An additive manufacturing apparatus has a build chamber, a build platform lowerable in the build chamber such that layers of flowable material can be successively formed across the build platform, a laser for generating a laser beam, a scanning unit for directing the laser beam onto each layer to solidify the material in selected areas and a processor for controlling the scanning unit. The processor is arranged to control the scanning unit to direct the laser beam to solidify material of a layer along a scan path, the laser beam advanced along at least a section of the scan path in an opposite direction to a direction in which the laser beam is advanced along a corresponding section of a corresponding scan path of a previous layer. The scan path may be a border scan path extending around a border of one of the selected areas of the layer.