How to Build an ADU in Los Altos

How to build an ADU in Los Altos
Panelists discuss how to build a conforming ADU in Los Altos
Written by lalahpolitico

Over 100 people flocked to Los Altos Youth Center to learn how to build an ADU in Los Altos. At the event, sponsored by the Los Altos Community Foundation,  they learned some basics about how they might finance, plan and build an Accessory Dwelling Unit in the City of Los Altos and in the county areas in the city’s ‘sphere of influence.’

How can they know if they qualify financially for a loan?   How can they find out if there is room on their lot to add an ADU to the back yard?  Should they convert that detached garage? What are the costs to expect?  How long will it take to get it done?  How can the City get credit from the State for the new ADUs being “affordable” units – when there is no more rent control?

Here is a lightly edited transcript of the speakers remarks about how to build an ADU in Los Altos and also of the audience Q&A that followed.

Over 100 people flocked to Los Altos Youth Center to learn how to build an ADU in Los Altos. At the event, sponsored by the Los Altos Community Foundation,  they learned some basics about how they might finance, plan and build an Accessory Dwelling Unit in the City of Los Altos and in the county areas in the city’s ‘sphere of influence.’

How can they know if they qualify financially for a loan?   How can they find out if there is room on their lot to add an ADU to the back yard?  Should they convert that detached garage? What are the costs to expect?  How long will it take to get it done?  How can the City get credit from the State for the new ADUs being “affordable” units – when there is no more rent control?

What follows is a lightly edited transcript of the speakers’ remarks about how to build an ADU in Los Altos and also of the audience Q&A that followed.

UPDATE June 10, 2019: David at Modern Empathy wrote me explaining that this article did not stress enough the common binding constraint on building an ADU in Los Altos. In particular, even though it is true that your lot size does not matter anymore, YOUR LOT COVERAGE STILL MATTERS A LOT.  For many homeowner situations, the existing lot coverage may mean you can’t build a full 1200 sq. foot ADU, but perhaps a smaller one, or maybe none at all.

Craig Mizushima
Chief Impact Officer
Housing Trust Silicon Valley


SUMMARY:  We offer a 3-year ‘construction’ loan up to $250,00 provided the ADU is rented to a tenant earning no more than 80% of Average Median Income. That means rent would be capped at $2000 for those two years.

How to Build an ADU in Los Altos, Craig Mizushima

Craig Mizushima of the Housing Trust of Silicon Valley introduced a 3-year term, low-interest rate, ADU construction loan program.

Transcript: Why do people want to build an ADU? Sometimes it is for their adult children who are graduating college and they don’t want them to leave the state. Sometimes it’s for aging parents or other people who are related to us. Sometimes the homeowner – who is in a position to downsize – wants to move into the ADU and leave the main house for their children and their kids to occupy. Sometimes it’s for a mentally disabled family member.

Housing is a crisis here. In order to afford the median price home in the country, you need to have a household income of 255,000.


How are ADUs being financed today?

These three ways.
You have to have a lot of excess income
You have to have a lot of untapped home equity
You have enough cash you’ve saved in the bank

The reason those have been the only ways to finance…

Because the capital markets – specifically Fannie May and Freddie Mac – which provide the secondary market, aka they are the ones that buy the home mortgages that banks write, they have a binding requirement.  In order to finance an ADU, the mortgage lender can’t consider any of the income from the ADU until it’s been in place for two years. And they also won’t consider anything but a second mortgage. They won’t consider a second deed of trust for any ADU construction finance either.

Over 400 people recently attended The Housing Silicon Valley Trust San Jose Workshop on how to get started with an ADU. Only 20% attending said they have the excess income/home equity/money in the bank to build an ADU. 80% have said they need financing and that to qualify they need to have the income from the ADU considered.

So we created a product/program to meet this need. It provides up to $250,000 of financing at a rate of 5%. It is a three-year product. It is not designed to provide permanent financing if you build an ADU in Los Altos. It is to provide a bridge where the capital markets are not providing assistance in the first 3 years.

If we can get an ADU built and leased for two years, then the normal conventional markets can step in and provide long term refinancing.

