Icicles are a perfectly normal phenomenon when on warmer days snow melts and the water produced refreezes, resulting in thin, short-lived icicles. What to watch for is the production of larger, thicker, more persistent icicles.

Icicles may look pretty on seasonal greetings cards, but yes, they can be a prime indicator that a property has a problem with its attic insulation. If warm air is leaking into the roof space it will melt snow, and the resulting water will freeze under the gutters or eaves.

Inadequate ventilation can also cause a build-up of warm air below the roof structure, leading to snow melt, ice dams, and icicles.

What Is So Bad About Icicles?

Icicles are a natural result of the normal cycle of a winter’s day, with the sun warming and melting snow, and the resulting water freezing as the day ends and the air temperature drops back below 32°.

However, too many icicles hanging from your eaves, or gutter, can, in turn, contribute to the build-up of ice dams on the lower edge of the roof, causing water to back up on the roof.

Standing water on your shingles may, through freezing and thawing cycles, eventually penetrate the roof covering and leak into the roof structure. The water tracking into the structure could cause rot, mold, and other structural damage.

Existing insulation, already inadequate, could be further compromised by the action of water ingress, compressing fiberglass and rendering it useless, thereby further contributing to the build-up of ice dams and icicles.

Icicles hanging from the gutters can put additional pressure on the fixings and the integrity of the guttering joints, which could lead to leaks or other problems once the thaw arrives in spring.

Large icicles, or accumulations or clusters of icicles point to a particular area where there is a problem with heat escaping from the attic and helping them to form.

In turn, these will lead to the creation of ice dams, or further structural damage due to their weight.

How Can I Remove Icicles?

Icicles, especially large formations, can be dangerous when they fall, so it is recommended that you do not try to remove them by force. Taking a hammer, or a rake to the icicles may result in more damage to the roof covering, eaves, or gutters.

If your icicles are up to an inch wide and a foot long, then you could use a rake to gently nudge the icicles so that they drop off the gutter. You could then use an ice-melting product to clear the gutter and any ice dam formation on the lower edge of the roof.

Do not stand directly beneath the icicles when you are working on freeing them from your gutter.

If you have a particularly large icicle formation on your gutters or eaves then it is advisable to ensure that no one can access the area below the icicles in case of injury from falling ice.

You may see the road crew spreading salt on the highway, or salt products sold to clear your driveway or sidewalk, but do not be tempted to use these to clear your roof or gutter of ice as salt is highly corrosive, and could cause further problems.

How Can You Prevent Icicles Forming?

Stopping icicles from forming in the first place will save your roof and gutters from further problems, so what are the best ways to prevent icicles from becoming a problem in the first place?


The best way to prevent icicles, and ice dams from forming on the roof is to address the insulation issue in the attic.

Local codes exist to regulate and advise on the level of insulation required. In the USA a minimum of R30 is required, and up to R-60 in climate zones 5 to 8, which cover most of the United States.

If you have an icicle problem, then the first thing to do is to check the level of insulation in the attic and bring it up to standard.


Odd as it may sound, keeping an unconditioned attic cool is key to the prevention of icicles and ice damming on the roof.

Proper ventilation will stop any warm air that does escape from the conditioned living area of the house from building up within the attic and causing snow to melt.

Air Seal

You may have checked your loft insulation and discovered that it is indeed up to code standards, but you still have an issue with icicles forming, so there must be warm air leaking into the attic somewhere.

Check any vents that pass through the attic space and ensure they are adequately insulated or sealed.

It is also a good idea to check that your flue, or chimney, is also properly sealed where it passes through the attic and is venting to the exterior as it should and not within the structure.

Eaves Clearance

Using a long-handled snow rake to clear the lower edge of the roof will help prevent a build-up of ice on the edge of the roof but be careful to not pull the rake across the shingle line to prevent damage to the roof covering.

When clearing snow from a roof always follow the slope of the roof.

Regular Gutter Maintenance

A key part of the maintenance schedule for your home should start with cleaning out the gutters after autumn when they are at the greatest risk of clogging with leaves.

Leaf build-up can slow the progress of water from the roof to the drains.

Making sure your gutters and downspouts are clear before winter gets underway will help in the battle against icicles and ice dams.

Heat Tape

In extreme conditions, it may be wise to consider using a heat tape that adheres to the gutter and roof edge and maintains a frost-free temperature on the surface of both, allowing the snowmelt to run off the roof.

Using a heated ice-dam prevention system stops water from building up and causing problems, but should always be used alongside proper insulation and ventilation within the attic space.


Justin's been in construction for over 20 years in both new build and renovation. With experience in both commercial and residential construction, he specializes in healthier and more energy-efficient homes.

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