If you are planning a custom home in Toronto, someone on your design team has probably brought up roof overhangs and sun angles. It sounds like a small detail. It is actually one of the cheapest ways to control comfort and energy use in a new build, and it is easy to get wrong if nobody does the math for your specific lot.
The short answer: yes, in most cases, a well sized overhang to block summer sun while still letting in winter sun is worth doing. The sun sits much higher in the sky in summer and much lower in winter, so a horizontal overhang above a south facing window can shade the glass in July and still let light pour in during January. The tricky part is getting the depth right for your latitude, your roofline, and the direction your home actually faces once it is sited on the lot.
Key takeaways:
- A correctly sized overhang can block summer sun while still letting winter sun into south facing windows, because the sun sits far higher in the sky in summer than in winter at Toronto’s latitude.
- Overhang depth is not a universal number. It depends on window height, wall orientation, how much winter light you want, and the roofline itself.
- South and west facing walls benefit most from a calculated overhang. North facing walls barely need one.
- Too shallow, and summer overheating and glare continue. Too deep, and you lose the winter sunlight that makes south facing rooms feel warm and bright.
- Overhang planning works best when it happens alongside lot orientation, window placement, and interior layout, early in the design phase.
Why This Works: Summer Sun vs Winter Sun
Toronto sits at roughly 43 to 44 degrees north latitude. That matters here because the sun’s angle above the horizon changes a lot between seasons.
- In late June, the midday sun is high in the sky, close to 70 degrees above the horizon.
- In late December, the midday sun is much lower, closer to 23 degrees above the horizon.
- Around the spring and fall equinox, the midday sun sits closer to 47 degrees, which is the transition zone between full shading and full sun.
A fixed overhang cannot move with the seasons, but it does not need to. Because the angles are so different, a single, correctly sized overhang can block most of the high summer sun from hitting a south facing window while still allowing the lower winter sun to reach deep into the room. This is the basic idea behind passive solar design, and it has been used in home design for a long time before anyone called it that.
| Season | Midday sun angle | Overhang effect |
|---|---|---|
| Late June (summer solstice) | About 70 degrees | Maximum shading possible |
| Spring or fall equinox | About 47 degrees | Partial shading, transition zone |
| Late December (winter solstice) | About 23 degrees | Deep light penetration |
How Overhang Depth Actually Gets Calculated
The depth of an overhang is not picked by eye. It comes from a simple relationship between window height and sun angle: the higher the window, and the higher the summer sun angle, the deeper the overhang needs to be to fully shade that window at midday.
For example, a window that sits about 8 feet below the overhang, on a true south wall in Toronto, needs roughly 3 feet of overhang depth to fully shade the glass at noon on the summer solstice, while still allowing full sun through at the winter solstice. Change the window height, the orientation, or how much summer sun you are willing to accept, and that number moves.
If your architect cannot walk you through this calculation for your specific home, the overhang is likely being sized by eye rather than by performance. It is worth asking to see the math during design review, before the roof framing is locked in.
One detail that trips this up: compasses point to magnetic north, not true north, and in the Toronto area that difference is close to 10 degrees. Sun angle charts are based on true north. If a site plan is oriented off a compass reading without correcting for that difference, the overhang math built on top of it will be off too, and the wall will not shade quite the way it was designed to. This is a detail worth confirming with your designer rather than assuming it was already accounted for.
What Changes If You Get the Depth Wrong
An overhang that is too shallow does not do much. You still get overheating and glare in the summer, especially in west facing rooms during late afternoon.
An overhang that is too deep creates a different problem. It can block too much winter light, leaving south facing rooms darker and colder feeling in the months when you want that sun the most. It can also start to feel heavy from the street, which is a design trade-off worth discussing early rather than after the roof is framed.
Getting the depth right depends on a few things working together:
- The height of the window below the overhang
- The exact orientation of that wall (true south behaves differently than southeast or southwest)
- How much winter sun you actually want in that specific room
- The roofline and any structural constraints from the framing
This is why overhang depth is not a one size fits all number. It is a calculation your architect or designer runs for your specific home, not a rule of thumb copied from a different project.
| Sizing issue | Summer result | Winter result |
|---|---|---|
| Too shallow | Overheating and glare continue | Full sunlight still gets in |
| Too deep | Good shading | Rooms feel dark and cold |
| Correctly sized | Heat and glare under control | Sunlight still reaches the room |
Where Overhangs Matter Most on a Custom Home
Not every wall needs the same treatment. On most Toronto lots, the sections that benefit most from a calculated overhang are:
- South facing living spaces with large windows, where summer glare and heat gain are the biggest issue
- West facing rooms that catch strong late afternoon sun in summer
- Covered porches or entries, where an overhang doubles as weather protection and shade
North facing walls get very little direct summer sun, so overhang depth matters far less there. East facing walls get strong morning sun, which is usually less of a heat gain problem than west facing afternoon sun.
| Wall orientation | Sun exposure pattern | Overhang priority |
|---|---|---|
| South | Consistent midday sun, predictable angles | Highest |
| West | Strong late afternoon sun, lower angle | High |
| East | Morning sun, less heat buildup | Medium |
| North | Minimal direct sun year round | Low |
Should Overhang Depth Change Room by Room?
