I did it at about 42" + ~3" of chair rail, with the aim of being higher than the backsplashes (not shown in this photo) and lower than the electrical outlets and switches.

Mine goes up to 2/3's of the ceiling height.

Forgot the picture.

Here's mine. It's 4 ft. You can put it at any height you want. We went with the 4ft. because it is the most cost effective. You can get 2 pieces out of one 8ft. length and have no waste. The baths are PVC and the bedroom is pine.

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Foyer, it's a chair rail height of 3 ft. Sorry, picture molding has not been installed as of this photo shoot!!

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Here's our master bath. It's 4' high painted pine.

msmarv, love your bathroom, very pretty.

Our wainscot is 42 in. at finish. We have beadboard and panel.