Glass-bottomed swimming pools divide opinion. For some, they are magical gravity defying feats of engineering but for those even slightly disposed to vertigo, their worst nightmare. But glass-bottomed and walled swimming pools are growing in popularity. For many commercial buildings, such as hotels, a glass-bottomed pool is a luxurious selling point, not to mention highly instagrammable. Additionally, they can add commercial value to a property but as this article demonstrates, they can also be a unique addition to a residential building project.
Glass has a reputation as a fragile and brittle material and many architects opt to use perspex (acrylic) over glass for pools that feature a window. However, with the right technological processes, glass can be strong and durable, making it a perfect material for swimming pool glazing.
Often employed for infinity pools, the transparent properties of glass provide the perfect optical illusion, making the pool edge appear boundary-less.
Most glass-bottomed pools require two sheets of laminated glass with PVB (Polyvinyl butyl) sandwiched between. Securiglas is a laminated, intrusion-resistant glass fitted with specialised PVB plastic interlayers and is the most common type of glass used for swimming pool glazing. Valuglas is a heat-strengthened laminated glass featuring 1.14 mm PVB interlayers to provide structural support. Securityplus is by far the strongest laminated glass on the market and provides five times more strength than conventional laminated glass due to the internal layer of reinforced DuPont SentryGlasTM. It is so stable it provides protection from the heaviest of stress loads (including hurricanes and explosions), making it one of the most suitable materials for a glass-bottomed swimming pool.
Here, we have rounded up five of The Building Centre’s favourite examples from across the globe, both commercial and residential, of glass-bottomed pools that truly defy gravity.
1. Jellyfish House by Weil Arets Architects
Designed by architectural firm Weil Arets, the Jellyfish House is a private home located in Marbella, Spain. The neighbouring buildings significantly obscure the property’s view to the coast, which guided the decision to cantilever the pool from the roof so that the Mediterranean sea can be enjoyed whilst swimming and sun-bathing. The building is constructed from white poured concrete- a contemporary example of the traditional architectural style of the region. Split over four levels, Jellyfish House is divided into two paths of circulation, a fast and a slow. The fast path leads to the glass-covered roof where a glass-bottomed swimming pool is cantilevered 9m southwest, with an uninterrupted vista over the Seirra Blanca mountains. The pool hovers directly above the outdoor terrace and a glass wall provides views into the kitchen and living area. The pool weights nearly 60,000 kg and the glass used for the window and base is 6m thick. The infinity edge gives the illusion of the sky, sea and pool meeting. Sunlight streams through the water and the laminated glass base, casting ripple reflections throughout the interior of the house, enhanced by specialised underwater lighting. Running the length of pool is an underwater bench which cleverly conceals a pool cover. The Jellyfish House is a perfect example of a building blurring the boundaries between indoor and outdoor and sun and sky.
Location Marbella Spain
Size 650 m2
Date of design 1998-2001
Date of completion 2013
Project team: Wiel Arets, Bettina Kraus, Lars Dreessen, Dennis Villanueva
Collaborators: Paul Draaijer, William Fung, Johannes Kappler
Described as ‘Floating between heaven and earth’ the Hotel Hubertus in Valaora is a bold renovation project from Italian architectural firm, NOA. The hotel sits at the foot of the ski resort Kronplatz in the Puster Valley and boasts an extraordinary cantilevered glass-bottomed pool, jutting out from the rooftop and supported by tree trunks. With an altitude of 1350m, the pool offers spectacular views as it appears to hover over the Dolomites, a mountainous UNSECO World Heritage site. At 25 meters long, the Olympic sized pool connects the ‘old and new’ areas of the site and blends seamlessly into the Alpine landscape, establishing a natural typography by mirroring the glassy mountain lakes common to the region. The pool has a width of 5m and a depth of 1,30m and floats 12m above the ground. It has no visible borders and the infinity edges have been constructed using anthracite-coloured stone. Given its location and the inclusion of a glazed window at the bottom of the pool, it gives the swimmers the feeling of floating above the earth.
Finished: May 2016
Typology: Hotel reconversion and extension
Special: 17m cantilevered pool, tree trunk facade
3. Hotel Indigo, Hong Kong Island by Adeas
Towering over Hong Kong's lively Wan Chai district, Hotel Indigo Hong Kong Island is an impressive 25 story boutique hotel. Designed by international architecture firm Adeas, the building features a spectacular glass-bottomed, cantilevered swimming pool on the roof. The pool juts 3m out over the street below, a feature that has contributed to the hotel achieving acclaim as one Hong Kong’s top 20 hotels. The cantilevered pool optimises the square footage of the hotel (without the cost of buying extra land) as the site itself is exceedingly narrow, at 12.1m wide. Glass is prolific throughout Hotel Indigo. The hotel windows are arranged as a curtain wall and the panels have been glazed with Low-E glass, reducing the solar gain and aiding heat retention in the guest rooms. The project has been the recipient of a number of high-profile awards, including winning the Built Leisure and Tourism Project Award in 2013 and the Cityscape Awards for Architecture in Emerging Markets in 2013.
Completion year: 2013
Gross area of the entire development: 8,500 sq m
Directors: Max Connop, Henry Chau
4. Market Square Tower by Jackson & Ryan Architects
Market Square Tower was constructed in 2015. The luxury flats are located in downtown Huston, Texas. Cantilevering 8ft out from the Penthouse apartment on the 40th floor of the 45 story building, this is the highest glass-bottomed pool on our list, sitting 500ft above the ground. A glass barrier stops the water (and guests) from flowing off the edge while the slightly curved base of the pool provides a fishbowl effect when viewed from below. The project has been awarded the 2017 Golden Trowel Award.
5. The Wall House by Guedes Cruz Arquitectos
Another residential project hailing from Portugal, The Wall House by Guedes Cruz Architects is a modern-contemporary concrete structure with an open plan layout inspired by the natural elements that blurs the interior and exterior space. The house is anchored by two bisectional swimming pools. Overlapping one another, the top pool is fitted with a glazed glass panelled bottom giving it the illusion of floating and allows swimmers to swim alone, but in unison.
Architecture Collaborators: Patrícia Maria Matos, Nelson Aranha