Call Now 1.800.265.1914

How Attic Insulation And Attic Ventilation Work Together

August 23, 2018

A good contractor will tell you right off the bat that the best approach to a comfortable home starts in the attic. The space needs to be well sealed, well insulated, and well ventilated for maximum effect on the rest of the home. This is because – warning: this may sound strange – your attic is not a part of your home’s building envelope, unless it has been renovated and finished into a living space. Your building’s envelope includes only spaces that are conditioned, and play an important role in how you feel in your home.

For professionals, a “truly insulated building envelope” is key to achieving optimum energy efficiency, resulting in less energy usage, lower energy bills, and increased comfort. For this reason, we think of the attic as its own envelope that requires just as much care.

The professional installers at Great Northern Insulation have been trained using these guidelines, so you can expect the best results if you choose us for insulation.

Interested in having GNI assess your attic for free? Click here to schedule your assessment.

Improving airflow and ventilation in the attic

For improved energy efficiency throughout a home, the best results are achieved when attic insulation and attic ventilation work together. It’s not enough to simply load up the attic with insulation materials. The space must be sealed for air leakage and ventilation must be assured.

Your attic intakes air from soffit vents. You may notice them if you look up at the underside of where your roof sticks out over your home. In a healthy, unfinished attic, outside air enters through these vents, follows up a baffle, circulates through your attic, and leaves through a ridge vent, gable vent, or other form of vent, such as a turbine vent (otherwise known as a whirlybird). When there is moisture accumulation in the attic space, this controlled motion of airflow helps to prevent condensation (which can lead to mold) and ice damming.

When there is insufficient or improperly installed attic insulation, combined with a lack of air sealing, heated or cooled air from the living space below can enter the attic and wreak havoc. This could be in the form of moisture damage, ice damming, and increased utility bills. This is also true if your attic is a finished, conditioned living space. In this case, you will want to take extra precautions to make sure the outside air and conditioned inside air do not mix. Either way, air leaving your living space costs you money to replace.

Interested in having GNI assess your attic for free? Click here to schedule your assessment.

Reducing moisture with ventilation in the rest of your home

The symptoms of excess air moisture and indoor humidity are palpable – the home simply feels uncomfortable, regardless of the weather. Windows may fog up, skin feels clammy and worse, there may be a mildew smell. These are signs that something is wrong and remedies are required.

Clearly, reducing humidity levels is a good start – that would be in the kitchen, the bathroom, and in the basement. That requires good local ventilation with high quality vent fans for each appliance or area that produces moisture or steam. Washers and dryers, cooking, and showering all contribute to air moisture. Here, effective venting is essential.

For professionals, the key to managing (and resolving) humidity issues in any space is ventilation and air sealing to control the flow. The fact is, indoor humidity is directly influenced (positively and negatively) by ventilation levels. As such, a professional approach to design and installation will deliver the best performance results overall.

Another concept to consider is that older, leaky homes relied on the leaks to exchange ‘fresh’ air with ‘stale’ air. With your new, air tight home, you need to make sure the air inside is still being exchanged, but at a controlled rate that doesn’t waste your home’s energy. Both HRV and ERV systems ensure that the home maintains accomplish this. These systems use the warm air leaving your home to heat the cool air entering your home during winter. An ERV will also exchange some of the moisture in the exiting air to the incoming air – another plus during winter.

Attic insulation from the experts at Great Northern Insulation

When it comes to installing attic insulation, it’s best to do it right the first time around. As home energy specialists, the team at Great Northern Insulation makes sure that air sealing, insulation, and ventilation are all accounted for when you are considering attic insulation. It’s a three-pronged approach to ensuring optimum home energy efficiency.

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!