If a builder or contractor has told you that skylights won’t work on your flat roof, you’ve been given incorrect advice. Flat roof skylights are not only possible, but there are also systems specifically engineered for them. The real question isn’t whether you can have natural light in your flat-roof home. It’s which system suits your roof, your climate, and your aesthetic goals.
This guide explains exactly how flat roof skylights work, what separates a quality installation from a problematic one, and what to look for when you’re ready to speak with a supplier.
Why standard skylights don’t work on flat roofs
Most conventional skylights are designed with gravity-fed drainage systems built into their flashing bases. They rely on a minimum pitch of 15 degrees to direct water away from the frame and seal. Install them on a flat or low-pitch roof and you’ve created a collection point for pooling water, which is a reliable path to leaks and long-term structural damage.
However, with the right skylight system, even flat roofs can enjoy natural light!
Systems built specifically for flat roofs
The good news is that several products are designed from the ground up for flat or near-flat applications. The choice between them comes down to one key decision: framed or frameless?
|
Feature |
Atlite (Framed) |
Velux FCM (Frameless) |
Infiniti (Frameless)
|
|
Style |
Framed, edge-to-edge glass |
Fully frameless |
Fully frameless, edge-to-edge glass |
|
Min. pitch required |
Flat 0° |
Flat/0° |
min 1° |
|
Water management |
Edge-to-edge glass (nowhere for water to pool) |
Perimeter drainage channels |
Edge-to-edge flass (nowhere for water to pool) |
|
Best for |
Those who prefer a defined frame aesthetic |
Minimalist, flush look |
Minimalist, flush look |
|
Interior appearance |
Feature skylight, visible from angles |
Sky-view feature |
Sky-view feature |
If you prefer a framed look: The Atlite is the standout option. Its edge-to-edge glass design is a genuine advantage: there’s no capping or frame section between the glass and the perimeter seal, so there’s nowhere for water to sit between rainfall events. It can be installed at pitches well below 15 degrees, making it well suited to Brisbane’s near-flat residential roofs.
If you prefer a frameless look: Both the Velux FCM and the Infiniti deliver a flush, minimalist profile with no visible frame. These are popular choices for modern builds and commercial conversions where the skylight is meant to disappear into the ceiling plane.
Our recommendation is generally to avoid pitching to 15 degrees unless structurally required. A skylight installed close to flat looks significantly better from both inside and outside the home. Plus, on a flat roof without a roof cavity, the visual effect is particularly striking. You can see the sky from multiple angles, and the skylight becomes a genuine architectural feature rather than a functional addition.
How waterproofing works on a flat roof
Flat roof installations differ from pitched roof work in one important way. On a pitched roof, flashing redirects water downslope and away from the skylight perimeter. On a flat roof, there’s no slope to rely on, so the installation must integrate directly with the roof flashing system.
For flat roofs in Australia, curb mount is the standard approach. A raised frame, typically 100mm or higher, sits above the roofline and the skylight unit sits on top. Pan and soaker flashings are then installed to run up and under the roof ridge, creating a continuous waterproof seal around the perimeter. This approach suits roofs with existing flashing systems such as EPDM rubber, TPO, or torch-on modified bitumen.
Custom flashings are designed to work with this system. The Atlite and Infiniti edge-to-edge glass design means there’s no capping between the glass edge and the perimeter seal, so water flows directly to the flashing line without sitting in a rebate. Perimeter drainage channels route water outward to the roof surface, where it drains through the building’s existing roof drainage points.
A properly integrated custom flashing system should create a single uninterrupted waterproof layer from the roof surface through the skylight perimeter. If a quote doesn’t include specific custom flashing integration detail, that’s a question worth asking before any work begins.
No roof cavity is a feature, not a problem
One characteristic of flat roof homes that sometimes concerns homeowners is the absence of a roof cavity. On a pitched roof, a light shaft is typically required to bridge the space between the skylight and the ceiling, which adds cost and can limit the visual effect.
On a flat roof, there’s a shallow cavity to bridge. The skylight sits almost directly above the room and this means you can see the sky from multiple angles, the light enters without restriction, and the skylight becomes a more prominent architectural feature. For rooms with limited natural light, this is a genuine advantage over what’s possible with a pitched roof installation.
Ceiling depth and any structural elements such as bulkheads can affect placement, but in most flat-roof configurations the installation is more straightforward than on a pitched roof with a deep cavity.
Sizing, placement, and what to discuss
Before your first conversation with us or before our assessor comes out to do your free skylight assessment, it helps to have thought through a few practical questions.
Sizing
A common starting point is that skylight glazed area should represent roughly 5 to 15% of the floor area of the room below. Larger openings bring more light but also more heat gain, which is why glazing specification matters. We can model both for a given room size.
Placement
A skylight positioned toward the south or southeast receives diffused light with lower direct sun exposure during the hottest part of the day. North-facing skylights deliver direct light and more heat. Learn more about skylight placement.
Multiple skylights
There’s no structural reason why a flat roof can’t accommodate multiple units, provided the roof flashing integration is planned for each penetration point. Some installers prefer to complete all penetrations in a single flashing works session to maintain waterproofing continuity.
If you’re ready to explore your options, speaking directly with a specialist who handles flat roof installations regularly, will give you a far more accurate picture than a general glazier or builder.
Thinking about a flat roof skylight for your home?
Roof Space Renovators specialises in technically complex installations, including flat and low-pitch roofs across South East Queensland. Get in touch for a consultation and we’ll help you find the right system for your roof and your goals.
Frequently Asked Questions
Will a flat roof skylight leak?
A correctly installed flat roof skylight should not leak. Leaks in flat roof applications almost always result from inadequate flashing integration, not from the skylight product itself. The other issue we sometimes see is when people have used pitched skylights (designed for a minimum of 15°) and installed them on a flat roof or a roof with less than 15° pitch, without pitching the skylight to 15°. Ask your installer specifically how they plan to integrate the skylight perimeter with your existing flashing system.
