Attached garage converted to guest house.

Garage converted into a studio apartment with a kitchenette toward the rear left.

Thousands of people take the plunge every year and transform their dusty, barely-used garages into beautiful living spaces.

When done correctly, a garage remodeling project can be accomplished quickly and with few hiccups. You can experience safety hazards, fines, and costly rework if it’s not done correctly.

Here are some things that you need to consider before converting your garage into a living space.

Apartment Usage

Before you begin any project, you’ll need to settle on a set of requirements for the space. It’s best to finalize your vision for the apartment during this phase.

For instance, your nephew will be attending a nearby university. He’ll need an inexpensive place to rent for the next several years. As you look forward to having him over for dinner each evening, the idea comes to you. Create a garage efficiency apartment. Your spouse is thrilled at the idea of clearing out the clutter in the garage and constructing a space that increases your property’s value.

It’s almost guaranteed that the requirements for the space will be different from those that you would have for a garage apartment that you plan to rent to a total stranger. The apartment for your nephew may contain only the basics for sleeping and studying. He can use the washer and dryer, shower, and stove in your main home without any hassles. For this setup, you can maximize the living space with a spacious bedroom and study.

garage efficiency apartment.

“Guest quarter” with sleeping area and small study. Ideal for overnight guests but not necessarily a rental.

Your college town is also very popular with other members of your family. When your nephew graduates, you anticipate making the apartment available to visiting family members throughout the year.

This scenario is very different from someone who wants to have her garage converted into an efficiency apartment for Airbnb or long-term student renters.

To rent to the public, you’ll want amenities such as a kitchenette and a full bathroom. Knowing how you want to use the space enables you to effectively communicate with architects, builders, and other tradespeople who you’ll need to design and remodel the space. It also helps you appropriately plan your garage apartment conversion budget.

Garage converted apartment with kitchenette.

Accessory dwelling with bathroom and small kitchen.

Defining the Type of Space

When you discuss your garage conversion project with a building professional, you’ll learn that there is a regulatory difference between the space that you want to create for your nephew and the one that your neighbor is considering for long-term renters. The space that you want to construct is called a guest quarter. This garage converted to a guest house usually has a living area, a bedroom, and a bathroom but no kitchen.

The living space that your neighbor wants is called an accessory dwelling unit, and it will include a kitchen, bathroom, separate entrance, and available space for parking. Once you’ve made your final decision about the type of apartment that you want, you’ll need to speak with an architect to bring your vision to life. Your builder will introduce you to an architect with proven experience with your type of project.

Your architect will discuss your requirements and evaluate your garage space. Some things that will impact the design of the space include its structural condition, zoning laws, electric service, sewage, and septic if applicable.

The Budget

We get email inquiries from prospective customers all the time, asking us to give quick ballpark estimates for home additions and even new home builds. People ask for these numbers off the cuff as if they were asking for a quote for an appliance. The problem is, that there is not a one size fits all formula for home remodeling. There are too many factors at play to give quick quotes without understanding the full scope of the project.

Very few people come to builders with a money’s-no-object attitude when it comes to getting a garage converted to a guest house. They usually have a ballpark idea of the amount they want to spend to get what they want out of the space. Sometimes this number is realistic; other times, it’s not. Here’s how that number gets figured out.

You are going to need blueprints that outline the design and building plans. This is how estimated costs are calculated by your builder. So, regardless of whether or not you have enough money to take on the complete garage conversion, you do need to budget for an architect or designer/draftsperson to create the design blueprint. That is always the first step, so budget for this at a bare minimum. Once you have blueprints, you have a roadmap forward for you to take to any builder to run cost calculations.

Getting Construction Blueprints Made

Anthony Ferrara of North East Remodeling Group going over plans with a client.

Anthony Ferrara of North East Remodeling Group going over plans with a client.

Typically, construction blueprints come from an architect, but they can also come from a “designer” or a “draftsperson.” The complexity of your project and the laws in your area will determine if you need a registered architect or if you can get by using an architectural designer or draftsperson. Usually, a phone call to your local building department can answer this question for you.

What’s the difference between an architect, a draftsperson, and a designer?

A registered architect’s skills are backed by 5-6 years of education and two years of on-the-job training. A registered architect is also legally responsible for their work.

