Aluminium Windows: Frame Sections, Advantages and Applications

Aluminium windows are windows whose frames and opening sashes are made from extruded aluminium sections. Fabricators cut these sections, join them at the corners and fit glass, rubber gaskets, rollers and locks. Most homes use them as sliding or casement windows, from Bengaluru apartments to villas.

What Are Aluminium Windows Made Of?

An aluminium window is a system of four parts, and each part affects how well the window works.

• Profiles: the shaped aluminium lengths, made by pushing hot alloy through a die (extrusion).
• Glass: single, laminated or double-glazed units.
• Hardware: rollers, handles, hinges and locks.
• Seals: EPDM rubber gaskets and brush (wool-pile) seals that keep out rain and dust.

What Are the Frame Sections of an Aluminium Window?

An aluminium window is built from a set of named frame sections. Knowing the names helps you read a fabricator's quote.

• Outer frame: the fixed section anchored to the wall opening.
• Track: the bottom and top rails a slider runs on. A 2-track holds two shutters; a 3-track adds a mosquito-mesh shutter.
• Sash (shutter): the moving frame that holds the glass.
• Interlock: the meeting section where two sliding sashes overlap and seal.
• Mullion and transom: vertical and horizontal bars that divide a large window into panels.
• Glazing bead: the clip-in strip that holds the glass in the sash.

Local fabricators also sell sliders by series. "Domal" sections have rounded edges, while slim series use narrow, flat faces. Ask for the section weight in kg per metre, because heavier sections usually mean thicker walls.

What Are the Advantages of Aluminium Windows?

The main advantages of aluminium windows are strength, slim frames, durability and low maintenance.

• Strength-to-weight: aluminium (2.7 g/cm³) weighs about a third as much as steel, yet slim sections can carry large panes.
• Slim sightlines: less frame means more glass and daylight than a uPVC or wooden frame of the same size.
• No rot or termites: unlike teak or sal frames, aluminium does not swell, warp or get eaten.
• Stable in heat: aluminium expands about 24 µm per metre per °C, against about 61 for uPVC.
• Low upkeep: powder-coated and anodised finishes need cleaning, not repainting.
• Recyclable: scrap aluminium can be remelted using about 5% of the energy of new metal.

Over a 1.5 m frame and a 30 °C swing, aluminium moves about 1.1 mm and uPVC about 2.7 mm.

Which Finish Survives Monsoon and Coastal Air?

Aluminium windows handle rain and humidity well, because aluminium does not rust the way steel does. The finish and the drainage decide how well they last.

Bengaluru falls in the temperate climate zone under the National Building Code (NBC) 2016, so standard powder coat suits most homes. Coastal cities such as Mumbai, Chennai and Goa need the thicker finish.

Do Aluminium Windows Save Energy?

Aluminium windows save energy only when the frame has a thermal break and the glass blocks solar heat. Plain aluminium lets heat pass straight through the frame.

• Thermal break: a polyamide (nylon-type) strip locked between the outer and inner aluminium, cutting the metal heat path.
• U-value: how fast heat passes through. Uw is the whole window, Ug the glass, Uf the frame. Lower is better.
• SHGC (solar heat gain coefficient): the share of sunlight heat the glass lets in. Lower keeps rooms cooler.
• Low-E glass: glass with a thin metallic coating that reflects heat.

Aluminium vs uPVC vs Wood vs Steel: Which Window Is Better?

Aluminium is better for large openings and slim frames; uPVC is better for insulation and tight budgets.

Prices vary by system, glass and city. One Bengaluru rate analysis by InfraLens puts a basic sliding window with 5 mm plain glass at ₹2,929–3,820 per sq m, about ₹272–355 per sq ft. Branded systems cost more; get at least three like-for-like quotes.

What Are the Disadvantages of Aluminium Windows?

The main disadvantages of aluminium windows are poor insulation without a thermal break, higher cost for good systems and sensitivity to poor fabrication.

• Frames feel hot in sun and can collect condensation in cold or AC rooms
• Thermal-break systems and double glazing raise the price
• Thin, cheap sections flex and let in dust and water
• Sliders seal less tightly than casement windows

Choose uPVC when budget or insulation comes first, or in cold hill climates without a thermal-break system.

Which Window Type Suits Each Room?

Aluminium windows suit any room, but the window type should match the room.

• Balconies: large sliding windows and doors with slim interlocks.
• Bedrooms and kitchens: casement windows for better airflow and a tighter seal.
• Bathrooms: top-hung or louvred ventilators with frosted glass.
• Living rooms: large fixed panes beside opening panels.

For styles and layouts, see our guide to window designs for home.

What Should You Check Before Buying, and How Do You Maintain the Frames?

Choose aluminium windows by checking the sections, finish, glass and hardware in writing.

• Standard: ask if the system meets IS 1948:2024, the BIS specification for aluminium framed doors, windows and sliders.
• Sections: profile brand, series and weight per metre.
• Finish: powder-coat warranty or anodic thickness in microns.
• Glass: type and thickness, and SHGC for sunny walls.
• Hardware and service: roller and lock brands, and spare-part support.

Keep the windows working with a short routine:

1. Before the monsoon, vacuum the tracks and clear the weep holes.
2. Wipe frames with mild soap and water; avoid abrasive or acidic cleaners.
3. Lubricate rollers and locks with a silicone spray.
4. Check gaskets and sealant each year and replace any that crack.