Tag Archives: Truss

Dead Load, Sliding Barn Doors, and Truss Spacing

This weeks PBG discusses a bottom chord dead load, installing sliding barn doors, and truss spacing.

DEAR POLE BARN GURU: Ok, just to make sure I understand that 10lb psf dead load rating would cover the bottom chords supporting ducts either resting on or suspended from them inside the conditioned space? My thinking is if the vents are within the conditioned space I would need minimal insulation to prevent surface condensation. ROB in ANNAPOLIS

DEAR ROB: 10 psf dead load is primarily to cover weight of ceiling gypsum wallboard. Your relatively light duct could be placed anywhere within roof system without adverse effects. A down side to placing duct work within a conditioned attic – effectively insulating roof slope plane and endwall triangles. For practical purposes this can only be achieved with closed cell spray foam. While being highly effective as an insulator, about R-7 per inch of thickness, it comes with a price tag not for those who are faint of pocketbook – usually around a dollar per square foot per inch of thickness. If you go this route, you need to eliminate venting eaves and ridge.

DEAR POLE BARN GURU: Good morning,

Figure 27-5

I need to get some pricing on a (2) 6’-0” wide x 8’-0” high sliding barn style doors for an agricultural building in Ware county Ga.

 

I have never purchased, or installed a door like this, so I was hoping you could help me get started.

 

Thanks, DAVID in KENNESAW

DEAR DAVID: Thank you very much for your interest. Hansen Pole Buildings only provides doors along with an investment in a complete post frame building kit package, due to high incidence of damage when shipped independently. We do have installation instructions available online: https://www.hansenpolebuildings.com/2016/07/build-sliding-door/.

 

DEAR POLE BARN GURU: What would the truss spacing need to be in our area that has a 40lb snow load? RODNEY in REPUBLIC

joist hangersRODNEY: In most instances a true double truss (not two single trusses spaced apart by blocking) will be most cost effective, as well as adequate to carry applied loads (along with properly sized roof purlins). However, depending upon a myriad of other factors such as eave height, truss span, roof slope and building length some other spacing may result in cost savings.

This will be just one reason I recommend consulting with a post frame building kit supplier who has sophisticated design software able to do a near instantaneous analysis of multiple possibilities. This supplier should also be able to provide site specific plans for your building, sealed by a registered design professional.

 

 

A Silly Extreme Example

I’m a voracious reader. A large portion of my daily reading is devoted to learning as much as I can about my industry and expanding my knowledge base.

On LinkedIn, I am a member of the “Truss, Panel & Building Components” discussion group. One of the members, Gene Marcoux, from Florida, had postulated, “If we have a chance to reshape the way things are going to be done, wouldn’t it make sense to have the whole structure engineered for structural integrity….”

I happen to personally agree with Gene’s statement. If a design professional did not do the structural design of your new pole building, then who did?

Building Code Book

IBC Building Code Book

Keymark Enterprises, Inc., of Colorado, provides structural engineering and precision manufacturing of wood components (such as trusses and wall panels). Their account representative, Steve Cummings had this take on the subject:

“In perhaps a silly, extreme example, think about a 20×24 garage on a farm in Kentucky. Right now there is no government check that it will conform to current code, no engineering requirement, no permit required, no inspection necessary. We all know, from experience and training, how to build this garage. What is the value of the increased requirements vs. the cost of building departments, inspectors, engineers and designers?”

In my humble opinion, while an industry expert may know how to properly construct this pole building, not everyone is an expert. All it takes is one error in the design of a connection (too few nails, nails too closely spaced, an incorrect hanger, etc.) or sizing of a structural member and a catastrophic collapse could be the result.

The Building Code purpose “is intended to provide minimum requirements to safeguard the public safety, health and general welfare through structural strength, means of egress facilities, stability, sanitation, adequate light and ventilation, energy conservation, and safety to life and property from fire and other hazards attributed to the built environment”.

In having no permit requirements, there is no one to insure the goals of the codes are met. Are we willing to sacrifice a life or lives, due to deficient design, all in the name of saving a few dollars?