Muntin grilles are purely decorative and have no structural function whatsoever. They are available in a variety of different designs. One of the most frequent designs is muntin grilles mounted between the insulating glass panes of a double-glazed window. In this case, various engineering design considerations have to be taken into account so as to avoid damage to the insulating glass.

The thickness of these muntin grilles should be less than the distance between the insulating glass panes to prevent the glass from breaking under certain weather conditions. Atmospheric changes cause glass to ÔÇślose formÔÇÖ and become convex or concave. This effectively means that the space between the insulating glass panes shrinks or expands as the glass panes curve inwards or outwards.

This phenomenon occurs because of the structure of the insulation glass and cannot be avoided. As a result, in case of expansion of the double-glazed space, the muntin grilles are no longer a snug fit. Movement of the window or glass causes the grilles to move as well. Moving or rattling of the window or glass occurs during ordinary opening/closing of the window as well as due to the vibration of air caused by passing vehicles. Air vibration due to the door to the room being opened or closed can also cause the glass to rattle.

As the window/glass vibrates, it is inevitable that the muntin grilles will hit the glass, causing a rattling noise in the process. The noise can be muffled by plastic or felt pads placed at the grille joints, however it cannot be entirely eliminated. The intensity of the noise depends on the extent of glass deformation as well as the size of the windowpane. Deformations are greater in cases of larger sheets compared to smaller panes.

Therefore, the occurrence of such noise, despite the presence of plastic or felt pads on the muntin grille joints, cannot be attributed to a fault in the glass or window. Pads can be objectionable on aesthetic grounds and are not always acceptable to the customer. For all the abovementioned reasons, it is imperative that the customer be made aware, in advance, of the possibility of noise as well as of the look of muntin grilles with pads.

Public Relations Services, Inles d.d. Ribnica, 30 July 2004