How to: Repair a Muntin

A muntin is the middle glazing bar of a sash window. It separates the two panes of glass.

In older-style villas, the muntin is a very thin piece of timber, with a curved contour on the inside.

Alas, over the years glass will break, and careless glaziers may gouge out the muntin putty with a spade. A hundred years later it is not uncommon for a muntin to be structurally ravished, and in desperate need of attention.

Unfortunately, repair is not as easy as wandering down to Bungalow and Villa and asking for a replacement muntin.   While they are available from businesses specialising in timber joinery, the exact originals seem hard to come by.Sash Window Missing a Muntin

So, we had two options, a) remove the muntin, and then glaze the window with a single pane of glass going for the slightly ‘not-quite-right’ look, or b) attempt to repair the muntin. 

We opted for the latter.

Here’s a step by step guide.


  • One ragged muntin
  • An old parting bead
  • Shed power tools


  1. Measure the dimensions of the damaged part of the muntin, and then remove it.

    Broken Muntin Muntin Measurements Partial Muntin Amputation

  2. Route a channel into the amputated part of the muntin. The replacement part will slot into this.

    Muntin Channel Cutting a channel

  3. Take an old parting bead, cut to measured length, and thickness.

    Parting bead de-thickened Old parting bead

  4. Insert and glue parting bead into the newly configured muntin channel.

    Muntin Repair

  5. Clamp overnight.

    Muntin repair And glued overnight

  6. Install into sash window.

    Muntin Reinstallation

  7. Repaint, reglaze and reinstall.


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One Response to How to: Repair a Muntin

  1. David says:

    Taiko is a good restaurant and a nice place to drink Sake too.

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