Here’s a guide to the average skylight sizes in residential and commercial settings, including standard dimensions and notes on fitting them between rafters or trusses:
📏 Common Skylight Sizes (2025)
🏠 Standard Residential Skylight Sizes
| Nominal Size (ft) | Actual Rough Opening (inches) | Best For |
|---|---|---|
| 2′ x 2′ | 22.5″ x 22.5″ | Small bathrooms or hallways |
| 2′ x 4′ | 22.5″ x 46.5″ | Bedrooms, kitchens |
| 2′ x 6′ | 22.5″ x 70.5″ | Larger open-concept rooms |
| 4′ x 4′ | 46.5″ x 46.5″ | Living rooms, atriums |
🔧 Most residential skylights are designed to fit between 24-inch on-center rafters, requiring a rough opening about ½” larger than the skylight’s frame.
🏢 Commercial or Custom Skylight Sizes
| Type | Typical Size Range |
|---|---|
| Flat Glass | Up to 4′ x 8′ or larger |
| Pyramid / Dome | 2′ x 2′ to 10′ x 10’+ |
| Tubular (Sun Tunnel) | 10″ – 22″ diameter |
| Ridge or Multi-Bay | Custom lengths up to 30’+ |
📌 Notes on Sizing:
-
Rough Opening: The hole in the roof must match the manufacturer’s rough opening spec.
-
Finished Framing: Should be 1.5″ wider and taller than the glass dimensions to allow for flashing and insulation.
-
Building Codes: Often require tempered or laminated glass in skylights.
☀️ Skylight Size Guidelines Based on Room
| Room Size (sq ft) | Recommended Skylight Size |
|---|---|
| 100–150 sq ft | 2′ x 2′ |
| 150–250 sq ft | 2′ x 4′ |
| 300–400 sq ft | 4′ x 4′ or multiple 2′ x 4’s |
Choosing The Right Skylight
Choosing the right skylight size depends on three key factors:
-
Room size and purpose
-
Roof pitch (angle)
-
Desired daylight or ventilation
Here’s how to choose the right skylight size for your needs:
🧱 1. Room Size & Function
A general rule is to size your skylight at 5%–10% of the room’s floor area:
| Room Type | Room Size (sq ft) | Recommended Skylight Size |
|---|---|---|
| Bathroom | 40–70 sq ft | 2′ x 2′ or a 14″ sun tunnel |
| Kitchen | 150–250 sq ft | 2′ x 4′ or (2) 2′ x 2′ skylights |
| Living Room | 250–400+ sq ft | 4′ x 4′, 2′ x 6′, or multiple smaller units |
| Hallway/Stairwell | 50–100 sq ft | 14″–22″ sun tunnel or 2′ x 2′ |
| Bedroom | 120–180 sq ft | 2′ x 4′ or 2′ x 6′ |
📐 2. Roof Pitch Considerations
The roof pitch (slope) affects skylight performance and appearance:
| Pitch | Ideal Skylight Type | Size Notes |
|---|---|---|
| Flat (0–3/12) | Curb-mounted or flat glass | Avoid large sizes unless well-drained. |
| Moderate (4/12–7/12) | Deck-mounted | Most standard sizes work well. |
| Steep (8/12+) | Deck-mounted or low-profile | Taller skylights may look too prominent. |
🛠️ Velux recommends increasing the skylight’s height (vertical dimension) if your roof is very steep, so more light penetrates deeper into the room.
🌞 3. Daylight & Ventilation Goals
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Fixed skylights: Best for light only (less cost, fewer parts).
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Ventilated (manual or electric): Ideal for kitchens, bathrooms, or humid climates.
-
Sun tunnels (tubular): For small or enclosed rooms with limited roof access.
🧮 Example: Choosing for a 200 sq ft Bedroom with a 5/12 Pitch Roof
-
Skylight Size Target: 5%–10% of 200 sq ft → 10–20 sq ft of glass.
-
Ideal Option: One 2′ x 4′ (8 sq ft) or two 2′ x 2′ units (total 8 sq ft).
-
Mount: Deck-mounted for a lower-profile look.
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Ventilation: Optional vented skylight if room has humidity concerns.
Solar Tube Installation In The East Valley
Elite Home Daylighting Systems offers tubular skylights and solar attic fan installation services to the entire Phoenix east valley. Service area includes Chandler, Gilbert, Mesa, Tempe & more! Contact us for a free quote today!
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