To install a thumb latch on a door, first position the handle plate on the outside. With a sharp pencil, trace the slot for the lever onto the door. Extend the penciled outline 1/z inch or so just enough to give the lever free play. Then cut the slot: first drill several small holes through the door; finish with a chisel. Attach the lever to the handle plate, insert it in the slot you cut, and screw on the plate. Inside, fit the lever plate over the lever and screw it to the door. Attach the latch bar and its keeper as shown. Mount the notched strike on the frame so that the latch bar rests in it when the door is closed.
Some thumb latches are fitted with pivoting cams to lock the bar in place. If such a latch is used on a bathroom door, childproof it by removing the cam. To maintain privacy for adults, install a barrel boltorspring bolt high on the door, out of a child’s reach.
Square spring bolt
Because a cabinet latch is opened from the outside only, you need not drill any holes through the door. Simply mount the latch on the door and the keeper on the frame. If the door is inset so that the frame must be mortised for the keeper, dab lipstick or crayon on the latch bolt and use it to mark the position of the keeper.
Open door partway, then reach inside to disengage latch.
The simplest gate latch is a pivoting bar that falls into a bracket on the gatepost; to lift the latch from the other side, attach a string to the bar and run it through a small hole 12 to 18 inches above the latch. A similar string arrangement works for a selfclosing latch-a good choice for a gate that must be childproof.