G35 Double‑Layer Soundproof Windows

Product Overview

Our add‑on soundproof window is installed on the interior side of your existing window, creating a double‑glazing system that works with your original unit. This approach delivers superior noise reduction without altering your building’s exterior, waterproofing, or interior finishes.

• Sound insulation principle: original window + 8 cm air layer + G35‑series sealed soundproof window.
  The air layer acts as an acoustic spring – it effectively attenuates low‑frequency noise below 250 Hz. As the air gap increases beyond 12 cm, the coincidence dip shifts further downward, avoiding the critical traffic‑noise band (63–250 Hz).

• Profiles: 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: 4 mm + 1.14 mm PVB + 5 mm laminated glass – excellent damping and sound blocking.

• Hardware: silicone and composite foam seals, 304 stainless steel handles, and ultra‑high‑molecular‑weight polyethylene (UHMWPE) guide rails.

• Why choose this?

• Popular product line – high cost‑performance ratio.

• Opens inward without occupying indoor space.

• Retains your original window’s function and appearance.

Patented Technology – Pulley‑Free Push‑Pull Sealed Soundproof Window

We developed a unique sliding mechanism that eliminates traditional pulleys and roller wheels, ensuring a perfect seal every time.

• 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 granted in 2018

• Utility model: Pulley‑free push‑pull sealed soundproof window

• Patent No.: ZL201822196141.1

• Inventors: Yang Qinyu, Zhou Zhiliang, Zhuang Hongyan

• Filing date: December 26, 2018

• Assignee: Shenzhen Soundscape Technology Co., Ltd.

• Verification: CNIPA

Industry Challenges We Solve

1. Developer‑supplied windows are typically ordinary insulating glass (5 + 9Air + 5). They have a pronounced low‑frequency coincidence dip in the 63–250 Hz range – causing that persistent “hum” and rumbling sensation when heavy trucks or trains pass by.

2. Mainstream door/window brands focus on high‑end aesthetics and thermal performance. They rarely specialise in acoustic solutions for roadside buildings – this is a niche that large manufacturers often overlook.

3. Budget constraints – units closest to major roads are often sold at a discount due to noise. Homeowners who compromise on location usually have limited budgets for noise control.

4. High‑end brand windows with excellent low‑frequency insulation cost 2,600–5,000 CNY/m². An add‑on soundproof window costs only 800–1,000 CNY/m² and often outperforms them when combined with the original window.

5. Removing old windows is often impossible or prohibitively expensive:

• Occupied homes – demolition damages waterproofing and interior decoration.

• Curtain‑wall buildings (hotels, hospitals, offices) – removal is structurally prohibited.

• Government‑subsidised housing (public rental, shared ownership, talent housing) – alteration of exterior walls is not allowed.
  In all these cases, an add‑on soundproof window is the only feasible solution.

6. Many vendors mistakenly believe that insulating glass (double‑glazed with a wide air gap) equals soundproof glass. This misconception leads to disappointed customers. Adding a second soundproof window is the cost‑effective remedy.

7. Online “soundproofing” products – soundproof curtains, seal strips, acoustic panels – ignore the Mass Law of sound insulation. Lightweight materials cannot block low‑frequency noise (see the material sound insulation table in the Noise and Vibration Engineering Handbook). They offer little real benefit.

Unique Product Advantages

• 15 years in the market – serving tens of thousands of users. 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 existing finishes.

• Preserves original window functions – your existing window continues to provide wind, rain, and security protection.

• Superimposed sound insulation – the original window plus our add‑on window dramatically increases overall sound reduction. With outdoor noise at 60–70 dB(A), indoor levels drop to approximately 35 dB(A).

• Combined thermal insulation – the 8–12 cm air layer creates a thermal buffer. Typical performance:

• Traffic‑noise spectrum correction Rw + Ctr ≥ 38 dB

• Thermal transmittance U‑value ≤ 0.8 W/(m²·K)
  No single‑layer window can match this dual‑window combination.

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 equipment 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 wish to move or undertake major renovation; industrial noise‑control projects; entertainment venues needing to meet boundary noise limits.

Common client profiles –

• New homeowners who cannot adapt to a noisy environment.

