What is the R value of glass block vs window?

Author: Melany Breitenberg  |  Last update: Friday, November 7, 2025

What is the R-value of glass block? The R-value for Premiere Series glass block is 2.08, which is more than twice the value for flat 1/8" sheet glass windows or roughly equivalent to a double pane thermal window. The Thinline Series R-values are slightly lower at 2.00.

What is the R-value of glass blocks?

Glass brick has an r value between 1.75 and 1.96, close to that of thermopane windows.

Do glass blocks have good insulation?

Insulation

Energy efficient glass blocks can improve the energy efficiency in your home. Many of these blocks are certified high thermal insulation capacity and have a double chamber inside the block. These glass blocks are assembled with a polystyrene frame that acts as a thermal break to reduce heat conductivity.

Is glass block better than windows?

Glass Block Window Advantages

Because of how thick they are, glass block windows insulate and offer thermal protection that's superior to single pane windows and comparable to double pane models.

What is the R-value of a glass window?

For instance, a window's frame would have a specific R-value, while the glass, or glazing, would have a different value. Here's an example: Single-pane R-value of glass that is one-fourth inch thick is around . 90, while R-value of a double-paned window of similar thickness would be nearly double at roughly 1.7.

Super-Thick Glass Makes High R-Value Windows Possible

What window has the best R-value?

Windows with high R values include double-glazed windows, triple-glazed windows, and argon-filled windows. Double-glazed windows have two layers of glass with a space in between, while triple-glazed windows have three layers of glass.

What is the difference between R glass and S glass?

R-glass – A reinforcement glass made with calcium aluminosilicates used where higher strength and acid corrosion resistance is needed. S-glass – High strength glass made with magnesium aluminosilicates. Used where high strength, high stiffness, extreme temperature resistance, and corrosive resistance is needed.

What are the disadvantages of glass blocks?

This article will detail seven major drawbacks of glass block windows, what to consider in the future, and how to choose the best replacement windows.
  • Limited Ventilation.
  • Maintenance and Cleaning Challenges.
  • Limited Visibility.
  • Poor Insulation.
  • Limited Design Options.
  • Potential Breakage.
  • Complex Installation.

Can you see through glass block windows at night?

You can still see vaguely into some types of glass block windows at night. Although there won't be clear definitions, passersby may still see shapes, shadows, and movement through the glass. If you want complete privacy, consider installing diamond glass block windows rather than the typical clear or wavy glass blocks.

Is the glass block outdated?

Are Glass Block Windows Attractive? While beauty is in the eye of the beholder, many current design experts, home decorators and architects agree that the look of glass block is outdated, unattractive and unnecessary.

What is the thermal efficiency of glass blocks?

Standard glass block is hollow one-chamber product, where the inner space is filled with under-pressured air. The thermal transmission (U-value) of such glass block is approx. 3.0 W/m2K. Energy Saving option brings a flat glass sheet insertion into the glass block, which eventually forms two-chamber system.

How long do glass block windows last?

Glass block windows are not only visually appealing but also built to last. On average, glass block windows have a lifespan of around 20 to 30 years or even longer if properly installed and maintained.

Do glass block walls require expansion joints?

All glass block panels shall be provided with expansion joints at the sides and top.

Are glass block windows good insulators?

We already discussed that glass block windows are excellent insulators so just be mindful of where you install them. We live in the Midwest. While it's very cold here in the winters our summers can get super hot!

What is the R-value of window foam?

Closed-Cell Spray Foam Insulation

Closed-cell spray foam has a far better R-value per inch than other, less effective insulations like cellulose, fiberglass, or even open-cell foam. All these have R-values ranging from R-3.2 to R-3.8 per inch. The R-value of closed-cell foam is R-6.5-7 per inch.

What is the R-value of 8 inch block?

According to the National Concrete Masonry Association (NCMA) the tested R-Value for a standard 8x8x16 concrete masonry unit (CMU) is 2.2 at 105 lb. density. The tested solid grouted R-Value for the same unit is 1.7 proving that air is a better insulator than grout (which is a form of concrete).

Are glass block windows a good idea?

Glass block windows offer a variety of benefits that make them an attractive choice for both commercial and residential use. From energy savings to severe weather protection, glass block windows are versatile enough to meet the needs of almost any project.

How much does labor cost to install glass block windows?

Hiring a pro to install your glass block windows ensures they will be uniform, aligned, and custom fit to your space and needs. Window replacement projects average around $400, and glass installation specifically costs $150 to $1,000 for prefabricated windows and up to $4,500 for a custom job.

What to use instead of glass blocks?

Acrylic blocks offer a great alternative to traditional glass block. It looks just like the real thing, but weighs and costs less. Acrylic is durable, energy efficient, and easy to install. You can use them for partitions, shower walls, or clock windows.

Are glass block windows burglar proof?

Unlike traditional window panes that are easy to shatter, glass blocks are thicker and more robust, making it extremely difficult for intruders to break in. This added layer of protection can give you peace of mind, especially if your basement houses valuables or serves as a family gathering area.

Can you put a vent in a glass block window?

Essentially, anywhere you have a glass block window, you can include a hopper vent. Keep in mind for the larger vents, there may be two locks rather than one, for added security.

Do glass block windows need maintenance?

The cost of installing a glass block window can vary depending on the size and complexity of the installation, but it's generally less expensive than installing a regular window. Plus, since they're strong and durable, they require little maintenance aside from the occasional cleaning.

What is the R-value of standard glass?

A single-pane window will have an R-value of 1. A standard double-pane window will have an R-value of 2. While a single-pane window with an R-value of 1 does not offer great insulation, you get a much better picture of its performance by comparing it to a double-pane window than to an insulated wall.

How to remove fiberglass from skin?

Removing Fiberglass from Your Skin

If you've come into contact with fiberglass shards or you have a rash and itchiness after you were exposed to fiberglass, don't rub or scratch the area. Immediately wash the exposed area with warm water and mild soap and wipe with a washcloth to remove the glass fibers from your skin.

What are the three types of fiberglass?

Fiberglass can be broadly categorized into different forms, each of which is used for different applications:
  • A-glass: Also known as alkali glass. ...
  • C-glass: Also known as chemical glass. ...
  • E-glass: Also called electrical glass. ...
  • AE-glass: Alkali resistant glass.
  • S-glass: Also known as structural glass.

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