How to Insulate Sheet Metal Duct Work

Taping a tear in wrapped duct work
  • 5-20 hours
  • Beginner
  • 0-500
What You'll Need
Measuring tape
Paint (optional)
Foil faced insulation batts
Duct tape / mechanical fasteners
Hollow core foam insulation

Sheet metal duct is one of the most common duct work systems used for cooling or heating purposes. Its alternatives include fiberglass panels along with foam boards. However, sheet metal duct is often preferable as it is considered to be more cost effective in terms of energy costs and it distributes/treats airflow into residential, commercial, and industrial spaces more effectively.

In effect, they are insulated to improve thermal performance and to avoid dripping and condensation. Types or designs of sheet metal duct include radial (round ducts) and extended plenum (radial and rectangular shaped ducts).

Insulating sheet metal duct work is only a moderately challenging project and using the tools and equipment mentioned, as per the steps mentioned below, you can go about the project with little difficulty.

Step 1 - Understand the Material Requirements

man working on a metal duct

Many people often hire a professional to do the insulation project. However, if you are comfortable with home-improvement projects and have some expertise in this domain then it should not be problematic for you to add the maximum possible insulation value. Metal sheet duct work is a recommendable material for insulation purposes and is often sealed using duct tape to help stop the heat and air conditioning from flowing outside. Therefore, before beginning your project use a measurement tape to get your dimensions straight and clear so your purchase is accurate. However, do allow some room for fixtures or walls especially when insulating pipes in cramped places.

Step 2 - Paint your Pipes

Once the purchase has been made, you may want to take advantage of the option of painting your pipes as it is difficult to paint them once they have been installed and insulated. Specific paints for sheet metal duct are available widely at local hardware stores and you may purchase as well as use them before the application of insulation material. It is worthy to note that wrap-on pipe insulations are also available and are especially useful for tight or cramped spaces.

Step 3 - Wrap the Pipes

wrapped duct work in an attic space

Use foil-faced insulation batts to wrap up the pipes but see to it that the whole thing is properly covered and any previous layers are thoroughly overlapped. You can fasten and secure the ends of the batts with duct tape, but that may cause the insulation to get spoiled. Therefore, mechanical fasteners are more advisable for usage than duct tape. Lastly, buy hollow core foam insulation, which is easy to install as it self-seals and works best with long lengths of pipe.

Step 4 - Specific Instructions

While insulating, see to it you avoid various common problems or pre-requisites that often arise or are required during this project. Do check on air velocity during the insulation process so the airflow can be optimized, examine the ducts and check for any possible leaks to effectively reduce your energy bills and do your best to avoid recurrent bends or turns in the design of ductwork as it might lead to inefficiency or a waste in energy.