I am a little confused. I’m about to do an installation of western red cedar shingles as exterior siding (18″, double coursed, #1 blue label, grooved, pre-primed, pre-painted).

Every official looking installation details source, e.g. the Wall Manual from the Cedar Shake and Shingle Bureau, calls for keyways of 1/8″ to 1/4″ depending on individual shingle width. I’m trying to reconcile that with the seemingly high percentage of shingle sidewalls that I see around here (Pacific Northwest) done with the shingles butted tight to one another.

I’m generally a follow-published-practices kind of guy, but the keyed look is less appealling. I routinely see shingles butted tight with no visible ill effects and and I’m tempted to go for this, but I’m left scratching my head.

Any helpful thoughts on this?

Thanks…