Need insulation upgraded or installed in your office, home, cottage or garage?

As Ontario's largest professional insulation contractor, we can help.

See what our customers say...

Ontario's leading insulation company since 1980

• More than 40 years of experience
• Proudly serving all of Southern Ontario
• Professionally trained and certified installers
• Third party manufacturer warranties on products
• 100% Satisfaction Guarantee

@2025 Great Northern Insulation / All rights reserved 

Have questions or ready to start your insulation project?

For over 40 years, we have helped Ontario homeowners and builders build safer, more energy efficient and sustainable communities. With a broad range of products and services, we are your insulation experts for existing home renovation upgrades and new residential home construction—satisfaction guaranteed.

We install insulation throughout the home

Professionally installed insulation will increase your energy efficiency, reduce your heating and cooling costs, regulate room temperature and improve noise pollution. Depending on your needs, we will install new, top up existing or remove old insulation.

Attics

Walls

Basements

Crawlspaces

Garages

Floors

Reliable and affordable products and installation

We offer high performance, brand name insulation backed by third party warranties. Our certified installers are professionally trained to install all types of insulation.

Proudly Serving all
of Southern Ontario

→ London, ON

→ Woodstock, ON

→ Etobicoke, ON

→ Milton, ON

→ Port Perry, ON

→ Barrie, ON

→ Gravenhurst, ON

→ Ottawa, ON

→ St. Catharines, ON

with Branch Locations in:

- Lori on Facebook

"It is a pleasure to recommend their product and quality service. I commissioned GNI in 1992 for a previous property and was so impressed that I saved the receipt and was a repeat customer two years ago. They have a long standing reputation for assessing and providing quality service and product."