Flying mullion fire escape window by Ron Currie

Below is an example of a flying mullion fire escape window. You generally find this on side opening windows less than 1200mm wide. Flying mullions are used when a single casement is just too large so two smaller ones are used instead. This function usually adds around 50 to the cost of the double casement window.

The window appears to be a normal 2 Sided opener. It's style is georgian and traditional.

One side is the master casement which opens as normal and uses the usual stay and fastener arrangement.

The other side is the slave casement. This has the mullion of the window attached to it and is held closed by flush bolts. See pictures below.

These pictures show the flying mullion section of the window. You can see the flush bolts in the mullion to hold the slave casement closed.

These pictures show the window from its internal aspect. The casement on the left of the picture is the master casement with the stay and fastener visible. When using flush bolts the slave casement appears to be a fixed (dummy) casement thus maintaining a very neat internal appearance.

Mock stormproof sliding sash fire escape window

The sliding mock sash window can also be adapted to a fire escape as pictured below, by hinging the bottom section. Please let us know if your windows need this. This will add extra cost to your windows.


As can be seen in the pictures above, the two sashes open to give enough room to form a fire escape. When closed the window gives the appearance of a sliding sash window.

Please click here to go to the window option page. Please read our treatment page.