Egress Window Requirements in a Basement Conversion
A homeowner is converting a 1,200 sq ft basement into two bedrooms and a living area. The basement has a ceiling height of 7 ft 6 in. The existing windows are 24 inches wide by 36 inches high, with a sill height of 60 inches above the floor. The local building code requires egress windows in every sleeping room. The homeowner wants to use the existing windows to save money. The contractor proposes to enlarge one window in each bedroom to meet egress requirements. The soil outside is clay, and the window wells are 18 inches deep. The basement is below grade, and the window wells are not covered.
1. Determine if the existing windows meet egress requirements, and if not, what modifications are necessary.
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The existing windows are 24 inches wide by 36 inches high, with a sill height of 60 inches. For an egress window, the code (e.g., IRC) requires a minimum net clear opening of 5.7 sq ft, with a minimum width of 20 inches and a minimum height of 24 inches. The existing window's clear opening is 24×36 = 864 sq in = 6 sq ft, which meets the area requirement. However, the sill height of 60 inches exceeds the maximum allowable sill height of 44 inches above the floor. Therefore, the existing windows do not meet egress requirements because the sill is too high. The contractor must lower the sill to no more than 44 inches above the floor. Since the basement ceiling is 7 ft 6 in, lowering the sill may be feasible, but it requires cutting the foundation wall and enlarging the window well. The window well must also meet code: minimum horizontal area of 9 sq ft and minimum projection of 36 inches. The existing window wells are 18 inches deep, which may not provide the required 36-inch projection. Also, the window well must be covered if it is deeper than 44 inches. Since the sill is 60 inches, the well is deeper than 44 inches, so a cover is required. The contractor must address these issues: lower the sill, enlarge the window well to at least 36 inches projection and 9 sq ft area, and install a cover. Additionally, the window must be operable from the inside without keys or special tools. The proposal to enlarge one window per bedroom may be sufficient if it meets the clear opening and sill height requirements. However, the contractor must also ensure that the window well provides a clear path to escape and that the ladder, if required, is installed. The existing windows are not compliant due to sill height; modifications are necessary.
2. What are the critical code requirements for the window well and window operation that the contractor must ensure?
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The contractor must ensure: (1) The window well has a minimum horizontal area of 9 sq ft and a minimum projection of 36 inches from the building wall. (2) The window well is covered with a grate or cover that can be easily removed from the inside without special tools, and the cover must support a live load of 40 psf. (3) The window sill height is no more than 44 inches above the floor. (4) The window has a net clear opening of at least 5.7 sq ft, with minimum width 20 inches and height 24 inches. (5) The window is operable from the inside without keys, and the opening mechanism does not require special knowledge. (6) If the window well depth exceeds 44 inches, a ladder or steps are required unless the sill height is ≤44 inches. Since the sill will be lowered to 44 inches, the well depth may be less than 44 inches, but if it remains deeper, a ladder is needed. (7) The window must be within 20 inches of the floor? Actually, the code requires the sill height not more than 44 inches, but there is no minimum. (8) The window must provide a clear opening that allows escape. (9) The window well must be properly drained to prevent water accumulation. (10) The installation must comply with local amendments. The contractor should verify these with the local building department.