5 Roof Joists Spacing Tips

Lead Image for 5 Roof Joists Spacing Tips
  • 1 hours
  • Beginner
  • 1

Roof joists are an important feature of roof installation that not only support the weight of a roof but also helps distribute the weight. This structural member makes sure that the weight is spread evenly over the entire roof. The roof joists are attached to beams and are placed parallel to each other and lined up horizontally. The network connects to the angled roof supports (rafters) which, in turn, evenly distribute weight to the beams and then to the walls. The entire stability of the home relies on the roof joists being spaced correctly and the article that follows will share some tips with you on how this is achieved.

1. Have the Roof Designs Examined

Some designs will not use roof joists. They use other means to distribute the weight by using other structural points. Prior to adding or removing a roof joist, always make sure the plans are properly made. If you are not an engineer or professional builder, it is important to take the plans to someone who is. You may find that you need more roof joists, fewer or none at all, but never guess or assume without the input from a professional.

2. Proper Distance

A roof joist is always spaced no more than 16-inches apart from another roof joist. If the roof is not completely square, you can decrease the space between joists but never increase the space. In other words, you would space a roof joist 15-inches apart from another roof joist but never 17-inches apart.

3. Measure from the Ends

When starting to space out the roof joists, always start at the end of the roof. Install a roof joist at each corner of the roof and then from these, you measure the distance for the next roof joist and so on until they all are in place. If the size of the roof is not even, you will end up installing 2 or more joists closer together than 16 inches.

4. Double Check Everything

This should go without saying but always check and recheck the work you are doing and the measurements you are taking. It may not seem like a big deal if something is off by an inch, but it can be. The weight will not properly be supported. For instance, a large snowstorm could cause the weight to shift to this weaker area and could cause a collapse. This extra inch can also lead to insulation being improperly installed or walls going up incorrectly. Before installing any roof joists, always measure the area at least twice. After all the roof joists have been installed, take the time to measure the spacing again.

5. Roof Joist Materials

Roof joists can be made of wood, metal, concrete or any number of materials. Just because one material may be stronger than another doesn't mean the spacing changes. You could use fewer joists with concrete but maintain the standard, regardless of the material being used.