The way our program works is the rents would need to be “affordable” for the duration of the loan, aka less than 3 years.  Affordable means capped at about $2000 a month. That is affordable to people in the 80% to 120% of Area Median Income. This is often described as the missing middle.  After that, you can charge any rent you feel is appropriate.

Jon Biggs
Community Development Director
City of Los Altos

Jon Biggs, Los Altos, How to Build an ADU in Los Altos

Jon Biggs is the Community Development Director in the City of Los Altos. He explained there is no minimum lot size, that the max size of an ADU is 1200 square feet but normal setbacks and maximum lot coverage regulations still apply.

Transcript: In  July 2018 the City Council passed new ADU regulations. Principal among the changes was the elimination of the minimum lot size.  It used to be necessary to have 13,000 or over lot size to have an ADU.  Now lot size does not matter.

 IF you have a single family dwelling on a lot that has a residential zoning designation, AND you have space on the site to comply with ALL the zoning requirements, — the setback requirements, the floor square foot area requirements, and lot coverage and so forth — you do have an opportunity to create an ADU on your property.

The maximum square footage for the ADU has been increased. It used to be capped at 800 square feet but now is 1200, so long as its not more than 50% of the floor area of the existing residence.

[Lalahpolitico: Note that if you have already built a large home on your lot – maxing out your allowable LOT COVERAGE per the zoning – you may NOT be able to build any size ADU or perhaps one that is much smaller than 1200 square feet. ]

There are other types of ADUs that can be created by conversion of a pre-existing accessory structure. Things like detached garages, detached pool houses. But that depends on the square footage of those structures and the other zoning limitations.

It used to be necessary to have 13,000 or over lot size to have an ADU on your house parcel.  Now lot size does not matter. The maximum square footage for the ADU has been increased to 1200 square feet. However, you must meet minimum setback and maximum lot coverage requirements. – Jon Biggs, City of Los Altos

I’m not an expert on ADU’s. But our Planning Department has great staff that help people navigate the rules and regulations we have. So if you are thinking of constructing one, come down and talk to our planners and find out how the rules apply to your particular lot. You can see if an ADU is possible in your situation. We can tell you if and how you can build an ADU in Los Altos

We’ve checked with the State and it is letting us classify the ADUs as lower-income units. In the future, we will be checking on the size of the units and rents being charged in some of the ADUs. In some cases, no rents are being charged. We want to make sure the income levels are in compliance, as Craig mentioned.

In Los Altos there are quite a lot of large lots. And many of them are underdeveloped.

I’ve worked with ADU’s for 35 years now in 5 jurisdictions.  It used to often be that an ADU had to go before design review and even city councils, and the application could be denied based on objections from neighbors or other concerns. The process has changed.

Now ADU proposals by State Law and the Los Altos law are considered magisterially permitted applications. That means if you come in with an application and have talked to the planner who confirmed you have the room and setbacks on your site, and you comply with other zoning, you can construct an ADU. We will sign off and approve that. Your application will move from the planning department to the building department. The building permit process is where the plans get approved so the proper inspections can be done to make sure it is adequate for occupancy and meets life and safety requirements.

This city zoning change allows homeowners to provide housing for their loved ones, to provide extra income so that they can continue to afford the house if they are reaching that point in their life.  Or they can provide housing for a variety of people who can’t afford the expensive housing prices.

Since the City Council adopted the new ADU housing regulation in 2018, that was probably the middle of 2018 [Sept. 2018], we have approved 32 ADU permits. This reflects well on this community.  [Lalahpolitico:  Since Sept. 2018 I counted only 12 permits on the city website. Was I looking at building permits and not planning approvals?  So 20 homeowners have not advanced their projects?] [Lalahpolitico: At a recent event, the City of Alameda Mayor told me her city has approved about 20 to 25 ADUs a year over the past 2 years.  So our Los Altos annual rate is theoretically about the same as their annual rate. Nice.]

Eion Matthews
Co-founder, Point


SUMMARY:  He represents an equity sharing program, not a debt program.  There are no payments and the term is flexible. There is no income qualification requirement. However, it has the more expensive cost of capital.

Eion Matthews, Point equity sharing, How to Build and ADU in Los Altos

Eion Matthews, Point explains equity sharing.

Transcript: Senator Bob Wokowski out of Fremont speared-headed the ADU by right state law. Send him a love letter if you build an ADU in Los Altos.

