Manufactured roof trusses offer economies of scale in labor and materials, making them less expensive than traditional rafters. Lumber retailers should have a salesperson available to assist with selection of trusses by manufacturers whose designs have been reviewed by structural engineers for added value and safety.
The width of the structure -- measured to the outside of each framed wall -- determines the span of the roof truss. Outside of the overall width or span is the overhang, beyond the plane of the outside wall, referred to as the soffit. Its depth can vary and will be depicted on the architectural design.
Railroad engineer Albert Fink invented the Fink truss in the 1800s. Used primarily in residential construction, it has the added bonus of light storage capabilities because of its open web structure, which also allows space for mechanical systems, such as air conditioning units. Other designs exist, but the Fink truss serves as a fair representation for average home construction.
Roof pitch or slope appears on the design plans as well. Roof pitch is the dimension of rise compared to run, with geometry that appears similar to a right triangle; for example, 8 inches of rise on 12 inches of run is referred to as an 8/12 pitch.
A structural engineer calculates loading requirements -- based on forces such as wind, water, snow and roof shingling -- to meet local building codes. The truss manufacturer should offer certification of local code compliance for perspective buyers.
The average cost of a Fink truss will vary from market to market. For example, this type of truss installed in the greater Boston region will average $3.87 per square foot of building area, according to the 2011 RSMeans "Residential Cost Data" book. The same truss in New York City costs about $4.42, compared to $2.59 per square foot in Raleigh, North Carolina. These prices don't include shingles or additional required framing materials such as furring, roof sheathing, soffit and fascia board. RSMeans bases its average on a truss span of 26 feet with a 1-foot overhang, 8/12 pitch, 24-inch spacing and a 40-pound loading factor.
- Wood-Truss-Design.com: The Fink Truss
- Residential Cost Data; RSMeans; 2011
- The House Designers: Benefit of Using Prefabricated Roof Trusses
- Encyclopaedia Britannica: Fink Truss
- Photo Credit Brand X Pictures/Brand X Pictures/Getty Images
How Much Does it Cost to Frame a House?
When it comes to buying a house, there are really only two options: to buy a preexisting home or to build one...
Typical Cost for Roof Replacement
A worn or damaged roof leaves your home vulnerable to leaks and damage, but it may take careful planning to fit a...
Trusses Vs. Rafters
The structure of a roof can include rafters, trusses or a combination of the two. Both trusses and rafters have a triangular...
Conventional Roof Vs. Truss Roof
Roof trusses are carefully designed framing members composed of multiple triangles connected by metal fastener plates. Standard roof trusses are available at...
How to Make Roof Trusses
Generally speaking, roof trusses are structurally engineered and manufactured by a licensed truss company, sent to you with a stamped copy of...
How to Build a 24 Foot by 30 Foot Garage
An owner-built garage can be constructed in a few focused days. A 24 by 30 foot garage is large enough to provide...
Cost of Repairing a Roof Truss
A roof truss is a frame, typically made of wood, to carry the weight of the roof’s exterior surface. Generally, a roof...
Cost of Building a Gabled Roof on a Mobile Home
Adding decorative features such as a gabled roof, a patio, porch or landscaping can increase the value of your mobile home and...
Joist Vs. Truss
In architecture and engineering, joists and trusts are two methods that support weight and provide structural integrity. While much different in design...