Is insulating glass tempered glass? Do you really understand the three taboos of insulating glass?

Today, insulating glass is widely used in building doors and windows, curtain walls and interior decoration, many owners and decoration practitioners still do not know much about the characteristics of insulating glass. Insulating glass has become the preferred material for modern buildings because of its excellent thermal insulation and sound insulation properties, but its difference from tempered glass and the precautions for use need to be clarified, which we will analyze in depth.

1. Is insulating glass tempered glass?

1. Definition of insulating glass

Insulating glass is made up of two or more pieces of glass combined by sealant and an aluminium spacer (or plastic spacer) to form a closed layer of air (usually filled with dry air or an inert gas such as argon). Its main features are:

• Construction: two sheets of glass + hollow layer (6–20 mm) + sealant.

• Function: heat insulation, sound insulation, anti-condensation, suitable for building doors, windows, curtain walls.

• Common specifications: such as 5+9A+5mm (5mm glass + 9mm air layer + 5mm glass).

2. Definition of tempered glass

Tempered glass is heated at a high temperature (about 650°C) of ordinary glass and then cooled quickly, so that the surface forms compressive stress, and enhances strength and impact resistance. Features include:

• Strength: 4–5 times the impact strength of ordinary glass.

• Safety: Small particles are formed when crushed, reducing the risk of injury.

• Uses: Widely used in doors, windows, curtain walls, shower rooms and other scenarios that require high security.

3. The difference between insulating glass and tempered glass

1) The process is different:

• Insulating glass: Multiple pieces of glass are sealed into an insulating layer through a combination process, with a focus on functionality.

• Tempered glass: Strengthened glass is enhanced through a heat treatment process with a focus on safety.

2) The structure is different:

• Insulating glass: multi-piece glass + insulating layer, emphasizing heat and sound insulation.

• Tempered Glass: Monolithic glass with an emphasis on strength and impact resistance.

3) The functions are different:

• Insulating glass: superior to thermal insulation (thermal conductivity K value 1.4–2.8 W/m²· K), sound insulation (can reduce noise by 30–40 decibels).

• Tempered glass: better than impact resistance and safety, and general thermal and sound insulation.

- Combined use: The single piece of glass of insulating glass can be tempered glass, ordinary glass or laminated glass. For example, 5+9A+5mm tempered insulating glass, that is, two pieces of 5mm tempered glass, has both thermal insulation and safety properties.

Insulating glass does not have to be tempered glass, but it can be made from tempered glass. Insulating glass is a kind of composite glass that emphasizes heat and sound insulation; Tempered glass is a single piece of glass that emphasizes strength and safety. In practical applications, tempered glass is often used as the base material (such as doors and windows of high-rise buildings) for insulating glass to take into account safety and function.

Second, the characteristics of insulating glass

1. Thermal insulation

The air layer (or inert gas) of insulating glass has a low thermal conductivity, and the thermal conductivity (K value) can be as low as 1.4W/m²· K, much lower than that of a single piece of glass (about 5.8W/m²· K）。 It is suitable for northern thermal insulation and southern thermal insulation needs.

2. Sound insulation

The hollow layer blocks the propagation of sound waves and has an acoustic insulation effect of 30–40 decibels, which is better than that of a single piece of glass (about 20 decibels). It is suitable for noisy urban homes or street-facing buildings.

3. Anti-condensation

The insulating glass is filled with desiccant (such as molecular sieve) to keep the air layer dry and prevent condensation on the glass surface, which is suitable for humid areas.

4. Durability

High-quality insulating glass can last up to 20–30 years, but it needs to be installed and maintained correctly to avoid seal failure or glass breakage.

3. Three taboos of insulating glass

1. Seal failure leads to performance degradation

Question:

The thermal and acoustic insulation properties of insulating glass depend on the tightness. If the sealant (butyl rubber, polysulfide rubber) is aged or improperly applied, resulting in water seepage or air leakage in the air layer, the thermal insulation coefficient increases (K value increases), the sound insulation effect decreases, and even condensation and mildew appear.

Reason:

• Use of inferior sealant, poor weather resistance, aging after 1-2 years.