It’s great if you have cash in the bank, use it.  But many will have to consider cash-flow vs. rate, cash-flow vs. cost of borrowing.- Eion Matthews

In Los Altos, your mortgages will be sold into jumbo pools, not Fannie Mae or Freddie Mac.  There will be securitized with a somewhat different mechanism. You still have to finance the construction. If your ADU is under 200,000, that loan of 5% from the Housing Trust is pretty hard to beat. But you have to qualify. There will be income requirements.

Looking at all your loan options–

There are unsecured loans, but the biggest ones are only 100 to 150 thousand dollars and those are only for ‘super-prime’ credit score and wealth holding folks.  You have to have a substantial income. This kind of loan amount might be enough in Los Altos if you are going to build a very small ADU.

Then there are secured loans. That means your home is collateral if you build an ADU in Los Altos.

Option 1. you could do a cash-out refinance on your mortgage. Rates are still pretty good right now.  But if you have cash out refinanced in the past 5 years, your rates will probably be higher. You will be increasing the balance of your mortgage overall, but you get a bunch of cash. This is a very popular option.

Option 2. Suppose you don’t want to touch your first mortgage. You could get a home equity loan or a keylock loan. Most of the banks and credit unions offer these. If you are prime borrower rates will be good. [However, I should point out that the advantage of option 1 – a cash-out refinance – is that rates are competitive and they are open to borrowers with lower credit scores than prime. These would be available to people whose credit scores might be in the 600’s. ]  In comparison, home equity loans may require higher credit scores and the time frame is much shorter term.  So your monthly payments will be high. Keylocks are 10 years of interest only, followed by 15 years where you are paying down the principal.  This loan is junior to your first mortgage so the rates will be a little higher than on your first mortgage.  If it’s a keylock the rates are variable; if it’s a home equity loan the rates are usually fixed. But you still have to qualify.

Option 3. My company, Point,  has a shared equity product. There are no monthly payments.  It is a very long term. You can get up to $250,000 programmatically – instantly. Or up to 500,000 on an exception basis. Which might be an amount required for many ADUs here in Los Altos.

We are one of a handful of companies offering these.  What’s different about them, is that you are sharing the equity growth of your home and that there is no monthly payment. We come in as a risk-sharing partner. And we are dependent on your home increasing in value in order for us to get returns on our investment in the ADU.  You can exit at any point in time.

A lot of people would use our equity products in the way Craig at Housing Trust, just envisioned – for shorter-term financing. There is total flexibility around the term.

But you should expect that equity financing, where there is no monthly payment and you get flexibility in the product, will probably end up being more expensive than debt products.

There is no income requirement. We are not dependent on the monthly rent payment.

When the ADU legislation first came out, homeowners that were doing it were using their own cash and assets. Then it expanded to people who got a refinance or keylock to fund the ADU. Now we are seeing a big uptake in the shared equity approach.

If you want to see if you can qualify for debt, you should go to your bank and just talk to them. They will tell you what their credit quality requirements are for their products.

Greg Popovich
Goldbar Builders LLC

SUMMARY: Goldbar Builders does site built ADUs.  We do 2×6 stick construction.  We build from the ground up. Just like you would a home.  We do the foundation and everything. We are an ADU specialist.

Greg Popovich, Goldbar Builders LLC, How to Build an ADU in Los Altos

Greg Popovich of Goldbar Builders LLC is a design-build firm specializing in site-built ADUs.

Transcript: If you have a concept, we can do the design.  We are a design-build contractor. We run the permits for you. We do all the legwork. The first step is to line up your financing, then you do the design element. Then there is the permitting process. You go through the build process and you get handed the keys. Then you have an ADU for an elderly parent, an adult child or a caregiver, or whatever you think it should be for.

We did a podcast with Senator Wokowski. Google for Senator & ADU podcast. We have projects all through the East Bay all the way from Lafayette to San Jose to Los Altos and up into Palo Alto. We also have a division up in Santa Rosa. We started out doing exclusively ADUs. We have a custom home background. In Santa Rosa we kept getting fire victims asking, please come build our house. We are only going to do 6 or so a year there and not overcommit.

