Skylight Installation Guide: Fixed, Openable and Tubular Options

Skylights have a reputation for leaking that mostly traces back to poor flashing installation rather than the product itself, and choosing the right type for the room, then having it flashed correctly into the roof, is what actually determines whether it performs for twenty years or causes problems within two. This guide covers the main skylight types and what a proper installation involves.

Fixed skylights

Fixed skylights do not open and are the simplest, most affordable option for adding natural light to a room without a ventilation requirement. They range from small units to large architectural glazing panels, and installation involves cutting the roof opening, framing it correctly to transfer roof loads around the opening, and fitting a purpose-made flashing kit matched to the roofing material the skylight sits in. The flashing, not the skylight unit itself, is where nearly every leak originates, because it has to shed water correctly at every lap with the surrounding roof sheet or tile.

Openable roof windows

Openable roof windows add ventilation as well as light, which matters in bathrooms, kitchens and roof-space conversions where moisture needs somewhere to go. They cost more than fixed units and require a slightly more involved installation to seal the operable sash, but for a bathroom without an external wall, an openable roof window is often the only practical way to get both light and ventilation. Manual and solar-powered openable options are both common; solar units avoid running mains wiring to the roof but rely on a rechargeable battery that has a service life of its own.

Tubular daylight devices

Tubular daylight devices (sold as Solatube, Sun Tunnel and similar) capture light through a small roof-mounted dome and pipe it down a reflective tube to a ceiling diffuser, making them the practical option for a hallway, walk-in robe or internal room with no direct roof access above it, or where a full skylight well is not feasible. They are cheaper and faster to install than a full skylight because the roof penetration is much smaller, and the flashing principle is the same: a correctly matched kit is what keeps water out, not the tube itself.

Matching the flashing kit to your roof material

This is the step most likely to be skipped by an unlicensed installer and the most common source of failure. A flashing kit designed for tile roofing will not correctly seal a metal roof and vice versa, and the kit also needs to suit the specific roof pitch range. If you are sourcing a skylight separately from installation, buy the flashing kit rated for your exact roof material and pitch at the same time as the unit, not as an afterthought, and confirm with whoever installs it that the kit is compatible before the roof is cut.

Who should install one

Cutting a structural opening in a roof and flashing it correctly is licensed roofing or roof plumbing work in every state, not a weekend DIY job, regardless of how straightforward the manufacturer's instructions make it look. A licensed roofer will assess the framing around the proposed opening, confirm it does not compromise a structural member, and warrant the flashing installation, which matters because a skylight leak that shows up two years later is far more expensive to trace and fix than it would have been to install correctly the first time.

Sizing and placement

As a rough guide, skylight area equal to around 5 percent of a room's floor area gives a noticeable daylighting effect without excessive heat gain; go much larger and you may need double-glazed or tinted glazing to manage summer heat load, particularly in northern and inland Australia. Placement matters as much as size: a skylight positioned over a stairwell or hallway can borrow light into adjoining rooms far more effectively than the same skylight centred over a single room, and a well-placed unit over a kitchen island or a dark internal bathroom often does more for the feel of a home than a much larger window would in a room that already gets good natural light.

Condensation and maintenance

Skylights, particularly single-glazed units in a poorly ventilated roof space, can develop condensation on the internal glazing surface in cold weather, which is often mistaken for a leak. Double-glazed units and skylights with a well-ventilated shaft largely avoid this, and it is worth asking your installer directly how the specific unit and installation method manages condensation before you commit, especially in cooler climate zones. Ongoing maintenance is minimal: keep the external glazing or dome clear of leaf litter and debris, particularly where a skylight sits near overhanging trees, since debris buildup around the flashing is a common early source of a slow leak that has nothing to do with the flashing installation itself.

Ventilation skylights vs whirlybirds

Do not confuse an openable roof window with roof space ventilation. Whirlybirds and powered roof vents ventilate the roof cavity above the ceiling to manage heat and moisture buildup, an entirely separate system from a skylight, which brings light and sometimes ventilation into the living space below. Many homes benefit from both, addressed as separate line items in a re-roof or renovation quote.

Browse current skylights and roof windows including fixed units, openable windows, tubular daylight devices and flashing kits, and read our re-roof cost guide if you are planning skylight installation as part of a larger roofing project. If you have a used but sound skylight or flashing kit left over from a job, list it here.