$50K to build, $150K to fix
Legalizing an un-permitted ADU isn’t easy, but it can be done.
By now, you probably know our stance on ADUs: they’re just plain smart. A new ADU can make your life more comfortable and put money in your pocket. It’s a pathway to more time and more freedom. For many homeowners, the best way to add an ADU to their property is to convert an existing garage or basement. At New Avenue, we’ve helped a lot of people turn their underutilized garages into something eye-catching, comfortable, and valuable.
An un-permitted ADU can cost a lot.
Amer, one of our top General Contractors, has been working to help a homeowner in California bring an un-permitted garage conversion up to code. The ADU was built by a previous owner, who probably spent around $50,000 on it at the time of construction.
That may seem like a bargain considering today’s construction costs, but since the unit is un-permitted, it can’t be rented out legally. It may also be unsafe as it wasn’t designed and built according to today’s codes and regulations. The total cost to get permits approved and then update the ADU will be around $150,000 or more.
It’s an unpleasant but necessary expense. Once the ADU passes inspection, the homeowners won’t have to worry about safety issues or the nightmarish legal complications that can come from renting out an un-permitted unit. (As an example, in many places, tenants of un-permitted ADUs have the right to stay, but the landlord does not have the right to evict tenants for nonpayment.)
If you have an un-permitted ADU, you have work to do.
Un-permitted ADUs are fairly common, so don’t panic if you have one. But if you’re starting a new ADU project, consider the value of doing it right. In legalizing an ADU, you’ll have to demonstrate that the building meets local codes as they are applied today, not how they were when the project was built. Unfortunately, in un-permitted construction, it’s unlikely that everything will be up to code, and even if it was at the time, those codes could have changed. As an experienced General Contractor, Amer has seen it all. Here’s his list of the most common code issues for un-permitted ADUs:
The grade is higher than the floor.
This causes drainage issues. You’ll most likely need to adjust the grade and install a French drain to deal with excess water and prevent it from seeping through the walls. Apart from drainage, this is a good sign that the sill plate and stud may be rotted out.The foundation isn’t adequate.
In permitting your un-permitted unit, you may need to hire a scanning company to verify the presence of reinforcing steel within the slab, stem walls, and footings. Another company will test the strength of the concrete. You’ll have to dig deep enough to expose the footings to verify the width and depth. Repairs, alterations, or replacement are often necessary and these can be quite costly.There’s no vapor barrier.
Even if the foundation is fine, you’ll have to put a vapor barrier on top of the slab. On a similar note, your exterior walls may need waterproofing.The plumbing isn’t up to code.
You need a sewer lateral from the ADU that ties into the city sewer line. The line cannot tie in under the crawlspace of the existing building. A lot of people try to connect to the main sewer line under the primary home rather than connecting to the city line. You also have to have correct fall (1/4” per foot) to keep the wastewater flowing away from the ADU, or else install a pump. In permitting an un-permitted unit, you must expose all rough plumbing, including underground plumbing, to verify that it meets code.The trim hides the building’s guts.
Normally this is a good thing aesthetically, but not if you need permits and are doing post-construction inspections. To get the necessary inspections and approvals, the inner structure of the ADU, including wiring and plumbing, will have to be exposed. Then you’ll need to seal everything back up once it’s up to code and has been signed off on by the inspector.The utility shutoffs aren’t accessible.
For gas and water, you have to have shutoffs at the unit, not just at the street. You must also have an electrical sub panel (80-amp minimum) within the unit with a shut off switch. The circuit breakers cannot be installed in main house.The water heater or gas line breaks the rules.
You can’t bring in hot water from the main house to the ADU; the unit needs a dedicated water heater. The details vary by city; your design professional can help you determine what type of water heater will suit your needs and satisfy your local ordinances. Your gas line has to be of adequate size for the load.Required ventilation is missing.
You’ll need the proper ventilation hood in the kitchen and a fan in the bathroom. To add this to an existing structure it means cutting holes in the walls and/or roof and the necessary weather proofing, trim, and other elements to make it safe and durable.The existing framing isn’t up to code.
You may have to hire a structural engineer to verify that the framing is adequate and, if not, to provide plans to bring it up to code. This can include wall framing, roof framing, or both. This is especially important in seismic zones as living spaces need to be adequately braced for earthquakes.Walls do not have the correct fire rating.
You may need to install fire-rated wall assemblies, especially if the ADU is attached to the main structure or is close to the property line.Roof nails may be incorrectly installed.
You may have to peel off part of the roof to verify proper roof sheathing nails and nailing pattern.No heating.
You are required to have proper heating in your unit. Electric heaters may require upgrading the electric panel and amperage supplied to the unit. Ductless mini-splits are another option to address heating in the unit.No cooking or inadequate ventilation.
Some cities require that rental units include cooking facilities. That also means ventilation for cooking appliances.The main electric panel needs upgrading.
When building an ADU, the main electric panel needs to be a 200-amp panel.
The “easy way” isn’t always easy.
If you’re building a new ADU or converting a garage, it’s tempting to skip the permitting process up front and save some money. Although it may seem like it will save time or money, it doesn’t hold up over time. Getting permits the right way will actually save you time, money, and frustration down the road. Your ADU will be ready to use or rent out from the beginning, and you’ll have peace of mind. It will also prevent having to do costly upgrades down the road if you decide to legalize the unit.
If you need to legalize an un-permitted ADU, don’t panic. The right design–build team can make your legalization process go as smoothly as possible.
