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How to Insulate Your Basement Walls and Ceiling

October 05, 2018

As a homeowner, you probably know the importance of basement insulation in contributing to energy efficiency and home comfort. But have you optimized the potential by insulating your basement walls and ceiling to the maximum? Today, it’s as much about energy efficiency as it is about home comfort, and doing it right, with the best insulation products, can make a big difference from season to season. Your basement, just like your attic, should be a top priority for insulation to improve your health and comfort. This is a home improvement with benefits that are both valuable and long lasting.

When insulating your basement walls and ceiling – don’t forget the floor

Without a doubt, insulating your basement walls and ceiling is of utmost importance. For the ultimate in performance, however, there’s nothing like insulating the basement floor if you can. Here, spray foam is used to seal and insulate the “under-floor” after which concrete is applied for a clean finish. If you’re just building a house, or doing major renovations, you shouldn’t pass on this option.

Insulating the basement floor enhances energy efficiency exponentially. And spray foam is the best product on the market for sealing and insulating the space from corner to corner. The basement floor will be completely airtight - airflow will be restricted and moisture collection can be reduced. Plus, it can act as part of a radon protection system to help protect you and your family from the dangerous gas.

When the basement floor is effectively insulated the entire home derives benefits. 

  • airflow and air leakage is blocked
  • moisture collection is prevented
  • indoor temperature is balanced
  • no more drafts - more comfort
  • significant energy cost savings
  • radon protection

There are good reasons why the basement ceiling should be insulated (and good reasons not to)

When insulating your basement walls and ceiling, it’s important to do it right – with the appropriate insulation products and a quality approach to installation. In a crawlspace or cold cellar that is un-heated, and does not contain any mechanicals or pipes, the ceiling should definitely be insulated – this will keep any heated air (or cooled air) securely on the main floor.

When insulating the basement ceiling it’s important not to cut corners. It should be done right, based on the building code, and with a product that will ensure performance. The important thing is to create an airtight envelope so that there’s no airflow between the wooden joists or any other infrastructure.

However, if there are water pipes, heating ducts, or other areas that can freeze over because of being unheated, you should not insulate the ceiling. You need the heat from the living area to move through your entire building envelope. If you are unsure if you should be insulating the ceiling of your basement or crawlspace, we can send an expert to your home for free. Just fill out the form here.

When insulating basement walls, various products are recommended

Once you decide on insulating your basement walls and ceiling, a couple of products are available:  fibreglass or mineral wool batts and spray foam. Each of the products has benefits, and each is designed to deliver specific results. Our expertise can help you choose the right insulation to suit your specific needs.  

Fibreglass and Mineral Wool Batts:

In North America, fiberglass or mineral wool batts are an effective insulation option for both the attic and basement. Batts provide good R-Value, good energy efficiency, and good lifespan. To improve performance, the basement should be air sealed before installing the batts.  A vapour barrier will also be wrapped over the batts to ensure they work optimally for years to come.

Spray Foam Insulation:

In the basement, spray foam insulation can be considered an ideal solution because of its innate capabilities. Spray foam does it all in one application - it blocks air leakage - it prevents moisture collection - and it provides a high R-Value. Spray foam stops “heat flow” in the basement, which guarantees optimum energy efficiency, and therefore lowers the costs of heating and cooling the home.

How necessary is it to insulate the basement walls below grade level?

Insulating basement walls below grade boosts the insulation performance and energy efficiency of the home. Below-grade foundations are often exposed to moisture (from the soil). To prevent this moisture from moving across the “building envelope”, the basement wall assembly must reduce/eliminate air leakage pathways. Making sure this is done professionally guarantees health and safety. We have nearly 40 years of experience with below grade basement wall insulation.

What to use - “faced” or “unfaced” insulation for walls and ceiling?

While it’s best to get advice directly from an expert (you can get a free advice about your home from an expert by filling out our form here), it’s also helpful to have some basic understanding when making decisions. This is particularly relevant when it comes to “faced” and “unfaced” insulation. And in the basement, choosing between the two is essential.

“Faced” insulation comes with a vapour barrier - it’s designed to prevent moisture accumulation. “Unfaced” insulation does not incorporate a vapour barrier. “Unfaced” spray foam insulation does not need a vapour barrier. “Unfaced” fiberglass batt requires a separate vapour barrier.   

In the basement heat flow must be blocked, and “faced” insulation does a good job. With spray foam insulation (unfaced) there’s no need for a vapour barrier because the installed material naturally acts as this barrier. A thermal barrier will need to be applied over the spray foam.

Building code can vary amongst local jurisdictions. Always check with your local building official and GNI consultant to ensure code compliance.

Does a well-insulated finished basement increase home value?

All things considered, a finished basement that’s well insulated will enhance real estate value. To begin with, your home has increased comfortable living space with an insulated basement. As well, the energy efficiency of the home is improved – and that means substantial energy savings for any homeowner (season to season).

In most homes, the return-on-investment when insulation has been upgraded far exceeds other home improvements. In fact, for the most part, renovating the kitchen or bathrooms is very much an aesthetic upgrade, while home insulation provides long term dollar heating/cooling savings.

Worried about the cost of upgrading basement insulation?

Today, there are rebates and incentives available when you upgrade home insulation. Customers of Union Gas and Enbridge Gas are eligible for various rebates when working with a Registered Energy Advisor. With Enbridge Gas, two energy upgrades are required. Retrofits could include such upgrades as complete basement insulation, exterior walls insulation, and attic insulation. With Union Gas, the Home Reno Rebate Program incentivizes "energy smart upgrades" and also requires at least two upgrades to be performed. Here, a homeowner could qualify for up to $5,000.00 in rebates. With both Enbridge Gas and Union Gas the Energy Advisor will perform an audit after all the work has been done to confirm the rebate.

With any basement insulation project, it pays to work with accredited energy contractors like Great Northern Insulation. Take it from our happy customers (read the reviews below). Working with GNI, homeowners are assured of high-quality products and high-quality installations. From air sealing, to insulation, to ventilation, GNI recommends the energy upgrades with the best return-on-investment. Find out more by calling Great Northern Insulation directly at 800.265.1914 or filling out a form.

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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.

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

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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.


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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).

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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.


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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.

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