You’ll need some space to work, as well as storing piles of fabric and stuffing.
The first step is to carefully remove the old fabric. Start underneath the chair. Turn it over and you’ll see a square of hessian, light cotton, webbing or other plain material that encases the skeleton of the chair. It’s your best access point to the rest of the upholstery, which will be stapled or nailed on. Using a pair of long-nose pliers, remove the fastenings, then peel off the covering. During all the fabric stripping steps, use a knife or screwdriver to leverage any staples or nails that are too tight to grip.
As you strip the fabric, label where it came from on the chair, making sure to mark which side the pieces come from, as the old pieces act as stencils for the new fabric. Also mark the pieces with the order in which they came off, as this dictates the way the new pieces go back on. Try and stack the old coverings together and in order to make life easier later.
Decide whether you want to keep and recycle the old stuffing, or use new stuffing. If it’s disintegrating and lacking any substance or spring, it will be best to start afresh. Older chairs may have internal springs. These are complex to rebuild, so if you find them inside your chair, leave them undisturbed. Once the chair’s frame is bare, check it doesn’t need repairs. If it’s wobbly, nail or glue the joints securely, remembering to use soft blows when hammering, so you don’t damage the timber.
Now the reupholstering starts. If sections of the old fabric are sewn together, take a photo of each constructed section, so you have a visual record of how to put them back together with the new fabric. Iron each fabric panel flat. Pin each piece directly onto your new fabric and use a marker such as tailor’s chalk to outline each one. Remember to pay attention to pattern matching so you don’t have any strange joins when you sew the new fabric together. Cut out the new panels using a sharp pair of scissors. Using tailor’s chalk, label each piece the same way you did the old version. Then sew together any sections that were stitched together originally.
Grab your staple gun and start working backwards. However your stuffing came off, put it back in reverse order. Some of it may have to be stapled in place, so get your staple gun going with evenly and closely spaced staples. Then comes the fabric. Again, however it came off, it goes back on in reverse order. Pull it tight, fold down edges and staple in place onto the frame, smoothing and keeping tension as you go, again with evenly spaced close staples. Lastly, replace the protective panel at the bottom of the chair.
Now you have your new chair and if you have any leftover fabric, consider making a cushion to add to the chair.