This Old Garage Repairing or Replacing Your Garage

By far the most common outbuilding we build is a garage. We replace a lot of garages that are falling down now because they were originally built without a foundation — just a slab on the ground.

The result is predictable. The weight of the garage walls eventually cracks the slab. The walls start to sag, then the roof. Finally, the door jams and stops working. It's at this point that we usually get a call with many variations of the same question: "How much will it cost to fix."

Unfortunately, at this point, the garage is beyond repair. There is no cure for the sags except to tear it down, repour the foundation and slab, and build a new garage.

Detached garages as large as 400 sq. ft. can lawfully be built without a full foundation in most localities. This includes a single-car garage and a small two-car garage (18' x 22').

We don't recommend it, however. Such garages do not last. Most of the garages we build have full concrete footings down to the frost line. Over this, we pour a thick 4" reinforced slab carefully sloped so that water drains quickly out of the garage. This is a garage that will last at least as long as your house. We can insulate the slab if you want to heat the garage now or later. We can build your garage using standard or post and beam framing.

If you want a storage loft, a full second floor, or a mother-in-law apartment over or beside the garage, we can do that too. Contact us for more information and a free estimate.

How Much Garage Do You Need?

While it may turn out that you actually need a heated, air-conditioned garage with extensive lighting and electrical service for all sorts of tools, including 3-phase 230v power for your industrial grade, computer-controlled, shop equipment, most people can get along with less.

How you are going to use your garage determines what features it needs. If you are just going to park your cars out of the rain and snow and store the mower and a few garden tools, the basic garage may fit your needs exactly. In fact, even a covered carport may work for you.

But, then it gets a little more complicated.

If you intend to use the garage for your primary outdoor storage, you will need to add at least 3' to the back. Some of this is for the actual storage, and some to enable you to walk around the parked cars. Bigger is better. We generally recommend five feet - two feet of storage and three feet to walk around to get to the storage.

Insulated Garages

Most existing detached garages cannot be effectively heated because they were not built to be heated — there is no insulation under the slab and no thermal break separating the slab in the heated interior from the footings exposed to the frigid exterior.

You can, of course, insulate the walls and ceiling, and this will help some. But, adding insulation to an existing non-insulated slab is virtually impossible to do cost-effectively. Insulated and non-insulated slabs are built quite differently. If you intend to heat the garage or may add heat to the garage later, an insulated slab is a must. Without floor insulation, cold simply flows in through the garage floor. So, if in doubt, insulate the slab. (For much more on insulation, see Insulating Your Old House.)


Plan on adding electricity if you want lights, outlets, or an automatic garage door opener. For detached garages, adding electricity is getting fairly costly since recent code changes mandate new safety features including a shutoff in the garage and dual masts for overhead lines - one at the house and one at the garage - or underground wiring. Neither of these options is trivial and can add substantially to the cost of a basic garage.

Our Basic Garage Package

Basic Two-Car Garage Click to view
our basic two-car garage (shown here with vinyl siding option) — truck not included, sorry.

For automated door openers, you will need at least one 15 amp. line from your house service panel to your garage. You will need a 50 amp. electrical service for heat and air-conditioning. Extensive shop tools may require 220-volt service.

Attached Garage

If you want the convenience of a garage attached to your house, the complexity grows even more.

We will need to build it just like your house with full footings. We will also need a fire door into the house and fire-rated gypsum board applied to all of the garage walls adjacent to your house. This is intended to prevent a garage fire from reaching your house long enough to give you time to get out.

Finding a good location for an attached garage is often a problem. Most older lots are not wide enough for a garage alongside the house, so we have to figure out ways to attach it to the back of the house with an orientation that permits you to drive your car into it without violating any of the myriads of zoning or building code restrictions or backing into the mailbox. Often the best solution is a semi-detached garage, that is, a detached garage connected through a breezeway.

Size is a cost factor. A two- or three-car garage costs more to build than a single-car structure. Add a loft for storage or a mother-in-law apartment above, and you can see why a basic garage costing less than $10,000 can quickly grow a price tag of more than $50,000 very quickly.

