I would say that the fact is 'saving' is singular and 'savings' is plural. This dictates the verb that follows. You could say A saving of $20 is ... or Savings of $20 are ...
A basement bathroom can be built for about $15,200, Fred estimates. Of that, plumbing is the largest component. These prices are based on costs for a small bath measuring about 6 by 8 feet, with 8-foot ceilings. However, many basements are limited to a 7-foot ceiling. Another potential cost-saving location for a new bathroom is the attic.
It can cost between $100.00 to $250.00 per square foot. The addition of the new bedroom and bathroom, it will not only provide the space that you need, but will add value to your home. You can expect a 75% to 90% or appreciation to the addition with permits.