Trapezoid windows
A trapezoid is what a window becomes when it has to follow something that is not level — a stair soffit, a mono-pitch roof, the raked ceiling of a mezzanine. One jamb stands taller than the other and the head runs on a slope between them, which changes two things at once: the sloping member has to shed water outward instead of letting it stand, and every bead and mitre along that rake is cut to an angle only the survey can supply. The arrangement that works puts the raking part in as a fixed field and keeps the opening leaf in the square portion beneath it, where ordinary hardware still fits.
- two heights and a rake what gets measured
- sheds outward the sloping head
- in the square field where the sash goes
What a raking head changes
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Sloping member
Head
Cut to the angle from the survey
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Outward fall
Drainage
Nothing stands on the rake
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Angled beads
Glazing
No mitre is a right angle
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Four unequal sides
Glass
Cut to shape, then toughened
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Square portion
Opening
Standard gear fits only there
Let's calculate
the cost of glazing
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Why choose aluminium windows?
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Durable EPDM seals
Three contours of EPDM seals keep the glass off the aluminium and close the gap between sash and frame, so dust, humid salt air and wind-driven rain stay outside.
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Foamed thermal inserts
Foamed inserts fill the profile chambers and stop air circulating inside them, so less outside heat and street noise passes through the frame into the cooled room.
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Polyamide thermal breaks
Glass-filled polyamide thermal breaks up to 40 mm wide keep the outer and inner shells apart, so the frame holds its shape and its insulation through a UAE summer.
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Energy-efficient double glazing
Double glazing up to 60 mm thick puts a sealed gap of still air or gas between the hot street and the cooled room, so less heat crosses the glass into the room.
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How a trapezoid window is set out
- Both jamb heights taken separately The difference is the whole shape
- Rake angle measured, not calculated Built slopes wander from the drawing
- Fixed and opening fields divided The sash is kept out of the rake
- Head detailed to drain outward Water leaves at the low jamb
- Cut and glazed in our Dubai factory Three to five weeks from approval
- Fitted and sealed, low side checked first Level set before the rake is trued
Articles
Partitions
Office partitions made of aluminium profiles are a simple, quick, and cost-effective way to organise efficient zoning within a large space, while maintaining interior unity.
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Aluminium office partitions with glass
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Full-glass office partitions
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Transformable partitions for the office
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Accordion partitions for the office
The honest downside
Living with a sloping head
The raking part is usually fixed and set high over a stair or a mezzanine, which makes it the hardest glass in the house to reach. Its inside face often hangs over a stair void, so washing it or changing a cracked pane can mean a tall ladder or a tower standing on the stairs.
Shading it is awkward as well. Blinds are made for level heads, so a sloping field on a sunny elevation stays bare or needs a made-to-measure fitting, and the glass is cut to four unequal sides, so any replacement is remade to the survey.
If nobody reads the rake from inside, a plain rectangular window on the landing, at a height you can reach, is simpler to shade, clean and replace, with the slope left in the wall. A trapezoid stays the right answer where the sloping line is part of the design and the glass is meant to follow it.
Consider instead
Single-panel windows
Frequently asked questions
On a gentle rake a top-hung leaf is possible, but the gear is special rather than standard and the stay has to hold a sash that wants to swing downhill. On a steep rake it is not worth attempting. The dependable arrangement is the one we draw first: the raking field glazed fixed, and a normal opening sash in the square part below it where the handle is also within reach from the floor.
With a bevel and a template taken against the actual soffit, not with the angle written on the architect's section. Stairs and roofs are built to a tolerance, and a slope that drifts even slightly over its length shows up as a wedge of daylight along the head once the frame is in — the one defect in this type that cannot be adjusted out afterwards. Our engineer takes the angle on site within 48 hours of the request.
Not when the rake falls outward, which is how we detail it: the top surface of the sloping member is capped and pitched so water runs off the face rather than sitting against the gasket. The arrangement that causes trouble is a rake that falls inward towards the building, where every heavy shower leaves a pool along the seal. It is worth checking which way the existing opening was built to shed.
Yes, and along a staircase that is usually the point. The raking fields and the square ones are made from the same profile system and share their mullions, so the sightline carries straight through the change of shape and the whole run takes one powder-coated colour. It is drawn as a single elevation and made as a single order, which is also how the levels stay consistent.
Related pages
Nearby pages and the rest of the catalogue.
- Aluminium-wood windows
- Arched windows
- Bay windows
- Casement windows
- Corner windows
- Custom shapes
- Double-panel windows
- Energy efficient windows
- Fire-rated windows
- Fixed windows
- Floor-to-ceiling windows
- Folding windows
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