I'm planning to act as GC on my future build also. I performed some preliminary research which indicated that fairly simple garage will cost $35-$45 per square foot--if you employ a GC. Most resources indicate that you can save 15% to 35% by acting as GC yourself.

However, this is for garage space, not apt space. The apt can vary tremendously depending on what goes in there. Presumably, you'll put kitchen and bathroom there. Those are costliest part of home, so $/sf will be significant for that small area containing kitchen and bath.

There are builders among the GW posters. I'm sure they can give better info.

Thanks you for your info. Those are similar to the numbers we had heard. The apartment portion may be more like $50sf? If I keep pinching the pennies. I have to keep in mind, the more I save on the garage, the more I'll have to spend on the main home ;)

Thanks again.

Per square foot pricing is only a rough guide.

Garages do not normally include kitchens and bathrooms, two of the most expensive areas in any house.

Check with local zoning also.
Garage apartments are not allowed in some places, especially in addition to a house.

In Ohio, the median construction cost for a house (using GC) is about $90/sf. However, kitchens and baths are expensive. They're cost centers. If you build a house w/ four bedrooms, a bonus room, a living room, etc., then the cost/sf goes down as the high kitchen and bath costs are "diluted" by the cheaper square feet. In a 900 sf apt w/ a kitchen and bath, the cost/sf will be much more than the typical cost/sf for an entire house.

Annie --

My own Ann and I will be doing almost the exact same thing, and it's the accommodation of various teenage children (are yours younger?) that has me most worried. Yikes! It's the most scary part of the whole idea. I cannot figure out how to easily give each person his or her own space to which they might retreat. Not upstairs in the apartment space, anyway. I'm seriously considering putting a couple of temporary bedrooms downstairs in the garage itself, but just don't know.

The zoning rules in my township do not allow me to construct TWO livable homes on the same property, so the garage must eventually be "attached" to the house. I have enough space on the land, re. setbacks, so am now planning to build the garage/apt "over there," proceed with footings & basement excavation "over here," build the house above that basement, and connect the house and garage with an enclosed single story "thing". If this thing were open, a covered, perhaps screened area and not conditioned space, I guess it would be called a breezeway. But we do plan to enclose it and will make this the mudroom and laundry.

Maybe. At least that's the plan right now.

The garage/apt will match the eventual house in style and quality. The apt will be "decommissioned" when we receive C of O for the real house (for tax reasons), but the infrastructure will be good, solid stuff in case we ever need the apt back (aging in-laws, wayward children, etc). The furnace, water heater, plus kitchen cabinets, stove, etc. will be CraigsListSpecials, the bathroom perhaps a bit better since it will remain in place. (Those kitchen cabinets will later be moved downstairs into the garage's shop area when we move into the house.)

Now to your actual question: I'm coming up with $55k to $75k estimates for construction of the 30x36 garage with apt above. This assumes 42 inch deep poured footings, poured frost walls, slab garage floor over two inches of foam, six inch EPS SIP walls, SIP roof, truss joists for garage ceiling / apt floor, fiber cement board & batten siding, decent windows. The building is only a story and a half, not two full stories, so the second floor apt is up in the eaves, as it were. With a 12/12 pitch roof, the 30x36 garage below only allows a 20x36 apt above with 5 foot knee walls.

Another key assumption for keeping the cost down --> I not only act as GC, but we do a vast majority of the work ourselves.

Two caveats: My two big cost unknowns are siding and roofing. Re. the roof: we want standing seam metal on the final completed house. I don't know exactly how much this will cost, but know it's either more, or a lot more, than even very good 3-tab shingles. Re. the siding: I have absolutely no clue how much to use for the HardiePlank cement board estimate. I would love to have someone here say something like, "The material-only cost for middle of the road, good quality board & batten cement siding is about $10 per square foot," or whatever the number is. That would be so very helpful.

To increase our (temporary) apartment living space/area, I am exploring other options.

I already mentioned putting a bedroom or two downstairs in the garage. This is tricky, since the bathroom is upstairs, and the actual stairs may be outside (what a pain that would be!). There is also the question of potential code violations (not in my plans) and what hoops I might have to jump through to make everything legal.

I am not particularly wild about the look of a long shed dormer on the garage roof, but may have to go that route for a bit more floor space. the increase would be perhaps 75 sq ft.

I am also considering raising the eave walls a foot (space above the garage doors to the actual eaves), which will allow the knee walls in the apt to move out a foot in each direction, again adding a bit more floor space. I wish I had a good piece of software to render some 3-D drawings, just to get an idea. Macv likes google sketchup, but I have not spent enough time with it to be considered even cumbersome, much less effective.

I am also considering a longer garage, say 30x40 instead of 30x36. But I really don't want a massive garage structure next to what I hope to be a relatively modest home. Again, I need to learn google's sketchup.

