DIY (do-it-yourself) Projects

Published on October 27th, 2015 | by Guest Contributor

How To Insulate Your Attic Duct System Step by Step (with Video Instructions)

As winter nears, many will begin to activate their home heating system to keep the house warm in the blustery and frigid temperatures that accompany the change in seasons. Ensuring your attic is properly insulated is essential to this endeavor. Taking this initiative will reduce energy costs, which in turn aids the environment and also puts savings in your pocket. As warm air naturally rises, the attic is the area of any home where heated air is likely to escape. Thus it is fundamental to ensure the attic is properly insulated to reduce this risk. Checking the insulation itself with a laser thermometer and repairing leaky duct joints are two established methods to optimize heating and eliminate expenditures.

What You Need To Get Started:

  • Laser Thermometer, Thermal Imaging Camera or Corresponding Smartphone Application
  • 1” to 3” Paint Brush
  • Mastic or Air Duct Sealant
  • UL 181 Duct Tape
  • 10-10 Mesh
  • Masking Tape
  • Eye Goggles
  • Protective Gloves
  • Caulking Gun
  • Silicone Tube

Assess Current State of Attic Insulation

Insulation itself keeps warm air in and prevents cold air from infiltrating any building. Before you can move forward and begin any improvement project for your attic insulation, it is imperative to actively gauge its current state. You can use a ruler, first, to measure the ground-level attic insulation applied to the floor of your attic. Here’s how, along with a guide to what it “should” be, at the minimum. This is an easy first step, but if you’re willing to invest a little money into a really cool tool, a laser thermometer is a great one.

A laser thermometer allows you to take the average temperature of an object or area simply by pointing and pushing a button. Typically, these devices are relatively cheap and can be found at leading hardware retailers for about $15. These tools often identify areas where drafts are exposed or locate holes in the insulation, which will in turn help you identify where repairs or amendments must be made. These devices through their advanced technology can even help detect the presence of weak insulation itself. Here’s an article about how to use a laser thermometer to assess your attic’s insulation.

Many experts suggest beginning by checking around doors, vents, windows, light switches and other openings. While engaging in this activity, it is important to be meticulous in where you aim the laser thermometer. Scan the areas in and around light switch panels and be sure to aim at the panel itself where the wiring is located. In addition, check regions most vulnerable to where a draft can most likely emerge, near the lips of windows, door jams or ventilation shaft openings. These regions are areas most likely to expose any weak insulation, a laser thermometer will be able to recognize a change in temperature in these specific vicinities. In addition, scanning the walls themselves can locate insufficient seals within existing HVAC systems, this is another great method to unearth a potential duct leak without an extensive operation that requires opening the wall itself. If you wish to see how to use this device to its full potential, watch this video:

For those wishing for an alternative to a laser thermometer, there are smartphone applications available. A great example of this is Seek. However, some of these applications are far more expensive than traditional laser thermometers.

Once you’ve identified spots in the attic that might need some additional insulation, you can add cellulose, fiberglass, recycled denim, or wool insulation in those areas. However, the bigger picture is the ducting that runs through your attic (unconditioned space) with conditioned air. If that conditioned (either heated or cooled) air leaks out, you’re literally throwing money away and adding to our global CO2 problem for no reason. So the next, and most important step is to…

Sure Up Leaky Duct Joints

The duct work is the backbone of air exchange and ventilation. With this being said, duct joints that leak can create enormous problems with efficiency. Ducts are composed of a metallic alloy material. Though strong, as they age they are all the more likely to corrode and erode from exposure to the elements and oxidation. Identifying leaky duct joints is simple to achieve. First, examine the duct joints and connections to discover any loose connections or tears in the seams. This can be best be done with the system powered on. This allows for you to quickly identify escaping air that will be felt slipping through the joints or tears.

In the event you uncover a torn flexible duct or a faulty duct joint, first you must clean the area to prepare it for taping and sealing. Using traditional soap and water with a rag will suffice. A common mistake made by many is failing to cleanse the region appropriately, which in turn leads to a poor seal and continuation of the problem. Once the surface is sufficiently cleansed, you can move forth with sealing the tear or loose connection with duct tape and then affixing a piece of fab mesh over the seam and completing the project with a layer of mastic sealant.

For heating ducts, you must use caulk mastic. This can be done using a putty knife, a common mistake made by many do-it-yourselfers is failing to properly cover the seal with an appropriate amount of caulking. Caulking can be costly, but being liberal with this material can rectify the situation for a longer period of time. It is important to never cut corners. To see how to get started and effectively complete the job, please watch this video:

Screen Shot 2015-10-27 at 2.06.19 PM

After cleaning the joints, put a layer of tape around it.

Screen Shot 2015-10-27 at 2.06.25 PM

Cover the tape with mastic

Screen Shot 2015-10-27 at 2.06.29 PM

Apply enough mastic to really cover up any potential leaks. You can even apply to other potentially leaky spots and seams.

Follow Up

                  After a couple of days, follow up by using a laser thermometer or a smartphone application if you wish to note any changes. What should be seen now are temperatures remaining consistent and matching ambient temperatures in the areas once affected. In the event the problem persists, you may need to repeat the steps again and determine if you missed any spots. In addition, you may also wish to consider and then discover if there was a failure in the repair materials. If neither was the case, you may be best consulting a professional to gain a second opinion.

Bio: Paul Kazlov is a “green” home remodeling enthusiast and an industry pioneer for innovation in home renovation. Paul writes for the Global Home Improvement blog and strives to educate people about “green” products such as metal roofing and solar. Follow him on Twitter @PaulKazlov

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  • TedKidd

    People think insulation is some panacea. Then they spend a bunch of money and are shocked at the disappointing results.

    It’s the air leakage. And air leakage exacerbated by mechanical pressure is the worst. Besides saving boatloads of energy, sealing ductwork can dramatically increase comfort and control.

    • Bob Blanchette

      Air sealing supplies are cheap s. the cost of insulation. Insulation manufacturers put more effort into selling high dollar purchases than air sealing products.

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