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 Glass Bricks

Facts & Info: Your Glass Block Questions Answered ...

                                         (Click on questions to go to answers)

Should I use Mortar or Silicone with my glass bricks?
My glass bricks are in a wet area... mortar or silicone in this case?
Do I need a frame for my glass bricks?
What is the difference between Cheaper and more Expensive glass bricks?
Should I use coloured glass bricks?
What size will my glass brick window need to be?

Glass Block Technical Data... Sound, Thermal, Light, Weight, Fire Resistance etc, I need facts.
Do you have Drawings of how to build my glass block window?

Do I need a Building Permit for a glass brick window?
There are so many options! Which one is right?


Go to Glass Brick Calculator

Should I use Mortar or Silicone with my glass bricks?     
This is a question that is often asked. There are a lot of positives and negatives for both silicone and mortar glass brick systems. These are probably best explained through listing the pros and cons for each system and letting you decide once armed with all the facts.
Silicone Systems.

Designed with the Do It Yourself ( DIY ) glass brick / block person in mind but is also readily installed by our professional trades people. A system that is relatively hassle free if the measurements of the frame or the opening provided are exact and square. Challenges arise with minute size changes between brands and batches of glass bricks. Aluminium strips and glass bricks are butted together with silicone sealant, which is also used as a finish for the joints.






Easy to stick the strips and the bricks together with alignment of the glass bricks achieved with little bricklaying skill required. Smaller joints between the glass bricks (3mm approx) mean that the bricks fit into different size openings than mortar systems with thicker joints (10mm approx). If you choose a Do It Yourself Kit, the cost of supply of materials only, is cheaper to you than our full service of supply and installation. Silicone joints merge in colour with the glass bricks showing less contrast between joints and glass. (the silicone is generally of a neutral colour).












Silicone systems have more components and therefore a greater cost to buy than mortar systems. The aluminium stiffening bars especially are more expensive. The silicone joints on the outside of the bricks (in other words, the finished product) are extremely easy to over fill or under fill leaving you with a messy finish that seems to get messier the more you play with it! (Even those skilled with silicone application can mess it up easily). Although easy to put together, if at any stage a glass brick gets chipped or broken and needs replacing, you have a major job of hack sawing out the aluminium stiffening bar above the damaged brick to create the room to fit a new brick back in. This process has just slightly weakened the panel. This will probably never cause a concern but if a number of bricks get replaced over time, the structural integrity of the panel will be considerably weakened. If you are considering a tall panel (perhaps 10 bricks high or more) then the variances in size of the glass bricks can make a difference to the desired finished height (in plain English this means that the finished height could be a few millimetres out by the time you reach the top). If the bricks are slightly smaller then you may end up with up to a 10mm joint at the top instead of the 3mm desired joint. If the bricks are slightly larger then you may end up with up a very tight fit at the top and perhaps even too tight in extreme cases (this generally happens when the bricks are bought from one source, the frame from another and the communication between the customer and the frame maker doesn't cover this possible problem).
 Mortar Systems.

Glass bricks are laid in mortar quite similar to house bricks but with white sand and white cement to give bright white joints. Galvanized steel rods run horizontally in the mortar joints between the glass bricks to add tensile strength to the panel. Works well in glass brick frames or in timber and even straight into brick or concrete wall openings.







Cheaper as a DIY kit or as a fully installed package than the silicone system. Mortar has stood the test of time. As our old brick homes prove. Consider the fact that European countries use massive amounts of glass bricks and they use the mortar system for installation. Mortar joints are easily scrubbed clean if they are dirty. You can use mould resisting sealers on mortar. (you can even take to them with a scrubbing brush without damage). Mortar is finished very neatly with our concave jointing tools and steady hands provide a superior and very professional finish. If a glass brick is to be replaced, the process of removing the brick and chipping away the mortar joint is an easy one and is replaced without compromising the strength of the panel. If an opening is not an ideal size or not quite square and parallel, there is room for adjustment in joint sizes with a mortar system whereas with silicone there is little to no room at all.




