I don't understand 12" OC for the top track which supports the weight of the shutters and 6" OC for the bottom track. Why so? Very nice and clear video. Am almost finished installing an accordion for an 8' x 8' slider and I used this video as a 'go-by.'
Thanks @prujoe1 for your question, the answer is we assume the Top Track is being installed to solid concrete and that the Bottom Track is being installed into hollow block at the window sill. Concrete has a greater structural capacity so the fasteners can be further apart.
