Installing a skylight is one of the best ways to bring more natural light into your home. Skylights instantly brighten up any space, providing beautiful views of the sky while reducing the need for artificial lighting during the day.
When it comes to choosing a skylight, you’ll first need to decide between a domed or flat design. Both have their advantages and drawbacks to consider. This comprehensive guide examines dome and flat skylights in-depth, weighing the pros and cons of each to help you make the right choice.
A Brief History of Skylights
Before diving into the dome versus flat debate, let’s take a quick look at the history and evolution of skylights.
Key Takeaway: Skylights have been used for centuries to naturally light interior spaces. Their design has evolved over time from basic openings in ceilings to complex glass and acrylic structures.
- Ancient civilizations like the Egyptians and Romans incorporated open ceilings and roof openings to let light into buildings. These early “skylights” provided interior illumination and ventilation.
- In the 1800s, new glass technologies allowed for basic glass skylight structures on ceilings and roofs. However, these had no weatherproofing and leaked substantially.
- Plastic dome skylights emerged in the 1900s as an affordable option constructed from acrylic or polycarbonate. Their dome shape allowed rain and snow runoff.
- Modern skylights feature insulated glass or plastic for energy efficiency. New shapes like flat and pyramid designs are also now common.
- Recent innovations include venting and operable skylights, remote-controlled shades, and tubular skylight pipes to direct sunlight into interior spaces.
Domed Skylights: An Iconic Design
Domed skylights are one of the most iconic skylight styles, featuring a transparent plastic or glass bubble rising from the roof. Here’s an overview of domed skylight benefits and considerations:
More Light Transmission
The curved dome shape enables domed skylights to capture and distribute more daylight into an interior space. As sunlight hits the dome, it reflects inward off the curved surface, transmitting light from a wider area of sky. This optical advantage makes dome skylights ideal if maximizing natural light is your top priority.
Weather Resistance
Dome skylights are designed to shrug off rain, snow, and debris. The sloped sides and smooth surface of the dome allow water, snow, and other material to easily slide off the roof. Flat skylights can accumulate standing water and debris which could impact durability over time.
Material Options
- Acrylic: Acrylic plastic is the most common material for domed skylights. Acrylic is lightweight, durable, and affordable. However, it can scratch or fade over time, reducing light transmission. New coatings help improve acrylic’s weather resistance.
- Polycarbonate: For extreme impact resistance, polycarbonate domes provide 250 times the strength of glass. Polycarbonate also blocks UV rays. But it also scratches easily and is prone to yellowing.
- Glass: More expensive glass domes offer the best optics, durability, and energy efficiency. However, the increased weight requires extra structural support.
Easy to Install on Flat Roofs
Since dome skylights shed water, they can be installed on dead-flat and low-slope roofs without needing pitch or slope adjustments. This makes them ideal for warehouse, commercial, and industrial buildings with large flat roof expanses ideal for ample daylighting.
Disadvantages of Dome Skylights
- Not as energy efficient as flat glass skylights
- Can leak over time if flashing and seals degrade
- Interior light may be diffused/distorted by dome curvature
- Dirt buildup can block light transmission through acrylic
- Condensation and clouding can occur between dome layers
When to Choose a Dome Skylight
Domed skylights excel at maximizing natural light. Choose a dome if your top goals are illuminating large dark spaces and minimizing artificial lighting costs. Domes work well if you:
- Have a flat or low-pitch roof
- Want to minimize glare
- Need extreme impact resistance
Flat Skylights: The Modern Choice
Flat skylights feature a sleek, contemporary design with a streamlined low profile. Here’s an overview of the benefits and considerations of flat skylights:
Superior Energy Efficiency
Flat glass skylights are vastly more energy efficient than domed plastic skylights. The insulated glass units feature double- or triple-pane construction with Low-E coatings, gas fills, and weatherstripping that provide excellent thermal performance. This keeps heat in during winter and blocks heat gain in summer.