Not every south facing window needs the same treatment, because not every room is used the same way or at the same time of day. On a custom build, it is possible to vary overhang depth slightly across an elevation depending on which room sits behind the glass.
- Living rooms and kitchens, used most during the day, generally benefit from the deepest overhang on that elevation, since summer sun there is strongest right when the space is in use.
- Bedrooms, used mostly at night and early morning, can usually work with a somewhat shallower overhang, since midday summer heat matters less and winter light is often more welcome.
- Home offices tend to need a middle ground: enough shade to avoid screen glare around midday, without losing the softer morning and late afternoon light.
- Dining rooms used mainly for evening meals can often handle a slightly smaller overhang, since dramatic natural light during shoulder season gatherings is more of a feature than a problem.
This kind of room by room tuning is easier to plan on a ground up custom home, where the roofline and window placement are still on the drawing board, than to retrofit later.
Overhangs Are Only Part of the Picture
An overhang is one tool, not the whole strategy. On a ground up custom home, it works best alongside other decisions made early in the design process:
- Lot orientation and how the home is placed on the site
- Window sizing and placement per elevation
- Interior layout, so the rooms that benefit most from winter sun are the ones with south facing glass
These decisions all get made together during design, which is part of why the design phase on a custom home takes real time upfront. Trying to add proper shading after the roofline is already set is much harder and often means compromising on the result.
| Design element | How it works with overhangs |
|---|---|
| Lot orientation | Determines which walls get sun and how overhang depth is calculated |
| Window sizing | Larger south facing windows increase winter gain, so overhang depth has to keep pace |
| Interior layout | Places the rooms that benefit most from winter sun behind the south facing glass |
| Roofline design | Sets the structural limits on how deep an overhang can realistically go |
| Decision point | During design phase | After construction |
|---|---|---|
| Overhang depth | Fully adjustable per wall | Limited by the existing roof structure |
| Window placement | Optimized for sun angles | Fixed |
| Home orientation | Positioned for best solar access | Permanent |
Frequently Asked Questions
Does a roof overhang actually make a noticeable difference in comfort?
Yes. On south and west facing rooms with large windows, a properly sized overhang measurably reduces summer heat gain and glare while still allowing winter sun to reach the room. The difference is most noticeable in rooms used during the day, like kitchens and living rooms.
Do overhangs work the same way on every side of the house?
No. South facing walls respond best to calculated overhangs because of how predictably the sun angle changes with the seasons there. West facing walls need shading too, but the math is different since the sun is lower and more angled in the late afternoon. North facing walls rarely need the same treatment.
Can I add a bigger overhang to an existing home instead of building new?
Sometimes, but it is more limited. On an existing home, you are working within a roofline and structure that already exists. On a ground up custom home, the roof, window placement, and orientation can all be designed together from the start, which gives far more control over the result.
Does this affect heating and cooling costs?
It can help on both ends. Blocking unwanted summer sun reduces the cooling load in warmer months, and allowing winter sun in helps rooms feel warmer and brighter during colder months. It is one piece of a well designed home, not a replacement for proper insulation and windows.
Can I use landscaping or exterior shades instead of building an overhang?
They can help, but they usually cannot fully replace a properly sized overhang. Deciduous trees planted on the south side lose their leaves in winter, which is useful, but they take years to mature and offer less consistent control. Exterior roller shades work for summer sun but need to be operated or automated, and they wear out faster than a fixed roof structure.
Does the type of window glazing change whether I need an overhang?
No. Even high performance, low-e glazing reduces heat gain but does not remove glare or the greenhouse effect from direct sun hitting the glass. An overhang and good glazing work together. Neither one replaces the other on a south or west facing wall.
Does overhang depth need to change for floor-to-ceiling windows?
Yes. Taller glass needs a deeper overhang to shade the same portion of the window, since the distance from the overhang to the bottom of the glass increases. If your design includes large or floor-to-ceiling windows on a south wall, that full height should be part of the shading calculation.
What happens to overhang performance on a sloped lot?
A slope can change the real vertical distance between the roof edge and the window below it, especially on a home built into a hillside. That relationship needs to be accounted for directly, since it is another reason overhang depth is specific to the site, not a number you can borrow from a flat lot.
Do I need the same overhang depth all the way around the house?
No. It usually makes more sense to prioritize overhang depth on the south and west elevations, where it does the most work, rather than applying the same depth everywhere. North facing walls rarely need it, and east facing walls are a lower priority.
A few things worth remembering:
- Overhang depth should be calculated for your specific latitude, window height, and orientation, not copied from another project.
- South facing walls give the most predictable return on a calculated overhang, since the sun angle there changes consistently with the seasons.
- An overhang that is too deep can leave south facing rooms feeling dark and cold in exactly the months you wanted that sun.
- This works best as an early design decision, alongside lot orientation and window placement, not as an afterthought once the roof is framed.
- West facing walls need their own approach, since the lower angle of late afternoon sun behaves differently than the more predictable midday sun on a south wall.
Planning a Custom Home in Toronto?
Overhang depth, window placement, and lot orientation all get decided together during the design phase of a custom home build. If you are planning a ground up build in Toronto or the Scarborough Bluffs area, these are exactly the kind of details we work through with you before anything gets framed.
Book a consultation with Habitual Homes
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