Are you enduring noise nuisance from the noise outside your bedroom windows ? Either is be traffic noise, noise from railways, industries, entertainment places ?
In a typical façade of a house, ventilation and windows are the least soundproof. Ventilation we will get into in another post, we’ll focus on the windows first.
Windows that slide have the worst sound insulation, then windows that open to the inside/outside an the best existing windows for noise reduction are fixed windows (that cannot be opened).

The main reason that windows let through so much noise is because they are much lighter than the brick walls that keeps them in place hence noise will always find the weakest link to get into a room.
Apart from the glazing itself (existing windows often have single glazing 4 or 5 mm thick), poor installation of a window/frame can cause noise to be transmitted easily. This will occur when the joints between the masonry and the window frame is not properly sealed. Special acoustic sealant can be used indoors and outdoors to improve imperfections due to poor installation of windows.
The next big cause of noise leakage through windows is the joints between the moving parts and the frame itself. With single glazing windows the joints are most likely not properly sealed. Proper seals are required, they’re easy to install and very effective.
Once cleared the 2 mentioned issues above, the last and most expensive one will be to change the glazing into noise reduction glazing, this means you’ll have 2 window panes with an airgap in between. This not only will reduce the noise but will also improve the thermal insulation of the windows.
Acoustic engineers can make calculations to consult which glazing would be optimal, but if your windows now are single pane 4 mm glass, a real improvement would be to change it to 4.1.4 – 20 – 6 mm. This means a laminated window consisting of 2 x 4 mm glass and 1 mm pvb foil in-between it, 20 mm airgap and 6 mm solid glass. You can get an easy improvement of 10 dB(A) by just improving joints, seals and the glazing. 10 dB(A) more noise reduction can be the difference between waking up from outdoor noises at night and enjoying a sound sleep !
If changing glazing is too expensive there are some other easy DIY ways to improve the noise reduction of windows.
You should always start with the simple and very affordable improving the noise transmission by adding caulk and seals.

If you don’t need the daylight (or you have windows in multiple facades) you could just simply put a closet in front of the window, this will reduce the noise transmission. (BlastBlock has a great range of products)
Next step would be to install seals between the moving parts. Of course if you don’t need to open your windows you can also caulk them !

You can also use heavy soundproofing window curtains to improve the soundproofing of your windows. These special curtains will noise only block the noise but also absorb a big part of it. Soundproofing curtains won’t disturb or can even improve the design and ‘feeling’ of a room. It won’t be as effective as blocking the windows with furniture but it can provide a substantial improvement of the noise reduction of your windows.

If you like DIY jobs, you can also add shutters to the outside of the windows that you’ll close at night. They should be from massive wood (don’t let light/noise through) and should have good seals to prevent from noise coming in easily.

Another way to drastically improve the soundproofing of existing windows is adding an extra window pane on the inside of the existing windows (secondary window), it can be fixed (if you don’t need to open your windows) or an opening window. If you have the space in your existing wall, this would even be better than exchanging the existing glazing as you can create a huge airspace between the exterior and interior window, anything between 8 – 20 cm would be perfect.

Some people recommend vinyl window film to improve soundproofing. This is not very effective and all other suggested methods will have a much greater improvement of the soundproofing than adding film to your existing windows. Effective soundproofing film simply doesn’t exist.
If you would chose to exchange your window frame and glazing and don’t want to spend money on an acoustical engineer to determine how much noise the new glazing would have to reduce, then you should know that noise reduction typically is measured or given as a STC (Sound Transmission Coefficient) value.
Existing windows with poor seals and joints will only give you an STC between 15 – 20 dB. A well installed thermal insulation window will give you up to 30 dB STC value. Regular soundproofing glazing can be up to STC 40 dB and special soundproofing glazing or adding a secondary window can have an STC value of up to 50 dB (which is comparable with a 400 kg/sqm brick wall, 20 cm thick).
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