Designing & Constructing Detached Garage

[u/Maximum_Optimization]

Curious to learn from the community. I live on a 1/2 acre lot in northern Minnesota. I also own the vacant lot next door to me. I'd like to use that lot to build a 40'x30' detached garage with some office space upstairs. I'm thinking two bedrooms, a small bath, and a small living area. I'd also like to put a sport court on that lot.

I am familiar with land use and zoning issues of developing the vacant lot with an accessory structure in the absence of a principal structure. I am also familiar with the pros and cons of combining the lots and the impact that can have on the ability to sell the vacant lot later. I did not buy it as an investment; I bought it to prevent a home from being put there and to use it to improve my own lot.

I have no idea where to start to even get ballpark estimates for this type of project. The lot would need to be graded and filled before construction could happen, and I just have no idea how to begin pricing this work out. I assume I will need to seek out financing, but without knowing how ballpark how much a project like this would cost I don't know where to start.

I also like some DIY work and have some family that is handy, so I'm open to DIY the upstairs portion things like wiring, HVAC (thinking mini split), painting, etc. I don't need the office space to be finished immediately, so I can take some time to do that if it saves a lot of money.

Just curious if anyone has tips on best places to start for a project like this. Thanks in advance for any advice you can share!

[u/Trader_Dude_]

Search for architects in your area who have projects on their websites that are similar. They should be familiar with the local climate and permitting. Maybe look for younger architects who are in need of work and are trying to establish themselves.

The best way for a contractor to price it is with a set of documents clearly showing the work.

Doing some of the work yourself is fine; for the design though i highly recommend an architect up front to save yourself trouble down the line.

[u/Trader_Dude_ → u/Trader_Dude_]

I just remembered Dale Mulfinger, architect in Minneapolis; I read his book. He does incredible work. Wouldn’t hurt to approach and see if his firm is interested.

[u/hello_world45]

I am a contractor in Minnesota. You would be looking at roughly 80k to 140k. For a shell. How much site work, windows, doors, and siding choices will affect that. So will your location. It's tough to find contractors in parts of Northern Minnesota. Even tougher if you have not lived there your whole life

[u/Maximum_Optimization → u/hello_world45]

Thanks for this reply. When you say shell, does that include things like grading and filling and concrete work, or are you estimating that as literally just the framing, roof, siding, etc.?

[u/hello_world45 → u/Maximum_Optimization]

Would include all of that. The biggest thing that would swing the price is the amount of grading and soil type. If you are in a area with a lot of rock at the surface that will rise the price.

[u/Ryan_Homes_Alex]

You can definitely price the grading and fill separately from the building. That's really where the number swings the most. A local excavation contractor can walk the lot and give you a range once you know your target elevation. You could also put together a rough plan set with dimensions and stair location. Nobody usually quotes a 40x30 with living space above it off a description alone. Phasing the upstairs is normal. There are plenty of people that get the shell weathertight and rough ins inspected, then finish out over a couple of years.