Bay & Bow Window Replacement in Oshawa, ON
Oshawa Prestige Windows & Doors takes on bay window replacement. Oshawa has street after street of 1960s and 1970s homes with bay windows in the living room, and by now most of them are cold at the seat and soft at the bottom. A bay window is a picture window with two angled windows beside it, pushing out past the wall. A bow window is four or more units in a gentle curve. Either way, it's the most complicated opening on the house. The sill decides.
Oshawa Prestige Windows & Doors provides bay and bow windows to Oshawa and surrounding Ontario cities, including Whitby, Pickering, Ajax, Courtice and Bowmanville. We always take a bay out full-frame, because the seat and top boards are where the rot hides. Most bays are a one-day job for a two-person crew, and you get photos of the opening before and after. For single openings in the same style, see casement windows.
Types of Bay Window Replacement in Oshawa
The window units can be any style. What changes is the shape, the angle and how far it sticks out.
30 Degree Bay Windows
The side windows sit at 30 degrees to the wall, so the bay sticks out less and fits a narrower spot. It's common in bedrooms and on homes with a porch close by. You get more glass than a flat window without a deep projection. We use this angle where a walkway runs right under the window.
45 Degree Bay Windows
The classic living room bay. The sides angle out 45 degrees, which makes a deeper seat and lets in light from three directions. Most of the bay windows we take out in north Oshawa are 45 degree units from the 1960s and 1970s. Good spot for a reading chair or a cat.
Bow Windows
A bow window uses four, five or six equal units set in a soft curve. It looks less boxy than bay windows do and works on wide walls, often in older two-storeys. The weight spreads over a longer span, so support matters even more. We'd say a bow suits a traditional house better than a modern one.
Bay Windows With Casement Sides
The most practical setup: a fixed picture window in the middle and a casement window on each side that cranks open. The fixed centre gives the view and the best energy rating, and the sides give fresh air. This is the combination we quote most often.
Bay Windows With Double Hung Sides
On older brick homes near downtown Oshawa, a double hung window on each side keeps the original look. Both sashes slide and tilt in for cleaning. They don't seal quite as tightly as casements, so we pair them with better glass on a windy side.
Garden Windows
A garden window is a small glass box that sticks out over a kitchen sink, with a shelf for herbs and side vents that open. It brings in light from above and both sides. Garden windows are small, so they cost much less than a full bay, and they swap into most standard kitchen openings.
Converting a Flat Window to a Bay
Want a bay where there's a flat window now? It can be done when the wall below is solid and there's room outside. The rough opening often stays the same size, but the new projection needs support and flashing. If the opening gets bigger, Oshawa needs a building permit, and we tell you that at the measure.
Why Oshawa Homes Call Us for Bay and Bow Windows
- Every bay comes out full-frame, so rot under the seat gets found and fixed
- New seat and top boards with insulation packed in, not just a glass swap
- Support cables or brackets sized for the new unit's weight
- Flashing and a drip cap over the top so water runs off, not in
- Before and after photos of the opening, sent to you
- A 5-year installation warranty on top of the maker's warranty
Durham towns we cover from Oshawa
$5M liability and WSIB
Insured crews on every job
How Much Does a Bay Window Cost in Oshawa?
A replacement bay or bow window in Oshawa usually costs $3,000 to $5,000 for a standard size, according to Canadian Choice's 2026 Oshawa price table. Bigger bows, triple pane glass, wood interiors and new seat boards push it higher. A garden window costs far less, usually close to a large single window.
| Item | Typical range | Source |
|---|---|---|
| Bay window, installed | $3,000 to $5,000 | Canadian Choice, 2026 |
| Bow window, installed | $3,000 to $5,000 | Canadian Choice, 2026 |
| Picture window centre, unit only | From $279 | Window Mart, 2026 |
| Casement side, unit only | From $358 | Window Mart, 2026 |
| Any window, installed | $800 to $4,000 per window | Home Depot Oshawa |
These ranges come from other Ontario window companies, so you know what's normal before we visit. A bay quote should list the units, the glass, the seat and top boards, insulation, support and the exterior trim. If one of those is missing, ask.
Why Old Bay Windows Go Cold and Soft
Bay windows stick out from the house, so each one is exposed on five sides instead of one. Most of the trouble starts in the same few places.
- The seat board, the shelf you sit on, was often built with little or no insulation under it. It feels like a fridge shelf in January.
- The top board under the little roof lets heat out and water in when its flashing fails.
- Old bays sag a little every year. The units pull away from each other and the caulking splits.
- Wood sills stay wet after every rain and every freeze-thaw cycle, then rot from underneath.
We've opened plenty of bays where the seat looked fine from inside and was mush underneath. That's why we never do a retrofit installation on bay windows. The estimator checks the boards with a moisture meter, and we photograph what we find.
What a Proper Bay Window Install Includes
A new bay is a small building job. We take the old unit out down to the rough opening, put in new seat and top boards with insulation packed under them, and hang the new unit on support cables or brackets. Low-expansion foam fills the gaps around the frame without bowing it. Outside, flashing tape and a drip cap send water away from the top. Then the trim gets new aluminum capping.
Bay and Bow Windows FAQ
What is the difference between a bay and a bow window?
A bay window uses three units: a large centre window with two side windows angled at 30 or 45 degrees. A bow window uses four to six equal units set in a gentle curve. Bays make a deeper, boxier nook. Bow windows look softer, fit wider walls and usually cost a bit more.
Can you replace just the glass in a bay window?
Sometimes. If the frames and the seat are sound and only one sealed unit has fogged, new glass can work. Most bays we see in Oshawa are 40 to 50 years old, though, and the seat or top board has rotted or lost its insulation. Then a full replacement is the only fix that lasts.
Do bay windows need extra support?
Yes. A bay hangs off the wall, so its weight has to be carried by support cables tied into the framing above or by brackets underneath. Old bays often sag because that support was weak or missing. We size the support to the weight of the new unit, which matters more with triple pane glass.
How long does a bay window replacement take?
Most bay and bow window jobs take one day with a two-person crew. Bigger bows, or bays with rotten framing under the seat, can stretch to a second day. Ordering takes 6 to 10 weeks for most custom vinyl units, and longer for wood-clad interiors or special shapes.
Is a bay window seat cold in winter?
An old one usually is, because many were built with little insulation under the seat board. When we replace a bay, we build new seat and top boards with insulation packed in and seal the gaps with low-expansion foam. The new seat should feel about as warm as the floor next to it.
Do I need a permit for a new bay window in Oshawa?
Not for a same-size replacement on a house. The City of Oshawa doesn't require a building permit to swap a window in the same opening. Turning a flat window into a bay, or making the opening wider, is an alteration and does need one. We confirm which applies at the first visit.
Book a Free Measure for Your Windows and Doors
Tell us how many openings and roughly how old the house is. We book a free in-home measure and give you a written quote.
Or call (289) 274-1333