Building a Garage Addition on to Your Home

Reasons Why you should Build a Garage Addition

By Mark J. Donovan




Hands down one of the best decisions I ever made in terms of a home construction project was to build a garage addition onto the side of my home. For over a decade I lived in my house before I finally made that decision. In that time I finished the upstairs of my home and built a family room addition. However, I could never seem to justify building a garage addition. It wasn’t until after a miserable New Hampshire window that I finally said enough is enough. I had finally had my fill of scraping ice off my car windows and brushing the snow off the car just about every other morning that miserable winter.

After I finally made the initial decision to build my garage addition I then spent a couple of weeks sketching it out and designing it.

One of the toughest issues I had early on with my plans was figuring out the appropriate size for my garage addition. Fortunately I chose to go big. Well, at least moderately big. The dimensions of my garage addition were 26 feet by 24 feet. This size garage has enabled me to easily park two cars in it, as well as a workbench, lawnmowers and snow blowers, and a whole host of other items.

When figuring out the appropriate garage addition size I also took into consideration the size of my home and how the garage addition would look relative to it. My home is of a colonial design, and as I mentioned earlier, has a family room addition attached on the opposite side and back of the house. The main house is 36 feet wide.

The side bump-out for the family room addition adds an additional 5 feet. By electing to build a 26 foot wide garage it only represented about 20% of the front façade of the house. As a general rule of thumb, a side home addition should represent no more than 33% of the entire width of the house. Any larger and the home addition begins to look out of proportion to the main front façade of the home.

Garage Addition Bid Sheet

Roof lines and the elevation of the garage floor were other major concerns when I was designing my garage addition. I had to work out a roof pitch that was the same as the main home and to set the garage addition at an elevation such that the garage addition did not intersect any of the upper windows on the main side body of the house.

Once I had resolved in my mind these three key issues, garage size, roof lines and elevation, I then began to sketch up detailed drawings of my garage addition. Included in the drawings were dimensions and precise locations for the two garage doors, windows, and two standard maintenance doors. Moreover I had to carefully consider how to position the short staircase in the garage to enter into the main home. In addition, since my garage addition was to include a finished space above it, I had to consider the floor plan of that upper level.

After I completed my garage addition plans I contacted a few home remodeling contractors and had each one come out to my home to review the plans and take a look at my proposed building area.

 Garage Addition Ideas

Once I had settled on which contractor I was going to hire I fleshed out my garage addition plans a bit more. I included detailed framing information and desired building materials such as specifically what type of garage doors I was looking for. I also added more specific details for the bonus room above the garage, details such as the location of knee walls, a closet and a full dormer. I then presented my final plans to my contractor and he gave me his final bid, along with a contract for me to sign.

A couple of weeks later we broke ground on the project. The excavator dug out the foundation hole, and the foundation contractor poured concrete footings, walls and eventually the slab floor.

After the concrete foundation walls and slab had cured for about a week, the framing crew showed up on the jobsite. Within just a couple of days the garage addition began to take real shape. Three weeks after the framers showed up on the jobsite my garage addition was completely closed in. The framing and exterior sheathing were complete and the door and windows were installed. In addition, the roof had been shingled and the exterior walls sheathed. They had also tied the addition into the existing home and re-sided the main home where the garage addition connected into it.

Once the garage addition was buttoned up tight, I parted ways with my contractor as planned and I took over getting the rest of the project completed.


Fortunately I had an uncle who was an electrician and did all the rough electrical work for me. I did all of the insulation and then called in drywall contractors to hang the drywall and tape and mud it. They do such a good and fast job that I felt it was well worth paying a bit more to have them do this dirty, yet artistic work. I also paid to have them prime and paint the walls.

Once the drywall installation was complete I took over and did all of the interior trim installation and finished electric. After I had finished the electric I had my uncle come over and check my work before calling in the building inspector.

The finished trim work was fairly extensive. Besides door and window trim, along with baseboard trim, I had to install railings. Suffice it to say I was busy every night after work and on the weekends for about a month doing the finish work. Fortunately I had a good miter saw and had some previous experience doing finished carpentry work.

After the finished trim work was done I then called in the carpet installers and installed carpet in the garage addition’s bonus room. In addition, I then installed garage door openers on each garage door.

Lastly, I called in the building inspector for the final inspection. I had previously called him in several times earlier in the project to check the framing, rough electric, and insulation tasks.

The total garage addition costs came in around $30K, thanks to my willingness to put in some serious sweat equity. If I had let a general contractor do the entire project turn key, it would have cost me $50K, at least that’s what the initial quotes were coming in at. Admittedly, those figures were from the early 2000 time frame. Today, to have a garage addition built of the same size, again which included a bonus room above it, would cost around $75K +/- 20% depending upon where you lived.

Again, even after all these years, I still remind myself how lucky I am to have the garage addition, when driving to work and passing by people sweeping the fresh winter snowfall off their cars in the cold frigid mornings.

For more information on building a garage addition see the Garage Addition Bid Sheet from HomeAdditionPlus.com. The Garage Addition Bid Sheet includes an extensive questionnaire (Request for Quote) that a homeowner can provide to prospective general contractors and subcontractors for bidding the garage addition. In addition, the Garage Addition Bid Sheet also includes estimated costs and time intervals for constructing a garage addition as well as a list of key home material manufacturers. Finally, the Garage Addition Bid sheet includes an extensive set of helpful tips and advice on making sure the garage addition is built properly and on time and budget.

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