• Factories failing environmental noise assessments.

• Entertainment venues receiving noise complaints.

Technical Theory – 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:

$${�}_0=10{\log }_{10}[1+{\left(\frac{���}{{�}_0�}\right)}^2]$$

Where:

• ${}_{}$ρ0= air density (1.18 kg/m³)

• $�$ = speed of sound in air (344 m/s)

• $�$ = frequency (Hz)

• $�$ = surface density (kg/m²)

For our glass panel 4 mm + 1.14 PVB + 5 mm, surface density ≈ 22 kg/m².
Theoretical single‑window insertion loss ≈ 30 dB(A).

Laboratory Test Results

• Test signal: steady‑state white noise at 80 dB(A).

• Installation: window frame sealed with cement mortar to eliminate flanking paths.

• Measured A‑weighted sound pressure level: 28.5 dB(A).

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

Usage Instructions

1. The window occupies only 35 mm of sill space – perfect for retaining your original window. Combined with the original unit, the traffic‑noise spectrum correction Rw + Ctr ≥ 38 dB.

2. Maintenance – if dust accumulates in the guide rails, simply wipe them clean to restore smooth sliding.

Summary & Core Philosophy

• Through years of in‑house R&D and repeated measurements, we have streamlined the design while reinforcing weak points. By thickening materials at critical acoustic areas, we fill every “sound‑insulation short board.” This pursuit of the optimal quality‑cost balance is why Feisbao 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 minimising flanking transmission.

• The one‑third‑octave sound insulation curve shows that our measured A‑weighted value (28.5 dB) closely matches the theoretical prediction. This confirms that our design and manufacturing processes are near‑perfect.

Frequently Asked Questions

Q1: My original windows are sliding, casement, or bay windows – will this fit?
A: Yes. The soundproof window is custom‑built to match the grid pattern of your existing windows. It opens at the same operable sections. At night, the two layers are nearly invisible.

Q2: Can I still open the window for ventilation?
A: Absolutely. Open the soundproof window first, then the original window for normal ventilation. Alternatively, you can pair it with our ventilation silencer – keep the soundproof window closed while slightly opening the original window to achieve both quiet and fresh air.

Q3: Can you block the low‑frequency “hum” from traffic, aircraft, or machinery?
A: Yes – our double‑window system significantly reduces air‑borne low‑frequency noise. However, it cannot stop structure‑borne sound that travels through the building itself (e.g., vibration from subway trains or compressors).

Q4: What causes structure‑borne sound?
A: Large moving sources (tire‑road contact, train‑rail interaction, compressor vibration) excite the building structure. This vibration propagates through walls and floors into your room.

Q5: How can I tell if the noise is air‑borne or structure‑borne?
A: A simple test – press your ear against the wall. If you hear sound inside the wall, it’s structure‑borne. For precise measurement, a professional vibrometer is needed. Air‑borne noise weakens with distance from the source; structure‑borne noise often feels equally loud everywhere and may even be stronger in corners due to reflection.

Q6: Will installation be messy? Do I need to move out?
A: No. It’s dry installation – we drill a few 6 mm holes for nylon expansion anchors, using a vacuum cleaner and wet cloth to capture dust. We also cover furniture with PE film if needed. No need to move out; the window is factory‑made and installed on‑site, typically completed in one day.

Q7: Will my curtains or window trim be affected?
A: We temporarily remove the curtains during installation and re‑hang them afterwards. Window trim is not disturbed.

Q8: Will there be fogging, dust ingress, or water leakage between the windows?
A: The soundproof window is completely independent from the original. It is not designed to be airtight against rain – that remains the original window’s job. In humid or rainy weather, temporary condensation may appear between the two layers but will dissipate naturally. Dust may enter the gap; you can open the soundproof window to clean it, or we can add a dust‑blocking partition.

Q9: Can it be removed later? Will it damage the original window?
A: Yes, it can be removed without any damage to the original window. However, removal leaves mounting holes and adhesive marks on the wall, which require patching and repainting. Since the window is custom‑made to your exact opening, it cannot be reused elsewhere – and scrap value is minimal. We generally advise against removal.