Double Hung Window Hardware Is Chosen at the Meeting Rail

Double hung window hardware comes down to a lock and a way to grip the sash. The lock is a cam-action sash lock on the meeting rail of the lower sash, paired with a keeper on the upper sash. The grip is a pair of sash lifts on the bottom rail, or a pull where the sash is tall and heavy. My recommendation for a traditional wood double-hung window is a non-keyed cam lock chosen by the depth of your meeting rail and the screw spacing in the product drawing, in the same finish as the other windows in that room. This guide is about traditional wood windows. Modern vinyl, aluminum and tilt-in double-hung windows often need locks, keepers, lifts and parts made for that manufacturer, so a generic cam lock is not right for every double-hung window; check the window maker's guidance first. One condition changes the recommendation even on wood: if the sashes no longer meet squarely, find out why before buying, because a new lock cannot pull together rails that do not line up.

Where the two sashes overlap, the lock has two jobs

On a double-hung window both sashes slide. When the window is shut, the top rail of the lower sash sits just inside the bottom rail of the upper sash, and those two overlapping rails are the meeting rails, which older catalogs call check rails. The lock body screws to the lower one. The keeper, a small hooked plate, screws to the upper one. Turning the lever swings a curved cam into the keeper, and because the cam is shaped like a ramp, the last part of the turn draws the two rails toward each other.

That draw is the part people underrate. A sash lock is not only stopping the lower sash from rising. It presses the rails together so the window stops rattling and the seam between them closes against drafts. A lock that catches the keeper but never tightens has done half its work. This is why the lock and keeper are sold and installed as a pair: where the keeper sits, how high and how far from the lock, decides how hard the cam pulls. I would choose a lock whose lever reads plainly as open or shut from across the room, since a cam left half turned is easy to miss on a window you rarely touch.

Some wide windows were built with two locks, one toward each end of the rail. If yours were, replace both and keep them where they were, since the window was designed to be held at two points.

Lifts and pulls go where the hands go

A sash lift is the small hook or finger plate screwed to the room-side face of the lower sash's bottom rail. You hook your fingers under it and push up. Whether a window takes one lift or two depends on its design and the manufacturer's guidance: many wider sashes were made with a pair, one near each side, and a narrow sash may be made for a single centered lift. Follow what the window was built for. If the sash is heavy, hard to raise or cocks in its track, the cause may be worn balances or a sash that is binding, and a larger handle will not cure that. A sash pull is a longer handle: a bar screwed to the bottom rail for a full-hand grip, or a pull on the upper sash for drawing it down from the top. Pulls make sense on tall, heavy sashes and for anyone who would rather grip with a whole hand than two fingers.

A lift is decorative hardware that carries a working load, so the screws matter more than they look. An old bottom rail has often been drilled, filled and painted several times, and a lift that pulls out mid-lift takes wood with it. If the old screw holes are stripped, the right repair depends on the condition of the wood and the hardware maker's installation instructions. Sound wood can often take a glued hardwood plug, left to cure before you drill a fresh pilot hole. Soft, rotted or split wood needs a proper repair or a replacement rail, and a glued sliver will not hold there. Either way, avoid stepping up a screw size until the rail splits.

Our double-hung sash locks come from Rocky Mountain Hardware, and the lock is the piece in this family that people see and touch most. Choose lifts at the same time, since they sit a short reach below the lock on the same sash and are judged in the same glance.

Measuring an old wood sash for new double hung window hardware

Most replacement trouble comes from a few measurements nobody takes before ordering.

• Rail depth. Measure across the top of the lower meeting rail, from the glass or glazing to the room-side face. The lock body has to sit on that flat without overhanging the inside edge or crowding the glass. Old wood rails vary from window to window and house to house, so compare that number against the depth listed for any lock you are considering.
• Height difference between the rails. With the window shut, look along the two meeting rails and see whether their tops sit level, or whether one is higher. The keeper has to land where the cam expects it. Keepers come in different heights and profiles, so this number tells you which style will engage. If the difference is larger than the lock's instructions allow, the cam will either miss the keeper or close without drawing.
• Screw spacing, mounting dimensions and clearance. Take the old lock off and measure the screw spacing of both the lock and the keeper, center to center, and note how the keeper sits relative to the lock (its offset across the rails and the clearance between the rails when shut). Compare each number with the product drawing. A larger footprint alone does not make a lock compatible, and a smaller one will leave the old outline showing, so match the mounting dimensions first and the footprint second.

If you are replacing lifts too, measure the old lift's screw spacing center to center before ordering. Lift spacings vary by maker, and there is no single standard to fall back on, so a lift that happens to match the old holes saves you a round of filling.

Lock the window and push on the rail

Before buying anything, lock the window and press the lower meeting rail outward with the heel of your hand, then try to raise the sash. If the rails shift, click against each other or let a draft through while locked, the cause could be the hardware or the sash. A lock or keeper that is loose, worn, damaged or out of alignment will do this, and so will old wood sashes that have shrunk, warped rails, worn stops or tired weatherstripping. Check the lock and keeper first: tighten the screws, look for wear or bending, and see whether the keeper lines up with the cam. If they are sound and the gap remains, a carpenter or window restorer adjusting the sash will do more than any lock, and the new lock then has something solid to pull against.

If the rails sit tight and the old lock is merely painted over, loose or not to your taste, you are in the easy case: match the screw spacing and mounting dimensions, reuse the screw positions where you can, and expect a short job per window. I would still trial-fit one window completely before ordering for the whole house, because old windows in the same house are rarely identical, and measuring each one is cheaper than returning a box of locks.

A bedroom window has to open without a key

Some sash locks take a key, and that raises a code question. Under the International Residential Code, the model code behind many local residential codes, the rule is that emergency escape and rescue openings must be operable from the inside without keys, tools or special knowledge. The requirement applies to the designated escape openings, which are typically a window in each sleeping room, and it depends on the code your locality has adopted. A keyed sash lock on a window that serves as an escape opening works against the reason the opening exists. Not every bedroom window is a required escape opening, so avoiding keyed locks on all of them is a conservative choice rather than a universal rule. Keep keyed locks for windows that are nobody's way out, and confirm with your local building department before putting one on any window in a room where someone sleeps.

One more honest limit: a sash lock holds the sashes closed and tight, but no lock makes a window secure on its own. The glass, the frame and the condition of the sash matter as much as the hardware.

Choose the windows as a set, then think about the doors

People often ask whether window hardware should match the door hardware. I think the windows are better decided as a group first. Sash locks often repeat at the same height across a wall, so a room with three windows shows three locks in a row, and one finish across those windows is the simple way to make that row look planned. The door knob, the door hinges and the window locks sit in different lines of sight, so the doors can share the window finish or go their own way; both work.

Rocky Mountain Hardware casts its window hardware in silicon bronze, with warm, coppery tones, and in white bronze, a paler alloy that reads toward silver. Each comes in a range of patinas from brushed to dark, with polished versions on some pieces. If Rocky Mountain Hardware door hardware is already in the room, ordering the windows in the same bronze and patina is the easy route. How any patina changes with handling depends on the finish, so read the maker's care notes before you choose. Finish names are not standardized across makers, so compare the actual metal rather than the names on two different catalogs.

The order of work, then: check the fit, measure the rail, choose the lock, and pick the finish last. On an old window, that order is the difference between a lock that pulls the sashes snug and one that only looks the part.