Abstract: This invention relates to an adjustable buttress for use in an electrostatic precipitator for spacing an end plate from a portion of a precipitator housing. The adjustable buttress is selectively positionable between a portion of an electrostatic precipitator housing and an end plate which is on one end of a plurality of plates in the electrostatic precipitator. The adjustable buttress engages the end plate for positioning the end plate a selected distance from the housing. The adjustable buttress includes an axle. A pair of arms is pivotally mounted on the axle. A rail is connected to each of the arms, and a buttress contact is mounted on each of the rails. The buttress contacts define a contact plane. A positioning device is connected to the rails for selectively moving the rails relative to each other to determine selectively the distance between the rails and thereby the distance between the axle and the contact plane for selectively holding the end plate a selected distance from the housing.