Porthmadog House is a replacement home on a sloping coastal site in rural North West Wales, with views across the bay, the estuary and towards Snowdonia. Designed by Strom Architects and delivered by Milliner Construction, the project responds to an exposed setting with a robust material palette of slate and corten steel, balanced by large areas of high performance glazing that open the main living spaces to the landscape. IQ Glass was appointed to design, supply and install the full glazing package, including bespoke coastal sliding glass doors in Wales, structural glazing, slim aluminium windows and rooflights.
Products Used
Featured In
2026 RSAW Welsh Architecture Award
14th Architizer A+ Awards Popular Choice win
Project Partners
Architects: Strom Architects
Builders: Milliner Construction
Photography: James Silverman
Location
Porthmadog, Wales
Designing a Coastal Home for Views, Exposure and Longevity
The architectural concept for Porthmadog House was shaped by two competing conditions. On one hand, the site benefits from expansive sea and estuary views. On the other, it is highly exposed to prevailing winds, rain and salt laden coastal weather. The design therefore needed to create sheltered, practical spaces while also maximising openness and daylight in the principal living areas.
Two slate clad ground floor volumes were used to anchor the house and provide protection from the elements, forming a sheltered entrance courtyard on the inland side. Between these heavier forms sit the social spaces, where glazing was used to open the interiors to the coastal setting. Above, a lighter corten steel volume spans across the base, with fins to provide shelter, privacy and articulation to the facade. For the glazing package, the challenge was to deliver large, minimal openings that could withstand the marine environment, support energy performance and maintain the architectural clarity of the design.
Coastal Sliding Glass Doors in Wales for Panoramic Views
IQ Glass, through its Midlands division, addressed the primary design challenge through a series of large format slim sliding door systems, creating wide glazed openings across the main living elevations. These coastal sliding glass doors in Wales were specified to frame views over the bay and estuary while allowing the social spaces to feel bright, open and directly connected to the landscape. The largest sliding door arrangement measures over 7.1 metres wide and 3.2 metres high, demonstrating the scale of glazing required to match the architectural ambition of the house.
To preserve the minimal aesthetic, the sliding doors were designed with slim framing and included a glass to glass corner detail. This allowed the glazing to read with greater continuity across the facade, reducing visible structure and strengthening the relationship between inside and outside. Given the exposed coastal setting, all sliding door frames were specified with a marine grade finish in RAL 7021 Black Grey, ensuring the aluminium systems were robust enough for the environment while complementing the restrained material palette of slate and corten steel. All glass was double glazed clear toughened safety glass with solar control and low E coatings, supporting thermal comfort as well as solar management within the heavily glazed living spaces.
Structural Glazing, Rooflights and Slim Framed Openings
Alongside the sliding glass doors, IQ Glass supplied a wider package of architectural glazing to maintain consistency of detailing across the house. Slim aluminium casement windows and doors were finished to match the sliding systems and specified with the same marine grade treatment and high performance double glazing, ensuring a coherent appearance and reliable long term performance in the coastal climate.
IQ also installed Invisio® frameless structural glazing, including corner to corner glass, to achieve particularly clean junctions where the architecture called for minimal visual interruption. Two automatic ARES® rooflights were integrated into the design as flush glazed elements, bringing additional daylight into the plan while maintaining the crisp contemporary roofscape. As opening rooflights, they also provide ventilation, helping fresh air move through the internal spaces when required. These rooflights were glazed with clear toughened safety glass incorporating solar control, low E coatings and a laminated interlayer for strength. Together, these elements allowed the glazing package to do more than simply provide views. It became a key part of how the building manages light, ventilation and openness across an exposed coastal site.
A Robust Glazing Package for a Welsh Coastal Setting
Material choice was central to the success of Porthmadog House. Strom Architects selected slate and corten steel for their durability and ability to weather gracefully, drawing on the industrial history of the area while ensuring the house would age well in an exposed location. The glazing package had to support the same long life, low maintenance approach. Marine grade finishes, solar control coatings and thermally efficient double glazing all contribute to that performance, helping the house remain comfortable and resilient despite its proximity to the sea.
The completed house has since received significant architectural recognition, including a 2026 RSAW Welsh Architecture Award and a Popular Choice win in the 14th Architizer A+ Awards. That recognition reflects the quality of the design as a whole but also highlights how carefully integrated glazing can support a calm, durable and highly site specific residential architecture.
Technical Glazing Summary
IQ Glass provided a full glazing package for Porthmadog House, including slim sliding door systems, aluminium casement windows and doors, Invisio structural glazing and ARES automatic rooflights.
- Large format coastal sliding glass doors in Wales, with the largest arrangement measuring approximately 7146mm wide by 3266mm high, including a glass to glass corner detail.
- Marine grade aluminium frames throughout, finished in RAL 7021 Black Grey to suit the exposed coastal environment.
- Double glazed clear toughened safety glass throughout, specified with solar control and low E coatings.
- Two flush glazed ARES rooflights measuring approximately 2192mm x 1400mm and 3992mm x 999mm, both incorporating laminated interlayers for additional strength.
- Frameless Invisio structural glazing including corner to corner glass to maintain minimal junctions and uninterrupted views.
Speak to IQ Glass About Coastal Sliding Glass Doors in Wales
Porthmadog House demonstrates how coastal sliding glass doors in Wales can be used as part of a wider architectural glazing strategy to deliver panoramic views, weather resistance and a clear contemporary aesthetic on an exposed residential site. By combining slim framed sliding systems, structural glazing and rooflights with marine grade finishes and high performance glass, the project balances openness with durability in a demanding coastal environment.
Early engagement with IQ Glass can support the design and specification of bespoke glazing solutions that respond to views, exposure, performance requirements and architectural intent. Contact our team to discuss how architectural glazing can be integrated into your next coastal residential project.
