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.
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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As part of New Avenue’s efforts to educate owners and architects about the timeline and costs to design and permit projects, we are sharing this detailed design proposal for an accessory dwelling in Albany, CA.
New Avenue shares design proposals, construction bids and actual costs so that you – as an owner – can be informed as you begin a project.
We try to educate owners, architects and contractors about the costs of comparable projects so that it is easier for you to manage your projects and create the addition, remodel, custom home of your dreams.
The permit rules in this attachment are important. We have been following the rules and contributing our two cents when possible.
Don’t be deterred. The picture on the cover is a shed! That’s not what wea are talking about here. Accessory Dwellings are homes. Many of them are two bedrooms with an upper floor, a large kitchen and all the comforts of any custom home. So the first pic you will see has got to go!
The City of Berkeley is currently updating their accessory dwelling codes and height is an issue that is being reviewed. Many cities struggle with this. This is a summary of what you get for 14′ vs. 18′
To calculate the maximum height you measure the height of a building from the soil to the peak of the roof.
An 18′ tall design the foundation is 1 foot, the first floor is 8 feet, a second floor is 7 feet, the floor between the two is 1 foot and the roof is 1 foot. That adds up to 18′ total. You get a decent second floor with a 7 foot height at the peak in this design.
In the 17′ tall design below you can see that the peak of the upper floor is 5’11”. This design is for a guy who is 6’8, so we have a major design flaw forced on us by the height limitation.
In the seconds design below, we were constrained to a 15′ height.
The owner here insisted on an above ground crawl space. Owners that don’t listen to our advice is just one of the countless challenges architects and contractors have, that’s another story though:)
In this design, the foundation is 1.5 feet. The ground floor height is 7 feet 6 inches. The floor thickness between the two floors is almost 1 foot, the upper floor is 5 feet 1 inch and the roof is one foot thicks. 1.5+7.5+1+5+1 = 15 feet total height.
This owner was not happy to have a 5 foot 1 inch tall upstairs. No one was happy with a 7 foot 6 inch main floor. Excavating and creating a dug out lower floor can solve this but then you have four retaining walls and a concrete floor and moisture issues that get expensive and frankly, it’s not that nice to walk down three of four steps to your main floor.
Adding a second floor can cut the per square foot construction cost in half – from $500 per square foot to $250 per square foot. That per square foot cost is how construction is measured and it is one of the best ways to create valuable usable space affordably.
These are the architectural plans for a small detached guest room in Oakland, CA.
New Avenue is the network of architects and contractors that you can trust. We have completed projects from $100,000 to over $2,500,000. You can sign up to use our project management system for free here: Get Started
Have any questions? We are available to discuss your goals & ideas. There’s no fee or commitment to set up a call. To request a call just click here and tell us when to call you.