Basement window shutters in Canada and the northern US: humidity, condensation and small windows

Updated October 22, 2026

The short answer: a shutter suits a basement window well, provided the basement is dry. The three things that are different below grade are cold glass, damp air and deep, small openings. Get the humidity right, keep the louvers open on cold days and measure the depth carefully, and a basement window looks like every other window in the house.

Why basement windows behave differently

A basement window sits in the coldest part of the wall, often right at grade, with soil on the other side of the concrete around it. In winter the glass gets cold, and the air beside it is frequently the dampest in the house. Natural Resources Canada notes that condensation is more likely in humid areas such as the kitchen, the bathroom and some basements^[2], and that humidity levels above 40 percent can cause frosting and fogging of windows^[2]. Its guide also lists basement windows among the openings through which the house draws in outside air^[2], so a leaky old basement window is cold as well as damp.

None of that rules out a shutter. It means the covering has to let the window breathe, and the room has to be kept dry enough for whatever you put there.

Get the humidity right first

Health Canada recommends keeping indoor relative humidity between 30% and 50%, using a dehumidifier as necessary^[1], and specifically suggests running a dehumidifier in the basement to reduce dampness year-round if you need to, with the windows closed while it runs^[1]. A hygrometer costs little and tells you where you are; check it on a cold January morning and again on a humid July afternoon, because a basement can be dry in one season and damp in the other.

Wood takes on and gives off moisture with the air around it^[5], and the US Forest Products Laboratory’s handbook notes that many of the challenges of using wood come from changes in moisture content or too much moisture in it^[5]. In a basement held in range, painted poplar shutters behave as they do upstairs. In one that stays damp for weeks, they’ll swell, and the louvers may tighten until the season changes. If water comes through the foundation, that’s a job for a foundation contractor, and it comes before any window covering.

In the northern US

The US EPA’s range is a little wider, 30% to 60%^[3], and it makes two points that matter in a basement: vent dryers and other moisture sources to the outside, and reduce condensation on cold surfaces such as windows, pipes and exterior walls by adding insulation^[3]. For a basement window, that means the glass and the concrete around it. A shutter isn’t insulation, but a window that’s been weatherstripped and a foundation wall that’s been insulated make the window warmer, and a warmer window is less likely to fog behind any covering.

Condensation: what to do on cold days

Health Canada warns that heavy curtains or blinds can trap the cold and moisture and cause condensation on your windows, and recommends keeping window coverings open so warm air reaches them^[1]. A shutter closed tight against a cold basement window does the same. Shutters don’t prevent condensation; they can make it better or worse depending on how you use them.

Our window condensation guide goes through the same problem for every room in the house.

Small windows, deep sills: measuring and mounting

Basement windows in a poured or block foundation usually sit deep in the wall, often with a wide concrete or drywall return around them. That’s good news for an inside mount: there’s usually plenty of depth for the louvers to tilt without hitting the glass. What you have to watch is the window itself.

• Hopper windows tilt in from the top. Make sure the shutter, closed or open, doesn’t stop the sash from opening, and measure the depth to the sash at its open position.
• Sliders often have a latch that sticks out. Measure to the first thing that projects into the opening, not to the glass. The inside vs outside mount guide covers how.
• Out-of-square openings are common in older foundations. Measure the width at the top, middle and bottom and the height at both sides, as the measuring guide shows. An outside mount with a frame can hide an opening that’s out by more than a little.
• Louver size. On a small window, wide louvers can look oversized because there are only a few of them; 2½ or 3½ in louvers usually suit a 16 in tall window better, and need less depth. Our louver guide compares the three sizes.

One panel or two

A hinged panel swings out into the room about as far as it is wide. On a 32 in window that’s the choice between one 32 in panel, which needs the most clear space in front of it, and a pair of 16 in panels that open from the middle. In a basement bedroom or a suite, where a bed or a desk often sits under the window, the pair is usually easier to live with. Most of the time on a high basement window you’ll tilt the louvers rather than open the panels at all, so put the tilt rod, or choose hidden tilt, where you can reach it from the floor.

Fastening is the other basement difference. Where the opening has a wood or drywall return, the frame fastens much as it does upstairs. Where the window sits in bare concrete, you’ll need masonry anchors and a masonry bit, or a wood surround fitted first; tell us in the window’s notes so we can talk it through before we build.

You can enter the depth to the glass for each window in the designer. It’s optional, but we check it before we build.

What small basement windows cost

These are live prices from our price list for one shutter in the basic build (flat moulding, paint stage 1, 3½ in louvers). Your price depends on the moulding, paint stage, louver size and layout you choose; the designer prices every window as you go.

Bedroom windows and egress

A basement bedroom window may have to serve as a way out in an emergency, and the rules for size, opening and what may sit in front of it are set by your local building code. Check your local code, or ask your municipality or building department, before you put any covering on that window or change the window itself. We can build a shutter for most openings, but we can’t tell you what your code allows.

Basement suites

If you’re finishing a basement as a rental suite, there may be help with the cost. In its 2024 Fall Economic Statement, the federal government said it would double the loan limit for the Canada Secondary Suite Loan Program to $80,000, with 15-year terms at 2 per cent interest, and gave converting an unused basement into a rental apartment as an example^[4]. Check the program’s current terms before relying on them; they were announced in December 2024.

For a suite, the case for shutters is practical. They have no cords, they wipe clean between tenants, and they give privacy on windows that often look out at a driveway or a sidewalk at eye level. They also stay with the house. The same rules apply: keep the suite’s humidity in range, leave room for the window to open, and check your local code for the bedroom windows. If the suite has its own bathroom or laundry, our humid rooms guide covers those windows.

Window wells and light

A basement window in a well gets less light than any other window in the house, and a covering that takes much of it away makes the room feel smaller. Shutters help here because the louvers tilt: angled up, they let sky light in from the top of the well and limit the view in from the yard. Keep the well clear of leaves and snow, and the glass clean; those make more difference to the light than any covering. Painted white or a light colour, the louvers bounce what light there is into the room.

A short checklist

1. Check the basement’s humidity in winter and summer. Bring it into Health Canada’s 30% to 50% range^[1].
2. Fix any water coming in before you order anything.
3. Measure each window to the first thing that sticks out, and note how hopper sashes open.
4. For bedroom windows, check your local code.
5. Note whether each opening is wood, drywall or bare concrete.
6. Plan to keep the louvers open on cold days so warm air reaches the glass.