G42 Sliding Soundproof Window

Product Overview

Dual‑window system – install a professional soundproof window on the inside of your existing window, forming a double‑layer sound insulation assembly.
Acoustic principle – original window + 8 cm air gap + G42 sealed soundproof window. The 8 cm air layer significantly attenuates low‑frequency noise below 250 Hz. As the air gap increases, the coincidence dip of the double‑window system shifts toward lower frequencies. Once the gap exceeds 12 cm, the dip moves below the critical traffic‑noise band (63–250 Hz).
Frame – custom‑extruded 6063‑T5 aluminium, multi‑cavity, equal‑surface‑density design based on the Noise and Vibration Control Engineering Handbook (Ma Dayou). Wall thickness ≥ 1.8 mm.
Glass options –

5 mm + 1.14 PVB + 6 mm double laminated glass
4 mm + 1.14 PVB + 4 mm + 1.14 PVB + 4 mm triple laminated glass

Hardware – silicone and composite foam seals, 304 stainless steel handles, and ultra‑high‑molecular‑weight polyethylene (UHMWPE) guide rails.
Why choose G42? – popular, cost‑effective, opens inward without occupying indoor space.

Patented Pulley‑Free Push‑Pull Sealed Soundproof Window

Our patented sliding mechanism eliminates pulleys and roller wheels, ensuring a perfect seal.

Polished laminated glass – surface roughness: arithmetic mean deviation Ra ≤ 0.8 μm, maximum height Rz ≤ 3.2 μm.
UHMWPE guide rails – weight‑average molecular weight ≥ 5 million, providing ultra‑low friction and exceptional wear resistance.
High‑purity seals – silicone strips with purity ≥ 98 %; composite foam EPDM seals with raw rubber content ≥ 40 %.
The polished glass slides directly on the UHMWPE rails. When closed, all gaps are sealed by silicone or EPDM tape – no air leakage, no noise bypass.

Patent details – Utility model patent No. ZL201822196141.1

Inventors: Yang Qinyu, Zhou Zhiliang, Zhuang Hongyan
Filing date: December 26, 2018
Assignee: Shenzhen Sound Environment Technology Co., Ltd.
Verification: CNIPA

Industry Challenges We Solve

Developer‑supplied windows – typically insulating glass (5+9Air+5) with a pronounced low‑frequency coincidence dip in the 63–250 Hz range. This causes a persistent “hum” and a rumbling sensation when heavy vehicles pass by.
Niche market – roadside noise control is a specialised segment that large window brands often overlook. They focus on aesthetics and premium finishes rather than acoustic performance.
Budget constraints – units closest to major roads are often sold at discounted prices. Homeowners who compromise on location usually have limited budgets for noise control.
Cost comparison – high‑end windows with excellent low‑frequency insulation cost 2,600–5,000 CNY/m². Adding a G42 as a second layer costs only 800–1,000 CNY/m² and delivers even better performance.
Demolition is often impossible –

Occupied homes – removing windows damages waterproofing and interior finishes.
Curtain‑wall buildings (hotels, hospitals, offices) – exterior removal is prohibited.
Government‑subsidised housing – original windows cannot be replaced.
G42 can be added inside without altering the original structure.

Misconception about insulating glass – many vendors believe wider air gaps mean better sound insulation. When users find it ineffective, adding a G42 as a second layer improves insulation by 20–30 dB(A) – a cost‑effective remedy.
Ineffective add‑on products – soundproof curtains, seal strips, and acoustic panels ignore the Mass Law – lightweight materials cannot block low‑frequency noise (see the material sound insulation table in the Noise and Vibration Engineering Handbook).

Unique Advantages

15 years in the market – over 10,000 units installed. Simple structure, failure rate < 0.1 %, extremely durable and reliable.
No demolition, no damage – dry installation; no wall cutting, no damage to window frames, wallpaper, or trim.
Preserves original window functions – your existing window continues to provide weather and security protection.
Superimposed sound insulation – with outdoor noise at 60–70 dB(A), indoor levels drop to 35 dB(A) or below.
Combined thermal insulation – the 8–12 cm air layer acts as a thermal buffer. Typical performance:

Traffic‑noise spectrum correction Rw + Ctr ≥ 42 dB(A)
Thermal transmittance U‑value ≤ 0.8 W/(m²·K)
No single‑layer window can match this dual‑window performance.

Applicable Scenarios & Target Users

Noise sources – near flight paths, subways, high‑speed rail, highways, main roads, bus depots, construction sites, square‑dance areas, and commercial districts.

Specific applications – mechanical/electrical rooms, production workshops, recording studios, home KTV, hotels – any space requiring sound containment.

Compatible window types – sliding, casement, bay, top‑hung, fixed – all can be retrofitted.

Ideal for –

Long‑term residents of noisy roadside homes who do not want to move or renovate.
Industrial noise‑control projects.
Entertainment venues needing to meet boundary noise limits.
New homeowners who cannot adapt to a noisy environment.
Factories failing environmental noise assessments.

Theoretical Calculation – The Mass Law

Sound transmission loss through a panel is governed primarily by its surface density (thickness × density). Other parameters contribute only about ± 10 %.

For normal incidence, the theoretical sound insulation R₀ (dB) of a homogeneous single panel is:

R₀=101g[1+(πfM/ρ₀c)2]

Where:

ρ₀= air density (1.18 kg/m³)
c = speed of sound in air (344 m/s)
f = frequency (Hz)
M = surface density (kg/m²)

For our triple laminated glass 4 + 1.14PVB + 4 + 1.14PVB + 4, surface density ≈ 32.5 kg/m².

