Call Now 1.800.265.1914

GNI's Consumer Guide to Preventing Ice Dams on Your Roof

November 07, 2018

With winter around the corner, it’s important for homeowners to understand more about ice dams. Ice damming can lead to damage to your roof, and possibly even injury because of falling icicles. It is also a possible sign that there is insufficient insulation or air sealing in your attic. This article tackles some common questions that we get about ice damming and how to stop it.

The most common questions we receive:

  • What is ice damming?
  • Why do ice dams form?
  • How can I prevent ice damming?
  • What are the most effective ways to stop ice damming?

Preventing Long Term Damage to Your Attic and Roof from Ice Dams

Ice dams are chunks of ice that hang from the edge of your roof. The problem arises when the mass of snow and ice slowly melts during the day. It causes water to pool under the shingles, through the soffits, and even throughout the attic (potential collecting and seeping into your ceiling).

In some cases, the visual signs of ice damming will be obvious, especially during winter. However, the best approach to preventing ice dams is to start preventative measures before winter even arrives.

At Great Northern Insulation, We Can Identify the Source of the Problem and Provide a Solution.

Solution #1: Sealing air leaks throughout the attic and roof cavity

Typical homes suffer from a high amount of heat loss (from inside the house) leaking out through your attic. That heat loss is caused by air leaks through all types of openings, gaps, and cracks in the “building envelope”. Air leakage, even in newer homes, must be effectively blocked.

Air sealing is integral to preventing ice dams, mainly because the freezing/melting cycle of winter ice is mitigated. As well, comprehensive air sealing will better insulate the home, therefore saving on energy consumption, and reducing winter heating bills (and summer air conditioning).

Solution #2: Checking insulation integrity – upgrading if needed

In addition to air sealing, it pays to check your attic insulation, even yearly. This will ensure that your R-Values are up to standard and providing the necessary thermal insulation, based on the geographic region you’re living in.

With Great Northern Insulation, our experts will inspect your insulation and recommend viable improvements. They will also suggest the type of product that will best suit your needs (batts, blown in, or spray foam).

Working with GNI, you can be sure of professional expertise. Where it’s simply “topping up” your existing insulation, or completely removing and re-installing insulation, R-Values will be brought up to code, providing optimum performance.

Solution #3: Improving air ventilation in the attic and roof cavity

Effective air ventilation in the attic and roof provides a proper balance of air exchange between the cold outdoor air and the slightly warmer attic air. This requires air sealing and insulating your attic to effectively separate your indoor living space from any outside air. If you are using your attic for living space, your approach will need to change.

Ensuring proper air ventilation is key to preventing ice dams, mainly because balanced air exchange keeps the temperature in the attic consistent, and averts the cycle of freezing and melting throughout a cold winter. Without the freezing/melting cycle, ice dams will not develop.

Are Icicles a Sign of Underperforming Attic Insulation?

In most parts of Canada, the roof gets hit the hardest during winter, especially during a severe winter storm. A well-functioning roof should not get significant snow build up - the snow should slide off. On the flip side, a roof and attic that is poorly insulated and ventilated will allow ice to accumulate.

If snow and ice is accumulating on your roof (and melting in certain spots), it’s a sure sign of heat loss - likely because of underperforming insulation or poor ventilation in the roof and attic cavity. During the winter, it’s a good idea to check the roof after a snowfall – there shouldn’t be any bare spots.

As for icicles, this is another sure sign of undesirable heat loss, often due to underperforming attic insulation. Icicles and ice dams are a symptom of poor insulation and ventilation and the underlying problems compromise energy efficiency in the home, which results in winter heating bills that are higher than need be.

Determining which Type of Insulation is Best for You

Because every home, attic, and roof is different, every insulation project will also be different. In particular, different insulation products (or combination of products) address different needs.