As a DIY kit, mortar systems require a bit more skill to put together than silicone systems. Mortar colour is quite white but not stark white like tile grout can be. Although the white colour can be a disadvantage if you have say, red grout in the tiles right next to your glass brick window, the mortar joints are finished recessed (this means that there is sufficient room to apply a tile grout of your colour preference to match colour schemes around the room).
My glass bricks are in a wet area... mortar or silicone in this case?     
This is an area where my opinion differs greatly from others in my industry.
(Please be advised that this is my opinion based on my experiences installing glass bricks and you should do whatever you feel is best based on all the information from a variety of sources.)

I hear often from customers that they have been advised that in a wet area, say a shower wall of glass bricks, they are better off using "anti fungal" silicone rather than mortar because it is easier to clean, mould resistant or more waterproof than mortar.
If you look at mortar as tile grout then you can consider that the mortar joints will require regular cleaning to prevent mould over time. This is made easier if you use a grout sealer (we recommend Sure Seal - an invisible drying spray application in a can) Products.htm. To the best of my knowledge there is no quick fix for cleaning showers or jointing materials that stop mould from growing on the surface.
If you look at silicone sealants used for shower screens and think of how the silicone looks after about 4-5 years, chances are you will have the same vision that I do: mould growing underneath the surface of the silicone where you can't get at it. The remedy for this unfortunately is scraping out the silicone joints (no easy or quick task I can assure you) and redoing the joints with fresh silicone. I would like you to ponder this question - If glass brick suppliers have access to a silicone product that is so mould free, why isn't the shower screen industry using it, eliminating mould altogether from the sides and bottom of their screens?

The advantage of mortar in this instance is that if mould begins to take hold, you can resort to good old fashioned elbow grease, a good scrubbing brush and mould remover to save the day.
If the mortar has discoloured then you could try bleach to whiten it up again (try a test area in a not so noticeable area first).

The disadvantage of silicone in this instance is that if mould starts, there's nothing you can do to stop it bar removing the silicone and starting over.

Do I need a frame for my glass bricks?     
There is no particular requirement to use an aluminium frame for your bricks. There are again, advantages and disadvantages either way.
Frameless Glass Brick / Block




You don't have to buy a frame! Timber frames may be substituted for aluminium which can create uniformity with other windows in your home. Occasionally, existing window opening sizes don't allow room for a frame, so messy alteration work can be avoided. Internally, plaster, timber or tiles can butt directly to the perimeter of the glass brick panel and leave a modern, streamline finish that can look quite effective.






For DIY people, this may prove to be a little more complicated than installing bricks into a frame. There is greater room for error in this application. Although not impossible for a DIYer, we recommend professional installation. If glass bricks are laid directly into brick or concrete wall openings, there is no movement allowance. This can mean that temperature changes or foundation movements can cause the glass bricks themselves to take the stress and one or more (in extreme cases) may chip or crack. In fire resistant applications, tests have only been done on glass bricks in frames so the frameless application is not appropriate.
Using Aluminium Glass Brick / Block


The frames are purpose made for glass bricks, they allow movement while providing stability (they stop the bricks from breaking and won't let them fall out). They give an attractive border to the glass bricks and are easy to install.


The sizes required for frames may mean that existing openings need modifying whereas the bricks may fit an opening nicely without a frame. It also costs more money to buy a frame.
Using Timber Glass Brick / Block Frames:  


There is no reason that timber frames can't be used for glass bricks if you feel you want to match other windows or the size suits an opening better. They just require more maintenance than aluminium i.e.: painting.
Using Steel (Fire Resistant) Glass Brick / Block Frames:  


If there is a requirement for fire resistance on say, a boundary wall, this can be achieved. 60 or 90 minute resistance is achievable with various 100mm or 95mm thick glass bricks but a steel frame is required to meet the tested and certified criteria.
New Breakthrough!
Using Aluminium (Fire Resistant) Glass Brick / Block Frames:  


Aluminium frames and normal 190 x 190 x 80 size Solaris glass bricks have now been deemed to achieve 60 or 90 minute fire resistance in Australia. The great advantage to our system is that the aluminium frame is 80mm wide (not the 100mm as needed with the steel frames) and the smooth aluminium surface is a far superior finish with powder coating or anodising than the rougher surface of steel frames.
What is the difference between Cheaper and more Expensive glass bricks?    
There used to be a definite difference in the quality between the Italian (Fidenza) and German (Solaris and Weck) glass bricks and the cheaper budget bricks from Poland, The Czech Republic (Vitrablok), Indonesian (Mulia & K.I.G.), Japanese (N.E.G.), and the various Chinese companies.