Theoretical single‑window insertion loss ≈ 35 dB(A).

Laboratory Test Results

Test signal: steady‑state white noise at 80 dB(A).
Installation: frame sealed with cement mortar to eliminate flanking paths.
Measured A‑weighted sound pressure level: 32.5 dB(A).

Note: This is the single‑window A‑weighted insulation, not the combined double‑window traffic‑noise correction (Rw + Ctr).

Usage Instructions

The window occupies only 42 mm of sill depth – ideal for add‑on installation. Combined with your original window, the traffic‑noise spectrum correction Rw + Ctr ≥ 42 dB(A).
Maintenance – if dust accumulates in the guide rails, simply wipe them clean to restore smooth sliding.

Summary

Through 15 years of in‑house R&D and continuous optimisation, we have refined the design while reinforcing weak acoustic points. By thickening critical materials, we eliminate every “sound‑insulation short board.” This pursuit of the optimal quality‑cost balance is why Flexible windows' products remain highly cost‑effective.
For any window, the glass area dominates the total surface – and its surface density far exceeds that of the frame. Maximising the glass area and embedding it deeply into the profile is the key to reducing flanking transmission.
The measured A‑weighted value (32.5 dB) closely matches the theoretical prediction (35 dB), confirming that our design and manufacturing processes are near‑perfect.

Frequently Asked Questions

Q1: Is it better to keep the original window and add a soundproof window, or to replace the old window entirely?
A: According to the Mass Law and the frequency characteristic curve of double‑layer systems, adding a soundproof window to the existing one provides an additional 2–3 dB of low‑frequency performance due to the air‑spring effect – a benefit that single windows cannot achieve. However, ensure there is no hard connection between the two windows (e.g., aluminium or plastic dust‑proof panels) to avoid creating a sound bridge. With an air gap ≥ 8 cm, the coincidence dip shifts to ≤ 125 Hz; larger gaps shift it even lower, so avoid the main traffic‑noise frequencies (125–500 Hz). In general, the combined performance of a double‑window system is unattainable by any single layer.

Q2: What if the original window is deformed or difficult to operate?
A: The soundproof window is completely independent of the original. However, if the original window is badly worn, leaks, or is hard to use, we recommend removing it and replacing it with our G60 casement soundproof window for a complete solution.

Q3: Can low‑frequency noise from trucks or buses be blocked after installation?
A: Low‑frequency noise travels farther, attenuates slowly, and penetrates walls and glass more easily. Installing a soundproof window with an 8–30 cm air gap improves low‑frequency insulation by 2–6 dB. Note that the quieter the environment, the more sensitive the ear – absolute silence is not possible. Our goal is to reduce noise to a comfortable, acceptable level. When 63–250 Hz sound pressure is kept below 45 dB, the perceived loudness is around 35 dB(A). For indoor loudness evaluation, the PNC curve is more representative of human perception.

Q4: How big is the difference between adding an ordinary window and adding a professional soundproof window?
A: Huge. Professional acoustic engineers analyse the on‑site noise spectrum and your expectations to recommend the right glass and configuration – and we guarantee the result in writing. Ordinary installers work by guesswork, often achieving less than 10 dB(A) reduction. Professional soundproof windows typically deliver 20–30 dB(A) improvement.

Q5: What decibel level can you guarantee after installation?
A: Based on your noise spectrum and window size, we recommend a configuration that typically brings the 10‑second average indoor level below 35 dB(A) – regardless of how noisy it is outside. We put this guarantee in the contract: if we don’t meet it, you don’t pay.

Q6: Do you charge for on‑site measurement? What tools do you use?
A: Measurement is free. We use a tape measure for dimensions (accuracy ±1 mm) and an AWA5688 spectrum analyser for noise.

Q7: Why use a tape measure instead of a laser distance meter?
A: Laser meters often give readings 1–3 mm too large – they can’t confirm if the beam is perfectly horizontal/vertical and frequently error on shiny surfaces (tiles, glass). For our required ±1 mm accuracy, a steel tape is more reliable.

Q8: Is add‑on installation considered unauthorised construction? Will property management object?
A: No – it’s like installing a TV or wardrobe. Indoor additions are private property rights. In 15 years, we’ve installed in every type of housing – public rental, talent housing, apartments, dormitories, and commercial units – without any issue.

Q9: How long does it last? Will sound insulation degrade over time?
A: We use silicone seals (purity ≥ 90 %) and EPDM (raw rubber ≥ 40 %) that remain flexible and effective for over 20 years. In 2026, we revisited users from 2011 – their seals were still in excellent condition. The sound insulation lasts as long as the window itself.

Q10: How much does add‑on installation cost? Compared to full replacement?
A: Add‑on installation averages 800–1,100 CNY/m², achieving dual‑window insulation > 40 dB(A). A single replacement window with > 40 dB performance costs 1,600–2,200 CNY/m², plus 500–1,000 CNY for wall repair.

Q11: Any hidden fees? Are measurement and installation charged extra?
A: No. We have transparent pricing on Taobao, JD, and Douyin. A 99 CNY measurement deposit is refundable if you don’t proceed. Installation is included in the contract total – no surprises. We discuss any site challenges (stairs, parking, obstacles) upfront and never add charges later.