Shedding Light on Your Dark, Scary Attic

CCI-Review, CCI-London and Area, May 2020

Attics are an important part of your building! Look, we get it. They can be dark, scary, and often overlooked. We will help you conquer that three-headed attic monster and enlighten you on what a functional attic can do for your building – and your wallet!

The most common attics in our climate zone are unconditioned spaces. This means they are not heated or cooled like the inside of your home. There are several components that make up this type of attic, including: roof shingles, shingle underlayment, sheathing, wood framing, passive vents, vented soffit panels, rafter vents, insulation, vapour barrier, air seal caulking/weatherstripping, an access hatch, drywall ceiling, and more.

Figure 1: Attic Components
Figure 1: Attic Components.

Let’s dive deeper into common issues we see in unconditioned attics, the three most important aspects of your attic, what a well-functioning attic can do for you, and what Edison Engineers can do for you!

Time to conquer your 3-headed attic monster!

The 3-headed attic monster – not so scary, just misunderstood. We want to make this monster happy, because when it is unhappy, it can create all kinds of problems for you, including:

  • Ice Damming

    • Damaged roof shingles, sheathing

    • Leaks into living space

    • Icicle hazards

  • Roof Shingle Failure

    • High shingle temperatures

    • Shorter asphalt life

  • Condensation in Attic

    • Mould growth

    • Wood damage/rot

  • Uncomfortable Interior Temperatures

    • Heat escape in winter (conduction)
    • Heat entry in summer (radiation)
    • More expensive utility bills
Figure 2: Ice Damming
Figure 2: Ice Damming

So, how do we make your monster happy?

Easy – we give it what it likes. This monster likes a cold space, a dry space, a space separated from its downstairs dwellers, and fresh air.

But how do we provide these conditions for your monster? By ensuring the three most important aspects of your attic (insulating, air sealing, and ventilating) are optimized.

Figure 3: A Happy Attic Monster.
Figure 3: A Happy Attic Monster.


The insulation in your attic is designed to limit thermal transfer between your conditioned living space and your unconditioned attic space. Types of insulation used typically include loose-fill or blown-in, 2’x4’ batt, or even spray foam. Older buildings will often have less than optimal levels of insulation due to the building code requirements at the time of construction.

Proper insulation can help create a thermal barrier between spaces, increasing comfort and even reduced energy use.

Figure 4: Properly Insulated Attic.
Figure 4: Properly Insulated Attic.

Air Sealing

Attic air sealing is the process of limiting air leakage between your conditioned living space and your unconditioned attic space. Ceiling penetrations such as light fixtures, exhaust fans, the access hatch, and along tops of walls are typical areas of concern. Ensuring these ceiling penetrations are sealed will help create a successful and functional air separation between the two spaces. Air sealing is typically provided by your drywall ceiling and/or a vapour control layer on top of your drywall ceiling.

Other key air control measures include making sure your bathrooms and clothes dryer fans exhaust to the outside and are not pumping hot, humid air into your attic!

Figure 5: Common Sources of Air Leakage.
Figure 5: Common Sources of Air Leakage.


Attic ventilation is the process of creating air flow through your attic, using low venting and high venting. Most attics in our climate zone rely on passive venting – a natural process where warmer air rises and gets replaced with colder air from below. Another main contributor to ventilation is wind. Low venting typically includes perforated soffit panels and high venting can include box vents or ridge vents.

Proper ventilation will help increase colder and dryer attic space conditions; however, the key contributors are proper air sealing and insulating.

Figure 6: Good vs. Bad Ventilation.
Figure 6: Good vs. Bad Ventilation.

Together, proper insulating, air sealing, and ventilating can provide you with optimal attic conditions – making your attic monster very happy! It will increase resident comfort, improve your building’s performance, and increase the service life of your shingles and other roof components.

What can an Edison Engineers do for you?

Have your attic space and roof shingles reviewed prior to setting final project budgets. This review will provide the Board with critical information on how your attic monster is feeling – and how your attic is performing – before you undertake repairs. It is far more economical to complete attic repairs or upgrades in combination with a shingle replacement project. This allows contractors to remove or repair damaged roof sheathing and provides easy access to your attic from the outside! No need to have contractors fighting through that attic hatch in your closet. Finally, reviewing and upgrading your attic with a re-roofing project will ensure you are maximizing your new roof’s service life and optimizing your investment.

It may also make sense for you to review and upgrade your attic during government home-efficiency rebate programs – when you can recuperate some of the upfront costs, and then reap the long-term energy benefits.