Glass block windows are, arguably, a more traditional type of window than thinner pane windows. They were initially used as early as the 1800s when it was necessary to let light into a space without weakening the structure. Because glass was mouth-blown in the early days of mass-production, it was far easier to blow thick blocks of glass than thinner panes. As a result, glass block windows become common for use in underground or underwater spaces like storage cellars or the decks of ships.
However, with the development of modern manufacturing techniques, thinner panes of glass became easier to make, and consumers began to demand windows that were easier to see through. However, glass block windows didn’t die out; the combination of strength and (relative) transparency has helped them find a niche. They are currently undergoing something of a renaissance as more and more people convert basements into usable space, and want window options that don’t compromise the structural integrity of their home.
If you’re thinking about installing your own glass block windows, this is the guide for you. We’ll walk you through the precise meanings of glass block windows, the advantages and disadvantages, as well as the installation process. That way, you can decide whether glass block windows are right for you and your home.
WHAT ARE GLASS BLOCK WINDOWS?
The first key question to ask is precisely what we mean when we discuss glass block windows. Most likely you will have seen glass block windows – although they are no longer common for underground cellars or on ships. Glass block windows are thick, translucent blocks of glass, commonly found in basements and bathrooms. Light can pass easily through them, although they do not allow anyone to see through them.
The strength that glass block windows provide is akin to masonry. Because they are large, solid blocks, they provide structural security as well as preventing security threats to the integrity of your home. This makes them an attractive material to use, combining the translucent properties of glass without any of the structural weakness. The windows are often placed in a grid pattern, held together with a mortar-type material.
This also means that there is no need for a frame, making the entire structure strong and less susceptible to damage from the elements. This makes them a useful addition to different parts of the home.
AVERAGE GLASS BLOCK WINDOW COST
The average cost to install glass block windows is between $350 – $1,200. However this price can fluctuate depending on the complexity of the job, the type of glass block windows, and if the glass block window is pre-built or if the blocks need to be install one by one. In general, you can expect to pay around $20 per square foot.
For historic reasons, glass block windows have become common in bathrooms throughout the United States. Prior to the 1950s, bathrooms in homes usually contained tubs and not showers. As shower technology improved and became feasible for people to install in their homes, many people did so. This caused problems with the layout of many bathrooms.
In the days of only bathtubs, it was possible to have a wooden-framed window above the tub to allow light in and air to circulate. However, the retrofitting of showers meant that wooden frames began to rot. Understandably, having a window next to a shower presents problems of privacy that many homeowners were uncomfortable with. As such, glass block windows became the solution to all problems. Homeowners could shower in private, and yet there was still natural light in the room.
ADVANTAGES OF GLASS BLOCK WINDOWS
There are obviously plenty of advantages to glass block windows. There’s a reason why they’ve been around for hundreds of years. However, if you’re thinking of adding in some glass block windows, and need a little more persuasion, some of the following may help:
Glass block windows have a certain aesthetic charm – even despite their practical origins. Using them in a bathroom creates a timeless glamor. You can even create an eclectic, bohemian feel by mixing and matching different sizes (and colors) of blocks to make the windows more of a feature.
Because of how thick glass blocks are, using them as an exterior window is far more energy-efficient than a traditional single pane window. In fact, a glass block window has the same efficiency as a double pane window. Increasingly, glass block manufacturers have attempted to capitalize on this angle, and many glass block windows carry an Energy Star label, denoting their efficiency.
Connected with energy efficiency, glass block windows do a great job of drawing in heat from the sun and keeping it in a room. In a cold climate, a glass block window can help to warm your space on a sunny day.
Because of how thick glass blocks are, they don’t allow for anyone outside to see through. For extra effectiveness in this respect, look for blocks that are manufactured with different patterns and textures, which serve to further increase the view from outside being obscured.
This is connected with privacy – because potential intruders can’t see inside, you’re less likely to be the victim of an opportunistic crime. In addition, because of how thick the blocks are, it’s not possible for someone to smash through without using a lot of tools and creating a lot of noise. If you are extremely security-conscious, you can look into bulletproof glass blocks.
Glass blocks are much more waterproof than standard windows, meaning you could help prevent your home from flooding in case of storms. Although they’re not totally waterproof, it could be the difference between a totally flooded home and a mildly damp one.
DISADVANTAGES OF GLASS BLOCK WINDOWS
Although the benefits of glass block windows are solid and clear (like the windows themselves), there are some drawbacks to installing them – there’s a reason why most windows are still single or double pane windows, and we don’t see buildings totally covered in glass blocks. Some of the reasons for this are outlined below:
Although this is listed as an advantage above, in an area with a hot climate, the same greenhouse effect that leads to a toasty warm bathroom in the winter, will lead to a roasting hot room in the summer. In fact, such is the effect of glass blocks when it comes to drawing in heat, it may be difficult to cool a room in summer even with air conditioning. You can buy heat reflective coating for glass blocks, which does help somewhat, although, for smaller rooms, glass blocks can be extremely warming.
Glass blocks don’t open, unlike other types of windows. This can lead to a ventilation problem, particularly in rooms that have problems with humidity. Unfortunately, rooms that have problems with humidity are the most likely rooms for glass block windows to be installed (i.e. bathrooms). You can install a hopper vent, which will help somewhat with ventilation, although this still doesn’t provide the same level of airflow as an open window. Plus, you’d need to install a new vent in your window, which has a labor and materials cost.
Because of the heaviness of glass blocks, you need to make sure that your wall and floor are capable of supporting them. For this reason, the best time to install glass blocks is when the wall is being built, as this allows for a strong enough support system to be put in place.
If you are replacing a window with glass blocks, you’ll need to do more than just switch out the frame and replace it with blocks, you’ll need to reinforce the wall and floor as well.
IS A GLASS BLOCK WINDOW FEASABLE FOR ME?
If you’re swayed by the advantages and have decided a glass block window is for you, you should hire a professional to come and assess whether your home is suitable for their installation.
THEY WILL USUALLY RUN THROUGH THE FOLLOWING:
Check the load-bearing ability of the floor and wall. If the walls aren’t strong enough, it is possible to add structural supports. If you don’t reinforce the wall, you may be damaging the structure of your home, leaving your home unsafe and you facing a major restoration bill.
Mock up where the glass blocks will go. If you’re installing a hopper vent, you’ll need to leave space for this. You should plan carefully where the blocks will fit.
Recommend the glass blocks for the space. The cheapest option is a pre-made glass block panel. However, you can get custom builds using individual, one-piece blocks. This is obviously much more expensive.
Give you a quote. You should aim to get at least three quotes for the work, which will allow you to get a better sense of what is involved in terms of time and money.
Friedrich Keppler, the owner and founder of a German glass producing company, patented a mechanical process improving the strength of glass block windows. His new technique was based on making reinforced concrete frames with thick glass blocks embedded.
It was this shift that created the modern style of glass block design. Companies were now able to produce glass blocks easily and cheaply and fit them together into large, strong structures. This technique is more or less what happens in today’s glass block structures.