Insulating water pipes can keep hot water hot and cold water cold, prevent freezing, reduce your energy bills, and improve the comfort of your home.

Ever wonder why you wait for hot water at the faucet, sink or shower when you first turn it on? This is caused by lost heat in the water line before it gets to the outlet. When you need hot water, you could be wasting gallons for the few minutes it takes for the cold water in the waterline to be pushed out. Point-of-use water heaters or circulating pumps can be added to a hot water system to help mitigate the wait time for hot water; but, they are quite costly to run and heat is still lost in the piping.

How to help keep your hot water hot.

A relatively easy and inexpensive way to keep hot water pipes warm longer is by installing thermal pipe insulation. When you insulate, the hot water waiting in your pipes will cool down more slowly than in uninsulated pipes. There are many benefits of insulating the hot water systems such as the water heater not working as hard to make hot water, lowering operating costs,  maintaining temperature for the comfort of your home, and possibly seeing a rise in the water temperature at the faucet. An added plus of insulation is protection against getting burned on hot pipes.

Why insulate cold-water pipes?     

There are many reasons to insulate all cold-water pipes. The most common areas to insulate are exposed pipe in the crawlspace, garage or attic where they are most vulnerable to freezing. However, freezing is not the only issue. Especially in the summer months, in unconditioned spaces, insulating will help keep that cold tap water cold. Insulation can also add protection against condensation, especially in high-humidity environments. A buildup of condensation can accumulate in these out-of-the-way spots which could go undetected over time, leading to extensive water damage.

Where to insulate?

Every section of water pipe in your home can benefit from insulation, but in some cases, it can be impossible to install if the walls have been sealed up. There are areas in your home that should be accessible that will definitely benefit from insulation. The best places to start are water pipe runs in any unconditioned spaces like a crawl space, garage, utility room, or basement with exposed piping.

What types of insulation are available?

Any material that has low thermal conductivity will perform well as an insulator. There are open and closed cell types of insulation as well as fibrous and foam. Foam insulation, unlike fiberglass, is a closed-cell structure that acts as a built-in vapor retarder (jacket) preventing moisture intrusion. Closed-cell  insulation products like Armaflex and polyethylene prevent condensation, moisture intrusion and loss of thermal efficiency.  These products are flexible and easy to work with in tight spaces.  They are also fiber-free and won’t cause the discomfort of fiberglass insulation.

How much insulation is required to prevent heat loss?

As the insulating thickness is increased, the prevention of heat loss levels off very quickly. Any additional insulation will result in diminishing return of heat loss prevention and costs. Over 70% of energy conservation can be achieved by the first half inch of insulation.

For full Armaflex installation instructions, download the Armaflex Installation Tip Sheet. For self-seal Armaflex, carefully peel and stick the self-adhesive edges for the longitudinal seams. Armaflex 520 BLV adhesive or Armaflex Insulation Tape should be used to seal butt joints for maximum energy savings.

Required Materials:

Products are available in-store and online at The Home Depot.

Required Tools:

  • Tape measure
  • Insulation Knife or Utility knife 

Helpful technical bulletins:


During normal operation, the temperature of a domestic hot water system will never get above 180°F and all Armacell insulation products may be safely installed on systems operating up to 180°F. Therefore, any Armacell insulation can be used safely on residential hot water pipes. When insulating near a hot water heater, especially natural gas hot water heaters, follow the manufacturer’s recommended guidelines to reduce potential fire hazards.