Architectural designers, also called “designers’ usually work under registered architects before becoming registered themselves. They are not licensed. While they may be on the road to having a license and the skill set of an architect, they’re not yet licensed and are not legally able to “stamp” blueprints that may or may not be required for your project. Yet another question to ask your local building department.

A draftsperson is skilled at turning drawings into technical blueprints that can be used by a builder to create a pricing estimate for labor and materials of a construction project.

While this is debatable, we think you can’t go wrong using a registered architect. That’s why we always recommend using a registered architect. We like using architects that we already have a working relationship with so that we can be sure communication channels are already battle-tested and proven in the field. There is nothing more frustrating for a builder and a client to have a project held up because the architect on the job is unavailable to clarify an issue with his blueprints.

That said, for smaller projects, you may be able to get away with using a designer or draftsperson, but you should confirm this with your local building department and understand what your liability exposure is for choosing to go in this direction.


Building permit costs are based on a percentage of the total projected cost of the project. Everyone knows someone who “saves” money by taking shortcuts and bypassing the permit process. However, a garage conversion project isn’t the time to follow that person’s lead. Local building codes help to ensure that home remodeling projects result in safe, habitable structures.

By following the law and getting building permits before starting your project, you allow building inspectors to later make sure that your new space is free of obvious fire hazards from electrical wiring and has adequate plumbing to remove wastewater from your property. But that’s not the only reason…

There’s also another angle to consider.

When you get a proper permit and your town building inspector signs off on the scheduled inspections, you get what’s called a certificate of occupancy, aka a “C of O.” This can become really important to you if you ever want to sell your home. If it’s established that additional square footage deemed as living space was added to the premises without acquiring a “C of O,” this will hold up the sale of your home. You can bank on that!

So do it right and have your builder pull the necessary permits. If you’re doing the work yourself, save yourself from future headaches and pay for the permits yourself.


Appliances can be a significant expense if you’re constructing an accessory dwelling unit. They aren’t much of an issue if you just want a guest quarter.

No garage conversion project is exactly the same. However, one thing rings true for most projects, converting a detached garage into an apartment generally costs more than transforming an attached garage into a similar space.

Plumbing and Sewage

In the case of your garage-to-guesthouse conversion for your nephew, you’ll save a lot of money by just constructing a bedroom and study for the space. You’ll incur additional plumbing costs if you decide on an apartment that includes a bathroom, kitchen, or washing machine.

It’s obviously easier and cheaper to add plumbing features to an attached garage apartment than to install the same features within a detached garage space. For attached garage spaces, you’ll likely need far less help from a plumber to set up the kitchen and bathroom plumbing connections.

In detached garage spaces, plumbers must run plumbing lines that extend to the new apartment. Getting water to the space and installing plumbing lines below frost level for proper drainage are activities that can add significant costs to your garage conversion project.

Setting up plumbing and sewage for your new space becomes a more complex issue when you have a private septic system. Your home’s septic system was initially sized for your home. Local building codes may deem your existing septic tank capacity as inadequate if you want to add additional bedrooms, bathrooms, and or kitchens.

Your new garage apartment may require upgrading your septic tank capacity from 750 gallons to 12o0 gallons or larger. Your builder can help you to determine if your new apartment will require a septic tank upgrade following local building codes.

Larger septic tank being installed.

Sometimes a larger septic tank is required by building code to accommodate an accessory apartment.

Choosing a Contractor to Convert a Garage Into an Apartment

A single or two-car garage apartment conversion can add significant value to your property over time. No investment beats a garage conversion for those who want to earn rental income. A garage already has a foundation, walls, roof, and wiring in most cases. Many homeowners break even on their investment after five years of steady rental occupancy.

If you don’t hire the right building contractor, your return on investment can be drastically reduced. Locate a contracting company with a proven track record of success with your type of project. When you believe that you’ve found the right company, ask for referrals and check reviews. The construction industry can be intimidating to navigate. A building company that has great-looking marketing can abandon your project for weeks at a time due to labor shortages. Pick a building company that has a dedicated team of tradespeople at its disposal.

Summing it up

In this modern age of Airbnb and remote work environments, people are trying to get more out of their living spaces. A  garage apartment conversion is an excellent investment.  You’ll need an experienced builder who can manage your project well, from acquiring appropriate permits to installing the final fixtures.

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