We're hoping to install a garden room as a home office. Will be 5m x 3m with a max height of 2.5m.
It would be built towards one end of our small garden facing the rest of the garden and runs along the side of our neighbours garden with 2 garages also bordering it.
The position of their garden and the surrounding houses and garages mean the don't get much sun - it's really just in the early evening once the sun clears the garage of another neighbour before it then goes behind another neighbours house that it hits their garden.
The garden room will run parallel to the existing garage with more than 1.5m either side.
I don't therefore think it will cause any additional issues as the garage already blocks the sun and the garden room is much lower and much closer to the garage than their small patio.
Their garden does gradually slope downwards so we are slightly elavated and it does sometime feel like we're overlooking them if we stand in that section of the garden but the garden room should give them more privacy as we won't have a window over looking them.
The builder has no concerns (but clearly they have a vested interest here) and if we decide we wanted to go ahead we'd speak to the neighbours first but interested in peoples opinion.