In San Francisco's overpriced real estate market, undeveloped building areas such as garages and attics are an increasingly valuable asset.  However, building density, zoning regulations and fire codes can make it challenging to turn these areas into legal and functional living space.  In this Glen Park starter home we faced the challenge of bringing light into a building sandwiched between its neighbors.  Three large skylights positioned above the windowless kitchen flood the marble counters in daylight,  a fourth enlivens the lower level den. Despite being below grade, the master bedroom feels bright and inviting, thanks to sliding doors connecting to the yard.