Barn Loft Construction
The two most common ways to build a loft in a garage or a barn is to use Attic Trusses or floor joists with supporting beams underneath. Using Attic storage trusses during construction is the simplest and most cost effective way to build a loft. Building loft with floor joists & beams is a bit more complicated and more expensive.
Attic Truss Loft:
During construction of the building, Attic Trusses are placed on top of walls (wall headers) and are spaced 24" apart. Attic Trusses are build to accommodate loft in the center of the building and are built with higher roof pitch to provide headroom and heavier bottom chord to support the loft area. Later, when the building is done, loft may be finished with plywood, guard rails and stairway, or left completely unfinished.
Tip: Due to the fact that Attic trusses are spaced 24" o.c. it's best to use thicker plywood when building the loft deck. We recommend the use of 3/4" T&G plywood.
Attic Truss Loft Advantage: Less costly to build, eliminates need for supporting posts creating a clear span structure, faster construction.
Attic Truss Loft Disadvantages: Loft space is limited to center part of the building only with inability to have a full loft.
Loft with Floor Joists:
When more attic space is needed such as in a full loft (see image), the loft must be built with floor joists and roof rafters. On wider buildings (buildings over 16' wide), floor joists would either need to be supported by center beam, or combination of beams & posts if constructing a wider building. Other option you may consider is the use of LVL or TJI Floor joists.
Tip: On a regular 24'x24' car garage, the best way to build a full loft is to either use TJI Joists or build up a clear span center beam out of (3) 1-3/4"x16" LVL beams and place 2x10 floor joists on top of walls and the center beam. On wider buildings, you will need to use combination of beams and posts or TJI floor joists may be used up to 30' wide buildings. Get more information on TJI Joists & LVL Beams from iLevel.com website.
The Advantage of Loft with Floor Joists: More usable attic space and ability to have your loft build with multiple configurations such as a full loft, half loft, loft over the center part with open sides or loft over the sides with open center (or any other design you can think of).
The Disadvantage of Loft with Floor Joists: More complicated and more expensive to build.
Click on image to enlarge