Answers To Your Questions About Floor Trusses
What Is A Floor Truss?
A floor truss is a geometric design using wood members fastened together with metal connector plates to form a structure which supports given floors load.
Are floor trusses something new?
No. A&R Truss has been building trusses for over 25 years.
What is new about them?
Almost universal acceptance of 4" x 2" floor trusses as an excellent method of floor construction.
Why have they become so popular lately?
There are numerous answers to this question; however, the most important are the many cost saving benefits.
What are some of the advantages of 4x2 floor trusses?
Longer clear spans.
In many cases, elimination of support beams.
Virtual elimination of squeaks.
Reduced sound transmission.
Lower costs for sub-contractors.
Greater nailing area for sub-flooring.
Finished basement ceilings.
Elimination of unsightly electrical wires, plumbing, and heating eyesores.
Speed of installation.
Size of rooms not limited by joist span tables.
How does a 12" deep floor truss spaced 24" on center compare in span to a 2"x 8" joist 16" on center?
Using a 55 psf load for the 4" x 2" floor truss and a 40 psf load for the 2" x 8" joists, you can span approximately 17 feet with the trusses and 13-feet, seven inches with the 2" x 8"s, depending on the grade of lumber used.
Do floor trusses deflect a lot?
NO! Floor trusses are not permitted to deflect more than 1/360 of the span length when under full load. To offset even this tiny deflection, camber is built into the truss. In addition, all A&R floor trusses are designed at L/480, which stiffens the floor even more.
How are floor trusses manufactured?
In shops specifically set up to produced uniform, quality floor trusses. Trusses are assembled and clamped in jig tables. Metal connector plates are then either rolled or pressed into the truss at the joints using special truss manufacturing equipment. After the truss is fabricated, clamps are released and the truss is ejected from the jig.
Are floor trusses designed by the trial and error method?
No... Floor truss configurations are designed and certified by either a registered engineer or registered architect.
What does an engineer or architect do with floor trusses?
Many things, however, basically they analyze the structure for span length, depth of trusses permitted, and loads that the trusses are to carry. They also evaluate special conditions such as stair and chimney openings, cantilevers, placement of exterior and interior walls, etc. Then, the truss is designed reflecting type of material, web placement, and plate sizes so that the truss meets all conditions requested.
Are floor trusses easy to install?
Yes . . . particularly on single story structures where the trusses can be erected and placed manually. On multiple story structures, a crane is usually used to lift the trusses to the desired height.
Are floor trusses heavy and unwieldy?
No... the approximate weight of a 12" high floor truss is five pounds per linear foot. Therefore, a 20-foot truss that is 12" deep would weigh about 100 pounds - a weight easily managed by one or two men. In addition, because of the open web design, there are always ample hand gripping areas.
Is cross bridging required?
A 2" x 6" continuous strong back is used in place of cross bridging. This helps distribute the load to five to seven trusses instead of only two to three trusses as bridging does.
Bridging and bracing are not the responsibility of the truss designer or metal truss connector plate supplier.
What kind of lumber is used in floor trusses?
Only the finest lumber available as listed in the "National Design Specification" manuals for stress graded lumber.
How much nailing surface is available on the trusses?
Because the lumber is used flat, both the top and bottom chords of the truss have 3 1/2 inches of nailing surface the full length of the truss.
Are stairwell openings difficult to do?
No. Several methods can be used to address stair openings. Consult Carson’s Truss Company when stair openings are a consideration.
Do contractors and builders like floor trusses?
Like anything different or new, the first job ordered may produce some skepticism. But after that, few contractors or builders return to the use of floor joists.
How about the ultimate consumer?
Builders who use floor trusses often state that consumers are delighted their basements are void of beams, posts, etc., and that in effect are complete living areas.
What steel is used in the connector plates?
The only steel permitted for use is metal connector plates by the Truss Plate Institute and all government regulatory agencies is top quality, prime galvanized steel. No seconds or reject steel is permitted.
How do we know the firm we are buying floor trusses from is qualified, reliable and reputable?
Carson’s Truss Company has been servicing our customers for 15 years.
We pride ourselves in the quality of our product.
You have our assurance that you will be entirely satisfied with our product,
or we'll be there to help you.
Remember, our reputation is at stake.