How to Replace Parting Bead and Staff Bead in a Sash Window

How to replace parting bead and staff bead in a sash window

Two slim strips of timber do most of the work of holding a double-hung window together, and almost nobody knows what they are called until one of them breaks.

The staff bead is the strip on the room side, running up both jambs and across the head, holding the inner sash into its channel. The parting bead is the thinner one buried in the middle of the jamb, separating the inner and outer sashes so they can pass each other. When either one is split, painted into a lump, or worn thin, the sash gets loose in its channel and starts to rattle in the wind. Draught seals will not fix that on their own, because the seal needs a straight, sound bead to press against.

They are cheap, and replacing them is one of the few window jobs where the result is obvious the first time you shut the window.

Take the staff bead off without destroying it

Score the paint line along both edges with a knife first. That one step is the difference between lifting a bead out cleanly and pulling a strip of paint and putty off the architrave with it.

Then work a broad chisel or a flat pry bar into the joint at the middle of the length, not at the end. Lever gently and move along, easing it out a little at a time. The bead is usually nailed with a few small brads and glued in by decades of paint, so it comes away in stages.

Old beads often crack anyway. That is not a disaster: they are cheap to replace, and a fresh bead in sound timber is what a draught seal needs to work against.

Get the parting bead out

With the inner sash removed, the parting bead sits in a groove up each jamb, held by friction and paint rather than fasteners. Grip it near the top with pincers or pliers and pull it toward the room, wiggling it out of the groove as you go. Do not lever against the jamb, or you will crush the groove and nothing will sit straight afterwards.

Old parting bead is almost always the worst piece of timber in the window. It is thin, it takes the most wear, and it is usually painted so many times over that the sash has to fight past it.

Size the new bead before you order

Measure two things: the width of the groove for parting bead, and the depth from the face of the jamb to the sash. Beads come in a few standard sizes and being a millimetre out either way matters. Too tight and the sash binds. Too loose and you have the rattle back.

Measure the full length of both jambs and the head, then add a little for cutting. Our Parting Bead and Staff Bead come in the profiles that suit Australian double-hung windows.

There is also a plastic parting bead and U-channel combo worth knowing about. The channel carries a pile seal, so the bead and the draught seal go in as one component. It is what we reach for when a window needs sealing and rebeading in the same visit.

Fit the new beads

Parting bead goes in first. Cut it to length, dry fit it, and tap it into the groove with a block of scrap so you do not bruise the face. It should hold on friction alone. If it needs hammering, it is too wide, and a few passes with a block plane fix that faster than forcing it.

Prime the back and the ends of the timber before it goes in. Nobody does this and it is why beads rot from behind.

Then refit the sashes and put the staff bead back. Pin it with fine brads rather than gluing it, because the next person to change a sash cord will thank you. Leave the bead just kissing the sash, not clamping it. The sash should slide with the weight of your hand.

While the beads are off

The channels are exposed and will never be easier to work in, so this is the moment for anything else the window needs. Fit brush seals into the channels, or run V-Seal where surfaces close against each other. Replace a tired sash cord. If a pane's putty has cracked, reglaze it before the sash goes back.

Put the window back together with sound beads, a working cord and seals in the channels and it stops rattling, stops whistling and stops dropping shut. That is most of what people mean when they say an old window needs replacing.

FAQ

What is the difference between parting bead and staff bead? Staff bead is the strip on the room side that holds the inner sash in place. Parting bead is the thinner strip in the middle of the jamb that keeps the two sashes apart so they can slide past each other.

Why does my sash window rattle? Usually worn or missing beads letting the sash move in its channel. Replacing the beads and fitting a brush seal takes the rattle out.

Can I replace sash beads without taking the window out? Yes. Both beads come out from inside the room with the sashes in place or lifted out. The frame itself stays where it is.

What size parting bead do I need? Measure the width of the groove in the jamb and the depth from the jamb face to the sash. A millimetre matters here, so measure before ordering rather than guessing from a photo.

Should I use timber or plastic parting bead? Timber suits a heritage restoration where the finish matters. The plastic bead and U-channel combo is quicker and carries the draught seal in the same piece, which suits a window you want sealed and running smoothly in one go.

What you need for this job

• Parting Bead. The thin strip that separates the two sashes. Order by the groove width you measured.
• Staff Bead. The room-side strip. Buy it before you start, because old ones usually crack on removal.
• Plastic Parting Bead and U-Channel Combo. Bead and seal channel in one. The quicker route if you are sealing at the same time.
• V-Seal with adhesive back. Peel and stick sealing for the surfaces that close rather than slide.
• Draught seal brush. Sold by the metre, for the channels the sashes run in.