There are a few types of ADU.  Detached, attached, junior ADU, internal conversions in a house.

The majority of the attached ADUs we do are when the property does not meet setback requirements for a detached ADU. Detached ADUs have pros and cons. One pro is more privacy. Some people don’t want in-laws to have access to their house if they build an ADU in Los Altos.

These detached ADUs, I like to call them cottages, granny flats, ohana units, casitas, guest houses. That all sounds much better than Acessory Dwelliing Units, ADUs. That was Governor Brown’s brain child. When we started out, people asked me, “ADU, what’s that?”

So what’s a Junior ADU? It’s an internal conversion. For example, you can take a master bathroom which has its own bathroom and adds a kitchenette. But you have someone living in your house now. Not someone living on your property.

Then there is the structural conversion. I wrote an article about garage conversions. People say to themselves, “I have this detached garage, it’s going to be a great ADU.” But a garage is made for a car, not for people. I have to look at the structure, I have to look at the earthquake risk, I have to look what type of engineering we’ll be doing, what type of infill of trusses, do we have to rip the entire roof off? 9 times out of 10, it is much less expensive to demolish the existing garage and start from scratch. So look critically at your garage, Does it lean a little bit to the left?

If it was built in the last 20 years, maybe we can meet the codes. But usually, the structure is sitting right on the slab. There are water intrusion issues. Garage conversions are not necessarily your savior.

If you do have a swimming pool, we can demolish it, and put an ADU there.

Cost to build an ADU in Los Altos? I’ve heard as high as $700 a square foot. We are in the ballpark of $325 a foot on up.  Going smaller with an ADU does not make it cheaper.

Think about it.  You still have the same components. You have the kitchen, the bathroom, all the utility hookups, the foundation, all the major costs of a house.  You are now putting those into a little house.

An example of a 500 sq ft ADU, site-built 2×6 stick construction, granite /quartz counter tops, soft close hinges/drawers, you’d be looking in the ballpark of $178,000. That includes design, us running the permits, [but not permit fees], includes the construction, us handing you the keys. This does not include gold-plated amenities.

So for a 1000 foot ADU your costs will change, dropping into the $325 a square foot range.  That would be about $327,000, including design, permit running, and all the 2×6 onsite construction. But if you need a raised foundation your costs go up significantly. The prior estimate is for a slab on grid. That raised foundation would add from 12 to 20 thousand dollars. If you are in a geotechnical zone and we have to drill piers down 50 feet like you do in Santa Cruz, you can go up $50,000 on your foundation. That should usually not be the case in this area.  However, there are some hillside areas around here, where there may be extra costs.  On an individual basis, we can go through what kind of foundation we will need to build in your situation.

Time Frame. Normally your project will be in design for 14 to 60 days.  It depends on how fast you want to approve the floor plan. Then things go rapidly. We do all the design. We run the permitting.

We have a number of floorplans you can look at to approve or use as a starting point.  SB 1069 allows 120 days for an approval or a denial of your ADU. The typical build is between 90 to 100 days for a site-built construction. Inspections are timely in Los Altos.  It can be a 24-hour turnaround.

Types of firms. You can find a pure design firm. The architects out there…they can be expensive. They can design in expensive amenities. Be sure they have experience in ADU building and also ADU design.

Drawbacks of building an ADU in Los Altos: You will be living on a construction zone for 100 days.  There might be some garbage over here one day, then the next day it’s gone. With the limited number of subcontractors around now, be happy if you see a sub every day!

We have a new program, HATS, housing affordability for teacher stability.  I work with Fremont Union High School District and other Districts.   The program is evolving.  We are working to help the teachers find housing.

David Klein
Founder, Modern Empathy


SUMMARY: An  ADU builder that provides a proposal and feasibility analysis for at no charge. They use and reuse pre-designed modules that can be pre-fab or built on site.

David Klein, Moderm Empathy, How to Build and ADU in Los Altos

David Klein represents Modern Empathy, a design-build ADU firm that offers a no charge feasibility review of your parcel.

TranscriptWe were focused on aging in place research for the purpose of new product development.  As a member of the Center for Age-Friendly Excellence, I heard over and over about housing challenges. My background is in high technology, and there has been an intersection with smart homes and conservation technology.  I started investigating home sharing online and offline marketplaces. With the changes in the ADU state law, I saw that the people who were interested in home sharing were also interested in ADU conversion. That’s how I came to focus on ADUs.

