Tag Archives: prefabricated wood truss

A Vaulted Ceiling, Pier Shapes for Brackets, and a Sloped Grade

Today’s “Ask the Guru” answers reader questions about a truss solution for a vaulted ceiling, a question about the use of square piers for brackets compared to round, and building post frame on a sloped grade.

DEAR POLE BARN GURU: I‘m wanting to build a barndominium on my property in Southern Tennessee. My design is 40′ deep x 84′ wide. Wall Height is 10’ My roof pitch is 12/12 (Gable) My question is what are my options to frame this roof and keep the ceilings vaulted? I’m not opposed to using steel trusses. Would a ridge beam be required? Can I use a 2″x2″ tube steel truss with a 24″ profile without the need of a ridge beam? Please see depictions of the Pole barn attached below. JAMES in KAPAA

DEAR JAMES: Best design solution is going to be prefabricated wood roof trusses. Wood trusses are subjected to far more stringent quality controls, than steel trusses. They also are easily engineered to support ceiling loads and make for easily finished eave overhangs. No ridge beam would be required.

 

DEAR POLE BARN GURU: Hello Mike. We have received our quote for our new monitor style home. Ryan has been most helpful in bringing this project forward as well as James in the drafting department. I have a question about a notation on the quote that Ryan suggested I ask you about. We will be using wet set brackets on piers for our foundation. The notation mentions “on square footings”. Is this actually required by engineering or just suggested to make insulating easier? The frost depth at our building site is prescribed at twenty four inches. Would piers normally be deeper than that for our area? Working on numbers now and anticipating getting started in the next few months. We are truly fortunate in that our building site is in a very mild temperature zone with very few winter building restrictions. Thanks to all of you for helping us move this project forward! RUSS in TILGHMAN

DEAR RUSS: Default setting in our Instant Pricing program is for square piers, for ease of insulating. Square often yields a lesser dimension, due to overall area. As an example, a 24 inch square footing is four square feet, a 24 inch diameter yields 3.14 square feet. This can easily be toggled, by Ryan, to allow for round piers, if you feel this would be more advantageous for your build. Using round piers, in order to minimize hole diameters, given your loading conditions, some holes (particularly those supporting sidewalls of your raised center portion) could be as deep as four feet. Clients utilizing square piers, typically dig holes with a mini excavator, as opposed to a skid steer mounted auger bit.

 

DEAR POLE BARN GURU: How is a post and beam built on sloping land? Wooden subfloor construction? MARK in BLAIRSVILLE

DEAR MARK: It would depend upon your intended building use, dimensions of building and amount of grade change. Most often we see clients filling sites to create a level grade, however we have provided plenty of elevated wood floors – both with and without crawl spaces. If you visit www.HansenPoleBuildings.com, navigate to SEARCH in the upper right corner, type in GRADE CHANGE and ENTER will bring up several articles on this subject.

Engineering an Open Pavilion

Engineering an Open Pavilion

Professional Engineer KEN in AIRVILLE writes:

Working on engineering a post frame equipment open pavilion 28×48. Only has 2 posts on the front wall and big ass flat girder for a header. See attached plans. I have done them all different ways before I a structural engineer who grew up at my father’s sawmill and been in the engineering and framing for 30+ years. Been reading your blogs especially all the info on knee braces. I agree the skin gives you 90% of lateral capacity over embedded posts or knee braces. But that is pretty much all we have to use on an open structure. I didn’t really want to use buried posts for longevity but may be best for lateral capacity. I only have 2 columns in the front holding the roof up so I wanted to come out of the ground with a big ole concrete pier in case it ever got impacted. Would love to discuss post frame design theory with you. One of your guys used to be a truss designer also I read somewhere. I know that industry very well been in it my entire life. Have a great day.”

Mike the Pole Barn says:

Thank you for reaching out and for forwarding your draft plans.

I was in ownership or management of prefabricated wood truss facilities for over two decades, in my “past” life.

Unless there is some strong objection, embedded columns are probably going to provide your best design solution, as well as being easiest to construct. You will want to specify UC-4B for treatment, as this should assure a lifespan greater than our grandchildren’s grandchildren.

If bracket mounts end up being your solution, look at using Sturdi-wall Plus brackets, as they have a far greater moment resisting capacity than do Simpson products and have an ICC-ESR approval.

I would look at placing low side columns every 12′, using a pair of trusses ganged together and notched into columns, with 2x purlins recessed between top chords, in Simpson hangers.

On high side, parallel chord flat trusses could be used for your ‘beam’, also notched into columns. Mono truss top chords could be run across top of trussed beam and look at making connection between mono trusses and beam a fairly stiff one.

Explore using full length treated glu-lam columns, without knee braces. Your knee bracing challenge is two-fold – you have to deal with forces being put into trusses by knee brace and toughest – coming up with a connection adequate to be able to transfer those forces. Your column sizes will be dictated by L/d ratio, so even if your knee braces were to work in the direction of truss span, you still have slenderness in length of building. It looks to me like a 6 ply 2×8 glulam from Rigidply (7″ x 8-1/16″) should be capable in both directions.

In order to not void roof steel paint warranty, look at a roof slope of 3/12 with an Integral Condensation Control factory applied to prevent condensation drippage.

The NFBA has available a Non-Diaphragm Design Guide (https://www.nfba.org/aws/NFBA/pt/sd/product/14888/_PARENT/layout_details/false), it may prove helpful for this project.