Radius arched aluminum window in a limestone wall, slim sightline

Aluminum windows

Arc-Top Windows

An arc-top window is a window whose top course curves into a radius rather than meeting in a square corner, producing a half-round, segmental arch, eyebrow, or full-arch elevation. Crateworks builds NFRC-certified arc-top windows in thermally-broken aluminum, with NFRC ratings maintained on the radius configurations, AAMA 2605 PVDF finish, and CSA A440-22 cold-climate on file.

Arc-Top Windows spec into Maison Collection builds. Multi-tag products are shown with the same canonical URL across every look they appear in.

Best for

Heritage facades and modern arched openings where the elevation calls for a curved head, dormers and stair landings, and transom-paired stacks above a square fixed picture window.

  • NFRC certified
  • CSA A440-22
  • AAMA 2605
  • STC 56

Crateworks holds NFRC certifications across casement, tilt-turn, fixed-picture, awning, sliding, bifold, entry, swing, and arc-top configurations. Cert IDs disclosed on quote.

CSA A440-22 cold-climate certified #80224506. U = 0.236 to 0.387 depending on configuration.

AAMA 2605 PVDF coating, 20-year finish warranty.

STC 56 acoustic per ASTM E90.

PLACEHOLDER: aluminum windows installed in a warm, naturally-lit interior
Shown in a finished interior. Reference image, pending project photography.

Built to your opening

Every window made to order.

You specify the configuration axes below; we build to it. Frame colors are called out by RAL number.

  • Size
  • Radius (half-round, segmental, eyebrow, full-arch)
  • Glass (double or triple LowE Argon)
  • Color (RAL)
  • Finish (AAMA 2605 PVDF)

In detail

Up close.

PLACEHOLDER: close detail of a slim black aluminum window sightline against daylight
Slim thermally-broken sightline, more glass per opening
PLACEHOLDER: close detail of multi-point window hardware on an aluminum sash
European multi-point hardware in 316 stainless
PLACEHOLDER: matte finish detail on a black aluminum window frame corner
AAMA 2605 PVDF finish, called out by RAL number

Regional posture

Spec by region.

One canonical product. Two regional postures with the cert and code considerations that change with the border.


Common questions

An arc-top window is any window whose head meets the jamb on a curve instead of a 90-degree corner. The common variants are half-round (a full semicircle), segmental arch (a shallow arc), eyebrow (a very shallow arch), and full-arch (a tall pointed or rounded curve). All of them are built around the elevation drawing.
NFRC ratings are maintained on Crateworks arc-top configurations. The cert applies to the standard radius profiles documented on file; tell us the radius and we will confirm what is on cert before you commit.
Yes, this is the most common layout. A half-round or segmental arc-top pairs above a fixed picture or awning window to extend the daylight without adding a sash that needs to open at height. The arc-top stays fixed; the unit below carries the ventilation.
Yes. This configuration is NFRC certified. CSA A440-22 #80224506 is on file for cold-climate Canadian projects. AAMA 2605 PVDF finish, 20-year coating. STC 56 acoustic per ASTM E90. Cert PDFs are disclosed on every quote.

More windows

The rest of the range.

Choosing a frame material? Aluminum vs vinyl windows breaks down the trade-offs.

Built to your opening

Get a quote on arc-top windows.

Send your opening sizes. Built to order in thermally-broken aluminum, shipped direct.