Of course this is a generalization that may or may not work since there may be considerable other factors that should enter the equation.
the value to a brick workshop and pool and landscaping has different vales. It will depend on where the house is located and what the neighborhood has in it or close by. The condition of the pool plays a factor as well...
The biggest thing is the overall shape of it and how the layout in the yard is. A pool and works hop can add value to a home. Depending on the price point of the home and the location will determine the overall value of it.
I can get a little more detailed for you if I knew the address and could see the workshop and pool so as to better tell you what value it can add....
Coldwell Bnakr United