Roof Truss Spacing Made Simple

roof truss framing

A roof truss is a structure that is essential for holding up your home's roof. It is also useful in securing the wall structure in homes with two stories. When building trusses, it is imperative that you build them correctly, as they form the framework for the top protective layer of your home. No need to worry though, because there are things you can do to make the job of building roof truss frameworks much simpler, such as spacing them correctly. Proper spacing makes roof trusses easy to install and more stable to hold up your roof and secure your walls.

Follow this guide to ensure the spacing and stability of your DIY roof trusses.

Planning Your Trusses

To determine how many trusses to create, you will first need to measure both the width and the length of the structure you are building. The trusses should be a little longer than the exact width to allow for overhang, and you will need sufficient trusses to mount across the length. Most are spaced between 18-26 inches apart.

Once you've calculated the number of trusses you will need, you should purchase the lumber.

Putting the Trusses Into Place

When you are ready to get to work, the first thing you should do is set the trusses approximately where they should go. To do this safely, you should have at least two people working on the job - though more are recommended. To make it easier, you should carefully lift the truss upside down so that it can be turned right into place once they are above the roof.

Start on one side of the building structure and set the truss against the wall. Repeat the process until all the trusses are set in place. Make sure to space each truss the same width apart. Performing this step on the ground will save you time and energy on the roof, as you will be able to have a crew lift the trusses to you and another crew member. Plus, you will not have to worry about figuring out truss space on the roof. This method is safer and more reliable.

Pro Tip—To get your marks for truss layout, divide the width of the span by the number of openings you will have between the trusses, and not by the number of trusses. For example, these 12 lines represent a dozen trusses set across a 20-foot span. There are 11 spaces created between them, thus; 20-feet x 12 inches divided by 11 spaces gives you the measurement for your layout of 21.81 inches. Convert the decimal to a fraction for layout.

Brace the Second Gable End

Another thing you will need to do is brace the second gable end on the roof and secure it. You do not have to brace all the trusses, just plumb the second gable. However, you will want to have boards that can be used as braces for the tresses. The best size board to use is 1x4 pieces that are 10 feet long.

After the braces are in place, you will mark the distance from the edge of the building to where you would like to attach your first truss. For instance, if you are spacing your trusses 18 inches apart, make a mark 18 inches from the edge. After the first mark is made, make additional marks every spacing distance down the building, in this case, every 18 inches.

Lift the Trusses

When lifting the trusses carefully onto the roof, the easiest way is to have two people hoist it up to two other people. Do one at a time and secure them into place. As you go, make sure that you allow the appropriate overhang for the gable on each side. You can set the first truss with the correct overhang and cut a piece of scrap lumber the same length and set them all to that dimension on one end.

If you take a few extra steps to measure out the trusses and mark them on the brace, installing them will be much easier and go much quicker.