Blown Insulation (Cellulose, Mineral Wool or Fiberglass)

Blown insulation is mostly used in attics and for drill-and-fills. All three types have effective insulation properties, and need to be combined with a vapour barrier when installed. They are also treated with a fire-retardant. They can also be combined with spray foam in the attic to create a powerful approach to air sealing and insulation. Though they all perform slightly differently in terms of R-value, they are all installed to code to achieve identical R-values, and can be trusted to keep you comfortable and help prevent ice damming.

Fibreglass and Mineral Batt Insulation for the Attic

Fibreglass and mineral batt insulation are more good options for the attic. The “batts” are made from recycled and some new materials, and provide a cost effective installation and excellent improvement to energy efficiency. The “batts” are placed strategically in the attic and roof cavity in order to create an insulating “blanket”. A steady hand and thorough knowledge of insulation and building science is needed – the “batts” must be perfectly fitted so that no gaps or openings remain. Importantly, this installation must include an effective air barrier and vapour barrier as part of the overall “batt” placement. This will minimize any air movement and help prevent air moisture from accumulating.

Spray Foam Insulation in the Attic and Roof

Sprayed throughout the attic, it creates an airtight envelope that very effectively seals and insulates the entire space. Professionally installed, spray foam does it all. Depending on local building code, it can be air barrier, a vapour barrier, and an insulation barrier all at once. Homeowners who decide on spray foam insulation are investing in long-term value. With a one-time application, the attic and roof cavity are sealed and insulated like no other product or combination of products.

Great Northern Insulation Effectively Air Seals the Attic

Air leakage throughout the attic (and the rest of your home) has an incredibly negative impact on energy efficiency. When an attic is sealed tight, air infiltration and exfiltration are much better managed, and the negative effects of air leakage are averted. Installed insulation will also perform better.

Before air sealing an attic, Great Northern Insulation uses a “blower door test” to identify sources of air leakage, and pinpoint weaknesses that need to be rectified. Once identified, air leaks can be effectively sealed, allowing for controlled air circulation throughout the “building envelope”.

Older Homes Tend to be More Prone to Ice Damming

Preventing ice dams in older homes can be challenging simply because of the design and construction of the home. The problem is that old-style roofing and attics incorporate a number of awkward spaces where air sealing and thermal insulation just can’t do a satisfactory job.

In these older homes, spray foam insulation is often the best solution – a good application will seal and insulate the entire space at one time. Most importantly, the hard-to-reach spaces, gaps, and openings are all blanketed. With spray foam, the cost is higher but results are superior.

Damage from Ice Dams May be Covered by Insurance

Clearly, preventing ice dams from forming is the best approach for any household – it’s the best way to prevent both short term and long-term damage. If you already have damage caused by ice damming, it’s possible that you have some coverage (depends entirely on your insurance plan).

Many homes actually have insurance coverage that includes specific “weather perils” – like hail damage or ice-related damage. This type of coverage may help to pay for repairs, although there are probably limits to the costs. Needless to say, the best investment is doing preventive work.

When it Comes to Preventing Ice Dams – Do it Right with Great Northern Insulation

If you’re dealing with ice damming and any of the associated problems, Great Northern Insulation is here to help. We can assess the problem, and increase your protection from ice damming. Our professionals are trained and certified to install insulation to perform to manufacturer expectations and the Ontario Building Code.

Working with Great Northern Insulation means working with home energy professionals who do it right the first time. GNI installs high quality products, along with installation work that is fully guaranteed. Everything is done without compromise, and with long-term results assured.

Get your project going by booking your FREE in-home assessment. Contact Great Northern Insulation at 1-800-265-1914 or fill out our contact form below.

