Curb Mounted vs Deck Mounted Skylights: Choosing the Best Skylight for Your Roof and Needs

Installing a skylight is an excellent way to bring more natural daylight into your home. Skylights create a bright, open feeling and can reduce your energy costs by allowing you to rely less on artificial lighting during the day. But when it comes to installing a skylight, you'll need to decide whether a curb mounted or deck mounted model is the best fit for your roof type and needs.

What are Curb Mounted Skylights?

Curb mounted skylights, sometimes called "curb mount" or "fixed skylights", are installed on top of a sturdy wooden or metal frame or "curb" along the roof edge. The curb raises the skylight several inches above the roofline and provides a base for securing the skylight unit. Curb mounted skylights tend to be smaller in size since they are constrained to the roof edge rather than spanning a large area.

Here are some key things to know about curb mounted skylight models:

• Installed on a raised curb framing at roof edge
• Curb provides a base for securing the skylight
• Better suited for flat or low pitch roofs under 14 degrees
• Smaller in size, usually 2x2 feet up to 2x4 feet
• Frame raises skylight profile several inches over roof

The raised curb design provides some built-in insulation against weather and condensation. Curb mounts also include flashed sides that help block water intrusion where the skylight meets the roof. This can help improve durability.

What are Deck Mounted Skylights?

Unlike curb mounted models, deck mounted skylights are installed directly onto the roof deck itself, without any kind of curb or frame raising it up. The skylight unit attaches directly to the roof structure with a built-in flange or frame.

Key features of deck mounted skylights include:

• Installed directly onto the roof deck/sheathing
• No need for additional curb framing
• Can be used on roofs with any pitch
• Allows for larger sizes up to 5x5 feet
• Sits flush with the roof plane

Deck mounting provides more flexibility in skylight location and size. Models are available to fit almost any roof pitch and manufacturers offer custom sizing. The lack of a curb gives deck mounts a lower profile that can be less visibly obtrusive.

Key Differences Between Curb and Deck Mounted Skylights

Now that you understand the basics of each type, let's look at some of the major differences between curb vs. deck mounted skylight models.

Placement on the Roof

One of the biggest differences is placement on the roof. Curb mounted skylights can only be installed along a roof edge or perimeter. Deck mounted models offer more flexibility to place the skylight anywhere on the roof where sunlight is desired.

Size and Light

Deck mounted skylights can be manufactured much larger, letting in more natural light. Their location flexibility also allows positioning to take best advantage of sunlight. Curb mounted models are more constrained by roof edges, so they let in noticeably less light.

Framing and Structure

The wooden or metal curb frame on a curb mounted skylight provides reinforced support. Deck mounted skylights require careful framing around the opening and may need additional bracing underneath to prevent sagging over time.

Appearance and Visibility

Deck mounted skylights sit nearly flush with a flat roof for a more seamless look. The raised curb and frame of a curb mounted skylight has a high profile that can be more visible from below. Curb mounts are also limited for low, visible rooflines where aesthetics matter.

Durability and Leaks

The curb frame provides some extra leak protection for curb mounts. But deck mounted skylights have more potential failure points where water could intrude without proper installation and flashing. Deck mounts may also require more maintenance over time as the roof decking itself degrades.

Energy Efficiency

Deck mounted skylights can often be customized with glass and glazing features for better insulation against heat loss. The lack of an insulated curb means curb mounted models lose more warmth around the frame. But extra insulation can improve their efficiency.

Maintenance Needs

Like flat roofs themselves, deck mounted skylights require ongoing maintenance as the decking underneath is more prone to wear. The robust framing around a curb mounted skylight adds support that requires less frequent repairs or replacement.

Roof Pitch Limitations

Curb mounted skylights only work on fairly flat roofs with a pitch of 14 degrees or less. Deck mounted models can adapt to almost any roof pitch with additional structural considerations.

Cost Differences Between Curb and Deck Mounted Skylights

In terms of upfront cost, deck mounted skylights tend to be more expensive. Labor costs are higher to install deck mounting since it requires more extensive framing and finishing work to integrate cleanly. Larger deck mounted skylights also mean pricier glass.

Curb mounted skylights have lower labor costs thanks to their self-contained frame. But material costs may be higher for the curb construction. Overall initial costs tend to be lower for smaller curb mount installations.

Use Cases and Considerations for Choosing Skylight Type

With their pros, cons and differences in mind, let's look at when curb mounted or deck mounted skylights tend to make the most sense.

When Curb Mounted Skylights Are Preferable

• On flat or gently sloped roofs under 14 degrees pitch
• For smaller skylights from 2x2 to 4x4 feet
• If placed near roof edges for ventilation
• In colder climates needing more insulation
• For a more budget-friendly skylight install

When to Choose Deck Mounted Skylights

• For larger skylights to maximize daylight
• If custom or asymmetric sizes are needed
• For placement anywhere on the roof, not just edges
• To integrate seamlessly on a flat or low-pitch roof
• In hot climates where heat loss isn't a concern

You'll also need to factor in your specific roof construction, local building codes, and the skylight look you want to achieve. Consulting a qualified contractor is highly recommended before deciding on skylight type.

Curb mounted skylights and deck mounted skylights each have their pros and cons in terms of cost, roof integration, efficiency, maintenance, and more. Key differences come down to:

• Curb mounts sit raised on an edge frame, deck mounts integrate into roof
• Deck mounts maximize light with flexible size and placement
• Curbs provide robust leak protection, decks need thorough flashing
• Deck mounts cost more upfront but require less repairs later

For flat or low-pitch roofs, smaller curb mounts are often the most affordable option. Larger deck mounted skylights tend to optimize daylight and provide seamless looks. Carefully compare the differences to pick the model best suited for your roof design and needs.

With smart planning and professional installation, curb and deck mounted skylights can be excellent choices to liven up your living space.