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Sunroom complaints usually arrive in the same order. Cold first, then noise, then condensation on the frames, then the admission — somewhere around the third winter — that the room gets used four months a year.

By then the frame has been blamed, the heating has been upgraded twice, and nobody has looked at the glazing schedule. Which is where the problem started.

Sunroom Windows and Doors: Glazing Options & French Doors

West Walls Overheat Because of a Number Nobody Checks

A west-facing sunroom, double glazed throughout, Low-E on every unit. Sound specification on paper. In use, the room was unusable from three until six in the afternoon, May through September. The owner spent two summers on blinds before deciding the glass was wrong.

It was, but not for the reason assumed. The U-factor was fine. What had never been specified separately was the solar heat gain coefficient, and on a west elevation that number does more work than the insulation value. Cavity slows conduction. Coating controls radiation. A unit can be strong on the first and mediocre on the second, and the spec sheet will still look complete.

West-facing units want a lower SHGC. South-facing glass can carry a higher one, because winter gain on that elevation is worth keeping. Neither adjustment is expensive at the drawing stage, and both are locked once the units are ordered. This reference on insulated glazing covers how the two figures are measured separately.

Sunroom Windows and Doors: Glazing Options & French Doors

The Draught That Wasn’t There

Cold in winter, sealed frames, heating recently serviced. An air test found nothing. The discomfort was radiant — inner pane tracking outdoor temperature, occupants near the glass losing body heat to a cold surface rather than to moving air. People call it a draught. That’s why it gets misdiagnosed for years.

The room had single glazing, chosen to keep weight off an older frame. Legitimate constraint, unexplained consequence. Clear single glass sits near U 1.0. Low-E argon double glazing generally lands between 0.25 and 0.30. Roughly the distance between a room in use through February and one closed in November.

Where weight rules out double glazing, specify the room as seasonal. Single glazing plus a larger heater is not a solution; it’s a running cost.

Sunroom Windows and Doors: Glazing Options & French Doors

One Mechanism Around the Whole Perimeter Rarely Works

A long sunroom, sliders all round, chosen for consistency and because the owners’ parents could operate them. The far end ventilated badly. Cleaning above head height was awkward. Nobody had modelled the room as a whole.

Sliders earn their place — no swing clearance, operable by almost anyone, useful in a family room or a rental. But a track needs clearance to run, and that clearance costs airtightness and acoustic separation against a compression-sealed casement. Casements press the sash into perimeter gaskets on closing and clear the full aperture when opened. Fixed glazing has no moving joint at all.

The rebuild used fixed panes along the sightline, casements for ventilation, one slider where everyone needed access. Visual consistency is a weak reason to repeat a mechanism that doesn’t suit the position.

French Doors: The Sill and the Hinges

French doors for sunroom connections do something windows cannot. Full-height leaves, clear opening, unbroken visual line between interior and garden.

Five years in, the complaint is almost never the glass. It’s the threshold, which is the first barrier against wind-driven rain, and a sill that drains poorly will undermine the assembly whatever the glazing cost. It’s the hinges and locking points, which have to hold compression through constant use and weather, with wide leaves adding load to both hinge and frame. Both belong in the performance specification. Neither is an installation accessory.

Sunroom Windows and Doors: Glazing Options & French Doors

Interfaces Fail More Often Than Components

Every case above had a component that was fine alone and a system that wasn’t. Procurement repeats the pattern: frames that don’t align, sills that don’t meet, tolerances from two suppliers never designed to coordinate.

Kanod supplies casement windows, sliding doors, folding doors and French doors alongside sunroom frame systems, so glazing, opening mechanisms and frame profiles get specified as one assembly instead of four purchases. On projects where several opening types share an envelope, that removes most of the dimensional friction that appears when separate suppliers own adjacent elements. Kanod’s aluminium window systems and sunroom solutions are worth reviewing during design development rather than at procurement, when frame, glass and hardware can still be adjusted together.

A sunroom’s performance ceiling is set by its glazing and its openings. Settling those alongside the frame, rather than after it, is what separates a glazed room that performs as intended from one that only looks the part.