However, the Asian manufacturers are catching up fast. There are now Chinese glass bricks that we use in volume and are consistently impressing us with uniformity in size, shape, flatness of glass and glass lustre. In fact, they are with the industry leaders as far as whiteness of glass colour.

Now is probably the best time to take advantage of the cheaper prices of the various Asian bricks available as the quality has come ahead in leaps and bounds but the general public is not informed well enough at this time for the manufacturers to justify increasing the prices too much.

This is destined to change in the near future.

For ease of reference, the glass bricks are grouped into A grade bricks and B grade bricks in the following descriptions borne from our experience over the years using each product,               

A GRADE glass bricks: German glass bricks / blocks - Solaris & Weck a.k.a. Seves
Italian glass bricks / blocks - Fidenza (a.k.a.) Vetro Arredo & Seves


B GRADE glass bricks:


Chinese glass bricks / blocks - Jinghua & Seves
Japanese glass bricks / blocks - N.E.G.
Indonesian glass bricks / blocks - Mulia & K.I.G.
Polish glass bricks / blocks
Czech Republic or Bohemia glass bricks / blocks- Vitrablok a.k.a. Seves      

Flat faces and straight sides  



The B Grade glass bricks generally have more bows, dips and valleys than the A Grade bricks. The faces bow out more or valley in more and the sides can have dips in them that generally are not present in the higher quality A Grade bricks. Again, in context you may never notice a difference if you don't compare one type of brick to another so this may not be an issue for you.
Front face of glass brick aligned with back face  





The B Grade bricks tend to be less in alignment than the A Grade bricks. To describe what I mean by this, imagine you have a glass brick sitting on a table top. If the back face of the brick was aligned truly with the front face then it would stand solid and not rock (similar to a table with one leg shorter than the others). The glass brick should also stand up exactly vertical (no leans to the front or the back). This is a good measure of true alignment. Once again, in context, all glass bricks vary in the accuracy of their alignment but the B Grade bricks stand up to this test with slightly less success than the A Grade bricks.
Consistent thickness of glass bricks  


The B Grade bricks seem to vary in thickness more than the A Grade bricks. The variance can sometimes be up to 5mm and can be noticeable on one side of the wall. The A Grade bricks also vary in thickness, just less than the others.
The finished result  





When the glass brick wall is complete, one side will be the chosen 'face' side of the wall, the more important side. This side should look relatively the same no matter what brick you use. The back of the wall is where any discrepancies can be noticed and they show up generally through different joint thicknesses i.e.: a thin joint then a thick joint or a joint that tapers from one end of a brick to the other. If the back of the wall is in an unimportant visual area then you may not be concerned about it, but if it is in an entertaining area you may think differently about your choices.
 Summary and recommendations







My advice is that if you want a silicone system glass brick panel then disregard the B Grade bricks because the inaccuracies may be too great for a proper finish. If you have a small panel that is less than about 60 bricks then the price difference may not be enough to compromise the quality you desire (especially if you choose the wavy patterned brick as the prices are quite close to each other). If you have a large area or a lot of glass brick panels then a cost saving using B Grade bricks can be quite significant (especially with patterns other than the wavy pattern). If quality is your main focus then go with A Grade bricks. They will give you the satisfaction and piece of mind that only top quality products provide. If cost is your main focus and this is very understandable given that glass brick walls can set you back a tidy sum of money then the B Grade bricks are the go. I just recommend that you have them installed in mortar because it has a lot more room to accommodate the inconsistencies than silicone systems do. 
Should I use coloured glass bricks?     
Coloured glass bricks / blocks look fantastic and can add a new dimension to an already stunning glass brick feature wall. They can set a window off really well as a border around the edge or a pattern in the middle. Even a solid window of one colour can be inspirational. There are a few possible considerations that may influence your decision to use them. They are priced at approximately $9-12 each plus GST. If the glass brick window is the main source of natural light into the room then it will be coloured light that fills the room. You may want to ask this question first: "Would I like a coloured light globe in this room?". If the glass brick window is not the main source of light then it may be a sensational idea as a feature. Coloured glass bricks may limit rooms to certain colour schemes if you want to redecorate. i.e.: green glass bricks may look wonderful with a subtle green or even creamy yellow room colours but may look odd if you decide later on to redecorate with subtle pinks.
What size will my glass brick window need to be?     
The measurements required for the different methods of installation are shown in the following quick reference calculator for ease of use.
If your computer won't allow the calculator to work then use the following calculations to work it out:
(requires Active X control to use and you probably need to allow pop ups temporarily to activate)

