Talk to a realtor in your area who can give you hard numbers. However, I would have to say that the project is only worth doing if you are able to incorporate that half bath into a master suite and add a shower or tub/shower. Depending on what type of footings were dug for the garage, your project may require demolition of the garage and new footings dug before you can use the space for living quarters.

If the realtor gives you an idea of the numbers on this as far as any gain in value to the home, you will then need to contact your local permits office and find out what type of permits and inspections you will need to go through to do this. Do not even think of doing it without, as it creates a big nightmare for you to have unpermitted work at any eventual sale time. Plus, lots of neighbors just live to turn you in to the codes people.

Then your third stop is a structural engineer to be able to assess the scope of construction needed for the project. As previously mentioned, the foundation will need assessing, as will the existing walls and roofing structure's ability to be insulated to current code without affecting the required head height. It could be a really simple project, or it might not be.

After you have gathered all of the above information, then it's time to develop a written scope of the project with all of the specs for the products that you want to use and the structural requirements of the engineer. Then you use that document to seek bids from contractors so that everyone is bidding on the same project with the same products. For a mid range master, expect costs to come in somewhere between 120-140K if you have to rebuild from the foundation up. If your foundation and existing walls will work, then you can probably shave off one half to one third of that amount. If you DIY everything, then maybe one half to one third off again. So, between 30K and 140K depending on what the reports say and how handy you are.

Wow--thanks for taking the time to write such a detailed response, Live Wire. I guess I could have saved you the trouble by saying in the first place that the entire house (including the garages) is built on a slab. The garages were actually built with the house, as opposed to being tacked on later. The ceiling is plenty high. If it was a major, major expensive project, we wouldn't even be considering it--that's for sure. We only want to do it if it will add more value to the house than it costs to do it.

Thanks again for your input.

You are confusing slab with footing. They are not the same.

The slab would need to have had an integral footing poured at the same time that it was constructed---a monolithic pour. The footing has to reach below frost level and be in contact with firm undisturbed soil. Most garages would only have footings on the perimeter walls, not at the opening, as that isn't weight bearing. A footing would need to be dug at minimum at the garage opening side. Plus, if the rules for footings have changed since the home was built to include seismic or high wind requirements, you would be required to meet those as well, which might be more expensive to retrofit than demolishing and building new if you are paying for labor on the job. Your local codes office will have the answers for you on this.

There is NO renovation that will assess as adding more value to the home than what it costs to do, unless you value your labor at nothing and DIY everything. That's too much HGTV talking there. All renovations are expenses and only to be done as an expense/gain calculation involving the greater utility or hobby activity that you gain from doing it, not any financial gain. If the primary goal is to "make" money on a renovation, then stop right there because that won't happen. If your goal is to make the house more livable for yourself while you inhabit it, and this project will do that for you, then it's possibly worthwhile to do, and you might not lose any money if you hold on to the home for an extended time period.

I'm sure there is a reason why... but assuming you have an attached garage, you're not messing with the roofline/second floor, so the loads of the building are staying the same, why do you need to do an additional pour for the front wall, its not supporting anything different?

I'd assume there is a header there that is transfering loads to either side of the door opening, I'd leave that in place, frame in windows around it.

now if you have the rest of the house on crawl space or basement and want to raise the floor, you'll have additonal load on the outside wall. depending on what you're footings are you may have to do some foundation work.

forgetting cost and all that stuff, where is this garage in relation to the rest of the house? is your bedroom going to be just a door in the living room or off the ktchen?

I've seen plenty of retrofits where they finish a garage or do some add on for a bedroom and it puts it in a really awkward spot, whch doesn't really work well, and will hurt resale value

chrisk327 is right, the loads remain the same. Most contractors would have poured footers( monolithic pour) around the entire perimeter but if not the headers transfer the weight to the footers. All you do is fill in under the headers.
I have done many garage conversions and your biggest issue for resale is that you have good traffic flow and that it is a sensible floor plan; in other words, does the bedroom have some privacy and is it close to a bath or Do you have to go through a labyrinth to get to the bath.
Build for a buyer not for yourself.

It's only worth doing if you can avoid this look.

Yes, the floor plan has to work.

Additionally.....

Years ago, my DH did a DIY conversion of the garage to a bedroom. The exterior of that wall was the nailed-shut garage door for many years. So the above look was avoided. It looked like a garage. (A large window was placed on the wall not facing the drive way.)

Fast forward several years, we took out the old garage door, resided that wall, took out the old drive way, graded the driveway and landscaped that space to work with the remainder of the yard. I would say that we spent WAY more on the exterior to fit the old garage into the rest of the house to avoid the "bad remodel look" than on the bedroom conversion.

The answer really depends on your local housing market. If the housing price would minimally detract from the incomplete exterior work, than I would leave the house like the above poster has shown. (These are starter homes and my guess is that if the selling price is right, the house will sell as is.) When there are glaring problems like above, then you DO have to deduct the 'unattractiveness' cost from your selling price! What that amount is hard to know for a given house...

If you are in a neighborhood where having an unattractive house would make it nearly impossible to sell the house, then you have to do the exterior conversion; that can get expensive.

Our house is NOT a starter home and we HAD to do the exterior work if we are to have a chance of selling eventually. I felt that we did not have the choice of doing it 'cheaply' as the pictures are shown. (Imagine paying someone to have the driveway taken out!)

Good luck...