Upholstery Foam for Chair Seats, 2 in Thick, 20 x 20 to 24 x 72 in

When an upholstered seat feels hard and flat, the foam inside has usually crumbled or packed down. New foam is the middle layer of a re-padded seat: it sits on the seat board or the webbing, batting goes over it, and the fabric goes over both.

This is polyurethane upholstery foam, 2 in thick, for dining chair and drop-in seats. It comes as a 20 x 20 in or 24 x 24 in square for one seat, or as a 24 x 72 in sheet for several seats or a bench.

Cutting it to the seat:

• Take the seat out of the chair and strip off the old fabric and foam. Keep the old fabric as a pattern if it is still whole.
• Lay the seat board on the foam and draw around it with a marker.
• Cut about 1/4 in larger than the seat board, so the foam fills out to the edge once the fabric pulls it down.
• Use a long serrated knife or an electric knife. Keep the blade upright and cut in long, even strokes for a square edge.

Then cover the foam with batting before the fabric. The batting rounds the edges, smooths the top and stops the fabric rubbing on the foam. Pull the fabric over, staple the middle of each side first, then work out to the corners, and finish with dust cover fabric underneath.

On a seat built on webbing, check the webbing before you fit new foam. Slack elastic webbing or jute webbing lets even new foam sink, so replace it first if it sags.

Foam, batting, webbing and the tools are all on the re-web and re-pad a chair seat project page.

Measure the seat board at its widest and deepest points. The foam is cut about 1/4 in larger than the board, so the piece you buy has to cover both measurements with that margin to spare.

If the board is no more than about 19 in each way, the 20 x 20 in square covers it. Up to about 23 in, take the 24 x 24 in square.

For a set of chairs or a bench, the 24 x 72 in sheet goes further. It cuts into three pieces up to 24 x 24 in, or one bench pad up to 72 in long and 24 in deep.