What are the New Brunswick building code requirements for egress window size and sill height in a finished basement bedroom?

Every finished basement bedroom in New Brunswick must have an egress window with a minimum unobstructed opening of 3.8 square feet (0.35 square metres) and a maximum sill height of 1,500 millimetres from the finished floor. This is a life-safety requirement under the NB Building Code — there are no exceptions, no variances, and no workarounds. If your basement bedroom does not have a compliant egress window, it cannot legally be called a bedroom, and it will not pass a building inspection.

The 3.8 square foot minimum opening refers to the clear, unobstructed area when the window is fully open — not the size of the glass or the rough opening in the wall. This is an important distinction because many windows have frames, hardware, and opening mechanisms that reduce the actual clear opening below what the glass size suggests. A window that appears large enough when closed may not meet egress requirements when opened. Casement windows (hinged on one side, swinging outward) are the most popular choice for basement egress because they provide the largest clear opening relative to their frame size. A standard 24-inch by 36-inch casement window typically meets the 3.8 square foot requirement, but you must verify the manufacturer's specifications for clear opening area.

The 1,500 mm maximum sill height (approximately 59 inches or just under 5 feet) is measured from the finished floor surface to the bottom of the window opening. In many older NB basements with shorter ceiling heights, this is relatively easy to achieve because the windows are already close to the top of the foundation wall. However, in homes where the basement floor has been lowered through underpinning, or where the existing windows sit unusually high on the wall, meeting the sill height requirement may require lowering the rough opening — which means cutting into the foundation wall.

Beyond the opening size and sill height, the NB Building Code also requires that the egress window must be operable from the inside without tools, keys, or special knowledge. A person unfamiliar with the window must be able to open it in an emergency. This eliminates any window that requires a special latch sequence or a key to unlock.

Permit and Inspection Process

Installing an egress window in a NB basement requires a building permit. In Fredericton, Moncton, and Saint John, the city building department processes permits in 1 to 3 weeks. In rural areas served by Regional Service Commissions, expect 2 to 5 weeks. Permit fees run $75 to $300 depending on the municipality and scope of work.

The inspector will verify the clear opening measurement, the sill height, that the window operates freely, and that any window well (required when the window is below grade) has proper drainage and does not obstruct the opening. If you are finishing a basement bedroom and the egress window does not meet code, you will not receive a final occupancy inspection approval.

Installation of a new egress window involves cutting the concrete or block foundation wall with a concrete saw, which is structural work requiring professional installation. Budget $2,500 to $5,000 per egress window in the NB market, including the window, foundation cutting, window well, backfill, and waterproofing around the new opening. This is not a DIY project — it involves structural modification to your foundation and must be done correctly to maintain waterproofing integrity, especially given NB's high water tables and spring thaw conditions.

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