Kya deLongchamps examines the practical, celestial and architectural potential of opening a roof to the heavens, with windows for every type of space.
WHY open to the sky?
It’s simply one of the most efficient ways to let light pour into your home.
Non-conventional windows, skylights and roof glazing answer a number of problems, gifting natural light from even flat roofs and inaccessible pitches.
Suddenly, a loft space becomes habitable, a neglected corridor is flooded in sunshine and a spare room sulking on the north side of the house, is bathed in welcoming diffuse illumination.
Piercing a blank ceiling can add dramatic visual flourish, showering light from a handsome deep reveal in a conventional ceiling and rhythmically framing the sky in a double-height room.
Roof windows can kick out whole areas of wall and roof in an attic conversion.
Banking wall windows and roof windows, upright units can run straight into overhead pitch roof windows sealed with specialised flashing to ensure a weather-tight fit.
With clever operational detailing, these larger modulars are capable of not just opening for views and ventilation but providing balcony space you can step out and onto.
Let there be light
In general if you can reach the handle to crank open a roof mounted unit, it is termed a roof window. If you have to use a remote control or a pole to open a unit, it is a roof light or skylight.
These can go as high as you like, taken right up to and over the ridge if you fancy. Wall-mounted or hand-held remote control units can smoothly coax open out-of-reach windows, offering a refreshing breeze on a summer’s day and useful rapid ventilation of humid areas such as kitchens and utility rooms.
With the correct thermal flashing and warm-edge glazing to ensure high levels of insulation, roof lights also passively harvest heat for the rooms below.
Modern quality units by companies including Fakro, Velux and Keylite are free of the early problems of ‘cold bridging’ and condensation common to many older roof lights.
Which roof window where?
The first thing to decide is just how much additional light you expect.
The quantity of windows, their glazed size and their position all have a part to play. Your choice should be influenced by the aspect of the roof (which direction it faces) and the pitch of the roof. Do you want windows that make a bold architectural statement?
* Consider where the light will enter the room and at what time of day. If you have living spaces crossed by a ridge, skylights either side can track the sun.
* In materials, a moisture-resistant polyurethane frame is a clear winner for bathrooms and kitchens, where humidity and steam will gravitate up against materials.
* Centre pivot operated from the top are ideal for a low pitch (in the loft especially) where it’s easy to reach and pull the window down with a bar to open it. Furniture can be placed directly beneath the window.
* Top-hung windows offer the clearest view as they are pushed up and out of the way. They require a suitable pitch and to be high enough from the floor (with a dwarf wall or matching fixed window below) for comfortable operation and safety.
* Vertical bi-lights. Here a top and bottom unit rise as double window and can marry a short wall and roof at the eaves.
The top unit generally operates from the bottom of the frame to throw open an uninterrupted view. The bottom window is either fixed or opens only for a controlled distance from the bottom to prevent falls.
Vertical banks of three windows generally start with a fixed window with two moving windows above.
* A side-hung upright lower window and a top-hung roof window can combine to create a ‘door’ leading out from the eaves to a balcony. Obviously with young children, supervision and control of access is crucial. Explore Velux’s Cabrio terrace and roof balcony ideas.
* If your downstairs room has no suitable place to reach the roof, a roof light in the attic matched to a diffused panel in the ceiling below can steal a valuable shaft of light from an uninhabited attic.
* Triple glazing is marginally more efficient but self-cleaning glass, Pilkington K, is crucial for any windows set in a roof. A specialised coating breaks down and sloughs off with the rain carrying dirt with it. Self-cleaning will add a premium to the price.
New integrated locks, longer bolts, and toughened laminated panes can delay entry through a roof window. Ask your supplier to run down the security features of their products as roof windows are a notoriously vulnerable point of attack for the nimble rogue.
Trickle vents, except in the case of a window for a passive house standard, will be integrated into your window, and different companies will tout their system as best. Test run the operation for yourself.
Flat-roofed extensions require a particular design of roof light and these are vastly improved from their early, leaky ancestors.
To go further, you can combine a number of lights or frame a larger area overhead in a lifted atrium style, gifting light from multiple directions. It’s possible to open up the roof, flat or pitched in glass with modular roof lights terraced together in a glass ridge or apex.
If your home is a protected or period structure you may need to choose a conservation-style roof light that will agree with its architecture. Loft windows, used to light an uninhabited area, have a lower level of detailing and are generally side-hung.
Roof window control no longer demands the perils of an extension pole. Explore the new wonders of remote touch-pad operation, not only venting from the roof lights, but opening and closing blinds and exterior awnings too (Velux Touch Screen Integra).
Solar power is the latest addition in terms of remote operation. Thermostatic control, smoke release, rain sensors, and timers can be programmed into windows. This level of management is worth considering for larger windows in main rooms over 2.5m high.
Piercing the roof anywhere is a serious business, as it is part of the sealed envelope of the house. If you don’t know your plenums from your profiles (and that’s just about all of us), call in a professional, fully insured, tax-registered installer provided by your window supplier.
Tunnel to the sun
Image: Velux Sun Tunnel with an additional Lovegrove solar powered chandelier. Velux.ie
It’s amazing the difference even a modest finger of light can make, and sun tunnels can be installed in rooms where you cannot break windows into the walls or use a full roof light, due to their situation.
Artificial light can make an en-suite or office usable, but there’s a gloom about an oppressive room that is dependent on an open door or a light switch.
Tubular skylights or sun tunnels offer an economic solution, and can also provide valuable extra light in addition to your existing windows.
Basically, an opening (26cm to 36cm) is made in the roof which connects to a rigid or flexible tunnel with a highly reflective interior finish.
A dedicated roof flashing and light catching dome seals the tube at the top, while another flat diffuser discreetly allows the soft light in through the ceiling. You can add a single tunnel or stagger them down a corridor, acting as passive spotlights.
Passing neatly through the attic, there’s minimal physical disruption. Short, rigid sun tunnels with a southerly aspect and a straight run from the sky, offer the best illumination.
Bouncing what light is caught by the tubular skylight is key, so be prepared to decorate with pale, reflective colours on the walls and floors.
Velux provides a handy calculator comparing the output of their product compared to a 60w bulb based on your location, the room size roof pitch and orientation. Prices start around €400 excluding installation for a 26cm model.
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