When undertaking roof framing yourself, you should be aware of some of the common mistakes in order to avoid them. Not only can mistakes require costly repairs, but they can cause regulators to give you a no-pass on a code examination. They can also cause potentially serious structural damages to the home if skirted around. Framing a roof involves very different procedures depending on the type of roof you are building, whether it is a gable, hipped or gambrel roof to name but a few. They all have basic components, though, and they work together to form the structure. Using the framing of a gable roof as the basis, consider some of these common mistakes to avoid them when you are doing your own framing.
Framing a Gable Roof
A gable roof is a two-faced roof. The two faces meet at the apex or ridge of the roof that runs the length of the home. Gable studs are vertical pieces that are positioned between the top plate of the main frame and the rafter or ridge board. Collar ties run horizontally between rafters a short distance below the ridge board.
Common Roof Framing Mistakes
The following are some of the more common roof framing mistakes. Because an improperly framed roof can have serious ramifications on the structural integrity of the home, it is best to start out by framing a shed roof first as a way to practice.
- Wrong Nails: It is a common mistake to use the wrong sized nails when constructing the frame of the roof. If the nails are too small or weak to handle the load, it could have a devastating effect on the roof.
- Line Length: The line length is the length of the rafters once they are cut to size. A rafter ready to be installed is cut in the shape of a parallelogram. The line length is the length from the top edge to the opposite top edge. This measurement must be precise or else the rafter will not fit properly to the ridge board or the top plate.
- Bird’s Mouth Cut: This is the two-sided cut made towards the bottom end of the rafter that enables it to fit snugly atop the top plate. The end nearest to the cut is the overhang that will create the eaves of the roof. If the angle of the cut is not properly measured in relation to the height of the ridge board and the length of the rafter, it means a wasted piece of lumber.
- Determining Pitch: The pitch is the slope of the roof. Pitch can either be denoted in fraction form or in inches. Thus, a 6/12 pitch means for each run 12 inches of run or horizontal distance, the roof rises 6 inches. Correctly determining the pitch accounts for the biggest problem among new roof framers. An incorrectly calculated pitch can affect everything from the position and angle of the bird’s mouth cut to the position of the ridge board.