What Christchurch's climate means for a skylight
A big swing between summer and winter sun
Mean daily solar radiation at Christchurch peaks at 22.3 MJ/m² in December and drops to 4.7 in June, and the city gets about 2,142 sunshine hours a year. That's a lot of summer heat through one opening and not much light in mid-winter. Where the skylight faces, the glazing and a blind matter more than how big the hole is.
Frosty nights and condensation
With about 34 frosts a year and a record low of -7.2 °C, a single-glazed skylight is a cold surface in a warm house. Most homes here are heated, with 86.17% using a heat pump in the 2023 Census, and warm indoor air meeting cold glass is exactly how condensation forms and drips down the shaft. Double glazing and an insulated shaft cut that back.
Hail and brittle glazing
Christchurch records hail on about 6 days a year, and NIWA names it and Kaikōura as the Canterbury stations where hail is most common. WorkSafe lists skylight glass and clear roofing among the brittle surfaces workers shouldn't walk on. Ask what the glazing is made of and how it stands up to hail.
Snow, wind and the flashing
Building Code clause E2 says roofs must shed rain and, where it snows, melted snow as well. Snow banks up against the uphill side of a skylight upstand, and nor'west gusts drive rain sideways under a poorly fitted flashing. A flashing kit made for your roof profile, fitted by someone who does them regularly, is what keeps it dry.
Cutting into an older roof
WorkSafe says any home built before 2000 may contain asbestos and that cutting or drilling is what releases the fibres, so a new opening in an older cement-sheet roof starts with a test. On a heavy tile roof, the tiles around the opening may need re-fixing too.
New, replacement or leaking?
Skylight leaks usually start at the flashing or the seal around the upstand, not the glass, and plenty can be repaired without replacing the unit. An old plastic dome that's gone cloudy, crazed and brittle is normally better replaced.
Replacing an old skylight with a comparable one in the same spot can sit within the Schedule 1 exemption from building consent. A brand-new opening cut through the roof framing is a different question, so ask Christchurch City Council or your roofer whether yours needs consent. Our skylights and roof flashings pages go further.
What makes a skylight job bigger or smaller
A tubular skylight through a simple longrun roof into a short ceiling space is about as small as these jobs get. It grows with a framed skylight, double or laminated glazing, a tile roof, a long shaft through a deep ceiling space, trusses or rafters that need reframing, and a consent if one is required.
A good written quote names the skylight and glazing, the flashing kit, how the shaft is lined and insulated, who makes good the ceiling, and whether any framing changes or consent are included.
What you can do yourself
You can
- Check the ceiling around the shaft for stains after heavy rain and photograph anything you find.
- Wipe condensation off the glass in winter and keep the room aired.
- After a hailstorm, look at the skylight from the ground or an upstairs window for cracks or crazing.
- Clean the inside of the glass from a stable stepladder indoors, if you're comfortable doing it.
Leave to a roofer
- Anything on the roof itself, including cleaning the outside of the glass.
- Resealing or replacing flashings.
- Cutting a new opening or changing framing.
- Replacing a cracked or brittle dome.
What to ask about a Christchurch skylight
- Tubular or framed, and which would you put in this room?
- Is it double glazed, and how does the glazing cope with hail?
- Will the shaft be insulated, and what will you do about condensation?
- Which flashing kit suits my roof profile?
- Does the opening mean cutting rafters or trusses, and will it need a building consent?
- On a roof older than 2000, will you test for asbestos before cutting?
Our take on skylights in Christchurch
For a dark hallway or bathroom, we'd look at a tubular skylight first: a small hole, a simple flashing and less heat lost on a frosty night. For a living area, we'd go double glazed with a blind for those hot December afternoons. And if an old skylight leaks, we'd want the flashing checked before anyone talks us into a whole new unit.
Want a roofer to take a look?
Tell us the job and your postcode. We match it with a Find My Roofer certified roofer who specialises in that kind of work, and they call you to quote. Your number goes to them alone.