Sobon Shed Variant Possible?

Scratch · September 02, 2005, 10:47:45 PM

Hey Everyone,

I'm in the serious planning stages for my first TF building. The shed design in Sobon's book is very close to what I have in mind. In fact, the basic design and several of the modifications he specifically mentions would fit the intended use almost to a "t".

Then, while looking through the TF Guild's forum, I found a post by Jim R. discussing this frame In http://www.tfguild.org/ubbcgibin/ultimatebb.cgi?ubb=get_topic;f=9;t=000021

That two story shed, widened to 16', with extra bents to lengthen it to 32-36', modified to have an ~10' wide barn door on each end, and a 1st floor ceiling of 9-10' would be PERFECT.

My primary questions - are those changes substantial enough that I'm really talking about a different building (and therefore need to seek out different plans)? Or, would they be easy changes and, if so, are plans for that 2-story Sobon shed available for purchase anywhere?

Ok, I'll hold the inquiry there until I get some feedback and see what y'all think.

Thanks in advance for your thoughts!

Paul

Jim_Rogers · September 03, 2005, 10:39:05 AM

Paul:
This shed, a Jack Sobon design, is called the "Dutch" house/shed/barn. It is called the "Dutch" design as it has a bent every 4', which is what the "Dutch" used to do.
We build this shed also, here at my workshops.
We are about to raise one this month in Northfield, MA on or about Saturday the 24th if all the plans work out.
I have built and sold several of these this size 14' x 16'.
You can expand these to different sizes with some minor beam sizing changes.
If you widen it to 16' you may need to increase the tie beam size to a taller beam. And the roof rafters which are 5x5 may have to go to 6x6 depending on your snow load.
Where are you located?
What is your snow load? per square foot? for your area.
You can make it longer but you'll have to cut and assemble some scarf joints in the plates. And in the sills if you're going with a standard wood floor, unless you can mill, hew or purchase some 32' or 36' beams.

When you take the one week course taught by Jack Sobon, you get two copies of this plan. One to use at a working drawing to make notes on, and one to take home for future use.
This course is held once a year and it's coming up shorty, this month at the Shaker Village near Pittsfield, MA.
I can forward you some details (privately) if you like to take the course.
Also, I have copies of the plans, but we need to discuss these details privately.
Either email me directly or call.

Jim Rogers
800-422-6250

Scratch · September 04, 2005, 10:24:04 PM

Thanks Jim!
I'm travelling this weekend, so connectivity is limited.
However, regarding the snowload issue - i live in southern Alabama, so snow load is 0. The wind load spec'ed in the chart on my original thread was for 104mph, I believe. This sounds about right, even with the new hurricane requirements, which my specific area IS NOT subject to.
I've read the section in Sobon's books regarding scarfing timbers to lengthen plates. Does the same theory apply to scarfing to lengthen sills? Specifically, since there are no braces over which to position the scarf for a sill, and I'm assuming you don't want to do it at the stub tenons where the posts hit, can you arbitrarily pick a spot between posts? Would it be advisable to ensure there's a footing/pier under the scarf?
Out of curiosity, why are the bents 4' o.c. on the Dutch barn and 8-12' o.c. on the shed in Sobon's book? The load paths don't appear any different and I'd sure like to be able to put an unobstructed 8' barn door on the side.

Hmmmm...maybe I'm not as far along in my understanding as I thought.

I appreciate the invite to contact you directly via email, and will do so once I'm home and can respond in a more timely and reliable manner.

Thanks for the reply and I look forward to hearing your thoughts!

Regards, Paul

Jim_Rogers · September 06, 2005, 09:30:34 AM

Paul:
You asked: "Does the same theory apply to scarfing to lengthen sills? Specifically, since there are no braces over which to position the scarf for a sill, and I'm assuming you don't want to do it at the stub tenons where the posts hit, can you arbitrarily pick a spot between posts? Would it be advisable to ensure there's a footing/pier under the scarf?"

If you have a continuously supported sill then the scarf location wouldn't matter. But if it's set on piers or footings at certain points then yes you need to follow the alignment shown in his first book on page 96.

You have to understand that over time the non continuously supported sill or plate will sag a bit in between supports. And will bend up and over support making a beam with a slight wave like appearance. The sag between supports is called "deflection". The rise over supports is called "inflection". There is a point between deflection and inflection where there is none of either, therefore no stress or reduced stress on the overall timber. It is at this point where you should make your scarf joint. Whether it's a sill or plate.

The graph on page 96 shows shear where it is the highest over the posts, and bending (deflection) is highest between the posts and over the posts. The graph shows a spot where they are both low and that's where the scarf should be.

The reason for a bent every four feet in a "Dutch" design is that the tie beam becomes a floor joist for the second floor. Using two inch tongue and groove decking lumber, which finishes at 1 1/2" thick and is usually done with a decorative vee-groove on the underside, it can span the four foot joist locations.

The 12' x 16' shed has a "loft", not considered a full second floor, therefore there is a lower floor load rating. And the loft is usually only on one end of the shed.

Adding an eight foot wide door to a side would remove one bent post and one floor joist. This would mean that there is no support for the plate and rafter over the middle of the door. Now you are slightly changing the overall sidewall design. It may be possible, by adding two more braces onto both the door posts to help support the plate over the eight foot span.

From the top of the sill to the top of the plate is 12 feet. The braces are laid out on a 30 inch spacing which means that the bottom of the brace will be down 30 inches from the bottom of the 6x6 plate. 144 - 6 - 30 = 108 or nine feet, to the bottom of the brace. This would give you a eight foot wide door with a clearance of nine feet.
Will that work for you?
You may need to add a horizontal piece for a nailer for the siding between the door posts or between the braces, depending on your height clearance needs.

Modifications can work if all aspects are reviewed.

Jim Rogers