I was able to recruit a strong team of architects and builders. Our chief designer is a prefab architect. She previously worked for Blu Homes – a high-end prefab home producer. She is a professor of design at CCA. Our head builder has long experience building homes.

ADUs are nice bite-sized projects.  If properly organized, a producer can come it, get it done, get it out. I hear developers say, “We are just banging them out.”  But you don’t want that to lead to sub-standard or cookie cutter ADUs. You don’t need to sacrifice quality or unique neighborhood character.

ADUs give homeowners a lever to address our personal housing crisis and also the community housing crisis. Yet we can maintain control of that character…We have design professionals focused on smaller footprints.

Let me take you through the story of a recent project. We are only a one-year-old company. Our first ADU was recently completed in Sunnyvale. We have several projects in progress in East Palo Alto, Redwood City, Los Altos.

The Sunnyvale homeowners had been thinking about this for years. They were looking for high quality and getting it done quickly.  They wanted to provide housing for their community. They wanted something that might fit their parents in the future. “What should the design be, so that we don’t need to modify it in the future.” They wanted it to add value to their property.

First, we communicated with the homeowners by email.  Our company is quite adept with satellite imagery and databases and city relations. So we can determine remotely how much floor area you can build on the given lot in different areas of that backyard.  Then we talk to the homeowners to understand their needs and desires and budget. We also ask how they are currently using the backyard – are their areas that need to remain very private? How do the neighboring homes affect the privacy or views in that backyard?

We quickly develop a design proposal based on that information. And also a cost estimate behind that design. We try to have a quick turnaround of the proposal process and estimates that are very accurate if you decide to build an ADU in Los Altos.

We reuse modules during the design process.  These modules are also suitable for pre-fabrication. But even if they are built on site, we know the specific bill of materials and the labor requirements.

We get through the design/proposal and cost estimate step free of charge. There are a lot of designer and builders that will charge for that initial feasibility analysis. It is a lot of work for the company.  You do have to visit the property. You often get into back and forth communications with the homeowner. People usually want to be compensated for that.

The problem is that a fee for feasibility analysis pushes so many people away. We want to open up the market. – David Klein

Yes, we hope to get immediate acceptance of our initial proposal, but usually, there is some iteration. In Sunnyvale, there were two weeks of iteration. They loved the initial design, but they wanted to evaluate different size kitchens, different roof slopes, different window sizes, things like that.

After 2 weeks we had an agreement, then we quickly prepared a plan set for the Planning Dept. of Sunnyvale. Most planning departments require an application fee. At the outcome of that process, you may be assessed more fees – traffic impact fees, park fees. That is another big deterrent for a lot of people. The cities are starting to get it. There are state bills in progress that may streamline things – reduce fees and reduce time limits for approval.  Cities are getting closer to over the counter approvals, pre-approvals of the project. San Jose is a good example –You can get initials on your plan over the counter.

Here if you build an ADU in Los Altos and it’s under 500 square feet you can get over-the-counter approval and a quite low fee.

After planning approval, typically you want to wait to go through structural engineering, construction documents, and title 24.  The planning dept. may want you to make changes. In this Sunnyvale example, there is a requirement that the ADU match the main house.  [Lalahpolitico: This is also the case if you build an ADU in Los Altos.] That means color, siding quality, roof slope, height.  It’s a subjective judgment. In Sunnyvale, the planner made us reduce the height to match the house.

Then we work with a builder who will specify everything and make sure the materials arrive on site, on time, just when they are lining up their hammers!  That’s the way you can do these projects very quickly if you build an ADU in Los Altos.

The total [building and impact] permit fees for that Sunnyvale project added up to 4,700 dollars. That’s for a 430 square foot unit. That fee would be similar in Los Altos. Total project cost including the permit fees ended up being $179,000.

We provide a homeowner flexibility in their housing arrangements with expertly designed ADU homes backed by a streamlined design-build system.  Also, these dwellings are extremely energy efficient.  We haven’t even talked about that!