Crystal Clear Optics
Flat glass transmits light with zero diffusion or distortion, providing crisp, clear views and sharp illumination. Plastic domes diffuse and bend light pathways, resulting in softer lighting and subtle image distortion.
Durable and Long-Lasting
Glass is highly resistant to scratching, peeling, yellowing, and other age-related degradation. Properly installed glass skylights can remain in flawless optical condition for decades. Acrylic domes require more frequent cleaning and eventual replacing to maintain light transmission.
Design Flexibility
Flat skylights come in many more sizes and shapes than domes. You can choose square and rectangular options to match the geometry of your space, rather than just a circular dome. Larger sizes are also possible with glass.
Seamless Integration
The flat profile of glass skylights can be installed flush and level with your roofline. This provides a clean, modern, integrated appearance. Bubble-like domes often look out of place on contemporary homes.
Disadvantages of Flat Skylights
- More difficult to install perfectly level and leakproof
- Glass can be prone to breakage/cracking if hit by debris
- Not ideal for flat or low-pitch roofs
- More expensive upfront cost than plastic domes
When to Choose a Flat Skylight
If visual clarity, energy efficiency, and durability are your top priorities, flat is the way to go. Flat skylights tend to make the most sense if:
- You have a sloped roof
- You want crisp, undistorted views
- Energy efficiency is important
- You prefer a contemporary aesthetic
Dome vs Flat Skylights: Direct Comparison
| Factor | Domed Skylight | Flat Skylight |
|---|---|---|
| Shape | Bubble/dome shape | Flat panel |
| Material | Usually acrylic plastic | Insulated glass |
| Light Transmission | Excellent due to shape | Very good with glass |
| Glare | Diffuses sunlight minimizing glare | More potential for glare |
| Appearance | Iconic dome shape | Contemporary, seamless |
| Installation | Best for flat roofs | Requires roof pitch/slope |
| Weather Resistance | Curved shape sheds debris | Prone to standing water |
| Energy Efficiency | Poor insulation without glazing | Excellent with insulated glass |
| Durability | Acrylic can yellow/cloud over time | Glass retains clarity for decades |
| Cost | $$$ | $$$$ |
Key Considerations When Choosing a Skylight
Beyond just dome vs flat, here are some other key factors to weigh when selecting the optimal skylight:
- Roof Type: Does your roof have sufficient pitch for water runoff? Flat roofs require domes or custom curbs.
- Location: Pick a location without overhanging trees or structures that could block sun access.
- Roof Materials: Is your roof shingle, metal, or membrane? Make sure the skylight integrates properly with the roofing.
- Energy Efficiency: Select insulated glass and optimal glazings for your climate. Consider solar screens or blinds to control heat gain.
- Size: Measure the room and ceiling carefully to choose the right skylight size. Bigger isn’t always better if it looks out of place.
- Light Shafts: Will the skylight need an enclosed shaft through attic space? Factor this into labor costs.
- Applicable Codes: Be aware of any building codes, zoning rules, or HOA regulations. Some require pre-approval for skylights.
- Cost: Budget for the skylight unit, flashing kits, curbs, light shafts, and professional installation.
Professional Installation Is Critical
While seemingly simple, skylight installation is complex. If done improperly, you risk leakage, condensation, drafts, glass breakage, and other problems.
Key Takeaway: We strongly recommend having a certified professional installer assess your specific roof situation and handle the entire skylight replacement process.
Trying to DIY install a skylight rarely goes smoothly:
- Cutting the roof hole correctly takes experience and specialty tools. Rushed improper cuts can cause leaks.
- Proper flashing techniques are vital for waterproofing. Improper flashing is the #1 cause of leaky skylights.
- Fastening the skylight securely to the roof deck and framing is key to prevent issues with wind, weight loads, and vibration.
- Integration with the shingles or other roofing materials takes skill to keep the roof weather-sealed.
