Add Washer / Dryer hookup

[Kiara Colon]

I've got a multi-family in DC (4-unit) and am a realtor. I've found that people want washer and dryer in their units, and not having it will create a high turnover rate, which is what we're all actively avoiding. I don't have the space to put a washroom in the building, so I'd rather add a washer / dryer combo to the unit. 

Does anyone have any reasons why they'd advise against adding a washer / dryer to a unit?