Do you know what happens in 90% of cases when I’m called to a site with problematic glazing? It turns out that the windows are good, the profiles are high-quality, and the insulated glass units are correct — but the installation is done with mistakes. And these mistakes turn premium glazing worth several million into a constant source of problems.
Mold on the reveals. Condensation on the frames. Drafts. Freezing. And after a couple of years — the windows start falling out of the openings because the fasteners have degraded. I have seen all of this with my own eyes. And in 99% of cases, there is one reason: installers either don’t know the technology or deliberately simplify it, saving time and materials.
Aluminum glazing is not like plastic windows in a typical apartment. It has different requirements, different materials, and a different approach. And mistakes here are costly — both literally (rework) and reputationally (an unhappy client).
Over the years, I have systematized all the typical installation mistakes. I developed a set of node solutions, instructions for installers, and introduced the position of a site inspection engineer who visits sites and controls quality. Because installation is no less important than the project itself.
Now I’ll tell you about the main mistakes installers make. And how to do it correctly.
Video
Error №1: galvanized fasteners instead of stainless steel — a direct path to disaster
Let’s start with the most critical mistake, which can literally cause windows to fall out of the opening. We’re talking about fastening the aluminum frame to the wall.
There are two main fastening methods: using mounting plates or drilling through the frame with anchors (concrete screws). In both cases, metal fasteners are used. And this is where the main problem begins.
Most installers use standard galvanized self-tapping screws. The cheap yellow ones from China. They attach the mounting plates to the aluminum profile — and that’s it, the problem is already built in.
What happens? When black metal (the steel screw) comes into contact with aluminum, a galvanic couple is formed. Even if the screw is galvanized, the zinc layer gets scraped off by the threads during installation. The bare steel is exposed, and an electrochemical reaction starts between the steel and the aluminum.
Acid is generated. The fastener begins to degrade. First slowly, then faster. After a year, two, or three (depending on conditions), the screw turns into dust. And the window is held in place by these screws.
I’ve seen a site where the windows were literally hanging by a thread. When we started dismantling them for rework, the mounting plates fell off on their own — the screws had completely corroded. These were windows weighing nearly a hundred kilograms each. If they had fallen while people were nearby — the consequences are terrifying to imagine.
Solution: only stainless steel fasteners
Only stainless steel fasteners can be used in aluminum. Stainless steel does not create a galvanic reaction with aluminum, does not degrade, and lasts for decades.
Yes, stainless steel screws are several times more expensive than galvanized ones. But this is the kind of saving that comes at too high a cost. The price of stainless fasteners is a fraction of a percent of the total glazing cost. At the same time, it guarantees that the windows will not fall out.
We purchase only stainless steel fasteners. This is прописано in our standards. Installers simply do not have a choice — there are no other screws available to them.
Moreover, even for fixing into concrete (anchors through the frame), we select high-quality screws with a thick galvanized coating. We do not use cheap Chinese yellow ones — their coating is thin and wears off quickly. We look for manufacturers with high-quality galvanizing — for example, the Belarusian “Sarmat.” Their coating is thicker and lasts longer.
Ideally, stainless steel should be used here as well. But long stainless anchors (120–150 mm) are difficult and expensive to find. Therefore, we allow galvanized fasteners, but only of high quality.
Error №2: fastening into the thermal break — a pointless waste of fasteners
The second common mistake is related to a misunderstanding of the structure of a thermally broken aluminum profile. Installers see the profile, see the thermal break in the middle — and drive a screw for the mounting plate into it.
This makes no sense. The thermal break is a plastic (polyamide) insert. It does not bear any load and has no structural capacity. A screw driven into plastic holds nothing. The window is essentially hanging in the air.
Moreover, the screw pierces the thermal break, нарушает its integrity — and creates an additional thermal bridge. In other words, it worsens the thermal performance without giving anything in return.
Solution: fastening only into the inner chamber
Mounting plates must be fixed only to the inner aluminum chamber of the profile — the part located in the warm zone, on the interior side.
The inner chamber is the section of the profile from the thermal break to the inner edge. It is made of metal, strong, and capable of bearing loads. A screw fastened into it holds securely and provides real fixing.
At the same time, the thermal break remains intact and is not penetrated, continuing to perform its function — breaking the thermal bridge between the external and internal parts of the profile.
Error №3: mounting plate on both chambers — a direct thermal bridgeмостик холода
Another mistake I see regularly: an installer takes a long mounting plate and fastens it to both the inner and outer chambers of the profile, on both sides of the thermal break.
