FAQ-Wood Trusses

Frequently Asked Questions

 

We welcome the opportunity to provide information on topics that are important to you.
Please review some Frequently Asked Questions below.

If you have a question not addressed, please contact our office.

 

Question: What type of lumber do you use?
Answer: In narrow widths (2 x 4 and 2 x 6) Canadian lumber is used. Wider dimensions (2 x 8, 2 x 10, and 2 x 12) Southern Yellow Pine is used.

 

Question: What do you mean by point loading?
Answer: Point loading describes concentrated loading applied to the dead load calculations of a roof or floor truss that is in addition to the loads indicated in the design criteria of a project. The point loading is located on the truss top or bottom chord. For example, a point load may be a roof top unit on a truss top chord or a folding partition wall on a truss bottom chord.

 

Question: What do you mean by safe loading?
Answer: Safe loading is an additional moveable live loading applied to a floor.This loading is in addition to loads specified in the design criteria of a project. Safe loading would be to account for a future use that would be different from the building’s original design intent. The amount typically is 2,000 lbs. applied to the floor over a 2’ 0” x 2’ 0” area.

 

Question: What is a roller gantry?
Answer: A roller gantry is a rolling press head that travels over a wood truss assembly table top. The roller, when passing over wood members with metal gusset plates in their proper place, applies uniform pressure to embed the metal gusset plates to connect the wood members and form a truss.

 

Question: Is there a time deadline from time of production and installation for a wood truss?
Answer: While a time limit is difficult to specify, a good rule of thumb may be one month. Exposure to moisture and the elements of weather does have an impact on this time frame. If any trusses are to be stored long-term they need to be covered with a protective material that allows for air and moisture to circulate around them. The material should not allow moisture to collect on the trusses. Trusses should also be kept off the ground and blocking placed under the trusses at regular intervals.

 

Question: I see trusses used just about everywhere. Where is not a good place to use trusses?
Answer: It is important that wood truses be used in areas that are well ventilated. Wood trusses are not recommended to be used in areas of high moisture or in a corrosive environment.

 

Question: What type of design software do you use?
Answer: Truss fabricators generally use design software that is furnished by the truss technology company that supplies the metal gusset connector plates. It is not software that is available for retail purchase.

 

Question: I have an addition and if I want to use trusses what information do you need?
Answer: Additions to existing structures need special consideration when using roof trusses. If the new roof structure is intended to match the existing, we recommend a call to schedule an appointment with one of our sales representatives.

 

Question: Where may I locate a heat chase in a floor truss?
Answer: The best place to locate a heat chase is at the center of the truss span between bearing points. While this rule may be varied, it is highly recommended that you contact a truss fabricator to discuss your request.

Note: The above information is based on the premise that the floor truss is uniformly loaded and is a simple span condition. If different conditions are present, the above information may no longer be accurate.

 

Question: I would like to change the look of my house ceiling from flat to a slope. What do I need to do?
Answer: Never cut, alter, or modify a structural member without contacting the truss company who produced the trusses. Baring that, you should retain a structural engineer to provide this assistance. Any modification made to a structural member can cause significant negative consequences.

 

Question: Can I buy metal plates and lumber and make my own trusses?
Answer: It is recommended that you buy prebuilt truss components built by a qualified truss fabricator. If you were to make your own trusses, you may not be able to provide the required calculations to local building inspectors that your “design” is correct.  There are other sources that can provide engineering calculations and specify dimension lumber and grades as well as plywood gusset plates. In the final analysis, this option would likely be more expensive than using prebuilt truss components built by a qualified truss manufacturer.