How to Seal HVAC Ductwork

Sealing ductwork can be one of the most cost-effective remedies for increasing energy efficiency. Yet it must be done thoroughly. Leaky ductwork can increase your costs and make your home less comfortable. If your duct system isn't sealed properly, carbon monoxide and other toxic fumes can build up in the home, creating an unhealthy living space. Another problem can occur when fumes from household cleaners, solvents, paints, etc., are pulled into the home's return air system through poorly sealed joints. Once these dangerous fumes are drawn into the hvac duct system, they can be re-circulated throughout the home.

The best solution for ensuring a proper seal and energy efficiency is to apply mastic and tape to every joint in the ductwork. The first step is to make sure the joint is clean and has been wiped down. This will allow the mastic to adhere properly and create a tight seal. You then want to apply a generous portion of mastic to coat the entire duct surface over the joint. You can use a brush or trowel to spread the mastic on. Then work the mastic into the joint, pressing and spreading lightly to achieve an even coat. You should strive to achieve a 1" overlap beyond the joint.

Then apply a mesh tape to reinforce the mastic. It's critical to make sure the mesh being used is designed for the brand of mastic used, so don't forget that!

By making these simple improvements to your home's ductwork, you'll save energy from day one and improve the comfort in your home! If you'd like help with this, we'd be happy to offer an analysis and estimate for your home's energy needs.

Green Space Construction Co. is a general contractor and energy efficiency firm in St. Louis with a focus on green building and renovations, weatherization, energy efficiency improvements, as well as traditional building practices. Our core values are composed of eco-friendly building, superior craftsmanship, and dedication to excellent customer satisfaction. Visit our website at GreenSpaceConstruct.com.