Silicone Slim Frame -         Number glass bricks wide x 193mm + 50mm (same for height) frame is 25mm x 86mm
Silicone Standard Frame - Number glass bricks wide x 193mm + 80mm (same for height) frame is 40mm x 80mm
Mortar Standard Frame -    Number glass bricks wide x 200mm + 90mm (same for height) frame is 40mm x 80mm
Mortar Opening Frame -     Number glass bricks wide x 200mm + 190mm (same for height) (double frame) of 40mm x 80mm

If you are trying to fit an existing opening and the sizes just don't fit, please call us for on on site measure and quote because we specialise in fitting existing openings and have many options available other than DIY options.

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Technical Data... Sound, Thermal, Light, Weight, Fire Resistance etc, I need facts.     
Sound Qualities:

The glass bricks we stock have a rating of 39db up to 45db. This means that they effectively reduce the noise by 39 to 45db coming through the wall. This makes them ideal for night clubs, homes on busy roads or train lines, noisy neighbours or budding young rock and roll stars in the making.

Thermal Qualities:
The thermal insulation qualities of our glass bricks is generally equivalent to a brick veneer wall (if shaded) or standard double glazing. The degree of insulation is known as the k-value of the heat transfer [h/m2k]. The k-value of our glass bricks are on average 3.00/m2. The insulating quality is better the lower the value is (The K value is the rate of heat transfer through a square metre of material per change in degree Celsius, from one side to the other.).

Light Qualities:
The light transmission of our glass bricks ranges from approximately 85% for our larger size bricks 300x300x100 or 240x240x80 with little or no pattern or colour in the glass down to around 60% for the smaller size bricks 190x90x80, 240x115x80 or 115x115x80 with very detailed patterns, dark tinting or frosting. The more popular sized bricks being 190x190x80mm with no colour in the glass generally will transmit around 79-81%. The light transmission is very similar to that of standard windows with a distinct difference being the ability of the glass blocks to radiate light around the room rather than being reliant on the direction the light source i.e.: the sun.

Weight Qualities:
The weight of our standard sized glass bricks being 190x190x80mm with an 8mm nominal wall thickness is approximately 2.4kg.
The bullet resistant security glass bricks 190x190x80mm with a 25mm nominal wall thickness weigh approximately 5.1kg.
Other glass brick sizes have a nominal wall thickness of 8mm and approximately weigh as follows:

190x190x80   - 2.4kg
190x190x80   - 5.1kg (bullet resistant*, +90min fire rated security block)
190x190x160 -10.2kg (double thickness block FRL -/90/60 (90 min flame resistant, 60 min heat transfer resistant))
190x90x80     - 1.5kg
190x190x95   - 2.6kg
190x190x100 - 2.6kg
300x300x100 - 4.7kg
240x240x80   - 4.0kg
240x115x80   - 2.1kg
115x115x80   - 1.0kg
*Tests have been done where a .22 pistol fired at the face of the glass brick has only penetrated one side giving a high degree of security for person and property.
+Fire Resistance Level of -/90/- (see below for more information)

Fire Resistant Qualities:
We have a number of glass brick / block systems that that achieve an fire rating (F.R.L.) of -/60/
- and -/90/- (Structural Integrity/Prevention of Spread of Smoke and Fire/Insulation).
These systems use either steel frames and specific 100mm or 95mm glass bricks or aluminium frames and specific 80mm glass bricks.
The Fire Resistance Levels (FRL) relate to certain qualities of fire resistance and if they withstand fire for a certain amount of time (mainly 60 or 90 minutes - 60 minutes in general for domestic applications and 90 minutes for commercial and industrial applications)).

