A curtain wall is an exterior facade solution built by fitting glass or panels into an aluminium grid of mullions (vertical members) and transoms (horizontal members) mounted in front of a building's structural wall. Depending on how that grid holds the glass or panel, curtain wall facade types fall into three main groups: capped, semi-capped and structural silicone. Each offers a different look, installation method and maintenance profile.
What is a capped curtain wall
In a capped system, glass or panel rests on the aluminium mullion and transom profiles and is then held in place by a visible pressure cap, fixed with screws or a snap-lock. This cap forms a thin frame line across the facade's outer surface. The biggest advantage of a capped system is that glass or panels can be removed and refitted on site relatively easily, which simplifies repair or replacement of a damaged unit. Because the grid lines are visible, this type suits projects aiming for a more classic or modular facade appearance.
What is a semi-capped curtain wall
In a semi-capped system, only one direction, either the vertical mullions or the horizontal transoms, gets a visible cap, while the other is left flush and sealed with structural silicone. The most common approach leaves the vertical lines flat and uncapped while capping the horizontal lines, giving the building a vertical, flowing emphasis (this can also be reversed). Compared with a fully capped facade, this system shows fewer visible frame lines for a more contemporary look, while still being somewhat more practical to install and service than a fully structural-silicone facade.
What is structural silicone glazing
In a structural silicone facade, also known as structural glazing, glass or panel is bonded directly to the aluminium grid using structural silicone sealant, with no visible pressure cap. From outside, the mullion and transom lines are almost invisible, and the facade reads as one continuous, unbroken glass or panel surface. This system is a common choice for office buildings, shopping centres and landmark projects seeking a modern, minimal facade. Getting the structural silicone's material quality and application thickness right is critical, so structural glazing work should always be designed and installed by an experienced team.
Comparing the three systems
- Appearance: frame lines are clearly visible in a capped facade, visible on one axis in a semi-capped facade, and almost invisible in a structural silicone facade.
- Maintenance and replacement: a capped system offers the easiest panel replacement; a structural silicone facade requires more skilled labour for any replacement.
- Installation precision: structural silicone facades demand the most care around bond thickness and cure time.
- Architectural effect: structural silicone delivers the most minimal, modern look, while a capped system creates a more modular, visible grid pattern.
Which facade material pairs with each system
A curtain wall grid can hold glass, composite panel, or a combination of both. When composite panel is used, capped or semi-capped systems are generally preferred, since mechanically fixing the panel edges adds a margin of security. With glass, all three systems can be applied; the choice depends on which look the design prioritises. Learn more about our composite panel option on the composite facade cladding page.
Selection criteria for a hot, coastal climate
In a coastal area such as Famagusta, the surface finish on profiles and cap elements needs to hold up against salt air. For structural silicone facades, the sealant grade must also offer strong UV and heat resistance, since its performance directly affects facade safety through the region's long, sunny summers. For capped and semi-capped systems, regularly checking the weatherproofing gaskets on cap profiles matters for keeping out water during North Cyprus's rainy, humid winter season.
Installation and design process
A curtain wall project starts with an on-site survey of facade dimensions and the supporting structure. During design, the choice of capped, semi-capped or structural silicone is settled based on budget, architectural preference and expected maintenance. The aluminium grid is prepared off-site or on-site and assembled at the installation location, then glass or panel is fitted. For structural silicone facades, bonding must happen under controlled conditions with the correct cure time. Learn more about our project design and manufacturing process.
Maintenance differences
For capped and semi-capped facades, maintenance mainly involves periodically checking the weatherproofing gaskets in the cap profiles and the tightness of screw fixings. For structural silicone facades, the key maintenance task is checking the structural silicone joints for cracking or loss of elasticity over time; if an issue is found, the joint needs to be resealed. In all three systems, the glass or panel surface is designed to be cleaned with standard methods.
Which building type suits which system
In residential projects, especially villas and low-rise buildings, capped or semi-capped systems are often preferred for their easier panel replacement and more economical installation process. Office buildings, shopping centres and landmark projects, aiming for a minimal, continuous look, often favour structural silicone. Industrial buildings typically pair composite panel with a capped or semi-capped system, balancing durability with ease of maintenance and replacement.
Why quality control matters for structural silicone
In a structural silicone facade, applying the sealant at the correct thickness onto a clean surface is a critical safety step. Temperature and humidity during application need to fall within the sealant manufacturer's specified range for the cure process to complete properly. For this reason, structural glazing work should always be carried out by an experienced, specialised team following the manufacturer's instructions exactly, since poor application can risk bond failure over the long term.
Frequently asked questions
What is the main difference between a capped and a silicone facade?
In a capped facade, glass or panel is mechanically fixed with a visible cap profile. In a silicone facade, there is no cap; glass or panel is bonded with structural silicone sealant, leaving the frame lines invisible.
Which projects suit a semi-capped facade?
A semi-capped facade suits projects that want a visible line in one direction and a flush look in the other, typically to create a vertical or horizontal emphasis. It sits visually between a capped and a fully silicone facade.
Is a structural silicone facade more expensive?
Cost depends on facade area, glass or panel type, sealant quality and the precision of workmanship required. These factors are assessed together after a project-specific survey.
What materials can a curtain wall use?
Glass, composite panel, or a combination of both can be fitted into a curtain wall grid. Material choice depends on the building's use and the desired appearance.
How is a structural silicone facade maintained?
The key maintenance task is periodically checking structural silicone joints for cracking or loss of elasticity. If an issue is found, the joint should be resealed.
Choosing between capped, semi-capped and structural silicone curtain wall systems comes down to your architectural goals and maintenance expectations, settled during project design. To discuss the right solution for your project, reach out through our contact page.
