Complete Guide to Installing Curb and New Roof Top Unit

Installing a new roof top unit (RTU) and curb can be a complex task, but with the right guidance, you'll be able to tackle it with confidence. The curb is the structural component that supports the RTU, and it's essential to choose the right type and size for your building.

A curb can be either a galvanized steel or aluminum frame, and it's crucial to select one that's compatible with your RTU's weight and size. For example, a 4x4 galvanized steel curb is suitable for a standard 20-ton RTU.

To ensure a proper installation, it's vital to follow the manufacturer's instructions and local building codes. The curb should be installed on a level surface, and the RTU should be centered on top of it.

For your interest: Top Home Renovation Companies

Before you start installing a curb and new rooftop unit, it's essential to prepare the site. Check the roof structure to ensure it can support the weight of the new unit, as mentioned in the "Roof Structure Assessment" section. This typically involves verifying that the roof can handle the additional load.

For more insights, see: What to Do with Furniture When Getting New Flooring?

Measure the roof deck to determine the correct size of the curb, which should be slightly larger than the unit itself. According to the "Curb Size and Material" section, a curb that's too small can cause the unit to shift or even collapse.

Review the local building codes and obtain any necessary permits before starting the installation. This is crucial to ensure compliance and avoid costly rework or fines, as noted in the "Permitting and Inspections" section.

Explore further: Move Hvac Unit

To prepare for a successful RTU installation, you'll need to gather the right materials. A pre-fabricated Roof Curb is essential, as it provides structural stability and aligns perfectly with the unit's connections.

Choose a durable, weather-resistant adhesive as your sealant to ensure a watertight seal. This will help prevent leaks and keep your RTU running smoothly.

Roofing screws or fasteners must be corrosion-resistant to withstand various weather conditions. This will prevent damage to your RTU and extend its lifespan.

To enhance energy efficiency and prevent condensation around the curb, use insulation material. This will keep your RTU running efficiently and reduce maintenance costs.

Here's a list of materials you'll need:

The location of a roof curb on a building determines the curb's style, the roof installation procedure, and the coordination of installation details.

A roof curb placed on the ridge of a gable building requires coordination of ridge details to properly transition those trims to the curb flange in a weathertight fashion.

The roof installation should be modified to a floating low-eave condition with the ridge pinned since the saddled curb placement on the ridge prevents thermal movement as it restricts the opposing forces of the two roof planes.

It's imperative that curbs installed on standing seam roof systems must be installed to allow thermal movement, especially in larger buildings with longer roof panels.

All support framing should be installed prior to installation of roof panels to ensure the roof panels can support the weight of the selected curb and unit.

A helicopter places an RTU on a roof curb, illustrating the importance of proper curb installation for efficient and safe operations.

Curious to learn more? Check out: Well Installation Cost

Installing a roof curb on a metal roof requires careful planning and execution. The location of the curb determines its style and the roof installation procedure. A roof curb placed on the ridge of a gable building requires coordination of ridge details to ensure a weathertight transition.

The roof installation should be modified to a floating low-eave condition with the ridge pinned, as saddled curb placement on the ridge restricts thermal movement. Larger buildings with standing seam roofs will have longer roof panels, so curbs must be installed to allow thermal movement.

To prevent leakage, ensure that roof panels can support the weight of the selected curb and unit while still operating at the desired design. This involves installing support framing prior to roof panel installation.

A helicopter places an RTU on a roof curb. (Photo courtesy of RCS–Roof Curb Systems)

Here are some key steps to follow during roof curb installation:

Inspecting the area before installation can help prevent common mistakes, such as not checking the structure of the roof deck on existing roofs. Installing the roof curb on a dry day and using proper fasteners, sealant, and flashing can also help prevent leakage.

To control vibration and noise from rooftop equipment, use high deflection coil spring isolators and high frequency neoprene noise pads to address vibration from fans and compressors, and casing radiated noise caused by duct turbulence and airborne noise.

Duct-borne noise from supply and return air fans can be controlled using an aerodynamic acoustical silencer on the supply fan and an acoustical plenum on the return air side, both with minimal pressure drop.

Breakout noise through the bottom of the rooftop unit can be controlled by the NOISEBLOCK STL acoustical panel located in the floor of the ESSR.

To prevent leakage, ensure the roof deck is structurally sound to hold the curb, and lay it out and screw it down to the deck. If the roof deck is not structurally sound, additional steel may be needed to support the curb weight.

A simple step to prevent leakage is installing the curb on a dry day. Installing the proper fasteners, sealant, and flashing is also crucial to avoid common mistakes like not flashing the curb properly or not checking the structure of the roof deck on existing roofs.

Readers also liked: Shed Roof over Deck

Here are some key considerations to prevent curb leaks:

Sound and Vibration Isolation is a crucial aspect of Isolation and Leak Prevention. It's a common problem in buildings, but there are effective solutions available.

Vibration from fans and compressors, as well as casing radiated noise caused by duct turbulence and airborne noise, can be controlled with high deflection coil spring isolators and high frequency neoprene noise pads.

Noise from supply and return air fans can be controlled using an aerodynamic acoustical silencer on the supply fan and an acoustical plenum on the return air side, both with minimal pressure drop.

Breakout noise through the bottom of the rooftop unit can be controlled by an acoustical panel located in the floor of the ESSR.

Here are the key components involved in sound and vibration isolation:

By understanding these control methods and incorporating them into your building design, you can effectively reduce noise and vibration, creating a more comfortable and productive environment for occupants.

Curb Leak Prevention is a crucial aspect of preventing leaks in metal roofs.

On-site shake-out meetings between installers and suppliers can help eliminate installation issues. This is according to Reasor, who found that walking through the details and making recommendations can encourage buy-in from the field.

A simple technique to prevent damage is to place walk boards around the curb opening during installation. This prevents the weight of the installer from deflecting the panels and overall damage caused by foot traffic.

A typical standing seam roof has a roof slope of 1/4:12, so any panel deflection that equals or exceeds 0.25 inches will create a flat spot in the roof that will cause water to collect.

The roof deck must be structurally sound to hold the curb, so lay it out and screw it down to the deck. If it's not, additional steel may be needed to support the curb weight.

Proper flashing is essential, and crews should have the proper training to install it correctly. A common mistake is not flashing the curb properly.

Curious to learn more? Check out: Flashing Shed Roof