Frequently Asked Questions



We receive dozens of calls each day from all over the country regarding TrimJoist™ products. The questions below are a small sampling of those most frequently asked. If you need further explanation on any of these topics or if we don't address your particular question here, please call us at 800-844-8281.




Why should I even consider an engineered joist when traditional solid joists are cheaper?  

What makes a TrimJoist™ different from other types of engineered joists on the market?  

Why do TrimJoist™ products come in different depths?  

If the 18-inch joists are strongest, why not always use them instead of the 12-inch, 14-inch, or 16-inch joist?  

What are the maximum spans for a given depth?  

At what on-center spacing are TrimJoist™ joist products typically used?  

Will I have squeaks with a TrimJoist™ floor system?  

Where can I get TrimJoist™ products for my next project?  

Can I order TrimJoist™ with special duct chase placement?  

Can I get custom engineering on my particular job?  

What about a computer program to analyze a TrimJoist™ for a given loading or support condition?  

Can I order free literature from TrimJoist™?  




Q: Why should I even consider an engineered joist when traditional solid joists are cheaper?  

A: Solid 2x joists are cheaper on a per unit basis. However, studies have shown that by the time culls, waste and labor are considered, a more superior TrimJoist™ floor system could have been installed. In addition, since TrimJoist™ products use 2x4 raw materials, the environmental impact is much smaller than the loss of large old-growth trees that are required for traditional joists. Approximately 35% of each TrimJoist™ is recycled material.



Q: What makes a TrimJoist™ different from other types of engineered joists on the market?  

A: The TrimJoist™ is a unique marriage of an open-web truss to a solid-web "I" section. This patented combination gives the TrimJoist™ unparalleled versatility and utility on the job site. The TrimEnd "I" sections allow for a custom fit, while the open web nature of the product allows for complete access to that valuable floor cavity space for ductwork, plumbing and electrical needs.



Q: Why do TrimJoist™ products come in different depths?  

A: The strength of any joist or beam is directly related to its depth. This relationship is exponential in nature. Thus, a 16-inch deep joist is about 34% stronger than a 14-inch deep joist and about 120% stronger than a 12-inch deep joist. By comparison, a 14-inch deep joist is about 64% stronger than a 12-inch deep joist of equal span. While these percentages are only approximations, they give some idea of how increasing the joist depth improves performance as well as utility.



Q: If the 18-inch joists are strongest, why not always use them instead of the 12-inch, 14-inch, or 16-inch joist?  

A: Sometimes there are architectural constraints that can only be met by smaller depth joists. Also, since a joist is often spanning only 16-feet or less, the additional strength of the deeper joists can become overkill. However, for spans greater than 18-feet, the superior strength of the deeper joists becomes very noticeable.



Q: What are the maximum spans for a given depth?  

A: Presently TrimJoist™ products are manufactured in 24-inch incremental lengths beginning at 4-feet and working up to a maximum stock length that is depth dependent. These maximums are as follows:
         Depth      Max Length
         -----      ----------
         12"        24-feet
         14"        26-feet
         16"        28-feet
         18"        30-feet
      

Thus it is possible to clear span 28-feet (allowing for end supports) with a 16-inch deep TrimJoist™. This works great in basement type construction by eliminating those unsightly pipe columns, extra beams and footings.




Q: At what on-center spacing are TrimJoist™ joist products typically used?  

A: Depending on the loading conditions (consult a TrimJoist™ span chart or our engineering department), TrimJoists may be placed at any spacing from 12-inches to 24-inches. It is customary to place traditional joists at 16-inches on-center. However, since the TrimJoist™ has a 3.5-inch wide flange, many contractors choose a 19.2-inch spacing to maximize the price/performance ratio of the product. Most contractor-grade tape measures now have a marker every 19.2 inches for just this very purpose. This spacing will also work out correctly for your plywood subfloor. By using a 19.2-inch spacing, the flanges of the TrimJoist™ are still only 15.7-inches apart. This makes the plywood subfloor behave like traditional joists at 16-inch centers.



Q: Will I have squeaks with a TrimJoist™ floor system?  

A: Any floor system can have squeaks, even those made from steel and concrete. The trick here is to eliminate those factors that can cause squeaks. These factors are typically poor nailing, subfloor joints that are too tight, excess dead wood and poor bridging. The TrimJoist™ has many features to help avoid these problems.



Q: Where can I get TrimJoist™ products for my next project?  

A: TrimJoist™ products are sold only through authorized dealers & distributors. These dealers typically maintain sufficient inventories to satisfy most customer demands. In geographical areas not presently serviced by a dealer, TrimJoist Corporation may be able to arrange factory direct delivery in truck-load quantities (typically 8,000 - 11,000 linear feet.)



Q: Can I order a TrimJoist™ joist with special duct chase placement?  

A: No. For engineering reasons, the center duct chase opening must remain close to the physical center of the truss. Beginning July 1, 1996 new ANSI standards went into effect for wood floor truss design. ANSI standards do not allow the duct chase to be off-center by more than 12 inches even in custom manufactured trusses.



Q: Can I get custom engineering on my particular job?  

A: Yes! TrimJoist Corporation maintains an engineering department for just this purpose. If you can send us a set of plans or adequate drawings via FAX, UPS, FedEx or email, we will assist you in selecting the correct joists for your application. Many of our dealers have in-house engineering capabilities as well.



Q: What about a computer program to analyze a TrimJoist™ for a given loading or support condition?  

A: Any licensed architect or engineer may request a free copy of our analysis program by calling 800-844-8281. This program is Windows based and is simple to use for anyone who understands uniform and concentrated loadings. The program also analyzes beams from a variety of beam manufacturers.



Q: Can I order free literature from TrimJoist™?  

A: Yes! And you can do it online by using our Free Literature page Or you may call us at 800-844-8281.


Copyright© 1996-2010 by TrimJoist Corporation, All Rights Reserved.
5146 Hwy 182 East, PO Box 2286, Columbus, MS 39704-2286
Phone: 800-844-8281 ~ Fax: 662-245-0040