Tag Archives: wood truss bracing

Fiberglass Panels, Accurate Info, and Truss Bracing!

DEAR POLE BARN GURU: I have four skylights with old fiberglass panels that are in need of being replaced. I doubt the design of the panel can be matched easily but am wondering if I send you a piece of it if it can be. I understand the way to go is with a polycarbonate, not fiberglass, panel. Thanks DAVE in BAY

DEAR DAVE: As you are finding out, skylights are problematic. Here is some extended reading on why: https://www.hansenpolebuildings.com/2012/01/skylights/.

If indeed you determine the only solution is to replace fiberglass panels with polycarbonate (me, I would replace them with steel panels and be done with the future headache) I would recommend a visit to the ProDesk at your local The Home Depot® as they can order in most anything and it usually comes in freight free, which can prove to be a significant savings.

DEAR POLE BARN GURU: I am buying a building immediately but your website is too intrusive to shop, so I will not be using you. I, like many others, do not like the setup for quotes because in most cases you turn into used car salesmen. BRAD in KNOXVILLE

DEAR BRAD: Thank you very much for your input. In order to be able to provide accurate pricing and design advice to our clients, we do need to gather some basic information. Things like where is your new post frame building to be constructed (so we get the correct climactic loading conditions), as well as how do we best reach you to discuss your proposed project. We get several hundred new inquiries each day, seven days a week, and frankly you are the first to voice an opinion as to our website being intrusive. If you have constructive solutions as to how we can best glean the information needed to be able to best provide our services, without coming across as being ‘intrusive’ we would welcome your input, as we always strive to improve.

Our Building Designers are highly trained professionals whose mission is to assist our clients in the quest for the ideal dream building which melds imagination, budget and available space. Post frame buildings are highly involved, engineered structures, which ideally require a fair amount of interaction between us and the client to arrive at the best design solution. We do not “sell” anything to anyone – we provide the assistance to our clients, as well as the education which enables our clients to invest in The Ultimate Post Frame Building Experience™, should they decide we are the best fit. Most of our clients have spent hours perusing the thousand plus pages of free information on our website and have decided they are going to own a new Hansen Pole Building long before they ever request a quote.


DEAR POLE BARN GURU: Question about my plans. On the drawings, my purlin spacing is noted as 31” OC. On the truss drawing, I see that it says the bracing for the top chord is 24” OC. Am I reading this correctly? 

It states: 

(Switched from sheeted: Spacing > 2-0-0).

and then below it talks about the Bottom Chord: Rigid ceiling directly applied or 6-9-13 oc bracing. What does that mean?


DEAR DAN: Truss drawings are designed without any knowledge of how a particular building is constructed, or what the final bracing system for the entire structure is – the permanent bracing design is left to the engineer of record (see General Safety Notes #2).

You will note the top chord bracing says 2-0-0 purlins then says the maximum spacing is 4-7-0 (least of the three drawings). The 31″ spacing on the plans is far less than the 55″ maximum.

Bottom chord bracing is a function of a maximum L/d (length divided by depth) ratio of L/80 for members in tension (truss bottom chords are in tension as they are preventing the walls of the building from going out). The width of a single 2x member is 1.5″ X 80 = 120″ maximum for a single width 2x member. You will note on the endwalls of the building there is a 2×4 nailed to the face of the bottom chord of the truss. This now makes the member three inches in width so technically it could be braced once every 240″ (or 20 feet). The same goes for the interior double trusses, the three inch width member is good up to 20 feet without being braced laterally.



Permanent Truss Bracing

I have to give a lot of credit to Building Department plan checkers and field inspectors. They have to know a lot of stuff, about a myriad of different areas of construction. Even one who is an expert at what is written in the Building Code itself, would be only fluent in a small portion of what it takes to construct a Code conforming building, as the Building Codes now reference a litany of other publications and documents. Think of it as being similar to the IRS income tax code.

Puts it into perspective, doesn’t it?

truss bracingPrefabricated roof truss drawings (provided by the roof truss manufacturers) give the recommendation for how the truss designer feels the trusses should be braced, however the ultimate design of the truss bracing system, is the responsibility of the building designer (registered design professional – engineer or architect).

Recently one of our clients advised our office of the request, from their building inspector, for an email or letter from the engineer of record on their new Hansen post frame building. The request was in regards to the truss bracing system designed by the engineer superseding the bracing shown on the roof truss drawings.

Although the following may sound like it is in a foreign language, on the first page of the engineered building plans is a series of “General Notes”. Note 9 says:


ANSI/TPI 1-2007 pretty much lays out who does what and how. Here are some relevant excerpts: Responsibility Exemptions.
The Registered Design Professional for the Building is responsible for items listed in 2.3.2, and is not responsible for the requirements of other parties specified outside of Section 2.3.2. Method of Restraint.
The method of Permanent Individual Truss Member Restraint/Bracing and the method of anchoring or restraining to prevent lateral movement of all Truss members acting together as a system shall be accomplished by: Method Specified by any Registered Design Professional.

The method of Permanent Individual Truss Member Restraint and Diagonal Bracing for the Truss Top Chord, Bottom Chord, and Web members shall be permitted to be specified by any Registered Design Professional.

On this particular project, general note 9 covered the permanent lateral truss bracing system and is sealed by the Engineer of Record. This makes the request for an Email or letter from the engineer to cover the same topic redundant, as well as an unneeded expense to the building owners (engineers do not just do work for free).

Potentially, the building inspector could decide to alter the truss bracing system designed by the Engineer of Record, however this opens up an entirely new can of worms. In making an alteration, the inspector could be in violation of the laws which govern engineers, as well as placing the jurisdiction in a liability situation should a failure occur.