How far should pole barn trusses be spaced?

Depending on your builder or building designer, the usual range is anywhere from 2′ on center to 10′ on center with the majority of builder’s either using 4′ or 8′ on center or a mix of the two.

So which is best?

A lot depends on the engineering of your truss and your local wind/snow loads that your building will have to withstand. Here in our local area of the Midwest, we get moderate amounts of snow, so we have to take into account especially heavy winters that can crush a building that is built poorly.

8′ on center works great and has it’s advantages like speed of setting less trusses and being built heavier duty to withstand the bigger loads and is by far the most common spacing in our area, alternatively here is a few reasons you might consider 4′ on center instead.

1. Added structure: Having trusses every 4 feet allows us the peace of mind that there is more brace points and connections to support the roof structure and give our client’s peace of mind that there will never be a problem of the roof “dipping” over the 8′ spans. As long as 8′ on center is built correctly, you will never have an issue with “dips” but if you have a builder that doesn’t understand the proper install of the wider span trusses, it can be an issue. Make sure your builder/you know how to set 8′ on center trusses properly and you won’t have any issues.
   
   

   4′ on center trusses resting on posts and doubled headers

2. Ease of hanging metal ceiling panels: With 4′ on center trusses, you can attach the metal ceiling directly to the bottom of the trusses without additional wood strapping. This is a great thing, especially seeing as it saves time and money of the extra wood needed to span greater than 4′ gaps. When we are planning a pole barn home, often we will suggest 2′ on center trusses for the home portion where drywall ceiling will be installed and 4′ to 8′ on center in the shop where metal will be installed.  

    

   Metal lined interiors are easy to maintain and keep looking clean!

3. Doubled headers: Traditionally, 8′ on center trusses rest right on top of the posts which are also spaced 8′ on center which is a very strong connection, but with 4′ on center, you still get that connection, plus the additional truss that is resting on doubled 2×12 headers that run the length of the building. Some people don’t like the extra headers though, as they can cut into interior space depending on your design.

    

   Doubled 2×12 headers with LVLs over door opening

4. This last point may not be a big deal to most folks, but some people enjoy that with 4′ on center trusses, they can lay our 2×4 strapping on the roof on the flat and provide not only a larger surface to attach our roof panel screws, but also, you don’t have to stagger rows, so you get nice, perfectly straight line of screws on the roof, no jumping up and down to catch 2x4s on their edge.  Not something that most people would notice, but it is a factor if you are self-building your barn. Here at Milmar we are comfortable building 2′ on center all the way through 8′ on center.

Do you have any questions about truss spacing? Feel free to Contact Us Here. We will be glad to get you a quote on your dream barn project.

Originally posted Nov 2, 2020