• The sealant is applied unevenly during installation and there are leaks.

• Long-term exposure to high temperatures, humidity or strong ultraviolet rays accelerates sealant aging.

Consequences:

The thermal and sound insulation performance is weakened, the indoor temperature difference is large, the noise increases, and the inside of the glass may become moldy.

Workaround:

• Choose a high-quality sealant that complies with the "Insulating Glass" (GB/T 11944-2012), such as silicone glue or polysulfide glue.

• Ensure that the construction specification is standardized, the thickness of the sealant is uniform (≥5mm), and there are no bubbles.

• Inspect the sealing strip and adhesive line regularly and replace it every 5-10 years.

2. Improper installation leads to unstable structure

Question:

The weight of insulating glass is large (5+9A+5mm about 25kg/m²), and if the window frame or installation process is not standardized, it may cause the glass to loosen, deform or crack.

Reason:

• The window frame is not strong enough (e.g. the wall thickness of the aluminum alloy profile < 1.4mm) to withstand the weight of the glass.

• The horizontal and vertical levels are not calibrated during installation, and the glass is not evenly stressed.

• No special gasket or blowing agent is used, and the contact between the glass and the window frame is unstable.

Consequences:

Glass falls off or breaks, which is a potential safety hazard; Seal failure, affecting heat and sound insulation.

Workaround:

• Choose high-strength window frames (e.g. broken bridge aluminum, wall thickness ≥ 1.4mm).

• Use a spirit level during installation to ensure a deviation of ≤ 2mm/m.

• Use special glass pads, filled with blowing agent and sealant to ensure stability.

3. Neglect of maintenance leads to shortened life

Question:

Insulating glass requires regular maintenance and can result in degraded or damaged performance if neglected, inspected or used incorrectly.

Reason:

• If left uncleaned for a long time, dust or acids accumulate on the glass surface, corroding the sealant.

• Frequent impact or heavy pressure on the glass, resulting in a cracked hollow layer or seal failure.

• Failure to repair the gap between the window frame and the wall in time, and water seepage affects the performance of the glass.

Consequences:

The glass surface is fouled, the sealant is aged, the hollow layer fails, and the life is shortened to 5–10 years.

Workaround:

• Clean the glass annually with a mild detergent and avoid acidic and alkaline detergents.

• Avoid heavy objects hitting the glass and install protective fences or anti-theft nets.

• Regularly inspect the window frame and wall seals, repair cracks, and prevent water seepage.

Fourth, the use of insulating glass precautions

1. Pay attention to purchases

• Specification selection: Choose the thickness of the hollow layer (6–20mm) according to the requirements, such as 6–9mm for the south and 12–15mm for the north.

• Glass type: Tempered insulating glass (such as 5+12A+5mm tempered) is used for high-rise buildings to enhance safety.

• Brand selection: Choose brands that meet the standards of "Insulating Glass", such as Xinyi Glass and CSG, and request quality inspection reports.

• Inert gas: Glass filled with argon is preferred, which has better thermal insulation performance (K value can be reduced to 1.1W/m²· K）。

2. Installation specifications

• Professional construction: Hire a qualified construction team and comply with the "Technical Regulations for the Application of Architectural Glass" (JGJ 113-2015).

• Waterproof treatment: apply waterproof sealant between the window frame and the wall to prevent leakage.

• Load-bearing design: ensure that the window frame and wall are load-bearing, especially for large areas of glass (e.g. 2m×2m).

3. Maintenance and Use

• Regular cleaning: Clean the glass surface quarterly to avoid stains and corrosion.

• Inspect seals: Inspect sealants and spacers annually and replace aging parts in a timely manner.

• Avoid high temperatures: Avoid using high-temperature equipment (such as electric welding) near the glass to prevent the glass from bursting.

Owners should choose high-quality insulating glass that meets national standards, standardize installation, regular maintenance, and avoid the three taboos to ensure heat insulation, sound insulation effect and 20-30 years of service life. Through reasonable purchase and scientific management, insulating glass can provide comfort and safety guarantee for residences.