them in from the outside after the frame is raised.

The wall boards being nailed to them help to hold them in place and also help with the support.

The amount of flooring that they hold up isn't that much.