How to estimate ADU permitting costs accurately

Question

We have a property in Los Angeles county that is a 2/1 main house with a detached garage conversion that's also 2/1.

The main house is 1200 sqft and the garage is 700 and originally a 6 car garage. The lot is about 8300sqft.

The conversion was already done by a previous owner.

We went to the local city planning office to ask a bunch of hypothetical questions and made the conclusion that it would be wise to make this a permitted ADU as the property would jump from being 1150sqft 2/1 to a 1900 sqft 4/2.

We asked them permitting costs etc and from what they told us they said they weren't going to make us tear everything down since it's already existing. but we would have to pay for permits and the inspector would come to see if anything is not up to code.

Question: what specifically will they be checking?

I'm all up for being up to code but are they going to tear up the drywall to see how far the studs are apart? Make us redo the windows because they're big or not big enough, etc.

The cost of permitting would be about $10k but that's without repairs. We plan to repair the bathroom and the electrical panel upgrade.

However if they will make us redo any sort of framing and or foundation work etc it would be better to sell the property as is.

Is there someone who we can call on a consulting fee to look at the ADU and advise up what is up to code and what isn't and how much it can cost?

Someone impartial not someone like a GC who will bid a job.

Matthew Forrest · Answer

@David L.

1) Current building codes state what standards your building needs to meet and for my project the city wanted me to "bring the building up to code." The base expectation seems to be that everything needs to be brought up to code so it's subjective what work needs to be done and what doesn't.

2) The planning department wanted a ICC approved vapor barrier because they didn't put down vapor barrier film under slabs in the 50s. This was something they were pretty strong on so I didn't fight them on this item. I ended up taking up my existing flooring and putting down the vapor barrier and new flooring. If you google it you can see many others in the LA commenting on this vapor barrier requirement.

3) I had some walls opened for plumbing and electrical so I was able to show that I have the right insulation. Opening a few holes isn't a big deal since patching is relatively easy. I also had to rewire some kitchen and bathroom electrical to bring it up to code, relocate a sub-panel that in a spot that no longer allowed according to current code, modify the shower to be single handle, install vacancy and moisture sensing switches in the bathroom, install motion and photo controlled exterior lights, install hardwired smoke/co detectors, etc. Overall I would say it was not invasive. Could have been much worse!

4) Total cost was under $40k

I don't know what a Certificate of Compliance is, but understanding all of the fees up front is a great idea. I neglected to do that and walked in to the permit office once day to pull permits and ended up with a bill for $6k in misc fees!

In terms of added value to the property, I have no idea what an ADU brings. In single family, most people buying it won't care or wont even know if something is permitted or unpermitted. If you're local I would be interested in coming to take a look and give you my two cents. I'm not an inspector or contractor, but I like looking at ADUs! PM me if that sounds good to you.

David L. · Answer

@Brian Larson Thank you, I will check out those sites

@Matthew Forrest That's interesting, basically the same situation here. I'm been familiarizing myself with the ADU requirements and visited the planning office here and spoke to the inspector. He gave us a bunch of handouts and stuff and assured us that at the very minimum we wouldn't be made to destroy the entire structure and re-do it. I believe since the garage is already permitted. However, it's an apartment now with dividing walls, 2 bedrooms, 1 bathroom, plumbing, kitchen, etc.

I'm not sure when it was built but I would have to guess it was at least 15 years ago or more.

Like you, I'm wondering what components can be left as-is, and what will need to be up to 2019 code standards.

Few questions for you:

1) Is it completely up to the discretion of the inspector and planning department on what will be required to be upgraded to modern code?

2) Did he make you pull up flooring to check for a vapor barrier? (We have tile and laminate already in place)

3) Considering your ADU was already finished on the inside, how much did he exactly make you change? and how much of it was invasive? (I.E. re-doing electrical, plumbing, etc.)

4) How much did the entire process cost you including permitting?

I was told I might have to do a Certificate of Compliance which is kind of weird considering it's a SFR and an existing structure that has nothing to do with parcels. It'll cost $1900 for the fees for the CC so I want make sure I didn't misunderstand this part.

This is an exit strategy we're looking for and trying to get started soon so that once it's complete and gets added to the square footage, we can sell the house.

What I need I think is a former code inspector or a builder who knows CA building codes well that we can pay for a walk thru and inspection and they tell us what we will need to fix before even considering to start the process. I would hate to have the actual inspector make us open up all the walls to check for insulation.

Matthew Forrest · Answer

@David L.

I did something similar last year to what you are looking to do. I purchased a property in Torrance with a 700 sqft “hobby room” that was configured (wall for bedroom, wall heater, bathroom, faux kitchen, new drywall and recessed lights, etc) as an apartment by previous owners. Some of this was done with permits and some was not.

Long story short, the conversion process was definitely not easy. Because it wasn’t a new build there was a lot of ambiguity with what could be as-built and what needed to be brought up to code. How in depth they go with meeting existing code probably depends on your plan checker/inspector. Personally I did not have to open the drywall to show studs/insulation, but I did have to apply a vapor barrier to the slab. I’m still not sure I understand why I had to do that.

When I was first looking into it, I got familiar with the ADU requirements so I could speak intelligently about it and walked the job with an architect that was also familiar with ADUs. I would recommend going that route. Let me know if you have any additional questions!

Brian Larson · Answer

Try looking into Maxable.com or Hausable.com both of them are consultants for ADUs.

David L. · Answer

@David L. I need to add that the garage itself was permitted and done to code I believe. Just not the interior conversion