SaveThe dark cushion completes the walnut slat wall behind it, so the window reads as one framed composition.
The quick answer
An NYC apartment window seat cushion should be thin, split and easy to lift wherever a steam radiator or window AC unit sits below the sill. Keep sill cushions at 2 to 3 in (5 to 7.5 cm), split long ledges so heat can rise between the pieces, and choose floor sofas that arrive vacuum-compressed in rolls small enough for a walk-up stairwell.
Field notes
Weather and light in New York City
Sun & UVDepends on the window (level 2 of 4)Light depends on the floor and the exposure
HumidityHumid (level 3 of 4)Humid summers, radiator-dry winters
Rain & stormsFrequent (level 3 of 4)Rain through the year
Snow & freezeSome (level 2 of 4)Some snow most winters
Watch for
Steam radiators
Window AC units
Stairs and narrow doorways
Plain-language levels from general climate patterns, not measurements. Your own porch, shade and window exposure matter more.
Heat from below, light from the side
In a New York City apartment, the heat usually comes from under the window.
The city's heat season runs October 1 to May 31. Between 6 a.m. and 10 p.m., when it is below 55°F (13°C) outside, rooms must be at least 68°F (20°C). Overnight, at least 62°F (17°C) in any weather. A cushion on a radiator sill sits over that heat for eight months.
Then summer. Humid days, and a window AC unit on the same sill.
Courtyard-facing rooms get little direct sun, and pale colors go flat. Corduroy and velvet hold a warmer surface in low light than a cool pale linen. Check a swatch in your own window.
Prewar sills, parlor windows and the fifth-floor walk-up
Prewar apartments have deep sills over radiators. Brownstones have tall parlor windows, and brownstone window seats have their own rules. Alcove studios have one wall that must do everything.
Then the stairs. One buyer moving into her first solo apartment in New York City wanted a floor sofa over 6 ft (183 cm) long for sleepovers, and had no lobby where a big box could wait. The sofa travels vacuum-compressed and recovers its shape within about 24 hours of opening. She wrote back that she was obsessed with it.
Window cushions use firm high-density foam, so even 2 in stays supportive. Floor sofa seats use a medium-hard cold foam that softens slightly with use.
A parent in the US was buying window-sill cushions for a daughter's apartment. She ordered fabric samples first. After seeing them, she chose her fabric with light blue piping and sent the workshop a photo of the rug, so we could confirm the pair.
The two sills were different sizes. One sat above an air conditioning unit. She kept both cushions at 2 in (5 cm), because the unit limited the height on that sill.
A low sill.
A thin cushion.
A window that still works.
Measured
Two sill cushions of different sizes, both 2 in (5 cm) thick
What it taught
Check for obstructions such as AC units before choosing thickness; 2 in keeps the profile low.
The apartment year, season by season
October 1: split any cushion that covers a whole radiator ledge, and keep the valve reachable.
Winter: lift sill cushions now and then so the underside airs.
Early summer: when the AC unit goes in, check that the sill cushion still clears the unit.
Humid July: wash covers at 86°F (30°C) and air dry.
Delivery day: unwrap every compressed piece, lay each flat, and compare firmness side by side.
Photographs for homes like these
Open any photograph large; each one has its own link and a Save button.
SaveIn an old apartment the radiator sits under the window; a shelf and a navy botanical cushion turn it into a warm seat.SaveA light gray corduroy cushion sits on a walnut board under a garden window, right beside the coat hooks. It is the spot for pulling on boots and for a quiet coffee.SaveTriangular wedges at each end turn a plain window ledge into a perch you can lean on from either side.SaveTeal-blue velvet on a paneled Victorian window seat, taking its color from the slate roofs and blue door across the street.SaveA charcoal window seat with fine pale piping tucked between walnut bookcases and an oxblood chesterfield.SaveSeat and pillows cut from one taupe honeycomb jacquard make a white window recess feel fully upholstered.SaveA narrow window ledge becomes a reading nook with a long piped pad in a soft oatmeal honeycomb, books stored right beside it.
A window seat cushion over a steam radiator should be thin and split in two, so heat can rise between the pieces from October 1 to May 31.
My wall is shorter than your floor sofa. Can you make it narrower?
The workshop's answer
Yes. Order the standard sofa and write your width in the order note; past builds have run from 50 to 74 in (127 to 188 cm) wide. Narrowing keeps the standard arms and backrests, which take up seat space: a 65 in wide build had a 45 x 25 in seat and a 13.5 in seat height.
A common question
How big are the sofa boxes? I have a narrow door and a long flight of stairs.
The workshop's answer
The sofa arrives vacuum-compressed in rolls of about 12 x 12 x 45 to 50 in (30 x 30 x 110 to 120 cm), usually 2 to 3 rolls plus a small box of metal bars. A doorway about 25.5 in (65 cm) wide or a narrow staircase is fine.
A common question
The floor sofa came out of the box flat. How long until it looks like the photos?
The workshop's answer
That is expected after vacuum packing. Unwrap every piece. Most fill out in 24 to 36 hours, reach the photographed shape in about 36 to 48 hours and are fully firm after 3 to 5 days. Shaking the cushions helps. If a piece is still flat after another 4 to 5 days, photograph it with a tape measure across the thickness and send that to the workshop.
A common question
How thin can a window seat cushion be and still let the window close?
The workshop's answer
2 or 3 in works for a low-profile seat, and cushions of exactly 2 in (5 cm) have been made so the window above can close. 1 in (2.5 cm) is too thin to sit on. Give your maximum height including the cover, because thin foam that is cut unevenly bulges.
Have it made
Have it made for your home — ask Hana’s workshop
Measure once, slowly. Write the numbers here. The workshop will go over them with you. — Hana
Leave your details and the workshop will call you to confirm measurements, fabric, foam and piping. No prices, dates or payment on this page: it is a request, not an order.
Before you measure the sill
Can a cushion sit on a sill above a steam radiator?
Yes, if it is thin and does not seal the radiator in. Split long ledges into two pieces so heat rises between them, leave the valve and radiator cover reachable, and lift the cushions now and then during the October to May heat season.
What colors hold up in a courtyard-facing room with little sun?
Screens and studio photos rarely show how a color behaves in low light. Order physical swatches and judge them at your own window, in daylight and under your own lamps, held against something fixed like the floor or the paint.
My window bench looks crooked in photos. Is it a trapezoid?
Maybe not. A buyer in the US sent a photo of a 14 x 30 in (36 x 76 cm) bench that looked like a trapezoid from the camera angle; it was a plain rectangle. Measure each side and send a sketch, not only a photo.
How do I fit modular seating to a 72 in wall?
One layout that worked: a full-size ottoman of about 35 x 35 in (90 x 90 cm) plus a second one cut to the remaining width, with a straight backrest instead of an L so the sides stay open. A shortened sofa also gets backrests scaled to match.
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