To determine the optimal location for your ADU, you should assess your lot based on legal property boundaries, zoning and development regulations, topography, and adjacent structures. Much of this information is available in your official lot survey, including your property’s zoning district. If you don’t have an official survey, search for the zoning map of your jurisdiction using the terms [“City of (your city name)” and “zoning map”]. Once you determine your residential code, search your local zoning ordinance using [“City of (your city name)” and “zoning ordinance”]. This will help you understand applicable development regulations, including permissible location and maximum size for your ADU. Proceed to the next step with this information.
Contact multiple general contractors, share your desired ADU design and project goals.
We suggest consulting with multiple general contractors as pricing can differ significantly. Shortlist to around three contractors and request cost estimates. Choose based on experience, pricing, timeline, communication, and a team with a manageable project load.
Select a contractor as soon as you want to begin the project. Given the volatility of materials and labor, and the busy schedules of most companies, locking in a contractor early in the process is advantageous. Your GC not only transforms the drawings into a physical building but also serves as the ADU project manager throughout. They act as the liaison between you and the City. More information on how to find a GC in FAQs.
Here are a few key areas in the design that your GC should review and organize as soon as your project is initiated to prevent construction delays:
The Project Site: Aside from understanding where on your lot your ADU should be built, the project site also has implications for other factors such as the ADU’s foundation and project planning.
HVAC: Our ADU designs recommend an energy-efficient and cost-effective system: a three or four-zone (your choice) ductless mini-split system for heating and cooling. Though locations and product selection have already been suggested, the actual system should be planned by a licensed HVAC contractor.
Electrical Power: The drawings specify appliances, equipment, and light fixtures with various power requirements that must be coordinated by a licensed electrician.
Plumbing: A selection of plumbing fixtures and their respective locations are specified within the drawing package. The fixtures, the piping, and the rough-ins must be coordinated and planned by a plumbing engineer.
Procurement: Order building materials with long lead times in advance. Some construction items can take a few months for delivery:
Structural Insulated Panels: Up to 12 weeks
Manufactured Foundation System: Up to 8 weeks
Windows and Exterior Doors: Around 6-8 weeks
Anything that may be out of stock when you start your project.
Your GC will oversee the building process from start to finish. The ADU House Plans contain all the information the contractor needs to begin the building process. We are around to answer any questions you or your contractor might have about the design or the drawings.
For any given parcel, the City will require a review of the ADU project for land use and zoning codes. (This step is necessary even if you purchase a Fast Track pre-reviewed design.) Since every site is unique, a Site Plan must be prepared in order to complete the permit application.
Obtain a topographical survey of your property which contains the legal boundaries of your property, road frontage, topography, utility locations, flood hazard areas, location and capacities of stormwater management, hard surfaces, and the footprint of the existing structures on the property. You can find a local land surveyor by doing a quick internet search or you might already have this document if you had a recent mortgage closing. The legal lot survey is necessary in order to develop a site plan that meets all the requirements of the City. A land survey generally costs a few hundred dollars.
Once you have your site survey, you can either have your contractor develop the Site Plan, hire Atmos Arc, or another design firm to create this necessary document for your project. This process should only take a couple weeks to complete.
Every project site possesses unique soil characteristics and topography. While our construction documents include a foundation design and layout, a site-specific foundation must be confirmed by a structural engineer.
For the Ascension Home design, the foundation manufacturer will coordinate with your lot’s geotechnical report to assess soil compatibility with Ascension Home’s design and structural load. They will then confirm the foundation based on this data.
Expect an additional project service fee of approximately $1,500 to the foundation manufacturer for this service. While the installation of a manufactured foundation is swift, taking only a couple days (as opposed to the weeks a traditional concrete foundation may require), the lead time for confirming and delivering the foundation components can extend up to eight weeks. Therefore, it is advisable for the contractor to order these parts while preparing other aspects of the building.
For ADU designs utilizing a slab-on-grade foundation, your GC will manage the coordination of geotechnical professionals and the engineering required for confirming the foundation design.
Once the site plan is prepared, your contractor will initiate the permit process by submitting an application through your local Building Permit Portal.
Along with your application, you need the site plan and the complete ADU drawing set. Your contractor will also need to submit some documents such as a certificate of workers’ compensation insurance.
During the review, the City may seek clarifications on the site plan or ADU design for final approval and permit issuance. Your General Contractor will manage this process, handling communications with the City. The duration of this procedure can range from one to two months.
At this stage, hopefully, your GC has already ordered materials that have long lead times and the items are being stored at or near your project site.
During Construction: We want to make sure you are getting the quality of construction detailed in the drawings. If your contractor has questions or is having difficulties implementing any part of the design, please contact us to help work through it.
Once the construction gets going, your contractor and you will need to schedule key rough-in inspections with the City before moving forward with each phase of construction. Your contractor will coordinate these and guide you through this process.
Only when all final inspections have been scheduled, can you file an application for a Certificate of Occupancy.
Once the ADU passes all required inspections, the City will give you the Certificate of Occupancy.
Atmos Arc is a full-service architecture studio that offers both pre-designed ADU plans and comprehensive services for custom architecture projects.