There is no logic in this. The outer chamber is cold, it is outside. The inner chamber is warm, it is inside. Between them is the thermal break, which interrupts heat transfer.
And a mounting plate is metal — an excellent conductor of heat. When it is fastened through both chambers, a direct thermal bridge is created. Cold from outside travels along the plate directly inside. The thermal break stops working.
The result: freezing in the areas where the plates are installed, condensation, and possibly even ice formation in winter. Overall heat losses also increase.
Solution: plates only on the inner chamber
Moreview accepts insulated glass units with a thickness ranging from 46 to 60 millimeters. This is a wide range that provides flexibility in choosing the glazing configuration.
If you want a single-chamber unit with an energy-saving coating — 46 mm is sufficient. If you need a double-chamber unit for better thermal insulation — 60 mm can be used.
The insulated glass unit is bonded into the sash using a special technology. This is not just installation with gaskets, as in standard systems — structural glazing with sealant is used here. The result is a single rigid structure that does not rattle, does not loosen, and works as a monolith.
Height up to 6 meters — capabilities that standard systems do not have
Error №4: fastening with concrete screws — incorrect drilling of holes
When we fix the window not with plates, but with through fasteners (concrete screws), the hardware groove of the profile is used. We drill through the frame into the concrete and drive in a long screw — the window is secured.
But there is a nuance here as well. Many installers drill straight through both walls of the groove. This creates a through hole where the concrete is visible. It is not aesthetically pleasing and not entirely correct.
Proper technique
We drill a hole only in the near wall of the hardware groove — just enough for the screw head to pass through. Then, using a thin drill bit, we drill the far wall and go into the concrete.
We drive in the screw — the head is recessed into the first wall, while the screw passes through the far wall and goes into the concrete. The hole in the near wall is covered with a plug (a plastic decorative cap matching the profile color).
The result is neat: from the outside, only a small plug is visible, not a through hole. In addition, the far wall of the groove acts as an additional support, distributing the load.
Error №5: cheap mounting foam
The installation joint between the frame and the opening is filled with foam. It may seem simple — just buy a can and apply the foam. But the quality of the foam critically affects the durability of the entire assembly.
Cheap foam quickly loses elasticity. It becomes rigid and brittle. With temperature deformations (aluminum expands and contracts, and the building also “breathes”), rigid foam cracks. Gaps appear, leading to drafts and heat loss.
This is especially important in timber construction, where the building settles and undergoes seasonal deformations. If обычная foam is used — within a year or two, the installation joint will deteriorate.
Solution: high-quality elastic foam
We use professional, high-quality foams. For wooden houses, we use special elastic formulations, such as Soudal Flexi-Foam (blue). It is soft and flexible, compensates for the деformations of both aluminum and wood. The joint remains airtight for decades.
Yes, such foam is two to three times more expensive. But aluminum glazing is a high-end product. Saving on installation materials is not reasonable. The cost of quality foam is negligible in the scale of the entire project.
On all projects, we use only verified materials. Installers are not allowed to bring their own foam. Only what is provided by the company is used.
Error №6: cheap or improperly applied PSUL
PSUL (pre-compressed sealing tape) is a tape that is installed between the window reveal and the frame. It prevents water from entering the installation joint and provides external sealing.
The quality of PSUL is critical. Cheap options quickly degrade under UV exposure. Black PSUL turns yellow, becomes brittle, and starts to crumble. Within a year or two, gaps appear in the installation joint, and water begins to penetrate.
I have seen sites where cheap PSUL completely disintegrated within one season. During inspection, it simply crumbled in my hands. We had to remove it entirely and seal the joints with sealant — a temporary solution, but there was no other option.
Solution: high-quality PSUL from trusted manufacturers
We use PSUL only from trusted manufacturers — mainly Soudal. Yes, these are expensive materials. But installation materials for aluminum glazing are not something to save on.
An aluminum window is expensive. It should last a long time. If you save 5$ on PSUL and then face problems a year later — that is not saving, that is poor judgment.
Error №7: ignoring vapor-permeable tapes on the exterior
Installation foam must be protected from sunlight and precipitation. UV radiation destroys the foam, and water washes it out. An unprotected installation joint will last one to two years, after which it will begin to degrade.
On the exterior side, the joint is covered with a vapor-permeable waterproof tape. This is an important term that many people do not understand.
“Hydro” — protection against water. The tape does not allow water to enter the joint.