Generally, the minimum size for a one-car garage is 12 ft. wide by 22 ft. long. For two cars, the minimum is 18 ft. wide by 22 ft. long. However, these numbers are a bare minimum. Most homeowners build their garages a little wider so they can open their car doors freely, and longer so they have enough room at the back to store things. Consequently, 24 feet is the most common garage length, and 14' and 22' the most common widths for one-car and two-car garages respectively.

When it comes to garage size, the rule of thumb is this: If in doubt, build bigger. You will appreciate having extra storage space for bicycles, the lawnmower, gardening tools, and sports equipment, especially since it is difficult to predict exactly what your needs will be five or ten years from now.

If you intend to use your garage just for car parking, keep in mind that car sizes vary a lot. You could one day trade your Prius for a Humvee. If you build a space sized for your sub-compact, you may have to park the SUV at the curb. In short, don't plan just for today. You are probably going to have the same garage for many years and it needs to fit what you are likely to do in the future as well as your current needs.

Planning Your Garage

Building a garage is a major undertaking. It is an addition to your house and should be taken as seriously as any other addition. A well-designed and constructed garage can add considerable value to your property as well as useful functionality while you still own the house. A poorly designed garage can easily detract from your property, lessening rather than increasing its value.

Are Formal Plans Needed?

Building a garage is generally not something to be done without serious professional planning. You will need detailed plans for the project. Oh, we know that 50 years ago good old Uncle Gus slapped up a garage on the Ol' Home Place over a weekend without plan one, and it's still standing — more or less.

Times have changed, though. garages need building permits in most communities. This includes a site plan to ensure that the garage does not intrude into zoning setbacks and does not overbuild the lot. There are restrictions on how much of your lot you can use for buildings, and this is determined by your zoning and the size of your lot.

Good plans are necessary not only to get building code approval but also to ensure that the garage is structurally sound, contains the features you need, and is designed to complement your house. Just as important, it helps ensure that you get only the features you need and that you are not paying for facilities you will never use.

Overall Design

The overall design and every exterior feature of your garage should complement your house. It should have the same or a coordinating siding and overall appearance. The roof shingles on your garage should be the same color and material as those on your house. The shape and design of the garage roof should also mimic the style of your home. If your house is a Craftsman Bungalow, a steeply pitched roof on the garage is out of place. If it is a Tudor Revival, a steep roof is almost mandatory.

The Garage Door

The garage door will have a dramatic impact on the overall look of the garage. It typically will face the front of your property and either add or detract from your home's curb appeal. The garage door needs to suit the architectural style of your home. You will also want to pick a door that is well made for years of service, and, if you are heating your garage, one that will be energy efficient.

Windows, Skylights, and Light Tubes

Windows can be problematic in a garage. Sure, they let in natural light, which is always a good thing but they also invite burglars to take a detailed inventory before they break into your garage. If you are storing a lot of tools and other valuables in your garage, you may decide, as a security measure, not to have windows at all or to place them high on the wall so that it is not possible to peek in without a ladder.

An alternative is one or more skylights or light tubes. Installing skylights or light tubes in a new roof as it is being built is fairly trivial compared to the mess of installing them in an existing roof. In most cases, a skylight is no more expensive than a good window. And, an opening skylight adds welcome ventilation on warm days but a light tube is less expensive and even more secure than a skylight. Not even the smallest and most agile burglar can squeeze through a 10" tube.

Equipping the Interior

If the sole purpose of your garage is to park your cars, interior design is easy. But, if you expect your garage to do more, planning gets a little more involved. A good interior design dedicates different areas of the garage to different purposes. Here is a typical list of functional areas:

• Vehicle parking
• Equipment storage: lawn mower, snow blower, and garden tractor
• Workshop or bench with tool storage
• Storage for recreational items (bicycles, sports equipment, toys) and gardening tools and supplies
• Trash and recycling
• Wood storage
• Extra refrigerator and/or freezer

A good plan also anticipates future changes and sets out a process for adding features to the garage as the budget allows.


And, while we are on the subject of interior design, let's not forget the organizers. If you have ever doubted American ingenuity just Google "Garage Organizers" and stand back. There is an organizer for everything, from custom-made cabinets to wire shelving and all manner of storage in between. Here are just a few:

Rev. 08/27/18