Different Types of Rooflights: Find the Perfect Fit for Your Space

Different Types of Rooflights: Find the Perfect Fit for Your Space

A rooflight (often called a skylight or roof window) is a glazed opening installed in the roof plane to bring daylight (and often ventilation) deep into a building’s plan. Unlike vertical windows, rooflights deliver light from above, which penetrates further into rooms, reduces reliance on artificial lighting, and can visually “lift” compact spaces. Rooflights come in fixed and opening formats for flat and pitched roofs, with options ranging from ultra-minimal frameless units to heritage-friendly conservation models. In short: they’re one of the most effective Types of Rooflights-driven tools for making interiors feel bigger, brighter, and more comfortable.

What are the main types of rooflights?

Below is a quick tour of the Different Types of Rooflights you’ll encounter most often, along with typical use cases.

1) Fixed (non-openable) flat rooflights

Pure “slice-of-sky” daylight with the slimmest sight-lines. Best over task zones (kitchen islands, dining tables) where you want even, glare-controlled illumination without moving hardware. Great for minimal interiors.

2) Opening flat rooflights (manual or electric)

Hinged lids (with gas struts or actuators) combine daylight and purge ventilation ideal for bathrooms, kitchens and compact rooms that steam up fast. Sensors can automate opening/closing for comfort and protection from rain.

3) Pitched roof windows (centre-pivot/top-hung)

Designed for 15–60° roof slopes. They deliver sky + horizon views when seated and rotate for safe cleaning from inside. Loft bedrooms, attic studies and stairwells are classic candidates.

4) Walk-on rooflights

Structural glass set flush into a terrace or balcony to light rooms below while keeping the upper level usable. Think basements, lightwells and tight urban plots where footprint is at a premium.

5) Conservation rooflights

Low-profile, slate/tile-friendly units that respect heritage sight-lines. Use in listed buildings and conservation areas where planners resist raised kerbs and bulky lanterns.

6) Modular/linear/ridgelight systems

Multiple coordinated modules (narrow strips, multi-panel arrays, ridge-line glazing) that spread light evenly across long rooms or deep plans. Modules are easier to lift/detail than one giant pane, and they’re service-friendly.

7) Lanterns, domes and pyramids

Sculptural roof forms that throw light down into the plan. Effective where you want an architectural feature as well as illumination; check planning/height considerations.

What is a class 2 rooflight?

You’ll often see “Class 2” in specifications discussing non-fragility i.e., how a rooflight behaves if someone  falls onto it. In UK guidance informed by ACR\[M]001 and CWCT notes, Class 2 indicates a non-fragile assembly designed to prevent a person from falling through if they stumble onto the unit during maintenance. It is not meant for regular foot traffic (that’s a different, heavier “walk-on” specification), but it provides essential safety where people may access roofs occasionally. In practice, Class 2 is widely treated as the minimum non-fragility classification for flat-roof rooflights adjacent to walkways.

Practical takeaway: If anyone can plausibly end up near your flat-roof glazing (maintenance routes, plant decks, terraces), ensure the detail is non-fragile Class 2 or better, with the right glass build-up and edge support.

What is an AOV rooflight?

An AOV rooflight is an Automatic Opening Vent (a Natural Smoke and Heat Exhaust Ventilator) that opens automatically in a fire to extract smoke and heat. Many AOVs double as comfort ventilators day-to-day, but their primary purpose is life safety: opening quickly (often to large free-area angles) to keep escape routes clearer and improve tenability for occupants and firefighters. AOV systems are specified to EN 12101 and coordinated with the overall fire strategy

Practical takeaway: If your project brief mentions smoke ventilation to a stair/lobby or deep plan, ask whether an AOV rooflight is required by the fire engineer and make sure its kerb, wiring and controls are coordinated early.

How to choose the right rooflight

A good selection balances purpose, placement, performance and practicalities:

1. Purpose (light vs. light + air):

• Even ambient daylight over a wide zone → fixed flat rooflights or linear modular strips.
• Heat/moisture control → opening rooflights (manual or electric) with sensor options.
• Feature moment or symmetrical daylight → ridgelights or lanterns.
• Usable deck + daylight below → walk-on units.

2. Placement & orientation:

• Put the opening over the task (island, desk, reading nook) for maximum useful lux.
• South/west exposures: pick solar-control glass (g-value \~0.35–0.45) and plan blinds.
• North/east: prioritise high visible transmittance (bright, diffuse light).

3. Performance (thermal, solar, acoustic):

• Ask for whole-window U-values (frame + glass) not just centre-pane figures.
• Choose g-value to suit orientation; add laminated inner panes for acoustic calm and warmer interior surfaces.
• Thermally broken frames and warm-edge spacers reduce cold edges and condensation.

