How much weight can an Adirondack chair hold?
Rated to 350 pounds. Tested to well past it.
The chair is rated for 350 lb (160 kg) in normal residential use. That is a conservative number: the seat is four one-inch solid boards on side rails that are also one-inch solid board, bolted with stainless steel through the thickness, and the failure load in testing is far above the rating.
What carries the weight
Two things. The side rails, which run from the front leg to the back leg and are the chair's spine; and the arm-to-back joint, which turns the whole thing into a rigid triangle. Neither is a pivot, a hinge or a thin section, which is why a fixed chair is stronger than a folding one. Folding vs fixed.
What does not
The slats themselves are not the limit; the frame is. Standing on the seat to reach a light is inside the rating. Standing on the arm is not what arms are for.
Commercial use
The residential warranty is twenty years; the commercial warranty is five, on the same chair, because a resort chair is sat in twenty times a day. The capacity is the same. Chairs for resorts and restaurants.