TJIs Vs. Lumber…What’s better?

Are you in the middle of a home renovation and wondering what type of flooring system to select?  Truss Joist I’s (TJI’s) offer perfectly flat long spans but dimensional lumber is cheaper and tried tested and true.  Both systems seem to have many benefits and drawbacks but which one is right for you?

TJI’s are an engineered joist system made out of dimensional lumber for the top and bottom flanges and oriented strand board (OSB) for the web.  The flanges are notched and glued onto the web with a water-resistant glue.  Depths of the joists can range from 9 1\4″  to 24″ and can span up to 80′ (depending on the floor loading).They were invented in 1969 and as of 2005 they make up over 50% of all new wood light frame flooring systems.

The most common benefits of using TJI’s are that they are light, engineered to resist twisting, warping and bending, minimal shrinkage to reduce squeaking, and consistent to ensure perfectly flat floors and ceilings.  TJI’s are typically slightly more expensive than sawn lumber due to fabrication costs.  However, since TJI’s are made up of multiple pieces glued together they are much less resistant to damage caused by water, and should always be stored in a dry environment.  Conventional untreated lumber should also be stored in a dry environment however since they are made of one solid piece without glue they are less susceptible to damage caused by water.  TJI’s should never be used in exterior areas where they may potentially become wet.  Specifications for TJI’s (such as allowable span and depths) very marginally between different manufacturers, but all design and installation information is usually available on the manufacturers website.  One popular manufacturer of TJI’s is Weyerhaeuser and they’re design guides can be found at http://www.woodbywy.com/trus-joist/tji-joists-for-eastern-canada.

With all of this information in mind, before you select your flooring system it is imperative that whoever is installing your floor is familiar and experienced with that type of flooring system and has done it before.  If they have not perhaps consider switching to another system or find another contractor who is.