How it works
Shaker: a stile at each end of every stretch and between every two panels, full height; rails fit between the stiles at the top and bottom, and across the middle if you ask for them. The panels come out all the same width, as near your width as the stretch allows.
Picture frames: as many evenly spaced frames as fit between the end margins with your gap between them, each two sides and a top and bottom mitred at 45°. Boards: full-height boards side by side, with the last one ripped to width where the stretch doesn't come out even.
Every piece is then cut from the lengths you can buy, longest first, by the same timber packer as the timber cutting calculator.
Questions
How wide are the panels?
As close to the width you ask for as the wall allows, all the same. For shaker panelling there's a stile at each end of the wall and between every two panels, so the number of panels is whatever comes nearest your width once the stiles are taken off.
How are picture frames spaced?
As many frames as fit between the margins at each end, with your gap between them, each as close to the width you ask for as the wall allows. Each frame is two sides and a top and bottom, mitred at 45°, measured to the outside of the frame.
What's a stretch of wall?
A length of wall the panelling runs along without a break: from a corner to a corner, or to a doorway or window. Measure each one and add it; each is laid out on its own, so panels always finish at its ends.
What does the top rail add?
A capping or dado rail along the top of the panelling, one piece per stretch (joined if it's longer than your longest length), mitred where stretches meet at a corner. It's bought as its own timber.
Is this the same as JoinerKit's panelling?
Yes. It's the same code that lays out wall panelling in JoinerKit, where you can draw it on the wall with the room's doors, windows and furniture, and see it in 3D.