A two-layer low-complexity scalable encoding scheme based on local Adaptive Spatial Resolution (ASR) is proposed. This scheme relies on a block-level spatial resolution adaptation in the enhancement layer encoder. For each block, the optimal resolution is either obtained via a rate-distortion optimization followed by a decision refinement process or by a prediction via motion compensation exploiting the base layer motion vectors. The proposed architecture has been integrated over of the High Efficiency Video Coding (HEVC) reference software (HM16.12) which is used as a base layer encoder. Compared to SHVC, the scalable extension of HEVC, experimental results show bitrate savings of 0.76 % as well as encoding complexity reductions of 47 % for the whole scalable encoder and 96 % for the enhancement layer encoder.