Here’s more about this Sunnyvale unit. They were able to hold the rent down. They got 64 people applying in 3 days on Craig’s list.  Teachers, EMT, police, etc.

UPDATE: Klein sent Lalahpolitico a note explaining Title 24 – a topic he did not get to talk about during the event. Title 24 Part 6 is State of California energy code. It was not trivial to pass it. In January it is expected to become more stringent in its standards for housing construction. It will require greater ‘energy efficiency’ and cleaner energy. His firm favors the changes. Homeowners doing remodels and additions will need to learn how to navigate the new rules and to understand their long-term energy cost effectiveness. Of course, Modern Empathy is there to help!

Margo Horn:  Let me acknowledge that Los Altos City Council member Jeannie Bruins and Planning Commission member Sally Meadows are in the audience tonight.

Audience Questions & Panelist Answers

Q: If I build an ADU in Los Altos, how does that affect property tax.  Answer: Biggs: The County Assessor looks at the value of the addition and adds that to your base.  Your main home is not reassessed.

Q: How about conversion? Answer: Biggs: Garage conversion may cost you more than a new build.  You do need to replace at least one parking space on the lot. But future State law may reduce that to 0 replacements.

Q: Do you see lower fees coming?  Answer: Biggs, the State ADU regulations are in constant change…in the direction of encouraging more ADUS by forcing cities to lower those fees [and other impediments]

Audience at the How to Build an ADU in Los Altos event at LAYC

Audience at the How to Build an ADU in Los Altos event at LAYC

Q: Is there a big difference in costs for detached vs attached ADUs?  Popovich:  For attached you have to demolish a wall, get the two floors to be level, marry up the foundations, etc.…so I would say it is 5% higher than detached.

Q: I want a solar energy home?  Do you do that?  Popovich: I don’t do it, but 2020 new laws may require that, not sure how that affects ADUs. I encourage homeowners to do it.

Q: How does shared equity work? Matthews: There is an appraisal up front. Limited to 80%, we discount that. But we credit what you use the loan for.  So it winds up being 80%

Q:  What happens when you sell your home? A:  Mizushima, the ADU stays with the property.  Matthews: if you sell,  a city can no longer require you to dismantle the ADU. That’s against State Law now.

Q: If an ADU is a rental, and with a SALT account, can you take depreciation?  Matthews: Yes, with a financial advisor you could set this up.

Q: Are there limits on the size or amenities of the kitchen if I build an ADU in Los Altos?  No maximums, but there is a minimum, namely the right electrical and plumbing infrastructure for a stove, oven, sink, refrigerator.  But a JDU has a lower bar – having only a microwave and a bar sink and bar frig will suffice.

Q: Is there a requirement to rent at below market rate?  Mizushima, once our 3-year loan is paid off, there is not a requirement to make it affordable to someone making $120,000. If the homeowner uses their own cash, there is not affordability requirement.

Q: If I build an ADU in Los Altos, do you require a special meter for water, etc.? Answer: Biggs and others… we don’t require separate meter here in Los Altos, but if you want separate bills…  It’s pricey. Don’t do that… A submeter is $600 a piece.

Q: Are are there any setback rules changes?  Biggs: No, however, if you have an existing accessory structure, you can convert that to an accessory dwelling unit even it does not meet the setbacks of a newly build ADU.

Q: How about building an ADU over a swimming pool?  [How much does it cost to fill in a swimming pool?] Popovich: One we did in the Santa Teresa area, cost $18,000 to $25,000 because it required compaction.

Q: How are basements counted if I build an ADU in Los Altos?  Biggs: If it is a detached ADU, the basement does count towards the 1200 square footage cap. But with an attached ADU, the basement does not count towards that ADU.

Q: Can you add fences inside the back yard so as to separate the ADU part of the backyard or to create a dog area?  Biggs: Yes, the only limit is the height – 6ft. plus see-through lattice same as with the lot line fences.

Q: Within the 1200 square feet is there any limit to the number of bedrooms or bathrooms you could create? Biggs:  No

Q:  What are the total fees typical of Los Altos, $4,500? Biggs:  The fees are $595 for a planning review. Then it goes to the Building Division and the building permit fee and the plan check fee depend on the value of work.  [the cost, including the cost of the amenities you are putting into the structure]

Popovich: Additionally, If you are over 500 sq. feet you have a school impact fee. That’s a one time fee. They range from $3.95 a square foot and up. Jessica Speiser: Los Altos School District Trustee. “On our recent 11,000 square feet ADU, it was $3600 to Los Altos School District and 1/3 of that [$1200] to MVLA.”

