One or more grids of redundancy coded shards, such as those stored or otherwise represented on grid encoded storage systems, are configured to be extensible. For example, a grid of shards may include data shards, derived shards (derived from the data shards), and null shard, indexed by, e.g., row and column. A grid of shards so configured may include data shards and derived shards in one set of columns of the grid, and the null shards in another set of columns of the grid. As additional data is added to the grid, the grid may be extended by converting some of the null shards into data or derived shards, on a row-by-row basis, and regenerating or re-deriving additional shards as necessary.