Wow. This turned into a long answer. Hope some of this jabbering helps.

~Allen

Annie and Allen: It seems like it would be easier to rent a place during the home construction. Why have you decided to go this route?

I've heard of people using trailers for that purpose as well. If you used a trailer you wouldn't have to compromise the design of your home by separating the garage from the main house, or by building a garage apartment that you wouldn't otherwise build.

I'm not sure how rapidly trailers depreciate, but if you buy a used one I'd be surprised if you couldn't recoup most of the cost by selling 4-5 years later. You could probably obtain a good deal now because the market is depressed.

You're undoubtedly correct about accomplishing more if you live on site, but be sure you know what you're getting into. If you think 4-5 years is enough, it may turn into 8-10. That is how most big projects seem to go.

Funny. And not. Funny because you caught me. Not because you're right.

My rule of thumb for years has been to take whatever my most reasonable estimated project time/duration is, and multiply by 2.5. Unforeseen hiccups mixed with the 80/20 rule. Argh.

My BIL got around the two houses on the same lot rule by connecting the second house to the first with a deck.

The county looked at it a little strange, but agreed it met the letter of the law.

I am giggling because of Allen's "jabbering". Sounds like our projects are similar.

Our children are small. 9,7,4. Thankfully, we are building on 5 acres just up the hill from the grandparents' house. So, we will have plenty of help and privacy as needed.

There don't seem to be any hang ups with building 2 dwellings on the property as long as it is deemed a Mother-in-law apt. I also love how you say, "maybe, at least that is the plan right now." It has been my motto for months.

Your plan sounds similar to our layout, but we plan on doing traditional stick 2x6 framing, Poplar B&B siding and 5V metal roofing. We are in the South so we won't need to have footers as deep as yours. We did just receive a quote on the footers and slab. It is $8500.

Darryl, my husband, will be doing all of the work himself except the slab and electrical. We have a local lumber supplier giving us a great deal on poplar board and batten siding and the Amish community near us will supply the metal roofing.

Re: Hardie B&B siding. We just renovated our 135 year old Farmhouse and we put Hardie B&B as the siding. We purchased the 4x10 Hardie Sheets and spaced 1x2 cedar battens every 1 ft. We can't remember the price per Hardie sheet off hand. I love the look of it. It was very simple to install. The main reason we are choosing to do Poplar this time around is because we have a small budget of $200K so that we can stay close to being mortgage free. WooHoo! And the Lumber supplier is only charging us $1ft.

I am also concerned with having a garage/workshop that is bigger than the main structure. We both work from home. He is a Realtor/ Woodworker and I am a seamstress. So we need the work spaces. Oh, so much to think about.

I have not heard of Google Sketchup. I will check it out.

Thank you for your jabbering. It has been very helpful.

@ mdfacc We have chosen the garage apt route because we have to have the garage/workshop anyways. Why not add the apt while we are at it. Long term plan is to rent it out or have available for my mom.

I would not mind one bit living in a camper for a year. Then, we would have it to travel around in too ; )

If budget becomes the issue Plan the garage apartment in a way that the garage apartment is one of the final bedrooms in the home and is attached. You may need to have crawlspace next to the garage if planning a basement in final home to separate the two but it would make a great guest suite, MIL suite, Nanny suite kids play room or even a rental room / apartment since it will have the ammenities. I know its not everyones answer but hey it then pays for itself. for a few years if you want. ?

Where are you going to live while you build the apt. you're going to live in while you build your home? You had better build a place to live first before you start the garage/apt.
You are caught in a cycle of diminishing returns. Just put in a doublewide mobile home for temporary quarters and when construction is complete, you sell the thing. Is a large garage/apt. on the wish list for the house even if you didn't need temporary housing? In the answer is no, then it's an unnecessary expense that takes resources away from the project.
It's a potential distraction and a project-within--a-project that contains its own set of pitfalls, while pushing the actual project further into the future. I think what you want is to get into your actual home sooner rather than later, and the apt.project becomes a delaying factor. You could lose an entire building season. Is that acceptable?
Travel trailer, motor home or doublewide would be my choice, as they will be up & running in days rather than months, and you will not lose the season.
Casey

@Casey I really like your suggestion.

Yes, we do need the large garage and workshop. My husband plans to build the actual home and needs the storage for the tools and such. He is a woodworker who builds furniture and random jobs. Also, I am a seamstress who works from home and my 4 industrial sewing machines will occupy a portion of the garage as well.

I do see your point and feel the same way about not taking resources away from the final home project. I am all for building a garage without the added expense of a 900sf apartment. Now, if I can just get my husband on board...

I think I'll start looking for a camper ; )

This is my plan too. I had originally planned on a detached garage with loft space above (and a bath), as a sort of guest suite. Now I'm thinking I'd do better to build it first and live in it as I build the big house. It is part of the original plan.

