Introduction
Adding more space to your home in Millbrae can really change your life for the better. A home addition gives you extra room to spread out and enjoy your house even more. It’s a great way to make your place bigger without having to move. In Millbrae, many people are choosing to add on to their homes instead of buying new ones. This lets them stay in the area they love while getting the space they need. Home additions can be anything from a new bedroom to a bigger kitchen or even a whole new floor.
Vital Guidelines for Home Additions in Millbrae
What is Permissible
Maximum Addition Size
You can add up to 50% of your current home’s size or 1,200 square feet, whichever is less.
Height Restrictions
New additions can’t be taller than 30 feet or three stories, keeping in line with nearby homes.
Setback Requirements
You must leave 15 feet of space in front, 5 feet on the sides, and 20 feet in back.
Floor Area Ratio (FAR):
Your total home size, including additions, can’t be more than 45% of your lot size.
Permitting Process Timeline
Standard
Regular home additions usually take about 4-6 weeks to get all the needed permits.
Historic Property
If your home is old or special, it might take 8-12 weeks to get permits approved.
Crucial Zoning Regulations in Millbrae
Zoning rules in Millbrae help keep neighborhoods looking nice and make sure new building fits in well with what’s already there.
Size Limitations for Home Additions
| Zoning District | Maximum Addition Size | Notes |
| R-1 (Single Family) | 1,200 sq ft | Can't exceed 50% of existing home |
| R-2 (Two Family) | 1,000 sq ft | Limited to 40% of existing structure |
| R-3 (Multi-Family) | 800 sq ft per unit | Must maintain open space requirements |
Height Limitations
- Single-family zones: Houses can be up to 28 feet tall or have two floors, whichever is less tall.
- Multi-family zones: Buildings can go up to 35 feet or have three floors, depending on which is shorter.
Building Coverage Rules
Your house and any new additions can only cover up to 40% of your entire lot.
Location Requirements
- Front additions: Must be at least 20 feet back from the street and match the look of your house.
- Side additions: Need to be 5 feet away from property lines and not block neighbors’ views.
- Rear additions: Can go up to 15 feet from the back property line if they’re one story tall.
Exterior Details
New parts of your house should look similar to the old part in style, color, and materials.
Parking
For each new bedroom you add, you need to add half a parking space to your property.
Guidelines for Obtaining Permits for Home Additions in Millbrae
Before you start building, you need to get the right permits. Here's what you might need:
| Permit Type | Description | Estimated Fee |
| Building Permit | Main permit for construction | $500 - $1,500 |
| Plan Check Fee | Review of your building plans | $300 - $800 |
| Electrical Permit | For any new wiring work | $100 - $300 |
| Plumbing Permit | For new pipes or fixtures | $100 - $300 |
| Mechanical Permit | For heating or cooling changes | $100 - $300 |
| Planning Review | Checks if plans follow city rules | $200 - $600 |
| School Impact Fee | Helps local schools | $2 - $4 per sq ft |
Property Compliance Requirements
Your home addition needs to follow certain rules to make sure it fits in with the neighborhood and doesn’t cause problems.
Parking
You might need to add more parking spots if you’re making your house much bigger or adding bedrooms.
Setbacks
Your addition can’t be too close to the edge of your property. You need to leave some space.
Open Space and Yards
You have to keep some of your yard open and not build on every part of it.
Eligible Properties for Home Additions
To determine your property’s eligibility for a home addition: Check with the city’s planning department. They can tell you if your property is zoned for additions and what rules apply.
Other General Plan designations that may allow home additions:
- Low-Density Residential: Allows single-family homes with possible small additions, keeping the neighborhood quiet and open.
- Medium-Density Residential: Permits larger additions or even second units, good for growing families or renters.
- Mixed-Use: Sometimes allows home additions above shops or offices, great for live-work spaces.
Development standards
Single-family Homes
Can usually add up to 50% more space, but must keep the same style as the original house.
Multi-family Properties
Additions are allowed but must not reduce parking or open space for other residents.
Historic Properties
Additions must be carefully designed to preserve the historic character of the building.
Property Designations
- Flood Zones: Homes in flood-prone areas may need to build additions higher off the ground for safety.
- Liquefaction Zones: Extra foundation work might be needed in areas where the ground can turn soft during earthquakes.
- Historic Districts: Additions in these areas must match the old-time look of nearby buildings very closely.
- Coastal Zone: Special rules apply to protect views and access to the beach for everyone.
Summary
Adding on to your home in Millbrae can be a great way to get more space without moving. It’s important to follow all the rules about size, height, and where you can build. Getting the right permits takes time, but it makes sure your addition is safe and legal. Remember to think about how your addition will look next to other houses and how it might affect your neighbors. With careful planning, you can create a bigger, better home that fits perfectly in Millbrae.
FAQs
A typical home addition in Millbrae can take anywhere from 3 to 6 months. This includes getting permits, which might take 1-2 months, and the actual building, which could be 2-4 months. The time can change based on how big and complex your project is.
In most cases, you can stay in your house while adding on. But it might be noisy and dusty. Some people choose to move out for part of the time, especially if the addition affects bathrooms or the kitchen. Talk to your builder about what to expect.
While not always required, having an architect is a good idea for most home additions in Millbrae. They can help design something that looks good and follows all the rules. For simple additions, you might be able to work just with a contractor, but complex projects usually need an architect’s help.
The cost of a home addition in Millbrae can vary a lot. A basic room addition might cost $200-$300 per square foot. So, a 500 square foot addition could be $100,000-$150,000. Fancy additions or adding a whole new floor can cost more. Always get a few quotes to compare.
Adding a second story is often allowed in Millbrae, but it depends on your specific property and zoning. You’ll need to check height limits and make sure your home’s structure can support another floor. It’s a big project that usually needs special permits and careful planning.
Yes, a home addition can affect your property taxes. The added value of your home will likely increase your tax bill. However, it also increases your home’s overall value. Check with the San Mateo County Assessor’s Office to understand how your taxes might change.
In Millbrae, kitchen and bathroom additions or upgrades often add the most value. Adding a master suite can also be worth a lot. Outdoor living spaces like decks are popular too. The best choice depends on your home and what buyers in Millbrae want most.
Yes, Millbrae follows California’s energy efficiency standards.
New additions need to meet certain insulation, window, and heating/cooling system requirements. These rules help save energy and can lower your utility bills. Your contractor should know the current standards.
If your permit is denied, you can appeal the decision. Millbrae has a process for this. You’ll need to file paperwork explaining why you think the denial was wrong. There might be a hearing where you can present your case. It’s often helpful to work with a local architect or lawyer for appeals.
The distance you can build from your property line, called a setback, varies in Millbrae. Generally, you need to stay 5-15 feet from side property lines and 20 feet from the back line. Front setbacks are often larger. These rules help keep space between houses and maintain neighborhood character.
Millbrae doesn’t have strict rules about materials for most homes. However, your addition should match or complement your existing house. In historic areas, there might be rules about using certain traditional materials. The city encourages using environmentally friendly and fire-resistant materials when possible.
Adding a roof deck is possible in Millbrae, but it comes with extra rules. You’ll need to check height limits and privacy concerns for neighbors. Roof decks often need special safety features like railings. They’re considered part of your home’s square footage, so they count towards size limits.
Millbrae takes earthquake safety seriously. If you’re in an area prone to earthquakes or liquefaction, your addition might need extra structural support. This could mean stronger foundations or reinforced walls. An engineer will need to review and approve plans to make sure the addition is safe in case of an earthquake.