“Vapor-permeable” — allows water vapor to pass outward. The dew point occurs within the installation joint, where capillary moisture forms. It must be removed so the joint can “breathe.”
If the joint is sealed with a non-vapor-permeable material (for example, simple polyethylene), moisture will remain inside, leading to deterioration and possibly mold growth.
Proper technique
On the exterior, we install a vapor-permeable waterproof tape (black, specialized). It repels water but allows vapor to escape from the inside.
For the lower junction (if the window is on a parapet) — the same applies, plus a drip cap installed above.
Error №8: improper waterproofing of floor-to-ceiling windows
A separate issue is floor-to-ceiling windows installed directly on concrete. It is very difficult to provide proper waterproofing at the bottom. We have tried many materials — various bitumen tapes from Technonicol, roll materials. The problem is that they are not vapor-permeable.
You heat them with a torch and stick them on — it seems to hold. But they do not allow moisture to escape. Over time, they come unstuck, and water begins to penetrate.
Solution: liquid waterproofing Frankosil
The only solution that truly works is liquid waterproofing, for example, Frankosil. It is expensive, but it works.
The process: the window is placed on the base, the first layer of waterproofing is applied, a special membrane is glued on, and then a second layer is applied. This creates reliable protection against water while still allowing vapor to escape.
On all projects with floor-to-ceiling windows, we use only this technology. We have not found any other reliable alternatives.
Alternative: STIZ A sealants
There is also another option — special sealants such as STIZ A (an exterior, vapor-permeable waterproof sealant). It can be used to seal the installation joint.
However, there is a nuance: STIZ does not perform well at the bottom, where there is intense water exposure. When water stands there continuously and the structure is constantly wet, it absorbs moisture and fails.
Therefore, we use STIZ only on the sides and at the top, where the load is lower. At the bottom — either liquid waterproofing (for floor-to-ceiling windows) or STIZ (if the window is installed high above the ground and the area remains dry).
Error №9: poorly applied interior vapor barrier tape
This is probably the most common mistake I see on projects. The interior vapor barrier tape is a critically important element, but installers often treat it carelessly.
Vapor barrier is needed to isolate the installation joint from moisture inside the room. Inside, vapor is generated (cooking, showering, people breathing), and it tends to enter the монтажный шов. If moisture gets in, mold will appear on the reveals, freezing and leaks may begin.
I’ve seen many videos online where black mold covers the reveals. In 90% of cases, the cause is the lack of a vapor barrier or poor sealing.
Typical installer mistakes
Proper technique
The vapor barrier tape must be of high quality. There are expensive options with a full butyl layer (for example, Soudal). There are cheap ones with two adhesive strips and a fabric-like middle — these are poor-quality and do not hold well.
The tape must be properly bonded both to the frame and to the opening, with no gaps and no loose sections. If it does not stick to the opening, primer must be used.
It should be installed at a 90-degree angle to the reveal surface, as close to the opening as possible, so that when the finishers come to work on the reveals, they can work easily and the tape does not interfere.
We include this in our installers’ guidelines. We also have an inspector who accepts the work and checks the quality of the vapor barrier installation. If it is done poorly, it must be redone.
Error №10: foamed and immediately closed — the foam did not have time to expand
The final mistake is related to the foaming technique. Installation foam expands by absorbing moisture from the air. This is a chemical reaction that requires both time and humidity.
Installers often do the following: they foam the joint, immediately cover it with a vapor-permeable waterproof tape on the outside and a vapor barrier on the inside. The joint is closed — but the foam has not had time to expand properly.
In a closed space without access to moisture, the foam expands poorly. This results in voids, cavities, and underfilled areas. Thermal insulation is reduced, and drafts may occur.
How we control the quality of installation
I may be overwhelming you with information, but this is important. Installing aluminum glazing is not just “fasten it and you’re done.” It involves many nuances that must be followed.
In our company, we have developed a control system:
Assembly details album — standard, proven solutions for different situations.
Standard installation materials — only tested, high-quality materials. We purchase them centrally and do not give installers a choice.
Installer instructions — step-by-step guides on how to install each assembly.
Installation inspector — a person who visits sites, accepts the work, and controls quality. If something is done poorly, they require it to be redone.
This allows us to maintain consistently high quality. The client receives not only a good design and high-quality materials, but also proper installation. And installation determines how everything will perform over the years.
Aluminum glazing installation is not something where you can cut costs. Cheap materials, rushing,
