Cost of an Addition in South San Francisco That Includes an Accessory Dwelling

We recently completed a 2 bedroom, one bath, kitchen and living room in 537 square foot addition.  This is for a 1,572 square foot home in South San Francisco.  Affectionately called “Grandma’s House”, this accessory dwelling is for the mother of the owners.

Below you can see the floor plans, site plans, and the budget for the entire project.


Project Attributes

Coverage of Lot

Addition in South San Francisco

Floor Plan


This budget is right before the final invoice. The “Budget” amount is the total cost of all design, engineering, and construction. You can see that the soft costs were approximately $35,000 before the project broke ground. The soft costs are mostly architecture time that we bill hourly. Budget for 537 Square Foot Addition in South San Francisco

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