Should You Install a Curb or Deck Mounted Skylight? Key Differences

Bringing more natural sunlight into your home can make a world of difference. Skylights are an excellent way to brighten up interior spaces and take advantage of solar light. But when it comes to installation, you'll need to decide between a curb mounted or deck mounted skylight. Both have their own sets of pros and cons to weigh.

You'll learn about performance factors like weatherproofing, leaks, insulation, and energy use. We'll also dive into appearance and design considerations, including customization options. And we'll break down the costs so you can budget appropriately. With the right information, you can determine which skylight mounting method is ideal for your home's needs.

Defining Curb Mounted and Deck Mounted Skylights

First, what exactly are these two main skylight types?

What is a Curb Mounted Skylight?

A curb mounted skylight requires a box-like structure to be built around the roof opening before installation. This skylight curb acts as an elevated shaft or bridge between the roof and the skylight unit. Curb mounted skylights sit on top of this sturdy frame.

The curb is typically made of wood, aluminum, or plastic. It must be securely installed on the roof deck and integrated with the roofing shingles. Flashing and waterproofing membranes are used to seal the curb and prevent moisture entry.

What is a Deck Mounted Skylight?

Instead of utilizing a curb, deck mounted skylights get mounted directly onto the roof deck. The skylight frame is attached above the opening using roofing screws driven into the decking boards.

With deck mounting, the skylight itself forms the upper part of the shaft. Special water diverters and robust flashing are used to prevent leaks. The skylight bubble fits snugly against the roof.

Key Differences in Installation and Framing

During curb mounted skylight installation, extra framing work is required to construct the skirt-like curb. But deck mounted skylights don't need this added step. The skylight frame attaches directly to the roof deck.

Curb mounted skylights have a box that raises the glazing area above the roofline for better light penetration. Deck mounted skylights sit lower and closer to the roof surface.

Comparing the Pros and Cons

Now that we've defined both types, let's compare some of the key pros and cons of curb mounted vs. deck mounted skylights.

Curb Mounted Skylight Pros

• Raise the skylight higher above the roof for better solar access and light diffusion into the room.
• Make it easier to install shades, blinds, or accessories inside the skylight shaft.
• Provide more interior space for ventilation systems or electrical controls.
• Allow for virtually vertical curb walls for maximized viewing area.
• Give greater flexibility in curb dimensions, allowing for larger skylight sizes.

Curb Mounted Skylight Cons

• Require more labor and material costs to construct the curb.
• Involve more complex waterproofing challenges with additional flashing.
• Have a higher exterior profile that stands out more on the roof.
• Limit roofing material options near the curb.
• May not work on low slope roofs without further modifications.

Deck Mounted Skylight Pros

• Have a lower profile that integrates cleanly with the roofline.
• Allow skylights on lower slope roofs down to 14 degrees pitch.
• Require less framing labor since no curb is needed.
• Offer a more streamlined, modern look with crisp lines.
• Provide good overhead clearance for roof access.

Deck Mounted Skylight Cons

• Don't raise the glazing as high off the roof resulting in lower light angles.
• Limit the potential skylight glass size due to deck mounting method.
• Make it harder to install accessories like shades inside the frame.
• Offer less space for ventilation or controls.
• Can only have slight curb angles rather than vertical walls.

Overall, both curb and deck mounted skylights have their own sets of advantages. You'll need to prioritize the factors that matter most for your particular home and installation requirements.

Which Provides Better Light and Views?

Due to their elevated curb position, curb mounted skylights allow sunlight to penetrate further into the home. The light also scatters better for wider room illumination. Views can be more expansive since the eyes are higher off the roof.

Deck mounted skylights still provide abundant natural light. But the views are more limited due to the lower roof mounting. Light diffusion may also be slightly constrained from the lower angle.

Evaluating Performance Factors

Let's explore some of the key performance differences between the two skylight types.

Weatherproofing Effectiveness

Proper weather sealing is crucial for any roof penetration. Curb mounted skylights require meticulous flashing and waterproofing around the curb's top and sides. The curb itself also needs a sub-flashing layer.

Deck mounted skylights utilize robust but sleeker flashing kits. The skylight frame has weep holes for drainage. Rubber boots with built-in flashing seal around fastener points.

When installed correctly using the manufacturer's guidelines, both curb and deck models can achieve excellent weatherproofing. The quality of the materials plus workmanship is most important.

Leak and Condensation Prevention

Skylights involve more sealing points than a normal roof section. Proper moisture control minimizes leaks and condensation.

Curb mounted skylight curbs should utilize waterproof membranes beneath the metal flashing. Sealants go around all joints. Anticondensation products prevent moisture buildup.

Deck mounted skylights also require comprehensive sealing methods. Condensation collectors channel away moisture. Dual-layer sealing tape and robust flashing prevent water entry.

Overall, curb and deck mounted skylights both have reliable technologies to combat moisture. Again, experienced installation is key.

Insulation and Energy Efficiency

Skylights are prone to heat loss and solar heat gain. Curb mounted models have more framing to insulate. The entire curb cavity can be filled with fiberglass or foam.

Deck mounted skylights don't offer as large an insulating cavity. But the frame still has room for perimeter insulation. Low-E coatings on the glass also boost efficiency.

When comparing curb vs. deck mounted skylight energy efficiency, curb mounting may have a slight advantage. But high-tech glass coatings help increase deck mounted skylights' efficiency as well.

Assessing Appearance and Design

Aesthetics often play a major role in skylight selection. Here are some key appearance factors when choosing between curb vs. deck mounted models.

Aesthetic Options and Customization

Curb mounted skylights offer near endless design flexibility. The curb can be shaped and sized to specification. Any roofing materials may be used.

Deck mounted skylights have pre-engineered curbs for streamlined installation. But units still come in multiple sizes. Bubble shape and glass tinting offer customization.

Overall, curb mounted skylights provide the most aesthetic versatility. But deck mounted skylights still give numerous appealing options.