Rafter or truss layout, like floor joist layout, is relatively easy compared with wall layout. Sometimes it is helpful to lay out for rafters or trusses on the top of the double plate so that once the wall is standing, the layout will already be done, and you won’t have to do it from a ladder. (See “Rafter layout on walls before the wall is stood up" photo.)
Special layout is often required for ceiling can-lights. Check on necessary clearance to make sure you provide enough room.
Roof layout is the process of taking the information given on the plans and writing enough instructions on the double plate for the roof framer to spread and nail the rafters or trusses.
Use the same reference points established for floor and wall building for starting layout on the roof.
Roof rafters and trusses are sometimes 24" O. C. as compared with 16" O. C. for floors and walls. In that case, only every third truss or rafter will be over a stud.
Before layout is started, check plans for openings in the roof required by dormers, skylights, chimneys, etc.
For roof trusses, lay out according to truss plan, especially for hip-truss packages.
Roof Layout Language
Rafter or truss
Tail rafter or truss
Double rafter or truss
1. Lay out for doubles, trimmers, and tail rafters or trusses.
2. Lay out for other rafters or trusses.
Rafter layout on walls before the wall is stood up
Writing layout is just like writing anything else. If the person reading it understands what you want to say, then you’ve done a good job. When you are done with the layout, take a look at it to make sure you can read it. If your writing is not showing up clearly, you might try a different brand of carpenter pencil. There are different leads, and some write better than others, depending on the condition of the wood. You can also use indelible marking pens, which are especially good on wet lumber.
Review the layout with the framer who will be reading it before he starts. If a framer doesn’t understand your layout, it takes more time for him to try to figure it out than for you to explain it to him. A little extra time spent on layout is usually a good investment. It’s not easy taking information from all the different sources that combine in the construction of a building and making it legible for framing, but if the layout is communicated clearly, it will help the framers do their work in an organized and productive manner.