In a curtain wall, everything seems to be perfect… until the first leak appears. And the problem is almost always in the same place: the rubber seal. Poor installation of rubber seals for glass in aluminium windows can ruin a façade that, on paper, was flawless.
Let’s review the most common mistakes when installing seals in curtain walls and how to avoid them so that the work does not surprise you with the first side wind or the first serious downpour.
What is actually tested in a curtain wall?
In a lightweight façade system, glass, aluminium and sealants work together to ensure watertightness, thermal and acoustic insulation. Rubber seals are responsible for:
Sealing the perimeter between the glass and the profile.
Accompanying the expansion of the aluminium and glass.
Preventing vibrations and air noise.
If you want to learn more about types and functions, you can find more information in this guide on seals for aluminium windows, types, measurements and installation.
Common mistakes when installing seals in curtain walls
Installation faults and incorrect seating
A classic: the seal for aluminium windows does not fit properly in its housing. This may be due to:
- Dirty profile (chips, sealant residue, dust).
- Insufficient pressure: the seal is ‘half out’.
- Stress caused by forcing the glass to fit.
Result: micro-channels of water, air whistling and, over time, premature deformation of the rubber.
Incorrect use (or absence) of lubrication
Fitting rubber seals to aluminium windows dry, especially on radii or corners, is an invitation for the seal to twist, mark or even tear.
- Without adequate lubricant, the seal gets dragged and stretched.
- If an unsuitable product is used (mineral oils, for example), it can damage the rubber or leave residues that attract dirt.
Ideally, a lubricant compatible with the seal material (EPDM, TPE, etc.) should be used.
Impossible radii of curvature
Another common mistake is to ask the seal to make a curve that it is not designed to make:
- Radii that are too tight for the rubber to follow.
- Deformations that open the sealing lip and allow water to enter.
Here the problem is not only one of assembly, but also of design: it is necessary to choose rubber seals for aluminium window panes with a geometry suitable for the curtain wall system and its radii.
Poorly resolved cuts and open joints
Cuts are a critical point:
- Poorly aligned straight cuts → the seal opens over time.
- Joints without adhesive or heat → micro-cracks appear where water can enter.
Short sections that generate too many joints in the same panel.
In many cases, it is recommended to cut at a mitre (45°) and secure the joints according to the system manufacturer’s instructions.
How to avoid these mistakes on site
Some basics that make a difference:
- Prepare the housings: clean thoroughly before installing the joint.
- Use compatible lubricants; never improvise with aggressive oils or soaps.
- Respect the minimum radii indicated by the curtain wall system.
- Plan lengths to reduce joints and make clean, precise cuts.
- Verify, with water tests, that the seal is working before accepting the façade.
> For more information on types and designs of curtain walls.
Do you need customised seals for your curtain wall?
Each façade system has its own particularities: glass widths, chambers, wind pressures, watertightness requirements… That is why a standard seal often falls short.
At ISOGOM, we specialise in the design and manufacture of custom rubber seals for aluminium windows and curtain walls, adapting:
- Geometry and hardness.
- Material (EPDM, TPE, silicone, etc.).
- Finishes and tolerances according to project requirements.
If you want to avoid surprises on site and reduce incidents due to leaks, contact us.