4. Structure & access:

• Flat roofs need insulated upstands and clear drainage/weep paths; pitched roofs need flashing kits matched to tile/slate.
• Check weights and routes for lifting; use modules where cranage or access is tight.

5. Compliance & safety:

• If accessible areas exist nearby, confirm non-fragility Class 2 or higher (or specify true walk-on where traffic is intended).
• If the fire strategy calls for smoke ventilation, coordinate AOV roof light details early.

Rooflights Comparison Table

Rooflight type	Best for	Ventilation	Typical thermal target (whole-window)	Stand-out pros	Watch-outs
Fixed flat	Even daylight over task zones; minimalist interiors	No	Refurb: ≤ 1.2 W/m²K · New build: ≈ 1.0 W/m²K	Slim sight-lines, low maintenance, great light-per-pound	No purge vent; manage glare/solar on S/W aspects
Opening flat (manual/electric)	Kitchens, bathrooms, compact rooms that need purge	Yes	Similar to fixed if spec’d with low-E/argon	Daylight + airflow; sensors for comfort/rain	More moving parts; detail for weathertight wiring
Pitched roof window	Lofts, bedrooms, stairwells	Yes	1.2 → 1.0 W/m²K typical	Sky + horizon views; many flip for safe cleaning	Check egress sizes; flashing must suit tile/slate
Walk-on	Basements, lightwells, rooms below terraces	Usually no	≈ 1.2–1.5 W/m²K (varies with structural build-up)	Two-for-one: deck above + daylight below	Weight/cranage; slip resistance and drainage planning
Conservation	Heritage roofs, planning-sensitive sites	Often yes	1.2 → 1.0 W/m²K	Flush external profile; sympathetic look	Slightly less visible light if glazing bars required
Modular/linear/ridgelight	Long rooms, deep plans needing even spread	Some modules open	1.2 → 1.0 W/m²K	Even illumination; easier lifting/serviceability	Mullion detailing for thermal continuity
Lanterns/domes	Feature daylight, vertical throw	Often yes	≈ 1.2–1.4 W/m²K	Dramatic shaft of light; strong presence	Taller profile (planning/visual impact)
AOV rooflight	Smoke ventilation to stair/lobby/deep plan	Yes (life-safety)	Performance secondary to EN 12101 compliance	Opens fast, large free area; can aid comfort vent	Fire-engineered system; controls & power coordination

Installation Considerations for Different Rooflight Types

Flat roof (fixed/opening/AOV/walk-on)

• Upstand & waterproofing: Insulated upstand typically ≥ 100 mm above finished roof; membrane lapped and dressed to manufacturer details. Keep drainage channels and weeps clear.
• Airtightness & VCL: Tape the frame to the internal vapour control layer to prevent warm, moist air tracking into the build-up.
• Non-fragility: Where maintenance access is possible, confirm Class 2 non-fragile build-up or specify true walk-on rating.

Pitched roof (roof windows/conservation)

• Flashing kits: Use matched kits for tile, slate or metal roofs; field-made flashings are a common leak source.
• Internal reveals: Insulate plasterboard returns to prevent cold-edge condensation; warm-edge spacers help comfort.
• Cleaning & access: Many pitched windows rotate for safe cleaning from indoors useful on upper storeys.

Modular/ridgelight/eaves glass

• Structure first: Align module sizes with rafters/joists to simplify trimming.
• Thermal continuity: Insulate at mullions and transitions; coordinate warm-edge spacers across joints.
• Movement joints: Allow for thermal and structural movement in long runs.

Walk-on units

• Loads & slip: Confirm live load (domestic vs assembly), anti-slip finishes and frost/snow strategy.
• Drainage: Ensure perimeter falls and channels are designed so that water is directed away and never allowed to sit against the laminated glass edges.

Conclusion

There’s no single winner among the Different Types of Rooflights only the best fit for your project’s goals.

• Choose fixed flat when you want the cleanest lines and the most daylight per pound.
• Choose opening flat or pitched when fresh air is as important as light.
• Choose walk-on to unlock daylight for rooms below while preserving terrace space above.
• Choose conservation to keep planners onside and character intact.
• Choose modular/ridgelight/eaves for even light across long or deep plans.
• Use AOV rooflights when the fire strategy calls for smoke ventilation.
• Wherever people may access the roof, ensure Class 2 non-fragile (or true walk-on) safety performance.

Get the purpose, placement and performance right, and your rooflights will deliver bright, comfortable rooms that look and feel larger without compromising weather tightness, safety or code alignment.

Ready to specify

SM GlassTech designs, manufactures and installs the full spectrum of rooflight solutions fixed, opening, conservation, walk-on, modular and AOV tailored to your plan, programme and budget. Send sketches or photos and we’ll turn them into a build-ready package fast.