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Colorado’s Leading General Contractor Corporation

Building an additional dwelling on your property is an awesome way to increase the value of your real estate, and provide so many more options for accommodation – not to mention potential income. But are accessory dwelling units legal in Colorado?

ADU’s, or AFS – Accessory Family Suites, and their regulations can differ for every state, or even sometimes by county, so it’s important to get to grips with the rules in your area

As ADU (AFS) specialists, we’ll be covering some of the main cities and areas in Colorado as we walk you through what you need to know in this article.

Accessory dwelling units are legal in Colorado

Yes, AFS is legal by rights, provided you can meet a few basic criteria. Let’s get you a quick response, then we can work through some of the details…

Colorado is actively encouraging the building of AFS’s, and they are permitted by right in all zoning districts where plots are occupied by a detached family home is allowed in use, but the AFS cannot be a separate detached structure. They must have their own facilities

Colorado encourages building ADU’s

It’s not surprising that Colorado or other states might encourage – or at least not discourage – the building of ADUs.

After all, they serve as an additional revenue source for the state and the local municipalities and can help local citizens to grow and expand their wealth and property values.

But that doesn’t mean you can simply start building. Keep in mind the major issues that arise …are not knowing local municipality regulations. So let’s cover some specific major cities here, their laws and regulations,

ADU regulations and laws for Colorado

This is largely dependent on the municipality in which you’re living, be it the Denver, Colorado Springs, or Fort Collins area.

But some common themes among all Colorado areas are that it must be a dwelling unit, meaning it needs to have its own independent facilities. And it must have common facilities such as a bathroom, kitchen, and some form of living space.  

For example, if you’re building an integrated unit, then it cannot be larger than 50% of the primary structure and owner-occupancy must be greater than 185 days of the year in Colorado Springs as described by the Colorado Springs government site here

But some by-laws do exist. If you live in the City of Golden in Denver for example, then there’s an additional step of applying for the right for any additional construction …and they only offer around 88 permits a year.

It’s understanding and interpreting these kinds of details that you may need assistance with. So if you want to get the full picture, then contact us and we’ll be happy to assist.

Where can I build an ADU in Colorado?

You can build an ADU in any of the major cities such as Denver, Colorado Springs, and Larimer county. 

Again, it is always best to check on a local level. For example, although Denver is very friendly to having ADUs being built, there are still many rules to follow.

Only about 15% of Denver is zoned for building ADUs although that number might increase, it could be another five to ten years before any new zoning laws come into practice.

Also using Denver as an example, they offer ADU permits in three different sizes, but the fixed costs are the same, so always go with the largest based on your available land area!

Where can I build an ADU on my plot?

There are two major ways to build an ADU, either integrated or detached. If you’re looking to build an integrated ADU, you can usually build three major types.

Either a second story above your primary structure, a finished expanded basement, or an integrated home attached to the primary residence.

Keep in mind that the architecture needs to be of a similar nature to the primary structure.

If you’re looking to build on your plot, then you can build on top of an existing secondary structure such as a garage or a completely new standalone unit.

Here there are rules again regarding the size increasing to 50% of the square footage of the primary structure, but cannot exceed 1250 square feet.

Please keep in mind that you are adding an additional piece of property. In most cases, requiring a new separate driveway, address, and parking area.

These are factors that will need to be considered in determining where on your plot you can build a detached unit. For one thing, it may need to be as far as possible from the primary structure.

Do I need all the permits before I start building?

In general, yes – you will need all the necessary permits in place. This will be very similar to the permits needed when building a primary home as well. These are usually based on the value of the home and will be assessed based on the cost associated with building the ADU.

Inspections will be needed to be shown on-site during construction as well.

Some permits are not required such as Transportation, Parkways, or Landmark reviews.

Check out the latest permit fee schedule for the city of Denver to get an idea of what additional associated costs besides construction are going to be needed.

Zoning clarifications and common zoning errors

This is simple and complex at the same time. Again, this is regulated to the zoning laws of every single municipality, mixed with the available size of your plot. Usually, if you have a plot size for a single-family home, that is it, and very few counties will allow for any sort of detached ADU unit. 

If you take a look at the City of Golden, the minimum lot sizes for an ADU are 7000 square feet and any ADU cannot exceed 10% of that or 700 square feet.

Tip: Your best bet is to always follow your specific codes that are specific to each municipality and get clarifications and approvals before starting any construction.

Common or illegal mistakes people make

A very common and potentially illegal mistake people make is not getting the right approvals and permits before building an ADU. Here’s a round-up list of the mistakes to avoid…

  • Check your municipality for the correct zoning area
  • Be sure you have the right amount of space to build your ADU
  • Ensure you have all the relevant permits
  • Be prepared for numerous, formal inspections, this is not a DIY project

It’s extremely important to check out all the relevant rules and regulations for your municipality, and ensure you are in the right zoning area. And that you have the right amount of space to build an ADU. 

In addition, you need to make sure your permits are in order. This is also easily summarized as an example in the Larimer County government site. This expands on what an illegal ADU looks like, and the actions that will be taken.

Remember, if there is a chance you make an illegal ADU, you will probably be asked to tear it down at your own expense.

Another common mistake people make is thinking that this is a DIY project. It is not and this is due to the fact that there are numerous inspections that are needed to be passed before and after construction. For example, in Denver, you must have a registered contractor handling this work

Also, do not assume that every municipality will be freely open to ADUs. Boulder, Colorado has some of the toughest restrictions on ADUs, as referenced by their Article in section G.

Any ADU requires a Limited Impact Special Review before a permit could even be considered in the Boulder, Colorado area. 

    Planning to build an ADU In Colorado?

    As long as the rules are followed, ADU’s are a great way to expand your assets and provide a home for a loved one or expand a growing business model.

    Either way, here at Ridge Construction, we are fully licensed, so we can guide you through any complexities of building your ADU in Colorado. Together with your local municipality, we can cover any questions you might have. So why not get in touch, and tell us what ADU you’re thinking of adding.

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