This communication reports on the lateral growth at planar selective area epitaxy (SAE) grown vertical sidewall ridge structures. This lateral growth is investigated as a function of the angle of the molecular beam with respect to the substrate surface, the width of the mask and the ridge size. The results prove that for molecular beams arriving perpendicularly to the substrate surface the lateral growth is about half compared to the conventional geometry. This enables the planar embedded growth of heterostructures as used in integrated device approaches using identical growth parameters as in the planar SAE.