ADU 101: Preplanning, Design, and Permitting [2 of 9]

This is part 2 of our 9 part series on ADU’s. On this episode, we preplanning, designing, permitting and zoning. 

Denver ADU Course
This post is part of the Denver ADU Course. The course explores the ADU building process in Denver.
Three Learning Options:
  1. Listen to episode “[ADU 2 of 9] 101: Preplanning, Design, and Permitting” on the Denver Real Estate Investing Podcast
  2. Watch the YouTube video at the bottom of the page.
  3. Read the blog post.


The thought of an ADU is an exciting prospect and there are many things to consider to get the process started of building one on your property. Before you put a for rent ad up on Craigslist there are some initial hurdles to clear before you can really start to make progress on getting an ADU built on your property. Most of the processes covered in this post are a time and financial commitment, but once you get past these parts the rest of the process should move much quicker and with less interference.


All of the steps through this process will cost time and most of them money as well. Thorough research will save you both in the long run. This is an extremely important step and this is where most of the detective work will take place. There are 2 key pieces to the preplanning process; first is the determining if your home is zoned for an ADU and second is the conceptual drawings. Each city has different zoning laws, with Denver’s being very strict, so it’s important to do your own research on your local ordinance zoning laws to determine if you are able to move forward in the process. Most cities have a web page dedicated solely to zoning and they can be found by search “your city zoning”. Here you can research what laws have been passed and what type of construction is permitted. If you are not able to find it on the website, call the department to verify. You will need to get familiar with the voices and faces in there anyway!

If your property is zoned for an ADU you can now safely move forward in the process of putting together a plan to get one built. Before you get full architectural drawings you will start with a conceptual drawing. This drawing will have a limited amount of measurements and details, most of them covering potential width and height of the structure, but will show door and window locations along with preferred material types. Some other important measurements like the bulk plane of the main property and any variances you are aware of at the time should also be included. It is worth the additional effort to find an architect who has experience working in your particular neighborhood or with building ADUs. Their experience will help limit the number of redraws and therefore money that is spent to get approval on the design.

Once you have your conceptual drawing you should start working with your historic landmark commission if your neighborhood is designated as one. This commission has the authority to deny any new construction from being completed so your renderings need to meet their criteria. The objective of these commissions is to keep the neighborhoods original character and feel. An older neighborhood that has all brick structures will probably require that your new construction is done in brick and possibly from repurposed brick to keep an authentic feel. Within Denver alone there are multiple historic neighborhoods: Baker, Curtis Park, Washington Park, and Capitol Hill to name a few.

Design And Permitting

By this point, you should have confirmed that your city allows ADUs to be built on properties and had conceptual drawings created and approved by any governing bodies that your neighborhood belongs to. The next step is full architectural drawings for the structure that you want to be built. This is a much more serious financial commitment, a property owner should expect to spend close to $10,000 on the drawings alone. For zoning to approve your plans they will need the mechanical, electrical, and plumbing plans along with the detailed architectural drawings of the structure. This process takes about 3 months and can extend much longer if the homeowner is not responsive to the changes the architect needs to make. These plans should be discussed with a builder simultaneously as well in order to limit the number of changes and redraws that could be required. With all of the plans completed, you can now submit them to your local zoning department.

The size of each city’s zoning department greatly varies. Denver has recently expanded theirs to help with the congestion that all the new construction has created. Arvada has a very well organized department that is excited about the idea of expanding ADU housing. A homeowner seeking zoning approval should still budget 3 months before receiving approval from the city for their construction project. The zoning department may require a few additional items if they are applicable to your situation. If you are tearing down an existing structure like a stand-alone garage they will want to see the demolition plans for the structure. They will also require submittal of required materials that a landmark commission has requested. I.e types of windows and bricks that they have approved for use in the construction.

If you plan on seeking adjustments for the new structure you will first need to get denied by the zoning department. Once they have denied your plans you can submit them to the Board of Adjustments for approval. Be aware that this process can take up to 6 months to complete and the property owner needs to show proof of hardship to get approval from the board. It is good practice to be in contact with your neighbors about your potential plans for the construction of an ADU and a letter of approval from all of your surrounding neighbors can be a powerful tool in getting the board to approve your plans. Even armed with these letters one should strongly consider if it’s worth the effort to try and convince the board about the adjustments that you are seeking.

Hidden Hiccups

Most things are not as easy as they seem and ADUs are no exception to this rule. While this is in no way an exhaustive list it does give you some more ideas of what could cause speed bumps in your journey to build an ADU.

It’s been mentioned several times already but be in contact with your historic landmark commission. They can single handily derail all of your plans. Be in constant contact with them and follow their guidelines very closely to avoid any costly rework.

Do thorough research on your local zoning laws to make sure that the type of structure you want to build is permitted. If you are not comfortable with the research you should hire someone to do the work.

If you plan on utilizing an existing structure you should have a builder inspect the structure to ensure that it is capable of being built on. If it is not able to support the weight the structure will need to be modified and improved upon or torn down completely.

Be in contact with your neighbors about your plans. If construction happens suddenly they are much more likely to be upset and file a complaint with the city which could halt your construction. As stated earlier, their knowledge and approval of the project can be an excellent tool when working with the various departments that must approve your plans.


We will dive deeper into the financing options that can be used for the construction of ADUs but regardless of which method you choose, it is wise to start the process the same time as you start zoning process. Even on the quicker end of things, an HELOC can take several weeks for approval and distribution of funds. If you decide to work with a bank that timeline will extend out much further along and you don’t want to run into an issue of not being to pay your builder or purchase materials for the project.

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Chris Lopez
Chris Lopez is a Denver area real estate entrepreneur and investor, as well as the host of Bigger Pockets’ House Hackerz and the Denver Real Estate Investing Podcast.
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