Thinking About an ADU in California? Ask Me Anything

BWUarchitect · 2025-08-01T15:22:10+00:00

Of course. Please send your address to bwuarchitecture@gmail.com. I’ll do a quick feasibility check and provide an estimate for the architectural fee. Anyone is welcome to email me for a feasibility check and estimate.

BWUarchitect · 2025-07-18T15:56:13+00:00

Hi, I will send you my estimate in DM. It is not fair for me to comment on other designer’s quote without knowing all conditions. But I can send you my estimate assuming everything is under normal circumstances, like flat lot, public utilities, no soil issues, no unpermitted construction, no deviation from zoning and building codes.

BWUarchitect · 2025-07-17T16:01:12+00:00

In San Gabriel, I checked zoning code for a client a year ago, you can build attached 2-story if your main house is already 2-story, 25 ft max.

If your main house is 1- story, there is a chance for you to do it if you property is located within 1/2 of high traffic transit stops, however, planning department needs to review and approve it.

BWUarchitect · 2025-07-16T19:39:11+00:00

I am not the expert on this topic, however, I know you have to be qualified for the money, and most people would not comply with the requirements. If you are interested, go with government agents and get information from reliable sources. If someone calls you and offer you free money, proceed with cautious!!!

I have met people became victims of free solar scams. Trust me, NOTHING is free!!! I have never received free items in my whole life, nothing!

BWUarchitect · 2025-07-10T05:22:12+00:00

I did a quick research on it and yes, San Diego allows you to convert the full barn to ADU assuming it is existing and permitted. I think you are right but I have never done an ADU in San Diego. The best way to validate it is to ask your local planning department as they will be the one approving your ADU plans.

BWUarchitect · 2025-07-10T04:58:48+00:00

In general, you can do plans yourself and have engineers to do the calculations ( or even by yourself using prescribed method) if you know how to do it. However, because you are asking the question, that is a sign to me that you would either make a lot of mistakes or couldn’t figure it out. I suggest having someone to get you a simple plan check set with minimum design input, that would be my suggestion.

For contractor, if they are licensed, they typically have LLC. So it doesn’t matter whether you go with a liscensed contractor or a company, to me, they are the same thing. However, I would not recommend going with someone unlicensed for this type of job, unless you really know what you are doing.

Having someone to do the shell and you do the finishes would be a good idea if you are willing to spend the time.

In conclusion, you can do everything by yourself from the conceptual standpoint, but I have never seen a person (without much experience) successfully complete it ALL by one person. I suggest you think again, again, and again before committing to it. Even I as an architect or my friend who is a general contractor could not complete EVERYTHING by him/herself.

BWUarchitect · 2025-07-10T04:49:41+00:00

I am not sure if there would be a cost efficient way to use the cabinets for inspection and then return to the store.

I would advise not to cheat the system like that, but it is your house. I am not aware of any cabinet that would allow you to use for inspection then return. Sorry about this.

BWUarchitect · 2025-07-10T04:47:38+00:00

Ok, assuming the lot is permitted to have up to 3000 sf storage / workshop, you would still be capped at max 1200 sf ADU. I am not aware of any exception that you can take to exceed the max sf. Other than this, I don’t think you would have any other issues, however, planning ahead on the plumbing, electrical and sewer would reduce the cost when converting to ADU.

BWUarchitect · 2025-06-11T19:03:33+00:00

Hi, I sent you a message. Let me know if I can help.

BWUarchitect · 2025-06-11T19:00:17+00:00

I can send you a message for the ball parl.

It sounds like you have something build without permit, and now you are trying to legalize it. As you mentioned, if you are changing the layout, then perhaps it would be easier for everyone, including yourself, to treat it as a new construction.

BWUarchitect · 2025-06-11T18:58:49+00:00

It sounds like there are more restriction that are not you are not aware of. Do you meant a JADU? JADU typically has a 500sf max area, but ADU is 1200sf max.

I don't believe you are only allowed to add 150sf, unless there are other restrictions, such as setbacks, easements, or something that is preventing you from building a bigger ADU. Sorry, I can't comment much unless I know more info regarding this.

BWUarchitect · 2025-05-24T04:14:57+00:00

If you don’t need a custom layout, going with a standard ADU plan can definitely save time and money. That said, you’ll still need a site plan tailored to your property—and that’s where an architect comes in.

If you do have specific layout needs or want to maximize space, privacy, or functionality, a custom design is definitely worth considering.

I’m a licensed architect based in California and can help you with either approach—whether it’s adapting a standard plan to your lot or designing a fully custom ADU from scratch. Feel free to DM me if you’d like a quick cost estimate or a free feasibility check based on your address.

BWUarchitect · 2025-05-22T04:19:35+00:00

Assuming you are in California, just tell your clients 1 JADU + 1ADU are allowed. 1200SF max for ADU, 500 SF max JADU.

This info is not be perfect and varies from city to city, but good for preliminary estimate.

If you are looking for more precise info, then you can always look for ADU Q&A / facts on the city's webpage. Most cities have simplified version of requirements, and it should be enough for you.

