Deciding on Curb or Deck Mounted for Your Skylight Project

Installing a skylight can make a dramatic difference in brightening up a dark room. But when it comes to deciding between a curb mounted or deck mounted skylight, there are some key differences to consider before choosing the right option for your home.

Curb mounted and deck mounted skylights each have their own sets of pros and cons in terms of cost, installation, performance, and aesthetics.

What is a Curb Mounted Skylight?

A curb mounted skylight is installed on top of a "curb" or frame that raises the skylight above the level of the roof. The curb is made of wood or plastic and is securely attached to the roof deck. The skylight frame then sits directly on top of the curb.

The main benefit of the curb mount method is that it lifts the skylight off the roof surface. This allows room for proper flashing and waterproofing around the perimeter of the skylight to prevent leaks.

Curb mounted skylights have a low profile look since the curb raises the skylight only about 6-12 inches off the roof. They are best for flat or gently sloping roofs where a high profile isn't necessary for sufficient light intake.

Benefits of Curb Mounted Skylights

• More weatherproof - curb allows for complete flashing around skylight
• Easier installation on flat or low-slope roofs
• Lower profile aesthetics closer to roofline
• Can accommodate smaller skylight sizes

Downsides of Curb Mounted Skylights

• More expensive due to extra materials and labor for curb
• Require sufficient attic space for the curb
• Not ideal for steep-pitched roofs
• Difficult to install on existing roofs without attic access

What is a Deck Mounted Skylight?

Unlike a curb mount, a deck mounted skylight is installed directly onto the roof deck. Flashing is attached around the bottom edges of the skylight frame and integrated into the roofing material for waterproofing.

Since there is no curb, deck mounted skylights sit nearly flush with the roof for a sleek, contemporary look. They are better suited for steeper pitched roofs where a higher profile allows the skylight to be positioned perpendicular to the sun's rays.

Benefits of Deck Mounted Skylights

• Cheaper and easier to install without a curb
• Flush aesthetics ideal for modern homes
• Do not require attic space underneath
• Perfect for steep-pitched roofs

Downsides of Deck Mounted Skylights

• More prone to leaking without a curb
• Challenging to properly flash on flat roofs
• Installation may require reframing if no attic access
• Limited size options compared to curb models

Key Differences Between Curb and Deck Mounted Skylights

Now that we've covered the basics, let's look at some of the main differences between these two skylight mounting methods:

Installation Location

The most obvious difference is that a curb mounted skylight is installed on top of a raised frame or curb on the roof. A deck mounted skylight attaches right to the roof deck itself.

Framing and Access Requirements

Curb mounted skylights need adequate attic space under the roof to construct the curb framing. Deck mounted skylights do not need an attic underneath - they can be installed against the ceiling framing.

Flashing and Sealing

The curb on a curb mount allows for full weatherproof flashing around the perimeter of the skylight. Deck mounted models rely on careful integration of flashing into the roofing material.

Profile Height

Curb mounted skylights have a low, close-to-roof profile. Deck mounted skylights sit higher off the roof surface due to the lack of a curb.

Cost

Curb mounted skylights come with the added costs of building the curb and extra labor. Deck mounted models are simpler and cheaper to install.

Factors to Consider When Choosing Curb vs Deck Mounted

When deciding on the best skylight mounting option for your home, there are several important factors to weigh:

Type of Roof

Curb mounted skylights are ideal for flat or gently sloping roofs. Their low profile and enhanced weatherproofing abilities make them perfect for these applications. Deck mounted skylights are better suited for steep-pitched roofs where they can be installed perpendicular to the roofline to allow for sufficient light intake.

Budget

In most cases, a deck mounted skylight will be the more budget-friendly option due to simpler installation without a curb. Curb mounted models require extra framing materials and construction labor. But curb mounted skylights may justify the extra cost if you need enhanced weatherproofing or low profile aesthetics.

Attic or Ceiling Space

Curb mounted skylights require enough attic space under the roof to construct the curb frame. Deck mounted skylights can be fitted against the ceiling framing if no attic exists. This makes deck mounting ideal for vaulted ceilings.

Features

Consider compatible features like ventilation, blinds, electric openers, etc. Some skylight models may only come in a deck or curb mount version. Choose the mounting method that provides the features you need.

Aesthetics

Do you prefer a low-profile, traditional skylight look or a sleek, modern style? Curb mounted skylights have a subtler contour. Deck mounted skylights make a bolder statement with their higher roofline profile.

Recommendations for Choosing Curb vs. Deck Mounted

Based on their unique benefits, here are some recommendations on when to choose each skylight mounting method:

Go for Curb Mounted If:

• You have a flat or low-angled roof
• Attic space exists under the installation area
• A low profile aesthetic is desired
• Enhanced weatherproofing is needed
• Budget allows for the added cost

Go for Deck Mounted If:

• You have a steeply pitched roof
• No attic space or access is available
• A modern, flush look is preferred
• Budget is a concern
• Skylight needs to be installed at an angle

Tips for Smooth Skylight Installation

Once you've decided on curb vs deck mounting, proper installation technique will ensure your skylight functions safely and effectively. Here are some tips for a smooth and successful skylight installation project:

Know Your Local Codes

Most areas require permits for skylight installation. Research local building codes to ensure your installation meets requirements.