Western Ontario

935 Keyes Drive
Woodstock, Ontario
Canada N4V 1C3

Phone: 1-800-265-1914

Fax: (519) 539-7946
TOLL FREE: 1-800-265-1914

Muskoka, Haliburton, Northern Ontario

1027 Elwell Park Road
Gravenhurst, Ontario
Canada P1P 1R1

TOLL FREE: 1-800-265-1914

Central Ontario

29 Ferndale Industrial Drive
Barrie, Ontario
Canada L4N 9V5

TOLL FREE: 1-800-265-1914

Greater Toronto Area

2 Guided Court
Etobicoke, ON
M9V 4K6

TOLL FREE: 1-800-265-1914

GTA East

103 North Port Road
Port Perry, Ontario
Canada L9L 1B2

TOLL FREE: 1-800-265-1914

South Central Ontario

450 Industrial Dr,
Toronto (Milton), Ontario
Canada L9T 5A6

TOLL FREE: 1-800-265-1914

Eastern Ontario

1035 Moodie Dr #1,
Nepean, ON
K2R 1H4

TOLL FREE: 1-800-265-1914

Niagara Region

25 Lincoln Ave
St. Catharines, ON
L2P 2C7

TOLL FREE: 1-800-265-1914


Great Northern Insulation - Better Business Bureau Profile.

Homestars Best of 2021 Award

Best of 2021

HomeStars has ranked Great Northern Insulation as a company that goes above and beyond in every aspect of business for the year of 2021.

Homestars Best of 2022 Award

Best of 2022

HomeStars has ranked Great Northern Insulation as a company that goes above and beyond in every aspect of business for the year of 2022.


GNI is the Authorized & Trusted Insulation and Air Sealing Installer for Lowe’s

Trusted for Over 40 Years

Over 40 Years in Business

At GNI, we service your project with the most experienced staff in the industry. Ongoing professional development is an obsession at GNI and we will not compromise at any level to bring to our customers the very best Installers, Sales Representatives, Customer Care Personnel, Field Superintendents, Estimating and Technical Support to your project.

100% Canadian

100% Canadian

Great Northern Insulation is recognized as Canada's largest full-service insulation contractor. GNI is 100% Canadian owned, proudly serving Ontario customers since 1980.

Foam Masters

Do it right the first time
- with foam mastersTM

January, 2021 regulatory phaseout of hydrofluorocarbons (HFCs) with the introduction of WALLTITE CM01. Using hydrofluorolefins (HFOs) with lower global warming potential (GWP) compared to HFCs, WALLTITE CM01 is the next generation of spray foam insulation.



Heatlok® Soya HFOTM leverages Honeywell’s latest Solstice® Liquid Blowing Agent technology. This new hydrofluoroolefin (HFO) blowing agent is the most environmentally conscious blowing agent produced to date, with a zero ozone depletion potential (ODP) and a global warming potential (GWP) of 1, which is more than two orders of magnitude (99.9%) lower than HFCs used in this industry.


3MTM products.
Quality + Performance = Savings

3MTM energy-saving products are designed to keep warm air in, and cold air out, while keeping energy bills down. Products optimize energy efficiency in buildings and homes; improve indoor environment for occupants; and effect the reduction of seasonal energy costs. 3M products are authorized for LEED credits (Leadership in Energy/Environmental Design).

Holmes and Holmes

Holmes and Holmes


Mike Holmes and his son Mike Jr. (MJ) convert MJ’s bachelor bungalow into a two-storey home for MJ and his girlfriend Lisa. Choosing the newest materials and build techniques, the father and son team follow Mike’s famous motto – “Make it right.” The show can be watched on HGTV and DIY Network.


Enbridge Incentives

The Home Efficiency Rebate Plus program offers up to $10,000 in home reno rebates – and Great Northern Insulation can pave the way.


Great Northern Insulation proudly abides by a renovation-specific Code of Conduct set by RenoMark™.


We are Verified & Bonded by eRenovate. When you choose to proceed with our services through their platform, you receive the gaurantees set forth through their program.

As Seen on Love It or List It

The GNI crew have been featured installing insulation on Love It or List It - have you seen our logo in an episode?

Climatizer Cellulose


CLIMATIZER PLUS cellulose insulation is manufactured from a minimum of 85% locally-sourced post-consumer recycled newsprint. Non-toxic additives are applied to the uniquely fiberized paper generating a building material with superior thermal and acoustic properties, as well as exceptional resistance to fire, moisture, mould and pests.

Please, enter a valid value

Incorrect values!