How To Fix It

How Hard Is It To Replace Ductwork?

An HVAC system is made up of various components, The heat exchanger, the blower, the coil, the condenser, the thermostat, and the evaporator. 

Then there is the ductwork that sits at the heart of the HVAC systems. This begs the question then-

So, How hard is it to replace ductwork?

The answer to this question is not just a straightforward “easy or not so easy”, it depends entirely on your level of experience in DIY and your preparedness to work in hot, confined spaces. 

For the beginner with no DIY experience, the task of replacing an entire ductwork system would be rather daunting

Whereas for the more experienced DIY’er this will be a nice little project to tackle.

How To Identify Ductwork?

The ductwork can be made up of different Metals or Flexible materials, this ductwork can be round or square-shaped. Airflow to the different rooms in your house or living areas are channeled through this maze of large diameter piping or as it’s more commonly referred to, Ducting. 

Without it, the HVAC system would be useless, 

For this reason, it is vital to do proper upkeep, servicing, and replacement of these ductworks routinely, which can become costly, and even the best-kept systems only have a 10 -15-year life expectancy.

Things to take into consideration:

When you decide to attempt the ductwork replacement yourself there are a few things to take into consideration.

  • Safety, you will be working in confined spaces with temperatures at least 5-10 deg warmer than ambient temperature (Safety with any project or DIY work is paramount to the success of the project)
  • Working in an area with a high dust content 
  • Planning, tools, and supplies.

It must be kept in mind that replacing your ducting will likely require you to work in an attic or crawl space above the ceiling of your house. This means that you would need to take into consideration that space might be tight, the attic or crawl space will only be able to carry a certain weight limit and that temperature may vary in range from 5 -10 degrees warmer than ambient temperature.

Similarly, the attic or crawl space may have a higher dust content due to it not being a frequented area in most houses, Dust can trigger asthma or allergies

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  • The correct tools will make the job a lot easier and having help at hand is well advised.
  • Depending on the size of your installation, plan the replacements in section,
  • Furthermore, tri and do the work in the cooler hours of the day and have your supplies and tools close by to avoid unnecessary exertion climbing up and down. into the attic or crawls space.
  • Replacing a small section or sections of HVAC ductwork can easily be done with a bit of knowledge and research, however replacing or repairing an entire HVAC ductwork system might require a higher level of expertise.

The Project:

Before starting any DIY project, it is a good idea to do some research and speak to some professionals in the field.

What sometimes seems rather straightforward, isn’t always the case. Starting off with a DIY ductwork replacement will be a lot easier if it is accompanied by a well-laid-out plan. (Measure twice, cut once).

Having the correct tools and materials makes the project go easier.

  1. Have a look at your existing layout and identify the scope of work that you will be attempting.

With modern technology at your fingertips, make use of your smartphones. Take clear pictures of the existing layout. (Plenty of Apps going around that can be of assistance when it comes to measurements etc.). 

In the absence of this technology, Good old pen, paper, and measuring tape will also suffice

  1. Make sure you choose the correct replacement materials; ductwork comes in many shapes and sizes as well as different materials.
  2. Think long term, Flexible duct is a lot easier to handle, but this material is known for being dust collectors as well as potential fire hazards and would more than likely need more frequent replacement then metal ducting. Metal ducting on the other hand will likely be a little more costly but have a much longer life span.
  3. You will need basic tools to begin your project
  • Claw hammer
  • tape measure
  •  circular saw (When supports and bases need replacement)
  • reciprocating saw (When supports and bases need replacement)
  • a drill with a 1/4″ hex head driver for the self-tapping sheet metal screws 
  • gloves to protect your hands and 
  • safety glasses for your eyes
  • Vacuum cleaner
  • Dust mask


  • Ducting Materials, Flexible or Metal (try and have your pieces made up in the case of metal ducting, professionals have an assortment of expensive tools to do this manufacturing onsite, you as a DIY’er, you need it to almost just be “Plug and Play”)
  • Mastic duct sealant or an approved duct tape
  • Fasteners (Rivets, Self-threading screws, Clamps)
  • Rags and an approved cleaning solvent

Getting started:

  1. First and foremost, assess the scope of the project, don’t fix it if it isn’t broken, unless you have no other choice because of layouts or other unforeseeable factors.

What might seem as a major problem can turn out to be as simple as replacing one or two pieces of duct or just proper joint sealing.

  1. Whether you are doing an entire ductwork system or just a section, it is always a good idea to note how the ducting is assembled or joined together.

As previously mentioned, take pictures, or make sketches. It will be a good idea as well to determine the age of the original installation as asbestos was used in earlier years and this will require the removal by certified professionals with the proper safety equipment and certification.

  1. As the area may have a build up of dust it will be advisable to get it as clean as possible as well.

Dust can cause problems in confined spaces, wear a dust mask where practical.

It is a good idea to rope in a friend or someone to assist you and be your health and safety watch.

  1. If time is not an issue, divide the project up into sections. Here the age-old adage of Quality of work over the Quantity rings true. (“You will never eat an Elephant in one bite”).

Once you have taken care of all the planning, cleaning, and research, you are now ready to begin.

A well-laid-out system would be designed to deliver maximum efficiency. Adding bends and curves to an existing system will lower this efficiency as to many bends and turns will cause restricted airflow. Adding or removing registers and dampening valves needs to be carefully considered.

The flow rate is measured in (*CFM) and plays an integral part as the switch from flexible to metal might see changes in some dimensions of your ducting and layout. *CFM is an acronym for Cubic Feet per Minute. CFM measures the volume of air, in cubic feet, for each minute it moves

  1. Before proceeding with any work, please take note of all electrical wiring and potential hazards.

You might need to isolate the electrical supply for the HVAC system, which is a good idea anyway.

  1. In many instances the cladding/insolation will have to be removed first. Removing old pieces of ducting would require removing duct tape or mastic sealant
  1. You will then separate the ducting by removing clamps, in the case of flexible ductwork or self-tapping screws if its metal ductwork
  2. Try and avoid removing to many pieces at once, work your way from one point to the next and always keep in mind that you are in a confined space and likely a few feet above the ground as well.
  1. Clear out old pieces of ductwork and rubble from your surrounds as you remove them, thereby eliminating trip and fall hazards as far as possible.
  1. Whilst removing ducting, be observant for any signs of rust or rot on any holding brackets or supporting structures. Replace this if necessary.


  1. As you start to re-assemble and placing the new ductwork, spend time on areas where there is a joint and make sure the joint is sealed thoroughly, leaks can cause your system to not deliver the required airflow and you will experience insufficient air flow. This will cause the demand on your HVAC unit to increase as it will try to compensate for the losses caused by improper joint sealing and leaks.
  1. Where flexible ducting is used, try, and have the ductwork suspended away from the ceiling below and in as straight a line as possible with minimal sharp bends and turns.
  1. Where metal ducting is used, ensure the supports are sturdy and will be able to support the load of the ductwork, especially if you decided to change from Flexible to Metal. 
  1. It is advisable to have your ductwork insolated after completion as this will assist with heat loss during the winter as well as protect from residual heat in the summer.

In conclusion, it all depends on the extent of the replacement or repair, your timelines, Cost, and the willingness to ask for help if you don’t succeed.
There is plenty of information on Google (https://hvac-boss.com) and YouTube, and if that’s not your style ask your local HVAC guy for some friendly advice.