| Wind exposure | Ask for the system's tested wind resistance classification against the actual site and pane sizes | Wind load rises with glass area; a rating that suits a sheltered plot may not suit an open one |
| Driving rain | Confirm the watertightness classification and the gasket arrangement, not just the U-value | Water ingress on exposed elevations is almost always a weathering-detail failure, not a glass failure |
| Drainage | Clear, generous drainage paths through frame and threshold, kept accessible for cleaning | Blocked or undersized drainage is the most common cause of standing water in a frame |
| Frame and system | Thermally broken aluminium, or a multi-chamber timber-look system where the elevation is traditional | Both are appropriate here; the decision is architectural, provided detailing is right |
| Hardware finish | Corrosion-resistant grades; stainless or marine-grade near the coast or open water | Hinges, fixings and locks show weather damage long before a good powder-coated frame does |
| Glass specification | Consider toughened or laminated where sizes and use require it, and solar control on big south or west-facing screens | Large exposed panes carry different loading and glare conditions from ordinary openings |
| Opening size and configuration | Fewer, larger fixed panes with targeted openers rather than many small opening lights | Every opening joint is a weathering joint; fixed glazing is inherently more weathertight |
| Thresholds | Weathered thresholds on the most exposed elevations; flush thresholds only with a resolved drainage detail | A flush threshold is achievable on exposed sites, but only if the drainage is designed for it |
| Installation detailing | Agreed sealing, cavity closer and reveal detail, with frames set into the reveal where the wall allows | Most exposure failures are at the junction between frame and building, not within the frame |
| Maintenance | Periodic rinsing of frames and hardware, drainage checks and hardware lubrication | Maintenance-free finishes still benefit from simple, occasional cleaning on exposed sites |