Sound Control

Recent renovations for this centrally positioned three storied apartment block included an upgrade from single Glazing to Double Glazing.  These apartments are well located near the corner of a major redevelopment site and close to a main road in Mt Eden.

renovations done at a Mt Eden apartment

Built just outside 2007 when the building code clause requiring most new builds to be Double Glazed, subsequently complying with NZ Building Code specifications.

The new owners requested a combination of Sound Control Glass, upgraded Thermal insulation and a security upgrade for the lower levels.

The Double Glazing Specialists reduced the noise by combining a special acoustic grade of laminated sound stop glass on the outside & Float glass on the inside with a 12mm space in between filled with Argon Gas (Sound stop Glass is two layers of glass bonded together by a clear layer of acoustic resin) — similar to that of a front windscreen in a car.  The laminated glass reduces sound due to the vibration-dampening effect of the interlayer in-between.

The Glass options the home owners requested also enables them to enjoy a very comfortable Thermal upgrade boosting performance levels of up to 88% heat loss reduction, also keeping temperatures cooler in the summer making this home a drier, cleaner & more comfortable home to live in.

The Double Glazing Specialists team have a huge range of quality hardware, in this case we have installed lockable window handles to all street level windows, placing these laminated windows amongst the safest and most secure around.  We often colour match the hardware to the colour of the Joinery as well.

Mt Eden apartments window locks

While our Double Glazed Sound Stop Units can provide up to approximately 60% (perceived sound reduction) through the glass, than Standard Float glass.  You can also get your building checked by an acoustic engineer who can assess your home and specify a solution to further enhance your noise reduction in your walls and liners.

The following Performance Data is derived from manufacturer’s data, acoustic test results, acoustic modelling software or an estimation based on the methods below:

Percieved sound reduction table
Glass typeglass / spacer / glassAverage STL RatingSTC RatingRW (dB)% Percieved (sound reduction)
3mm float - single glazed   24 26 26 0
4mm float – single glazed   25 28 28 10
6.38 PVB laminated single glazed 3mm / 0.38mm / 3mm 30 33 33 35
7mm SoundStop – single glazed 3mm / 1.0mm / 3mm 34 36 36 50
20mm Double Glazed Unit 4mm / 12mm / 4mm 28 30 30 20
20.4 mm Double Glazed Unit 6.38mm PVB Laminated / 10mm / 4mm 33 37 37 53
25mm Double Glazed Unit 7mm Sound Stop / 12mm / 6mm 38 40 40 60
Sound Transmission Loss (STL)
The average sound transmission loss is useful for determining the effectiveness of glazed panels to isolate exterior Noise (such as traffic) from a building.
The average STL is measured in decibels, the higher the average STL dB figure, the more effective the glazing will be in reducing sound transmission.
Sound Transmission Class (STC)
The sound transmission class is useful for determining the noise reduction offered by internal building elements, such as partitions and walls.  It is a measure that relates the sound reduction performance against sounds which normally occur inside a building such as phones, music, voices etc, the STC is a numerical class rating and can not be compared with the STL.
The higher the STC the higher the overall sound reduction.
Weighted Sound Reduction Index (RW)
The weighted sound reduction Index is now the most common index used internationally since it’s adoption in the NZBS & ISO standards.  This index has largely replaced the Rm & STC index because the weighted reduction incorporates frequency modified correction for the human ears response.  The RW is reported in dB and is a composite rating of sound reduction at frequencies from 100 – 5000 Hz.  Numerically, it is comparable to the STC values but the numbers are in decibles.
Perceived Sound Reduction
The percentage by which the human ear detects a lessening in sound pressure or noise is known as the Perceived Sound Reduction.  A 10dB reduction in sound pressure level is generally perceived as a halving of the original noise.  Sound reduction values are weighted and used to calculate the perceived sound reduction as a ratio relative to the RW for 3mm clear float which commonly used in older homes.
The dB difference in the Rw value for a glass type when compared to 3mm float is calculated as a perceived sound reduction percentage.
The vibration noise of a truck for example passing by on the road (bass) is one of the more common examples of noise passing through into a house, that we have experienced.  Other than that our customers have given us great feedback of quieter homes and better sleeping.
Thermal upgrade and Noise control at this Hibiscus Coast home