A garage has electric. An apartment has electric, plumbing, and HVAC. I recently had a two car garage built. I think it cost a little over 100k. That’s high because it has a tile roof, it had to be incorporated into the existing house, and I am in a high cost area. If I had built a garage with a similar size apartment above it, I would expect it to cost more than double. About ten years ago I had neighbors who built a 2.5 car garage with an apartment above in a lower cost area and it cost over 200k. A garage apartment is not just sheet rocking some extra space under the roof. It’s the difference between building what is basically an oversized garden shed with electricity and a small house.

Let me back up. I have been a general contractor for houses and a business. I understand every aspect of the construction process and have done many of the projects myself. I've decided to have someone else do the building this time since it's a new area.

I don't know where you built, janedoe2012, but those are outrageous prices. A two car garage can be built for $40-$50/sq ft. That must be some tile roof.

Where are you building a garage for $40 to $50/sf?

The roof materials alone were over $10k, the door was over $7k, cost includes new driveway. Four windows, local codes require the interior to be sheetrocked. I agree, it is an expensive garage. But I needed the materials to match the quality of the existing house. So I had to pay up. I don’t doubt a two-car garage could be built for much less, but 20 - 30k? That seems really low. I’m guessing that would be no windows, unfinished interior, very inexpensive garage door. To go from that to an apartment, you have to add stairs, plumbing, HVAC, windows, doors, flooring, insulation, trim, painting, sheetrocking, lighting, bath fixtures (and a kitchen?), etc. Either the structure is going to have to be much taller, or you are going to have a more complicated roof with dormers. A basic garage and a garage with an apartment above it are apples and oranges. An apartment isn’t an incremental expense.

Assuming you are building the garage, the only saving by adding an apartment would be the cost of the foundation and the roof - otherwise it's going to cost the same as a 600 sq/ft house.

^ I would think that you have to adjust for the area. $60/sf sounds low to me and the smaller the space you are adding on, the more per sq foot it will be due to the fixed costs not based on size. The only real way to know is to get legitimate estimates from someone that is lic and insured in your area to build and has the aptitude, and the time to take on this small job.

Sophie Wheeler, I'm a woman who has contracted out several builds for personal residences and one commercial business for myself. You don't need to be licensed to contract out work done by others - that's what the term general contractor means. I do carry liability insurance during the build process; but thank you for your concern.

I've decided to GC this one out too since I can't really swallow the profit margin the builder requires. But yes, the cost of a garage can be done $40-50 sq ft (maybe closer to $50) if it's not attached to house. I'll let everyone know what it ends up costing.

Our two car garage, connected to the house, with two bedrooms, a good size bathroom above, Anderson windows and its own heating/cooling system, cost $265,000.00 complete.

JudyG Designs: If a homeowner doesn't pull a permit - for work which her town requires a permit (I am 100% SURE that adding living space above a garage requires a permit in every town of the U.S.) - then the homeowners' insurance will refuse coverage. Could be catastrophic financially (personal injury or death if there's a fire, for example). (Obviously read your own insurance policy, but I'd be surprised if that isn't universal.)

Sophie's and janedoe2012's cost ballparks are accurate for my area too (HCOL). A basic 2 car garage - detached from the main house - with only electric (no living space or heat or foundation) - would be minimum $60k where I am, but probably more. I'm only referring to construction costs through licensed GCs who pull permits.

JudyG, which state are you from? CA? $265,000.00 ( 2 attached garage with 2 bedrooms 1 bath addition ) sounds very high for here by the Great Lakes in NY. You could buy a whole house ( 2500 sq ft) with 4-5 bedrooms, 2-3 baths plus 2-3 car garage. Houses here are much cheaper than CA though.

Lisa, please let us know the cost of your carriage house. Which state are you from?

JudyG, yes, a homeowner is technically responsible since he/she pulled the permit -- mind you it's only the building permit as the electrician, HVAC, and plumber each pull his/her own permit -- but the homeowner has the almighty leverage called the 'checkbook'. It's easy to put in a contract that all work must meet building code. Obviously contractor doesn't get paid if something fails an inspection. Honestly that hasn't been an issue for me as contractors have been competent and experienced.

Summersrhythm, I will be building in central Florida. I'm currently in Ann Arbor where I built a nearly 'passive house' - very well insulated, tight, triple glazed windows, passive solar, concrete floors in basement and first floor. High SHGC on southern windows. Upper windows are clerestory for the rooms on north side of house.

I have no idea of the cost between Mich. and Fla but I can’t imagine a huge cost difference between building a 600 sq ft house and a 600 sq ft apartment over a garage.Since you still need all the interior work , electrical, plumbing , HVAC that you need in a house with no basement like a garage.I actually find it odd you are asking if you have been building in this area.

Here is the cost for building a garage in 2017 (you can input your zip code for the avg cost in your area):

https://www.homeadvisor.com/cost/garages/build-a-garage/

Even in Central Florida (I'm in S Florida - PBC) you can't get a 600 sf garage, withOUT the in-law apartment, built for $25,728 and the largest size of said garage was 24 ft x 24 ft and the smallest size is 12 ft by 24 ft. That average is for the entire US which completely dilutes the information. In order to use an average, you would need to provide specs and use an average local to the area. Averages fall apart when applied to large diverse areas. You can see that the range is $6k to $56k which tells you that the "average cost" in that garage is an unreliable number. Get your specs together and have local bids.

I can tell you that if you are from out of the area, you will pay more. What I mean by that is out of state buyers will be charged a higher price IME. This is especially true in Central and North Florida.

Hi Lisa, any update on the price?

I decided to contract out the house build myself (again). I'm new to area but I'm finding that once you find a couple contractors, you will find others and people will recommend others.

Totally jumping on this late, but Lisa, any update on the price? I'm looking at doing the same in a few years, but I'd like to start budgeting now. Thanks!

I don’t know where Sophie’s comments that I bookmarked on this thread went, but they were more than relevant. And still ARE relevant.

“If you think a garage can be built for $40 a square, you’re either building virtually substandard crapola, or you’re not a real licensed and insured GC. I’d put money on the latter since you had to post a question on Houzz that no Pro ever would.

A garage apartment is just a small house. It has all of the expensive parts and very little of the inexpensive ones. Not to mention the problem of running plumbing g pipes through the garage in unconditioned space. It will be more expensive per square foot than a house. Much more. If you think you are being charged too much, then go right ahead and build one of your 40K specials and see how far that actually gets you.”

“You do not hold a GC license with the state, correct? Liability insurance does not cover illegal contracting. And you can only contract for a personal residence that you own under limited circumstances. Karma will out.”

”Stop claiming to be a GC illegally contracting for a commercial building. Do you carry liability and workman’s comp as is required for new construction?

”I have been a general contractor for houses and a business. I understand every aspect of the construction process.” Not.”

Jennifer Tobias Durandard, it's too hard to tease apart the cost of just the garage alone because everything was bid together with construction, electrical, and plumbing. So I can't be of more help, sorry.

GreenDesigns seems to have misunderstood a few things. My $40-$50 per square foot price regarding a garage was a simple, regular garage. It would not be a garage with an apt above it which is essentially a little house. Sorry he/she misunderstood and flew off the handle. Sophie Wheeler's comments seem to have gone away but these comments fill that void with their rudeness.

Lord have mercy, grow up people.

Lord have mercy on you - this post is over 2 years old. Get a life.