Although most of the projects I’ve worked on have been custom designs for clients, occasionally people have reached out asking about buying a plan set of one of my completed projects. For a variety of reasons, starting with a pre-designed ADU plan can be a great option for some people. Be it to save time, save costs, or simply start with a known commodity, pre-designed ADUs have many advantages. At the same time, I believe in the benefits of designing for the specifics of place and the value that custom design brings to each project. An ADU that responds to the surrounding landscape, the local climate, the conditions of your backyard and main house, and your lifestyle, tastes, and needs can’t be overlooked. To think through what option is best for you and your needs I’ve put together the following pros and cons of Custom Designed ADUs vs purchasing Pre-Designed ADU Plans.

Custom ADU Design - Pros

• A designer guides and advises you along the way, helping you make the best decisions for your project.

• You get a project designed specifically for your needs and that fulfills your goals and ideas.

• A custom design responds to your property, existing house, the landscape, and context.

• Style is variable based on your taste.

• All of the design decisions are made together with your input - you can participate in selecting materials, fixtures, systems, etc. that meet your needs, taste, and lifestyle.

• Options are limitless - each aspect can be tailored for you.

• The design process can be a lot of fun as we work through various layouts and design ideas.

• The design team can help facilitate the permitting process, the selection of the General Contractor, and assist during the construction process.

Pre-Designed ADU Plans - Pros

• Can save a significant amount of time - we find the custom design process for an ADU typically takes about 4 months before submitting for permit review.

• Can save costs, potentially tens of thousands of dollars - custom design fees can be approximately 10% of your project budget.

• You can see what you are getting before you buy - it is more like buying a product rather than a service.

• As soon as you purchase the plans you can get a pretty accurate cost estimate for the project from a general contractor fairly quickly.

• The design has been tested through built projects - you are not the guinea pig.

• It takes less mental energy. Most of the decisions are already made so you can focus on other things you enjoy in life.

Custom ADU Design - Cons

• The design process takes a significant investment of time to work through all the various decisions.

• Design fees are an investment and will be higher than the cost of purchasing a pre-designed plan. (We recommend budgeting 10% of your project budget for custom design fees).

• It is difficult getting an accurate cost estimate until the design work is complete.

• You don’t know exactly what the project will look like until you hire a designer and work through the iterative design process.

Pre-Designed ADU Plans - Cons

• Making changes to the design adds cost and time.

• Each location has different rules regulating ADUs, so you have to make sure the predesigned unit will work for your location and property.

• You are on your own to work through the permit process and select a General Contractor for your project.

• The design is not specific to your property or local climate.

• You may be compromising on the design - you pick from what is available rather than what is the perfect solution for your goals, ideas, and property.

As you can see, there are definitely benefits and drawbacks for each approach. It really depends on what your goals are, what the end use of the project will be, the specifics of your property, and your budget to determine which is the best option for you.

Typically we recommend custom designed ADU for those who have challenging properties - steep slopes, lots of trees, tight spaces, etc. - or for those who want something more bespoke and luxurious. If you are building an ADU for an aging family member, or are planning to downsize and move into the ADU yourself, a custom designed approach will best serve your needs, goals, and lifestyle.

On the other hand, if you are working with a tight budget, are building the ADU to use as a rental property, or have a simple property that is easy to build on, a pre-designed ADU plan is a great way to get a head start on the project. A pre-designed option is also great if you like DIY projects, are comfortable handling some of the research, or want to take on the permitting and/or construction process yourself. These are also great for builders who are looking for plans to start with.

Either way, we believe that ADUs are great project types and we encourage everyone to consider how they can benefit your life. We also want to make these projects accessible to people of all income levels and property types. That is why we believe that there isn’t a right or wrong way to approach these projects. If pre-designed ADU plans makes a project attainable for you then it is a great way to go. If you have the time and resources to invest in a custom design that is tailored for your specific wants and needs, then it is well worth the investment to go the custom design route. Either way, we would be excited to help you build an ADU and are happy to offer both options for your consideration.