Hidden Sash Windows
nothing on the glass

A window where the operable sash sits behind the outer frame instead of in front of it. From outside you see frame and glass, with no second aluminum line around the opening leaf - so an operable window looks identical to a fixed pane beside it. Inside, the sash is there and works normally. The European system providers call it hidden sash, concealed sash, or hidden vent depending on the brand.

Hardware that does not sit on the face of the sash. The version I quote most is Cortizo's Arch Invisible: the handle is integrated into the sash profile and operated from the side of the leaf, so from the front the window shows no lever at all. It is a separate option from the hidden sash itself, and only some systems offer both together - which is the specific combination most of my clients are asking for when they say they want a window with nothing on it.

Cortizo's invisible handle for hidden sash windows. Rather than mounting on the face of the sash, it is built into the sash profile and actuated from the lateral side, which leaves the interior face completely clear. It works with side-hung, tilt & turn, and turn-tilt leaves, and it is the reason the COR 70 Hidden Sash is the system I point people to when both the sash and the hardware need to disappear.

Yes, but less than most people expect. The profile is a different extrusion rather than a different technology, so the premium sits in the tens of percent rather than in multiples - and it lands mostly on operable units, since fixed panes are unaffected. On a facade that is largely fixed glass with a few operable units for ventilation and egress, the impact on the total is modest. Send me a schedule and I will price both versions side by side.

Smaller than a standard sash, and this is the constraint that decides most projects. Typical limits are around 4 ft 3 in wide by 7 ft 10 in high on standard hardware, or 3 ft 11 in by 11 ft 6 in on heavy-duty side-hung hardware, with sash weights to about 350 lbs. Large openings get split into a fixed pane plus a smaller operable leaf - which is exactly the look the system is designed for anyway.

That depends on the size of the operable leaf, not on the hidden sash detail itself. Because the maximum sash is smaller than a conventional one, egress openings need to be checked position by position rather than assumed. Tell me which openings are egress on your plan set and I will size those leaves first and build the rest of the elevation around them.

The concealed-sash systems are built primarily around inward-opening leaves - side-hung, tilt & turn, and bottom-hung. If your project needs outswing sash with interior screens, that usually means a different system, and I would point you at the outward-opening European casement lines instead. Ask early, because this decision drives the whole package.

The same way they work on any inward-opening European window: the screen mounts on the exterior side of the opening, in a slim frame or a cassette with a roller. It sits outside the sash swing, so the window still operates normally. Worth planning at the drawing stage rather than after delivery.

Several of the European system houses have a version - some call it hidden vent, some call it a concealed sash variant of an existing platform. The differences that matter are whether the handle can be concealed as well, how deep the glazing rebate is, and how large the sash is allowed to get. I quote across providers rather than pushing one, so the pick comes down to your sizes, your climate zone, and your budget.

Roughly 16 weeks from an approved estimate to delivery on site: production in Europe, crating, ocean freight, customs clearance, and final-mile trucking. Hidden sash profiles are standard catalog items for the providers that offer them, so they do not add lead time on their own.