Make backrest adjustment part of arrival
Begin a trial of plastic base office chairs with height-adjustable backrests by asking users to set up the seating themselves. Provide the operating instructions, then observe which actions are clear and which require explanation. Establish whether the backrest can be positioned while seated or whether users need to stand; the operating method needs individual confirmation. Ask each person to move through the available settings and identify useful back contact. The presence of adjustment matters less than its practical value if users cannot find a suitable position or reliably return to it during a normal working day.
Examine the plastic base in its setting
Look below the seat as carefully as you assess the backrest. Plastic construction does not establish the base dimensions, the chair's total weight or its stated load capacity. Check those characteristics directly against the workplace brief. Examine where the base sits relative to desk supports and how users place their feet around it. If the seating has castors, confirm their suitability for the floor and assess movement at the workstation. For office chairs beside storage units, include the turning and approach space needed when drawers are open or colleagues are passing behind the occupied desk.

