If you are struggling to find enough space in your garage, you may be considering a DIY project to enlarge it. Extending your garage is often a viable solution when you don’t have enough room.
But, before you get in over your head, make sure you have a good understanding of the scope of your project and all that it will entail.
While almost anything is possible with a bit of know-how and determination, extending a garage’s structure is a serious undertaking that requires a careful approach.
Can You Expand an Existing Garage?
Adding some square footage to a garage isn’t that complicated. But, the scale of the project depends on a few factors.
The most basic factor is the original garage’s design. If it is attached to your house, things get more complicated quickly. And if it integrates into your house and there are rooms of your home adjacent to it, the scale of the project will grow.
If your garage is free-standing and unattached, the undertaking is a little bit more limited. But, ask yourself, do you have a solid carpentry background? Expanding the frame of your garage is going to require measuring, cutting, and installing lots of lumber, including studs, floors, sheathing, and a roof. And that’s true regardless of the type of garage we’re discussing.
You’re also going to need to have at least a basic understanding of the permitting required to do such a project. The required permits will vary according to where you live, but modifying the height, width, electrical layout, or foundation of a garage will typically require you to first get a building permit from your town or city.
Then when the work is nearing completion, you will need the local building department to come and inspect the work and sign-off on it before you put on the final touches like drywall and paint.
3 Ways to Expand Your Garage
There are many ways to expand a garage. But let’s focus on three.
Garage Bump Outs
A bump-out extension is a cost-effective way to create a small addition to a structure. Instead of an actual expansion, a bump-out essentially adds a small mini-room to your home. Typically, a bump-out will be shorter than your existing structure and won’t span the entire width.
To build a bump-out, a background that includes basic carpentry skills will be pretty helpful. If you have made a shed, deck, or other small structure, you can probably build a bump-out.
You may end up needing an architect or an engineer to help calculate the size of your new header. Otherwise, your new construction could compromise the existing structure of your garage and even the rest of your home.
When you’re ready to move forward, you’re going to remove a portion of the interior wall of your garage to accommodate the bump-out. Keep in mind that you are limited by the size of your header. If you don’t want a support column in the middle of your bump-out, your header will need to span the entire opening.
Once you’ve exposed the inner structure of the wall’s framing, support the overhead load with temporary supports. Then, you will install king studs at each end of the bump-out to support the new header. King studs run from the floor plate to the top plate. Building codes often require them, so make sure you include them.
Once your king studs are in place, you can cut out the existing wall studs at the height of your new header. Remember, the actual dimensions of a piece of wood often do not match its nominal or labeled size. For instance, a typical 2×10 is actually 9.5 inches.
Now that the top section of the existing studs is cut out, knock those out of your way. Push your new header into place on top of the existing studs. It should fit tightly, so use shims as needed. It should also be tight against your king studs. Now, you can cut and nail in your jack studs. Jack studs, also called framing studs, will run from the floor plate to the new header, sandwiched against your king studs.
Now, you can knock out the old wall framing and remove your temporary supports. Garage walls often sit on concrete blocks. So, you will need an angle grinder or concrete saw to cut the concrete and a sledgehammer to break it up.
Finally, you can start building the platform for your new bump-out. Bolt a ledger board to the existing garage foundation, using concrete anchors to fasten it, making sure it is level and far enough below grade to accommodate a new floor.
Mark, dig, and pour footing holes for your platform. Set 4×4 posts into the footings when the concrete has hardened.
Cut the posts to the correct height using a level placed on top of a board spanning from the post to the ledger, representing the new floor. Mark and cut off the posts at the bottom of your leveling board when the level indicates you’re at a level height.
Floor joists come next. Then you can fill in your post holes the rest of the way with dirt. Lay down your subfloor and floor across the joists and nail them down one at a time.
Finally, it’s time to build your walls. It’s easiest to frame them out on the ground and then stand them in place when they’re all complete. Start with the section of the wall that spans the opening. When that’s plumbed and nailed in place, you can measure back to the existing garage wall. This technique is one way to account for any lack of plumb in the existing wall.
Add some bracing, especially at the corners, and make sure everything is plumb before you nail it in place.
Next is building the roof. If you’re matching a flat roof, that’s pretty easy to frame out. But if you want to match a pitched roof, you’re going to need to install rafters. Either way, you’ll have to remove a bit of the garage’s siding to accommodate the height of the new roof, so everything fits together nicely.
When the roof framing is complete, add your fascia and sheathing. Now you’re ready to complete the exterior of your bump-out with roofing and siding. You should do your best to make the details match your existing garage. Everything will look better if the overhangs, soffit, trim, roof, and siding all match from old to new.
Before you can really start using your new bump-out, consider adding electrical, lighting, plumbing, and insulation. Then, close in the frame with drywall. Now, tape, mud, sand, and paint for a finished look.
Building Up
Sometimes, a bump out just isn’t sufficient. If you really lack space and you want to add some value to your garage as well as square footage, you might consider adding a second level.
This is a much more involved project than a simple bump-out. So, if your eyes were watering thinking about doing some simple framing and integrating a new header, this might be out of your DIY range. You’re also going to need the foundation assessed to see if it can carry the increased load of your vertical expansion. That’s the job of a professional engineer.
The concept of adding a second level to your garage is pretty simple, and the added space over an existing garage can be a perfect storage area. Or, you might be interested in converting it into an apartment, playroom, or master bedroom suite.
Framing out a new second story isn’t really that difficult. But, designing a floor that can support the new weight without interfering with the car parking area below is a challenge.
You’ll also have to integrate this new story with the existing siding, roof, windows, and the rest of the finish items that make up your home. This can be another challenge, particularly if your home is more than a few years old. You may have difficulty finding new materials to match the old, so it may make sense to only go in this direction if you are considering redoing much of the exterior of your home at the same time.
Lengthening or Widening the Garage
A bump-out might be too small for your needs. And, adding a second story might be way too much of a project to undertake. But how can you get the additional space you need in the garage?
If you can handle doing some foundation work, extending your garage by lengthening or widening may be the goldilocks winner. Not too big and not too small.
If you lengthen your garage, you may be able to leave the door as is. You can even make it long enough to accommodate multiple vehicles. But, if you widen the garage, you’ll probably also want to enlarge the door or even add a second one. It’s up to you to think about what’s right for you.
If you have a car that you drive rarely, and you want it out of the elements, a lengthened garage might do the trick; you can just rotate vehicles closer to the door as needed. But that can be impractical if both vehicles see regular use.
But a deeper garage makes a lot of sense for an added workshop, exercise, or home office space.
Whichever direction you decide to go, you’re going to need to lay a new foundation. That will likely require some excavation, adding a further aspect to your DIY repertoire. And, it may make sense to demolish the existing wall that will be removed first to make sure everything is well-integrated.
But, once the new foundation is in place, your carpentry skills are going to be put to the test.
You’ll need to frame out the new space and completely integrate it into the existing structure of your garage. That means you’ll need a thorough understanding of construction, permits, and a sizable amount of material. Lumber, electrical, HVAC, and all of the other existing systems will need to integrate into your new space.
Final Thoughts
You can undoubtedly expand an existing garage. But, you will be limited by the size of your lot, zoning, permitting, know-how, and budget. All of that said, having the additional space you need in your garage is very useful.
If you need to get more out of your garage space, you have these three options to consider. And, if none of these work for you, you could even build a second larger garage and convert your existing garage space into living space!
When you go to expand your garage, it’s also a good idea to make sure your garage is ventilated as well as organized and properly lit.
