Why Choose a Box Window
- Clean lines that fit contemporary and craftsman architecture
- A deep sill for herbs, plants or display space
- Side windows that can open for cross-ventilation
- A compact projection that fits where a full bay will not
If you prefer angled sides, see our bay windows; for a single large pane, consider a picture window.
Our Pre-Installation Inspection
Framing check
We confirm the wall framing and header can support the opening and the projection, and look for rot or termite damage.
Siding and weather barrier
We examine the siding and house wrap around the opening so the new flashing can tie into it correctly.
Measurements
Precise measurements of the rough opening and exterior clearances ensure the unit fits square.
Flashing and Finishing
Box windows have more seams than a flat window: a top, a bottom and two sides that all meet the wall. Each must be flashed so water runs out, not in. We install a sloped top cap or roof, seal the joints, insulate the floor of the box and finish the exterior to blend with your siding. Inside, the head and seat boards are trimmed to match your interior.
Pricing and Planning
Cost depends on size, glass options, whether the sides open, interior finish and how much reframing the wall needs. We give you a free written estimate after measuring. Box windows are also popular during additions and remodels; see our new window installation page for new-construction openings.
Common Questions
What is the difference between a box window and a bay window?
A box window has sides at 90 degrees, giving a rectangular projection. A bay has angled sides, usually 30 or 45 degrees, for a more traditional shape.
Are box windows energy efficient?
With insulated, low-E glass and an insulated floor and top, they perform well. Poorly sealed projections are the main source of drafts, so we focus on those areas.
How long do box windows last?
Quality units that are properly flashed and maintained can last for many years. Keeping exterior caulk and paint in good shape helps.
Can a box window work as a kitchen garden window?
Yes. A box window over the sink with a deep, durable sill is a natural spot for herbs. We can add a moisture-resistant sill surface so watering plants does not damage the finish.
How do I maintain a box window?
Clean the glass and frames gently, check the top cap and exterior seals each year and keep plants on the sill from dripping onto wood surfaces.