Casement windows are popular with many people because of their soundproofing properties. When it is completely closed, the air between the panes insulates against penetrating noise. When the window is opened inward, the sound insulation is reduced, but the exchange of indoor and outdoor temperatures and the ingress of light are more important.
Two panes in the wall bond
Casement windows with double and triple panes take full advantage of the benefits of double pane glass. The use of a cavity between the two panes makes the window more soundproof, which is not possible with a traditional single window.
In general, the sound insulation function depends on the overall structure. Even though the gap between two sashes improves the sound insulation level of the window, the frame and seal must be installed as a way to reduce noise penetration.
Sound bridges and membrane
When installing casement windows, the joint between the frame and sash must be adequately sealed and filled. In many older buildings, this gap is a major reason for noise transmission, which can be amplified by sound waves traveling to the window frame.
The frame of the box window must be mounted in such a way that it cannot form a membrane that could absorb sound waves. The window sill must also be installed vibration-free so that it does not act as a sound bridge to the window frame. Insulating the window reveal from the inside often increases sound insulation.
Profiles and glazing
The degree to which a casement window blocks sound also depends on the profile of the window seal. If the inner window has an offset, milled wood profile, then the window frame acts like a continuous solid wood to the sound impact.
Normally, the installation of a modern wood profile on the inside of the window is enough to convert a casement window into a soundproof window. Sound insulation can also be improved by installing insulated glass or by applying soundproof foil.
Tip: If you get a particularly insulated type of window glass, this usually refers to the energy value. So for self-insulating glass, please check if it is also soundproof.