Cost of Building Permits for a Custom Home in Mill Valley and Marin County

Millennials Take Marin!

In idyllic Mill Valley of Marin County, CA there is an interesting trend happening.  People are building new custom homes again – and the clients are a surprising bunch: Millennials!

To quote one of New Avenue’s partner architects who is designing the home we feature in this article, Heidi Richardson: “We now have eight new houses in planning review. We haven’t seen anything like this in over a decade! They are coming up in droves!”

The following is a brief summary of one of Heidi’s current projects. The goal in this article is to inform future clients about the timeline and costs of a major remodel or  a new custom home in Mill Valley or Marin County. 

When did these clients hire you?

  • They had a false start with their first architect (that means they fired him or her) and hired Richardson Architects in February of 2016. This was 10 months ago.
  • The planning permit set was submitted in May 2016 (four months after starting). Planning is the first of two big permit processes. The second part is Building Permits.
  • The building permit was submitted in Nov 2016, (nine months after starting)
  • Heidi expects plan check comments back in Jan 2017, they will answer the questions in these comments and resubmit.  Then they expect the permit to be issued in February 2017 – almost exactly a year after starting.
  • This will probably have nine or ten months of construction.  Some bigger projects go up to 11 or 12 months.

The owners moved into their home in 2012. After five years there they will move out for most of 2017 while the construction occurs. They will be moving into their new home about two years after they decided to hire their first architect.

It is entertaining and a bit scary to note that the new owners purchased the home in 2012 for $825,000.  The last owners bought the home in 1971 for $26,000.  That’s right, $26,000!  The old owners realized 8.9% in appreciation per year, every year, for the 41 years they owned the home.  If this continues to appreciate at 8.9% per year for the next 41 years too, the home will be worth $29,000,000. 

What are the owners goals for their home and their design?

  • The owners had a FEMA problem. Flood problems are rampant “here in the land of creeks.”
  • The original home is a one story home and this growing family needs more space
  • They have two young girls and wanted the girls on the upper floor
  • They want a bigger home with the spaces a family likes to have such as a family room, living room, open kitchen and dining area.
  • They don’t want to pay for the schools in San Francisco.  Two private schools can easily cost $60,000 per year which equals the cost of an additional $1,000,000 in mortgage!

What were the design challenges?

First off, when an owner wants to build a new home, it is really hard to find a lot where you can build something.  Let alone something over 4,000 square feet.

For those with the really big budgets Marin doesn’t allow any houses over 7,000  square feet. It is a very rare lot that allows houses anywhere near that size.

A home in the FEMA flood zone like this one, is not allowed to change the footprint.

What was the building process like?

  • In Mill Valley inspections are surprisingly good.  
  • Planning seems to be the thing people want to avoid because it is subjective.
  • The architects know the triggers that can stop a building permit and know how to manage that process. It takes 3 months. It’s a lot of paperwork (often described more colorfully) but most of the time the inspectors are exceptionally good.

What permits were required?

  • Most people who call Richardson Architects have done their homework enough to know they never want to go to planning commission or they know they have to and they want to hire them to do it.
  • The director of the planning commission says at least 5 months to go to the planning commission.  That is how long the Mill Valley project actually needed too.
  • To get a new house through planning commission anywhere from $35,000 to $55,000 in architecture costs. These are hours paid to the architects.
  • At least $20-$30,000 in fees for planning permits.  This is based on 1% of estimated construction cost.
  • So much work is done for planning.  The first two phases of the design process are Program Development, Schematic Design and they  will be 100% completed.  The third phase is Design Development and that will be 50-70% completed by the time of planning approve.  After this there is engineering and construction documents for the building permit. Then you’re ready to bid and build.
  • Surveyor, landscape, impact fees for school, road, water, sewer are all additional.  
  • Building permits are another $40,000-$80,000 just for the architect’s time.  
  • Interior elevations and interior work are additional as well.

In sum, you can spend $150,000-$200,000.  This is for a $1,500,000-$2,500,000 home.  This adds up to approximately 10% for design, engineering and permitting which is fairly standard across the industry.

Here are several of the design images to give you an idea of the old vs. the new in Mill Valley homes.

Existing Front Elevation: 

Front Elevation Existing

Proposed Front Elevation:

Front Elevation NewUpper Floor


Existing Side Elevation: 

Side Elevation Existing

Proposed Side Elevation:

Side Elevation New

Rendering Lower Floor

You can view Heidi’s work here:

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Have any questions? We are available to discuss your goals & ideas. There’s no fee or commitment. To request a time for a call, just click here and tell us when to call you.