Dummy sash windows

Dummy sash windows are fixed panes made to look like opening windows, so that every visible pane lines up. They are a cosmetic extra, and whether they are worth paying for comes down to how much you care about the look, and how much light the room needs.

What dummy sash windows are

A window often has top opening windows beside fixed panes. The opening mechanism makes the opening windows look different from the fixed ones, because the frames don’t sit level. A dummy sash fixes that. Sheerwater Glass describes them as fixed panes with sashes that imitate the look of opening windows, so that all the visible panes sit in line, and says they serve only a decorative purpose. The result is called equal sight lines.

You see them on mullioned windows and bays, where the dummy sashes sit next to the ones that actually open. Only the panes with handles open, and the others are the dummies.

The case for dummy sash windows

Hand on heart, I have to agree that they often do look better, if you know what you are looking for. A window with equal sight lines is also common on older and period-style houses, as Sheerwater says, so dummy sashes can suit a home of that age. If you have decorative glazing, a dummy sash keeps the pattern the same in each pane.

However, to have them or not to have them bothers most people very little.

The case against dummy sash windows

There are three points against them.

Light. A dummy sash takes up more of the frame than a plain fixed pane, so it reduces the area that lets in light. I’d say they block quite a bit more light, though Sheerwater, which fits them, says only slightly. In a room that needs more light, they could be a mistake.

Security. An opening window has locking points built into its frame. A dummy sash has none to fit, and with some makes I have seen it fixed to the main frame with only a few self-tapping screws. That could make it a little less secure than a properly locked opener, so ask how yours is fixed.

Cost. They cost more to make, in both materials and labour. A salesperson may tell you they are “free”, but the cost of every one is built into the price you are quoted.

What to ask before choosing dummy sash windows

You choose how much to spend on extras, so think about it carefully and don’t make a snap decision. Before you order, ask the firm:

1. What does each dummy sash add to the price, itemised?
2. How is each one fixed to the frame?
3. How much glass area will I lose in each window?
4. Can I leave them off the rooms that need the most light?

The last question is worth asking. In a bedroom or a landing, the extra detail may not matter much, but in a dark kitchen it could.

For what a window costs without the extras, see the price guide for a single replacement window, and put any quote through our quote checker. More on how windows are put together is in windows explained, and on whether to believe the pitch in buyer beware.