Plastic siding made to simulate clapboards is now made with an integral top locking strip having a downward projection spaced from the body of the siding into which an upturned projecting strip, on the bottom of the next higher course of siding, can be fitted when applying the siding to a house. The present disclosure eliminates this integral locking strip and provides instead small nailing clips of a special construction which are less expensive and which are constructed so that the siding can be nailed in place loosely, which is desirable to permit thermal expansion and contraction of the siding.