The first fire resistant quality measured in this three part breakdown of fire rating relates to structural integrity - e.g. will the structure maintain load bearing capabilities in a fire. This first part is not applicable to glass bricks as they are not considered to be a load bearing element (they will not bear the weight of other building elements other than themselves)

The second fire resistant quality measured relates to the prevention of spread of smoke and fire and is the fire rated quality most often required. This part relates to the ability of the structure to keep smoke and fire on one side of the wall for at least 60 or 90 minutes.

The third fire resistant quality relates to insulation - the prevention of thermal radiation through the wall.

Our fire rated glass brick / block systems can achieve the following FRLs:

FRL -/60/- , FRL -/60/60, FRL -/90-/, FRL -/90/60.

The systems that achieve -/60/60 and -/90/60 are quite expensive as they require double thickness glass bricks (2 glass bricks stuck together purpose made for this requirement) and must be specially ordered in from Germany as they are not a stock item.

Most, in fact every fire rated project we have done to date, the relevant authorities have been satisfied with the -/60/- and -/90/- FRL classes of our glass bricks.
The chances are very high therefore, that they will satisfy your requirements also.

To view a copy of the CSIRO approval letters click on link below:
CSIRO 60 Min Fire Rated Glass Block Brick Letter Of Opinion.pdf

CSIRO 90 Min Fire Rated Glass Brick Block Letter Of Opinion.pdf

For further fire related information visit CSIRO at

Compressive Strength Qualities:
Greater than 600 PSI or 100kg/cm2  
Please Note: The purpose of these figures is for calculating the bearing weight of the glass brick wall's own structure and not other elements intended to be supported by the glass brick wall as they are deemed not to be a load bearing element.
The bearing surface of an individual glass brick will withstand 15,000kg.
Further information currently being updated...


Do you have Drawings of how to build my glass block window?     
We have the following lists of drawings for your convenience (at the moment we only have cross section drawings showing how building alterations will look when existing windows or walls are modified to suit glass bricks but we will be adding other drawings soon)

Glass brick drawings For Brick Veneer Homes:

Brick Veneer Aluminium Frame Plaster Reveal
Brick Veneer Aluminium Frame Timber Reveal
Brick Veneer Full Thickness Timber Frame And Reveal
Brick Veneer No Frame Plaster Reveal
Brick Veneer No Frame Timber Reveal

Glass brick drawings For Solid Brick Homes:

Solid Brick Aluminium Frame Plaster Reveal
Solid Brick Aluminium Frame Timber Reveal
Solid Brick Full Timber Frame And Reveal
Solid Brick No Frame Plaster Reveal
Solid Brick No Frame Timber Reveal

Do I need a Building Permit for a glass brick window?     
There is no general rule that will cover all regulations for all city councils but there is a very general rule of thumb that may assist you to understand what you may need (please note that the responsibility is on you to verify the requirements of your council's building department and you should not rely on the information presented here as an authority).

No building permit required: (check with your building inspector) for window or door openings that are being replaced with glass blocks but the opening size remains unchanged (mainly due to no over head structural support being modified)

Building Permit required: (check with your building inspector) for window or door openings that are being made larger and structural support modifications needed)

The weight of the glass brick panel, planning restrictions including heritage and national trust restrictions and Body Corporate regulations also need to be taken into consideration.

Here are some useful links for building permit requirements:
MBAV Building Permit and Planning Services

Victoria Online Building Permits

There are so many options! Which one is right?     
There is no right or wrong with the design you choose or the materials you use. What I have attempted to provide you with here is my experience after having worked with these materials and coming across all the pitfalls described above. Glass bricks are generally something that you want because you really love the look of them! So experiment with a sketch or two to get your design right. Throw in some colours or patterns or even a stepped or curved frame and bring your imagination to life! Chances are that if you love them, lots of others will too. Even if others don't agree with your choices because it doesn't suit their tastes, so what? as long as you love them you can be satisfied. Borrow some artistic license and enjoy!



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