Install A Bathroom Skylight

  • install a skylight into a bathroom

The bathroom is not normally the first place we think of to install huge windows, as it is a space requiring privacy not views. 

Most bathrooms have small windows, usually positioned up high, and as a result the natural light is often quite lacking. And in some homes the bathroom is located in the centre of the layout plan, making it windowless.

Installing a flexible shaft skylight is the easiest way to give a bathroom an illumination upgrade. Unlike a traditional roof skylight, a shaft is flexible and reflective, so can be fitted to funnel light anywhere, even in a two-storey building.

Choose a kit

Skylight kits feature a roof dome, flexible shaft and ceiling diffuser. They come in a variety of sizes with round or square shafts and domes.
We bought a round Acol Skylight Kit, from Bunnings, but the supplied shaft wasn’t long enough to reach from the flat Colorbond roof to the ceiling of the ground floor bathroom.

To solve the problem we bought a 300mm diameter mylar/polyester bonded light shaft measuring three metres long, costing $51. This type of 300mm light shaft  is ideal for small bathrooms, toilets and also hallways, but is generally recommended for a maximum length of only two metres.

At the stretch required of the shaft for this home, a 400mm diameter skylight would have been preferable, but wouldn’t fit through the upstairs cabinetry it needed to pass through.

To install the skylight, we cut a hole in the corrugated metal roof for the dome using a jigsaw.

Another hole was made in the bathroom ceiling for the diffuser, and as the shaft extended through an upper storey, an additional hole was cut through the upstairs flooring.
TIP If possible install the dome in a north-facing aspect on the roof for maximum light benefit.

Locating the holes

Installing a skylight in a single-storey home is a simple matter of running the supplied two-metre shaft from a standard kit directly through the roof cavity to the ceiling below in your desired location.
For a two-storey home an additional shaft has to be purchased and must be concealed as it passes through the upper storey, affecting the positioning of the skylight. The shaft is flexible so you don’t have to maintain a direct line to achieve a good result.

Step 1. Cut the floor hole

Locate the floor joists then cut a 310mm diameter circle template from cardboard and use it to scribe a circle on the floor between the joists. Drill a 10mm starter hole then cut the circle using a jigsaw with the pendulum action set to high.

Step 2. Mark the roof hole

Drop a plumb bob from the roof sarking to the centre of the floor cutout, ensuring the roof hole is between battens. Use the template to scribe a circle, cut away the sarking with a utility knife and drill a 5mm hole through the roof centrepoint.

Step 3. Cut the roof hole

Locate the drilled hole on the roof, using the template to scribe a circle. Drill a 10mm starter hole and cut out using a jigsaw with a metal cutting blade and the pendulum action off.

Step 4. Attach the shaft

Stretch the shaft to fit over the base collar of the dome and secure together, overlapping both the collar and the shaft with the supplied aluminium tape. Position the shaft through the roof hole and let it drop to the floor carefully.

Step 5. Secure the dome

Slot the dome through the roof hole and square up the aluminium tray. Use a soft-faced hammer to shape the tray, matching the roof profile. Secure the dome by sealing the edges with roof and gutter silicone, adding roofing screws if needed.

step 6. Install the diffuser

Mark the ceiling hole and cut with a plasterboard saw then pull the shaft down, cutting any excess. Overlap the shaft and ceiling ring, securing with aluminium tape. Slot the diffuser into the ceiling ring, push it into the hole and secure with the supplied screws.

Click on the diagram

Follow the labelled diagram to install the skylight. It has the name of all the parts and the measurements to help you install the skylight.  

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