It will definitely NOT be 900 sq ft. And it will be just me - not a whole family - so I can get away with a small studio.

I have no interest in a trailer or something similar. The little town I am building in would not be too pleased (though I don't think they can stop me), and my insurance would be completely different. Also, why spend money on an extraneous structure (wheels or no)? I want the garage anyway - might as well build and live in it first.

The other part of my situation is that I can't rent. Renting seems like throwing money away, but even if I wanted to, I can't. I have two Great Danes - who would rent to me? They need their own space and their fenced in yard. If I go ahead and build on my own property and put up my own fence, the dogs are not a problem. Renting with them... is impossible, at least where I live.

Also, I am in SE TN, and costs are much lower here that almost anywhere else in the country. While it may cost $X anywhere above the Mason-Dixon Line or west of the Mississippi, here in the South, most construction related expenses cost less.

I say if you want the garage anyway, then it sounds like a great plan to me! If you really DON'T want the garage, well, maybe not.

I agree if you need the garage and the garage apartment, it sounds like a good idea . . . but if you don't need an apartment big enough for a family of 5 in your forever after home, I would check into the mobile home idea. If you buy it used and sell it used, you may come out fine in the financial aspects of it.

I think you can probably rent them also?

Remember when Gov. Huckabee lived in a triple wide behind the Governor's mansion while it was being renovated . . . if it was good enough for the governor :)

I did not know that about good ol' Huck ; )

The decision is in the end yours.
Here are the problems I find with garage apts
bonus rooms.
Keep in mind that my pov is energy efficiency and
better building practices....
Full depth of insulation between garage and living space.
If the insulation is not in contact with both the garage and living space the temp difference will cause condensation to form. Floors are cold, rot, mold grows,

The living area is surrounded by ambient and sometimes
attic space. The walls should be treated as exterior walls,
as temps are more extreme. Not only insulating the wals
but installing and sealing foam sheating boards to the exterior of these walls. This foam needs to extend between joists/trusses to the garage ceiling. This will stop air infiltration and the insulation will perform as spec'd.

Lots of people seem to think that insulation stops air
movement..which foam insulation does..but conventional
insulation filters the air.

These type of living spaces are hard to heat and cool due to all the air movement and heat/cold transfer, Calls from homeowners and hvac companies with these type situations
provide a good portion of my income.
Good for me...but if in the planning stage these sealing
methods would have been incorperaterd..it would have been
a better deal for the homeowner.
In the long run if the apt/living space wassealed..
the cost of living in these areas would have been
minimal. When it is completed...it is costly to retrofit.

I'd prolly look at a mobile home, the shop/storage area
wouldn't be in use all the time as it would be with a
family living in it for a year..(or longer)

Best of luck!

Hi all, Just wanted to chime in on this thread. I am starting my 3rd self-built home project. (Yes, I need to have my head examined) I run a remodeling company so it's not completely insane.

Previous comments about kitchens and baths being core expenses are right on the money--- so to speak. They are expensive. Building one in an apartment and then a new one in your finished house is really shooting yourself in the foot.

Try this instead. Build with the foot print of a 3 car garage, say 38 x 25, but only utilize the space a two car garage would generally take up as garage space--- 25x25. Use the 25x10 part to put your permanent stair, a foyer and your permanent kitchen in. Now you can think of the space over the garage as a second story of your finished home. You can get 2-3 bed rooms and a bonus out of the space with a hall bath.

Unless you really need an apartment this approach can save a bunch of cash.

Someone was asking about standing seam metal roofing. If you use the commercial folks you see on TV expect to be asked to pay $65 a square foot. I had one come out and give me a quote just to check it out. It was a real manipulative "hard sell" with all these "bonuses" and "programs" available "if you sign today." Be very careful. No matter how you slice it it's a rip.

Either HD or Lowes will special order metal roofing for you. Its's not hard to install. (Be careful, wear sneakers and don't bend down on your knees, it is really slick.) If this is your forever house, install 40 year architectural asphalt. It looks nice and will likely outlive me.

Good Luck and Be careful out there!

Bruce

We are adventureous. We lived in 794 sq. ft. apartment to build our "Dream" home ourselves. The catch; nine in our family. Very tight to say the least. It can be done. We are doing an apartment over a garage for our son who is away right now. We will have to make sure to insulate properly and I had been researching about insulated garage doors and I think thicker walls would help as well. Good Luck!!!

mdfacc, how is the home building going? I found this thread and had to join the Garden Site LOL to email you. My hubby and I are getting ready to do the apt garage to home and was curious of your next step :)

I'm planning the same idea on 20 acreas. I want to build a 3-car garage with apartment above it. I sent Building Cmsr an email asking if zoning will allow this. I also asked whether the main residence will have to be attached or can they be separate structures. nyone have any ideas? MaAssachusetts.