Glass curtains vs aluminium enclosures: which to choose for your terrace
Short answer: Frameless glass curtains are better if you want clear views, to be able to open the terrace up almost completely and to change the façade as little as possible. A thermally broken aluminium enclosure with double glazing is better if you are after thermal and acoustic insulation and a genuinely weathertight seal, so that you can use the terrace as an extra room. In price per m² they are close; the difference lies in how you are going to use it.
What is the difference between glass curtains and an aluminium enclosure?
Both options enclose the terrace, but they work in different ways.
- Frameless glass curtains: tempered glass panels, usually 8 or 10 mm thick, that slide along a top track and a bottom track. There are no vertical frames between the panels. When you open them, they all gather at one side and the opening is left practically clear.
- Aluminium enclosure: sliding or casement windows with an aluminium frame running all the way round each panel. It can have a thermal break and double glazing with an insulating air gap.
Neither option is better in the abstract. There is a better option for each terrace and for each use.
Point-by-point comparison
| Criterion | Frameless glass curtains | Thermally broken aluminium with double glazing |
|---|---|---|
| Views | Excellent, with no vertical frames | Good, with visible frames |
| Opening | Almost complete, with the panels gathered at one side | Partial with sliding windows |
| Thermal insulation | Moderate: blocks the wind and makes the most of the sun | High |
| Sound insulation | Moderate | High |
| Water and air tightness | Good, but not total: small gaps remain between the panels | High, with seals and a watertightness rating |
| Impact on the façade | Low | Medium to high |
| Guide price | €200 – €450/m² | €250 – €400/m² basic; €350 – €550/m² or more with a thermal break |
| Maintenance | Cleaning the glass and tracks | Cleaning the frames, runners and seals |
Prices are a guide only and vary with the measurements and the system. For the details, see our guide to how much it costs to enclose a terrace.
Which insulates better against cold and noise?
Aluminium with a thermal break and double glazing. It is a system designed to insulate: the air gap in the glazing and the barrier in the frame slow down the passage of heat and noise.
Frameless glass curtains make a terrace far more comfortable than leaving it open. They block the wind, hold back the rain, reduce street noise and, in winter, let the sun warm the space. But they are single-pane (monolithic) glass with small gaps between the panels, so they do not insulate like a double-glazed window. Anyone who promises otherwise is exaggerating.
Which is more watertight in the rain?
Aluminium. Good-quality sliding and casement windows have seals and drainage designed to carry the water away, and they are tested to rate their watertightness.
Glass curtains keep out normal rain without any problem. In heavy, wind-driven rain a little water may get in through the gaps between the panels or through the bottom track. On very exposed terraces this is reduced with drained tracks and a good installation. If wind is the big problem on your terrace, you will want to read how to protect your terrace from the levante.
Which gives better views and a wider opening?
Glass curtains, by far. With no vertical frames, your view of the sea or the garden is uninterrupted. And in summer you can gather all the panels away and have the terrace as open as it was before.
A two-panel aluminium sliding window only opens up half the width. With three or more tracks you get a wider opening, but part of the space is always taken up by the panels slid to one side.
What about planning permission?
Both need council approval and, in blocks of flats, the agreement of the community of owners. Glass curtains usually have a slightly easier time because they change the façade less. Even so, it depends on each town hall's bylaws. We explain it in our guide to planning permission in Andalusia and our article on enclosing a terrace in a block of flats.
When do we recommend glass curtains?
- Terraces with views you want to keep.
- Homes on the coast where the terrace is used mainly from spring to autumn and, in winter, you want to keep the wind out.
- Buildings where the community of owners requires a discreet enclosure.
- Porches and bar and restaurant terraces that want to open up completely in good weather.
- Combined with a bioclimatic pergola or a patio roof to create a covered, enclosed space that you can open up whenever you like.
When do we recommend aluminium?
- You want to make the terrace part of the living room or use it as a study or bedroom all year round.
- The terrace faces north or insulation is your priority.
- There is a lot of traffic noise and you need real sound insulation.
- You need very high watertightness because the terrace is extremely exposed to rain and wind.
For aluminium enclosures and windows we work with systems from manufacturers such as Strugal or Finstral. For glass curtains, we use systems such as those from C3 Systems.
What about maintenance?
Both are easy to look after. With glass curtains, you just need to clean the glass and keep the tracks free of sand and dirt so that the panels slide smoothly. With aluminium, clean the frames and runners and check the seals from time to time. On the coast, rinsing with fresh water every so often extends the life of any hardware exposed to salt air.
Can't decide between the two? We'll advise you on your terrace
The best way to decide is to look at the terrace, which way it faces and how you are going to use it. We visit, measure and give you a free quote, with both options if that makes sense. Take a look at our glass curtains, check our prices and write to us via our contact page or by WhatsApp on 665 26 11 55.
FAQ
Which is better, glass curtains or an aluminium enclosure?
It depends on how you will use it. Glass curtains win on views, a fully open front and a discreet look on the façade. Aluminium with a thermal break wins on thermal and sound insulation and on watertightness.
Do glass curtains insulate against cold and noise?
They make a terrace far more comfortable than leaving it open: they block the wind, hold back the rain and reduce noise. But they do not insulate like an aluminium window with a thermal break and double glazing.
Do glass curtains let water in?
Not in normal rain. In heavy, wind-driven rain a little may seep in through the gaps between the panels or the bottom track, which can be reduced with drained tracks and careful installation.
Are glass curtains safe?
They are made of tempered glass, which is much stronger than ordinary glass and, if it does break, shatters into small fragments. In exposed areas or where there are children, you can opt for thicker glass or laminated glass.
Sources
Related articles
How much does it cost to enclose a terrace with glass curtains? Guide prices per m²
As a guide, enclosing a terrace with glass curtains in Spain costs between €200 and €450 per square metre installed; a basic sliding aluminium enclosure is around €250-400/m² and a bioclimatic pergola €400-900/m². The final price depends on the size, the glass thickness, the opening system and how easy the site is to access, which is why only a quote based on real measurements gives you the exact figure.
Read the guide
Do I need planning permission to enclose my terrace? A guide for Andalusia
Yes. In Andalusia, enclosing a terrace always requires some form of council approval: usually a declaración responsable (self-declaration) or a minor works licence, depending on each council's bylaws and on whether the enclosure changes the façade and the built area. If you live in a block, you also need the agreement of the owners' association.
Read the guide
How to protect your terrace from the levante in Cádiz
The most effective way to protect a terrace from the levante in Cádiz is to enclose the exposed side with securely anchored toughened glass curtains and, if you also need shade, to combine them with a pergola or roof designed for wind loads. Conventional awnings must be retracted when the levante blows hard, and on the coast every material has to be able to withstand the salt air.
Read the guide