Avoiding Short Courses
On some installations of horizontally-run roofing materials, situations exist that will result in problems with shingle course alignment. These problems typically occur above dormers or other large protrusions. They will also occur on buildings that have off-set eaves. In order to make the courses align or “catch up” with one another, a short course of shingles of less than full vertical exposure can be installed although many property owners will find the look of such short courses to be objectionable.
By carefully analyzing each roof design before starting the installation, such areas where course alignment difficulties might occur can be identified and strategies can be developed for dealing with those areas.
By checking measurements down from the ridge to the starter and to all shingle courses on either side of a dormer or other protrusion, care can be taken to ensure that the courses will line up above the protrusion. Particularly careful attention must be paid to this when valleys exist above the protrusion as shingle courses can have a tendency to “grow” on either side of a valley. In some cases with such protrusions and in all cases with off-set eaves, a two-piece starter system can be employed using a separate drip edge with an extended leg going up the roof deck and then a separate Siding Starter or Slotted Starter installed on top of the drip edge at an appropriate level to make the shingle courses align.
In situations where a short (less than full vertical height) course of shingles is absolutely unavoidable, potential complaints about aesthetics can be minimized by having the short course be the first course on whichever roof plane will make it the least apparent. Short courses are created by cutting down the panels and field-folding new top locks or by installing a Siding Starter horizontally on top of what will be the short course.
Questions concerning specific areas where course alignment problems will occur can be addressed to Classic Metal Roofing before proceeding with the roof installation.