Subdividing square buffer in sub-units using QGIS?

Question

I've been trying for a while now to create a grid inside a square buffer, so that it can be divided into a pre-defined number of sub-units. Creating a grid that covers the whole area is not ideal because the grid's squares will not be properly aligned with the square buffers and I need that in order to be able to count how many grid's squares are occupied by houses inside the buffer. I have 150 buffers in a single layer, and i'd like to have the grids only inside them.

I am still quite new to GIS.

Answer 1

See this answer to Drawing graticule with GDAL/OGR?, which basically uses the built-in Create grid plugin:

Vector -> Research Tools -> Create grid