Remodel and Renovation
May 2, 2023

Home Addition Process: Who to Hire to Build a Home Addition

Home Addition Process: Who to Hire to Build a Home Addition

You love your home and location but you want to give your family more space. Who do you need to help you do an addition? A home addition is far more complex than a remodel within the existing footprint of the home, and it requires more specialists and more planning. Here’s a list of all of the people you may need to hire to pull off your addition—and how much they may cost you.


An architect will create most of the design plans for your home addition. This includes new design options, in several different views, during the schematic (conceptual) design phase. And then more detailed plans for construction documentation, like additional measurements, elevations, side of the house, cross-sections, reflected ceiling plans, and other specifications.

Typical cost: 10-15% of the total remodel cost, or $10,000-$30,000


Often your architect will handle creating the as-built floor plans and exterior elevations of your home as it currently exists. It will show up as an extra charge on your architect’s fees. Sometimes you may prefer to get your as-built plans drafted by someone else, or your architect may refer you out to someone who specializes in drafting as-built plans.

Typical cost: $1,000-5,000


A survey can confirm the boundaries of your property and how your home is situated on it, which is necessary to ensure your addition falls within local setback rules that determine how far from the edge of your property lines you can build.

Typical cost: $300-1,500

Geotechnical (Soils) Engineer

A geotechnical engineer is used to evaluate the condition of the land you’re building on. Understanding the type of soil tells you critical characteristics like how it will move, how much water it will absorb, how it will drain, how much it will be compacted, and how it needs to be reinforced.

Typical cost: $1,000-5,000

Civil Engineer

A civil engineer is used for modifications to the lot outside of the home. You can think of anything that is from the ground down, like site grading, retaining walls, drainage and sewer lines, and utilities.

Typical cost: $1,000-5,000

Structural Engineer

A structural engineer is used to ensure the structure of the home is built in a safe and durable manner. You can think of anything that is above ground. They’ll do a variety of calculations based on the weight of the roof, multiple floors, and other aspects of the home.

Typical cost: $2,000-10,000

Title 24

Title 24 is a set of California codes that require a building be energy efficient. Typically it involves demonstrating energy efficiency when installing new windows. Sometimes it requires hiring a separate specialist, or sometimes an architect or engineering firm will have a Title 24 specialist who can confirm compliance.

Typical cost: $250-1,000


The most important hire for your home addition, a general contractor will oversee construction of your home addition. They’ll hire various subcontractors and manage the project according to a schedule. They’ll also handle any change orders and unforeseen issues that arise during construction. Contractors typically bill one of two ways: as a flat fee for the project, or with a markup on labor and materials.

Typical cost: depends on scope of remodel

Interior Designer

An interior designer can help you with the design of all of the finishes in your home. Not only things like paint and furniture, but also more permanent finishes like cabinet facing and light fixtures. While entirely optional, the bigger your project, the more you may want to consider hiring an interior designer. Typically they charge $100-250 per hour and prefer to work an entire project rather than just a couple of hours of advice. They also will order materials for you. They have access to industry discounts that can save you money (but they also take a markup of 10-30% on the materials they order). If you don’t hire an interior designer, you’ll need to make hundreds of decisions on your own or in consultation with your contractor or architect. 

Typical cost: $2,000-10,000

The Bottom Line

Due to all of the specialties involved, you may pay anywhere from $15,000 to $60,000 for design, engineering and planning for a large home addition before you even start construction. Construction costs of an addition also tend to be higher than for a remodel within the existing footprint of a home. Additions are expensive, so Dreamie often recommends trying to figure out how to make better use of the existing space with a remodel and only resorting to an addition as a last resort.

How Dreamie Fits In

Dreamie handles the first two steps of the design process instead of an architect: creating as-built floor plans and creating a variety of conceptual design options. This work can cost $5,000 - $15,000 from a traditional architect. For an addition, Dreamie creates itemized cost estimates for different options, which can help a homeowner understand if an addition will ultimately fit their budget—before you spend thousands on all of the prep work with the specialists above. Want Dreamie’s help saving you time and money on your remodel or addition? Request remodel designs here or give us a call 415.322.0090.