We have written separately about row spacing and sightlines and about what seats do to a hall's acoustics. This article is the third leg: the seat itself, specified so a factory can quote it without guessing. Auditorium chairs are bought once a decade and bolted to concrete, which concentrates the cost of a vague spec wonderfully — every ambiguity gets installed, four hundred times, in rows.
Structure: what the seat hangs from
The load path decides longevity. Beam-mounted rows carry seats on a continuous steel beam anchored at the ends of the row (fewer floor fixings, cleaner cleaning line, the standard for new construction); pedestal (floor-per-seat) mounting fixes each standard to the slab and tolerates uneven or stepped floors better; riser mounting bolts to the vertical face of the tier and frees the floor entirely. Name the steel: upright and beam wall thickness in millimetres, and the finish system (powder coat over pre-treatment for interior halls). Ask what the frame is tested to — EN 12727 is the ranked-seating standard, and its test level matters: a lecture room and a multiplex earn different severity, and "passes EN 12727" without a level is half a sentence.
The tip-up mechanism: the moving part that defines the product
Everything else on the chair is furniture; the tip-up is machinery. Gravity mechanisms lift the seat by counterweight — no springs to fatigue, a soft self-close, the default for premium cinema. Spring mechanisms cost less and can close faster and louder; damped versions buy quiet at a price. Specify three things: the mechanism type, the close behaviour you want (silent self-close is a line item, not an assumption), and the cycle life the maker will state in writing. Ask to see the mechanism module removed from a seat — serviceability matters, because in year eight you will be replacing mechanisms seat by seat, not rows.
Foam and cover: where the budget actually goes
An auditorium seat is sat in for two to three hours without a posture change, by every body shape sold a ticket. Seat foam wants moulded PU at a stated density — with the number on the drawing, not "high density" — and different density for back versus seat. Covers split three ways: heavy-contract fabric (warm, acoustic-friendly, needs stated abrasion cycles), PU/vinyl (cleanable, the choice where spills are the business model), and leather-face for VIP rooms. Whichever way, two spec lines are non-negotiable: the flammability regime for your market — we covered TB 133, TB 117-2013 and EN 1021 in depth — and replaceable cover construction. A cover you cannot re-order and fit on site turns a cigarette burn into a mismatched seat.
Fixing, floors and the numbers the installer needs
The seat meets the building at the anchor, and the anchor meets whoever built the floor. State the floor construction per zone (slab, raked slab, steppings, timber riser), the anchor spec into each, and who supplies setting-out drawings. Curved rows need the radius per row, not "curved". If the hall wants aisle lights, cup holders with power, or USB in the armrests, the wiring rides the beam — decide it now, because retrofitting power through four hundred installed standards is a renovation, not an order line. And agree the spare parts package at purchase: a percentage of covers, mechanisms and armrest tops delivered with the container, while the dye lot and the tooling are guaranteed to match.
The one-page spec, assembled
Mounting type and steel gauges; EN 12727 level; mechanism type, close behaviour, stated cycle life; foam densities by cushion; cover article with abrasion and fire compliance; anchor and floor schedule; row geometry; powered options; spares package; and the acceptance test — a pre-shipment inspection that includes cycling a sample of mechanisms, not only counting cartons. Send that page to three makers and the quotes come back comparable. Send "cinema chair, red, good quality" and the cheapest quote will win — once. Our cinema and auditorium range is quoted against exactly this field list; ask for the drawing set with the price and read them together.