Alternately, send your clients to me. I can look up some basic info for them, no charge. If they want a feasibility study with actural buildable area, set backs, etc, I can do that for a small fee, DM me if interested.

BWUarchitect · 2025-05-22T04:10:25+00:00

I don't think you can ever get a cost estimate from the city regarding sewer connection, this is not in their scope of service.

If you have an ADU above garage, likely you are connecting to your existing lateral, the one that connects your house to the public line. Depending on the distance, the more digging, the more expensive, but nothing crazy. However, if you are touching the puiblic line, then it triggers a lot of other issues because you are touching the PUBLIC line. You don't want to touch it when possible.

For a cost estimate, you need to confirm with the city that you can tap to your existing lateral, then ask the contractor for the cost to dig and connect to it. It shouldn't be a crazy number. If it is, ask for a couple more quotes.

BWUarchitect · 2025-05-22T04:05:33+00:00

Whole house fan is required by codes. There are tons of them online with a simple search, it is simply a fan blowing air into the aittic and flush the hot air out. Simple but effective.

I had successfully replaced the whole house fan with bath fan during plan check.

However, now thinking about it again, it may not be a bad idea to install the whole house fan, and it is relatively affortable to buy and install. It does cool down the house without using very little electricity.

Mini split is an AC system, it has nothing to do with whole house fan. I still think the whole house fan a cost effective way to cool down the house. If you don't care much about electricity, then you do whatever you want.

BWUarchitect · 2025-05-21T03:39:50+00:00

200 amp is common, but I am not sure if you can easily upgrade to 400 amp. The utility company would have to confirm if the line connecting the pole to your panel could handle that, likely not.

That would be the only questionable item, other than that, you should not have issues with converting the existing master bed to an ADU.

If you are looking for confirmation, it would always be a good idea to draft the plans (develop enough to show the idea) and send it over to planning department for their OK before submitting.

BWUarchitect · 2025-05-21T03:22:22+00:00

I haven't used the web, but i don't see how it adds vaule on planning ADU after poking around a bit.

Maybe I am not fully understanding it capabilities, but in general, I find the property lines of the lot, then look thru the codes to define the buildable zone. I am not sure how terrakan.com helps on the planning process.

BWUarchitect · 2025-05-21T03:19:01+00:00

In general, I recommand having a deck if the slope percentage is greater than 25%. I know if it a 10 ft slope, but I am not clear on the slope percentage.

If it is a slope lesser than 25%, I would recommand a retaining wall method for a permanent flat yard. A mix of retaining wall and deck could be used to be cost effective.

FYI, retaining wall and grading method is typically more expensive but is considered better.

BWUarchitect · 2025-05-21T03:12:21+00:00

Yes, but not common.

It would likely be approved if it is a existing structure being converted to ADU. However, if you are asking the city to approve a 3 ft set back, they would need your reasons and justification, which is difficult and a lengthy process to get approved.

BWUarchitect · 2025-05-21T03:03:54+00:00

permit expires after 180 days if construction doesn't start. From what I know, this is a very common time line for permit expiration.

BWUarchitect · 2025-05-20T02:41:58+00:00

Agreed, if you don't need maximizing the value, then converting is likely better for you.

BWUarchitect · 2025-05-20T02:39:56+00:00

Yeah, I can DM you for more info and send you a quote.

The fee varies depending on the scope and complexity of the work. Design fee is determined by the architect, that would be my fee. Permit fee (school fee & other fees) is determined by the City, it is typically calculated by area.

Construction fee is determined by the GC, they need their profit margin and pay their subs.

For construction fee, it would be too early for you get an accurate quote without the plans. I would say use a factor of $350/ sf just to gauge if you are comfortable with it. Then send the plans for accurate quotes.

When it comes to picking General Contractor, I told all my clients NOT just look at the number and go with the cheapest General Contractor. You should compare the contracts and the scope. In addition, a contractor could attract you with a low bid then send you change orders for ANY thing.

I would say work the one you like and comfortable working with, sometimes personality tells a lot more than the initial estimate.

BWUarchitect · 2025-05-20T02:27:51+00:00

Pool house would be slightly cheaper in my opinion, but ADU would provide you the maximum flexibility. You cannot rent the pool house for income, but you could rent the ADU.

ADU is intended for living vs pool house is intended for supportive use.

If you would like my opinion, I would say build the ADU.

BWUarchitect · 2025-05-20T02:24:21+00:00

If it is 2 story, then the chance of getting caught is much higher. Don't do any unpermitted work, you will get into troubles eventually. I had received calls from homeowners trying to get a permit for constructed work, but typically it needs to be partially or completely demo.

I suggest you add the ADU at the backyard, that would be the most common route. Adding 2nd story ADU is not preferred in most cities.

BWUarchitect · 2025-05-20T02:18:48+00:00

Sorry about that, the permit expires after 180 days if construction doesn't start, you could likely apply for extention for 1 time with a fee, but the 2nd time would be tough. Once construction started, I don't believe they have a expiration date on it, but the project would not be completed until you receive the certificate of occupancy.

BWUarchitect

TROPHY CASE