Picture these scenarios: You've agonized to measure, double-check, and line up a complicated roofline, but after nailing up the rafters, you notice that the fascia lines are out of whack. Or, you've cut out all of your tair stringers, only to realize they don't fit and now you're racing rush-hour traffic to the lumberyard. Here are a few layout methods with built-in double-checks that can help solve problems before they start.
Layout Direction. When framing walls, pull all layout measurements from the same control point, and always move in the same direction, for example, start at the front of the building and always move left to right. The direction doesn't matter as long as it's the same throughout the building, including the second and third floors. Consistent layout direction ensures that studs, rafters, and joists align throughout construction. This makes life easier for installing duct work, pipes, or conduit later, leaving any bay useable as a chase throughout the structure.
Repeating Wall Patterns. Plate and detail any lined-up, same-dimension walls at the same time, so you only pull your tape once for multiple walls. For example, architects often load long hallways with closets that are usually the same size; cutting them and laying them out in one shot is easier, more accurate, and faster than laying them out as you go. It's also common to see repeating wall patterns with bedroom and partition walls, where this method also works.
Stairs. Once you've calculated your layout, cut the plumb cut and seat cut only on your first carriage (a.k.a., stringer or stair horse), then do a deck-to-deck test-fit to see if you figured it correctly, including making sure it's laid out correctly for the finished floor thickness. If it fits, cut the treads and use the carriage as a pattern. If not, you can see your mistake and how to correct it, and you haven't wasted both a stringer (unless your measurements are way off) and time cutting out all of the treads.
Real-Time Rafters. For laying out exactly how your rafters will look -- before you cut them -- you can use the second floor deck as a giant sketch pad. Transferring your framing square calculations to a scale sketch clearly illustrates the important details, including bird's mouth, overhang, and how they hit the top plate. While it may be overkill for a simple gable-end, the technique really comes in handy when you've got multiple pitched rafters coming together that all require a common fascia line or common interior wall height. The sketch (done with pencil and chalk line) shows you what adjustments are necessary to get the rafters to fit -- and it does so before you cut a single board. One note of caution: This technique only works if the walls you build are plumb and level.
Trusses. Once you've set and plumbed your gable truss, 25-1/2-inch-long guide blocks can be used as a convenient way to keep the subsequent trusses plumb and ensure they land on layout for plywood. Nail a block to one truss, then set and plumb the truss. After nailing the next truss to your layout lines on the top plates, bring the outside edge of the cord flush to the edge of the block and pop two nails through the block into the cord. Stagger your blocks so they don't butt into each other. This takes the guess work out of measuring and holds the truss in place as you build your roof.