- Attic light shafts require careful framing and insulating to prevent heat loss/gain and moisture issues.
Skylight Accessories Enhance Functionality
Once you’ve selected the ideal new skylight, consider accessories and upgrades:
- Flashing kits – Self-adhering membranes that weatherproof the installation edges.
- Insulated curbs – Raised mounting curbs (more for domes) that add insulation value.
- Blinds – Shades that block light when needed for darkness or temperature control.
- Remote controls – Allow you to easily adjust automated blinds and vents.
- Rain sensors – Automatically close venting skylights when moisture is detected.
- Light pipes – Highly reflective tubing to direct sunlight from the roof into interior spaces without traditional skylights.
- Glass tinting – Tinted films can reduce glare and heat gain if excessive sunlight is an issue.
Key Takeaways on Dome vs Flat Skylights
Key Takeaway: There is no universally “best” skylight. Choose based on your roof type, lighting needs, climate, and aesthetic preferences.
To summarize dome vs flat skylights:
- Domed skylights maximize light transmission but aren’t as durable or energy efficient as flat glass. Domes excel on flat commercial roofs.
- Flat glass skylights offer crystal clear views, contemporary aesthetics, and excellent thermal performance. They require sufficient roof slope.
- For residential use, insulated flat glass skylights are generally the better option unless you have a flat roof or want softer lighting.
- Acrylic plastic domes are more affordable upfront but may need replacing sooner than durable glass skylights.
- Carefully measure the opening size needed and have professionals handle the complex installation process.
- Accessories like rain sensors, shades, and light tubes can further enhance skylight functionality.
The ideal skylight maximizes the benefits of natural light for your unique space while keeping out weather and matching your aesthetic vision. With proper selection and professional installation, both dome and flat skylights can significantly brighten up any home or building interior.
Frequently Asked Questions About Dome and Flat Skylights
What are the main differences between dome and flat skylights?
The main differences are:
- Shape – Dome is a curved bubble shape. Flat is a flat panel design.
- Material – Domes are usually plastic (acrylic). Flats are insulated glass.
- Light quality – Domes diffuse light, flats have crystal clear optics.
- Installation – Domes fit flat roofs. Flats require angled roofs.
- Energy efficiency – Flat glass is far better insulated.
Do dome or flat skylights let in more light?
Due to their shape, domes can transmit slightly more sunlight. But glass flats let in ample lighting with perfect clarity, while plastic domes diffuse the light. For most homes, flat glass skylights provide ideal light levels without distortion.
What are the best materials for skylights?
For domes, acrylic plastic is standard. It’s affordable and durable but can fade/cloud over time. Polycarbonate is extremely impact resistant. Flat skylights are usually insulated glass, which provides the best optics, insulation, and longevity.
How much do skylights cost installed?
Installed costs vary based on skylight size, type, roofing, and labor. Basic plastic dome skylights range from $350-800 installed. Flat glass skylights installed normally range from $800-3000 depending on size, features, and accessories.
Should I choose acrylic or glass skylights?
For optimal durability, light quality, insulation, and longevity, glass is superior. However, acrylic plastic domes cost less upfront. Glass requires more roof slope and professional installation. Evaluate your goals and budget when deciding.
Conclusion
Skylights are a great way to brighten up any dark interior space with natural illumination and views of the sky. When choosing a skylight, carefully consider your needs in terms of lighting, energy efficiency, roof structure, climate, aesthetics, and cost.
Domed acrylic skylights excel at transmitting ample soft, diffuse light, especially on flat low-slope roofs. Glass flat skylights offer crystal clear views, contemporary styling, smaller size options, and excellent thermal performance. They require sufficient roof pitch for water runoff.
For many homes, flat glass presents the best skylight option. But you may prefer a dome depending on your goals, budget, and roof type. Getting the skylight professionally installed is highly recommended to prevent leaks, cracking, and other problems. With the right skylight choice expertly installed, you can enjoy beautiful natural daylight for years to come.