Adding a skylight: choosing the type and getting the roof right

What the job involves

Skylights are priced per unit installed, and the type sets the bracket. Tubular skylights, which pipe light down a reflective tube, are the budget option and brilliant for hallways, bathrooms and robes. Fixed glass skylights are the mainstream choice for living spaces. Openable or motorised units with rain sensors and blinds sit at the top and add ventilation as well as light.

The roof and ceiling do the rest of the work. Installing through a raked ceiling where the skylight sits directly overhead is straightforward; a flat ceiling needs a plastered light shaft built through the roof cavity to channel the light down, which adds real cost. Tile, metal and low-pitch roofs each need different flashing kits to stay watertight.

Glazing is the choice that quietly matters most. A single-glazed skylight leaks heat in winter and pours it in over summer, so double glazing with UV or thermal coatings is worth the extra on any skylight you'll live under.

How the cost works

A tubular skylight brightening a hallway or bathroom sits at the bottom of the range, a quality fixed double-glazed unit through a raked ceiling lands in the middle, and a motorised opening skylight with a rain sensor, blind and a plastered shaft through a flat ceiling reaches the top. The estimate on this page adjusts for the type and the ceiling, so read any figure as a guide.

The skylight type is the baseline, and the ceiling is the multiplier — a flat ceiling needing a built-and-plastered shaft adds a clear premium over a raked one. Size, glazing and extras like blinds, rain sensors and remote operation each add on top. When comparing quotes, check whether the shaft, flashing and any plastering are included, because those are the parts a cheap number tends to leave out.

Choosing the right installer

Skylight installation crosses roofing and, for the shaft, plastering; a motorised unit tying into a new circuit brings a licensed electrician in for that connection. The waterproofing is the part to get right — a skylight is a hole cut in your roof, so flashing suited to your roof material and pitch is what keeps it from leaking. Judge installers on how they talk about flashing and roof type.

Think about position and glazing, not just the unit. North and south-facing skylights give softer, more even light than a hot west-facing one, double glazing controls the heat, and in bushfire-prone areas the skylight needs to meet your BAL rating. An installer who raises orientation and glazing before quoting is thinking about how the room will actually feel.

Mistakes to avoid

Skylight regrets usually come from single glazing, a hot orientation, or a quote that skipped the shaft.

• Choosing single glazing, then losing heat in winter and gaining it in summer
• Putting a skylight on a hot west-facing roof instead of a softer north or south aspect
• Not confirming the light shaft, flashing and plastering are in a flat-ceiling quote
• Overlooking BAL rating requirements in a bushfire-prone area
• Assuming any flashing will do rather than a kit matched to your roof and pitch
• Skipping the licensed electrician on a motorised unit's new wiring