If you've decided that roller shutters are the ideal shading and security solution for your new windows, congratulations! You've made an extremely practical choice. However, the order doesn't end there. There's a crucial question your aluminium fabricator will ask - one that often catches homeowners off guard:
"Do you want the shutter box built-in or surface-mounted?"
For a roller shutter to work, it needs an axle around which the slats wind and a "box" to conceal them when raised. Where exactly this box is positioned dramatically affects the clear height of your balcony door, the room's brightness and even the home's thermal insulation.
Let's look in plain language at what each term means and which is the right choice, especially if you're renovating an older property.
It's called "built-in" because it sits directly on top of the window profile. The window and the shutter box form a single, inseparable unit manufactured at the factory and installed as one piece inside the wall opening.
This is the cleanest and most elegant solution. Because the box sits right below the lintel, it blends harmoniously with the window. Often, from the building's exterior, the box isn't even visible, keeping the façade perfectly flat.
The inspection cover (for changing the motor or strap) is on the interior side of the house. You don't need to go out on the balcony (or lean into the void from an upper floor) to repair it.
This is its biggest drawback. The box takes up roughly 18 to 22 centimetres of the total wall opening. If your opening is already low (e.g. 2.10 m), adding a built-in shutter brings the clear passage height down to 1.88 m! You literally risk hitting your head.
Because the box communicates directly with the interior, if you don't choose a thermally broken box with internal insulation, it will let plenty of cold and noise in during winter.
It's called surface-mounted (or add-on / "fascia") because it doesn't go inside the wall opening but is bolted onto the exterior face of the building, directly above the window.
Because the box sits "outside and above" the wall, your balcony door exploits 100% of the available opening. This means taller doors, more airflow and abundant natural light in the room. It's the ultimate solution (and often the only option) when renovating old apartments with low lintels.
The box sits entirely outside the building envelope. There is no hole communicating with the room interior (especially if the shutter is motorised and only a single cable passes through). Freezing air stays permanently outside.
The box protrudes from the building façade like a small "hood". Although modern designs come in oval and very sleek shapes, it remains a visible element that slightly alters the exterior look. In some strict apartment blocks, it may conflict with the co-ownership regulations.
If the shutter breaks down, the technician must open the cover from the outside. If the window is on an upper floor without a balcony, access is extremely difficult.
The choice between built-in and surface-mounted is purely a matter of geometry and available space.
Here the choice is almost always the Built-In (Thermally Broken) Box. The engineer has planned large openings from the start (e.g. 2.40 m height), so the 20 centimetres won't be missed. The result will be ultra-modern and aesthetically flawless.
If the total wall height (from floor to top marble) is below 2.20 m, the Surface-Mounted (Add-On) Box is the wisest move. It's not worth sacrificing height, light and comfort just to keep the box hidden on the façade.
For small, high windows that nobody walks through, the height loss usually doesn't bother us. A built-in box fits there without any problem.
💡 Tip: Before deciding, measure the opening height precisely (from floor to lintel). If it's above 2.30 m, a thermally broken built-in box is the optimal choice. Below 2.20 m, the surface-mounted box literally saves your headroom.
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