metal connector plates Archives

True Double Trusses

ASABE (American Society of Agricultural and Biological Engineers) published ANSI/ASABE S618 “Post Frame Building System Nomenclature” in December 2010. For those who are unfamiliar ANSI stands for American National Standards Institute (www.ansi.org). ANSI is a private non-profit organization overseeing development of voluntary consensus standards for United States products, services, systems and personnel.

In ANSI/ASABE S618, a Metal plated connected wood truss would be described as, “A truss composed of wood members joined with metal connector plates (also known as truss plates). Metal connector plates (MCP) are light-gauge, toothed steel plates. The most common type of light wood truss.” Ganged wood trusses are defined as, “A truss designed to be installed as an assembly of two or more individual light wood trusses fastened together to act as one.”

Reader RON in FORT BENTON writes: “I built a 24 x 36 x 10 pole building from a kit 30 yrs ago. And I have had a 20 x 28 x14 built by local professionals about 8 yrs ago. They each have 12 or 14 foot distances between posts. The trusses are the regular double 2 x 6 construction with 1 on opposite sides of the posts with blocking between them at the bottom. The side girts have been 2 2x6s configured in the L shape. I am not sure what you call that. Now looking at examples of kits, they seem to use (double?) 2×4 construction for the truss. Has there been a big change or am I just missing something. I like the 2×6 approach and am not sure how much difference it makes in final costs. I am looking into a 48x36x? monitor type building in, at times, very windy location. Thanks.”

Even though some very high grades of 2×4 lumber are available to metal plated connected wood truss manufacturers (such as 2850msr), only in very small spans and light loads would they work for top chords of double trusses spaced upon 12 or 14 foot centers. For bottom chords, it might be possible to get to 30 or 36 foot width spans, provided loads were light.

Learn about Machine Rated (MSR) lumber here: https://www.hansenpolebuildings.com/2012/12/machine-graded-lumber/.

For Hansen Pole Buildings, any time we are using a “real” double (more specifically ganged) truss system, we specify top chords to be a minimum of 2×6, regardless of loads. I say “real” because placing a single truss along each side of a column (as you have described) is not a double truss. They are two single trusses, acting independently from each other. A true double truss system, such as used by Hansen Pole Buildings, features trusses physically attached face-to-face by means of mechanical connectors (e.g. nails, bolts, etc.). This allows for two members to actually load share, reducing probabilities of one weak single truss failing and pulling a roof system down with it.

When I was first in the metal connector plated wood truss industry back in 1977, my employers – Dutch Andres and Tom Vincent at Spokane Truss, had just invested in a machine which would fabricate what would be called a 4×2 floor truss.

These trusses revolutionized the way floors could be constructed – freeing up areas below them from the need for load bearing walls and columns in all of the most inconvenient places!

Rick Ochs is new to the inside team at Hansen Pole Buildings, and earlier this week, he posed a question:

“Hey Mike,

No rush… I have been viewing tutorials from WTCA (Wood Truss Council of America) on trusses and structural building components. I was wondering why we don’t spec floor trusses instead of the traditional 2×10 with hangers. Cost I presume.

Thanks!”

Here is my response to Rick:

Floor trusses will be significantly more expensive.

Let’s say you have a 2×10 at .6285m (current price at The Home Depot®) so a 12′ would be $12.57.

(“m” happens to be lumber people’s secret code for 1000 board feet)

If they were even 16″ o.c., you are talking 0.79 per square foot for the cost of joists.

Floor trusses are going to run around $4.40 per lineal foot, spaced 2′ on center, this makes the cost per square foot for the joists at $2.20.

For a floor span of over 24′ trusses are certainly the way to go.

To which Rick responded:

“I’m thinking it would take a little more math on the builder/customer part to compare against labor cost savings of setting floor truss vs time required to set hangers, cut and nail joists.”

Personally, I have metal connector plated wood floor trusses in two of my personal buildings – in one case spanning 30 feet and the other 48 (yes a 48 foot clearspan floor).

Here are some of the benefits of using wood floor trusses:

Larger sheathing attachment, with 2×3 or (usually) 2×4 nailing surface,
Spacing up to 24” o.c. maximizes efficiency, decreasing installation time.
Each unique truss is engineered to proper codes and loading.
Speeds up mechanical installation (think heat ducts) with the open webbing thus saving dollars.
Span longer distances than conventional lumber or I-joists.
Special bearing, cantilever, and balcony details are easily built in.
Less pilferage, it is unlikely a 20’ truss is going to walk off the jobsite.
Faster jobsite build times, saving jobsite labor, construction loan interest, vandalism, and environmental damage.

Wood floor trusses can also be designed to limit the deflection and vibration, read more here:

https://www.hansenpolebuildings.com/2015/12/wood-floors-deflection-and-vibration/

In the global scope of life, having a wood truss supported floor is a fairly economical upgrade, which is certainly something worth investigating.

Tag Archives: metal connector plates

True Double Trusses

Wood Floor Trusses

What will you use your

building for?

Approximate

building dimension

Your building. Your way.

Your building. Your way.

Can we text you to setup

appointments?

Are you a

robot?

Your request has been received!

Thank you!

There has been an

error!

Building KitPrice

Pole Barn Guru Blog

Ask The Guru

Pole Building Learning Center

Photo Gallery

Paint Your Building

Most Viewed Blogs

Latest Blog Posts