Backer rod is just a thin foam-type "string/rope" you jam into the crevice to fill excess space. Always use a THIN (not thick) bead of caulk if going over backer rod, it will last better. Backer rod is only when you have a significant gap to fill, of course.
I am not a big fan of caulk in the coop (b/c of being eaten) EXCEPT that I *am* a big fan of using in plywood seams and other joints, and between quarter-round molding (if any) at floor edges, with the caulk being put in AS the joint is being constructed. Then all excess wiped off. So the joint is filled internally and nowhere for mites to live in there.
Pat
I am not a big fan of caulk in the coop (b/c of being eaten) EXCEPT that I *am* a big fan of using in plywood seams and other joints, and between quarter-round molding (if any) at floor edges, with the caulk being put in AS the joint is being constructed. Then all excess wiped off. So the joint is filled internally and nowhere for mites to live in there.
Pat