Audience at the How to Build and ADU in Los Altos event at LAYC

The audience at the How to Build an ADU in Los Altos event at LAYC

Q: If I build an ADU in Los Altos, are porches counted? if covered how do they count in square footage?   Biggs: For the ADU, the 1200 measures only inside the exterior walls of the ADU.  A covered porch or a projection like a bay window or window seat on ADU would count toward the lot coverage limit of the parcel. They are not part of 1200 though.

Q: From the perspective of a builder, some people get permits in 20 days, some in one year. How can the process be simpler for customers? Biggs: I would encourage any builder or homeowner to come in first thing and talk to a planner about what the limitations or opportunities are for your site. We have a checklist that shows all the information that we require on the plans. And it specifies what is permitted in terms of an accessory dwelling unit. If you can provide all that information in clear, concise plans that is the best way to shorten the entire review process. The planning staff is there to help you out, provide answers, and help you get to a point where you do have a complete set of plans so you can go through the process expeditiously.

Q: When is the best time to come? Is early in the morning the best time to come to the planning department? Biggs: Well…inaudible [Lalahpolitico: Last month when I visited the city hall, I noticed that there is now an appointment booking process for 15-minute sessions to talk to a planning/building person. Just go to one of the two PC kiosks. Or ask one of the nearby seated staff if you need to. Or you may decide to wait for help. For walk-ins often there is no significant waiting. This reservations system may have been an experimental pilot program. }

Q: Are there any green building requirements if I build an ADU in Los Altos? Or any fire sprinkler requirements? Biggs: In Los Altos no.  Craig: In some other municipalities, or when an ADU is too far from a fire hydrant, it may trigger a need for sprinkler in the ADU. Lalahpolitico: the municipal code reads that if the main house has fire sprinklers, the ADU must have them too.

Afterwards Question:

Q: If you build an ADU in Los Altos or the surrounding county, are new hookups for sewer, water, required? Answer: Jessica Speiser, Trustee Los Altos School District. No, you don’t need to pay for new hookups. Lalahpolitico agrees and can confirm that the state law allows the ADU to connect to the existing service and pipes.


Jon Biggs…City of Los Altos

Chapter 14.4  Accessory Dwelling Units – of the Municipal Code

All Ordinances:

In all ordinances above, you can find Chapter 14, and zones for single-family homes by size range of the parcel 10, 20, 40. Those numbers refer to the typical size of lots in that zone, smaller to bigger.

Most common SFH zone is R1-10 Single Family District.   When you find the relevant size of your house parcel, you can find out about setbacks and lot coverage that apply to YOU. If you recently rebuilt the home on your parcel with the maximum house size allowed in the ordinance, you will not be able to add an ADU.  There is no free lunch. If you have not already built out to the max, other constraints apply. Talk to the Los Altos Planning Department.

Craig Mizushima… visit

Matthews’ web site is

Popovich’s website is

Klein’s website is


For an explanation of how Los Altos regulations on setbacks and LOT COVERAGE affect the feasibility of an ADU in your situation, take a look at our prior posts. Our city council was moving towards an 800 square foot size limit on Accessory DWELLING units over months and months of delay caused by rewriting the Accessory STRUCTURE ordinance. (These are workshops, pool houses, etc.) At the September 2018 council meeting, the majority vote suddenly swung to a 1200 square foot ADU limit for all parcels provided that the parcel could conform with the other conditions.

1) For an explanation of setbacks, lot size and LOT COVERAGE see

City Improves Incentives for Granny Units in Los Altos

2) For a review of the city council wavering about the terms & conditions in our local ADU ordinance see

Create your granny unit ADU or pool house in Los Altos…

During the long period when the City had no ordinance, the state law applied.


About the author


Norma Schroder is an economics & market researcher by trade and ardent independent journalist, photographer and videographer by avocation. Enthralled by the growth of the tech industry over the decades, she became fascinated with the business of local politics only in the past several years.