a molded plastic sliding panel used for covering an exterior building wall surface is made up of a body portion , an attachment portion provided above and adjacent to the body portion , a top locking portion extending horizontally across an upper portion of the sliding panel and a bottom locking portion provided at the bottom of the body portion . the top locking portion is adapted to engage with the bottom locking portion on an upper adjacent siding panel . the attachment portion can contain a plurality of apertures provided therein which sequentially become more elongated as they are positioned toward a side edge of the attachment portion in order to deal with thermal expansion and contraction of the panel .