Project Backyard Shop: Wiring and Interior

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Story and Photos by Tom Suddard

We wanted a haven for building cool cars, and we were willing to work for it. After planning, paying for and assembling a 24×30-foot garage in our backyard, our freshly painted new building was still far from a functional shop. It needed electricity, insulation, drywall and air conditioning. (Hey, it’s Florida, and we don’t like dripping sweat on our paint.) We grabbed our safety glasses and headed to the backyard to finish the job.

I'm So Wired

We wanted a fairly robust electrical system in our new garage, so we ordered a 100-amp breaker panel on Amazon. How’d we decide on 100 amps? We added up the amperage of every appliance we could picture using at once–air conditioning, compressor, a few lights, a welder–and opted for just a little more capacity than that total. We also asked a few friends for their recommendations. Why reinvent the wheel when the data is already out there?

Installing the panel only took a few screws and a quick read-through of the code requirements to make sure its placement was kosher. Then it was time for the hard part: powering the panel.

There are two ways to do this: Have your electric company run a new power line and meter to your garage, or install a new breaker in your house’s electrical panel and then bury a big wire between the two buildings. We chose to feed the garage from our house, as the previous owner had installed an oversized electrical panel that left plenty of capacity for a 100-amp garage circuit.

The first step of connecting our garage to our house: yard work. We needed a trench nearly 2 feet deep to house our giant wire and hopefully protect it from post-hole diggers and meteor strikes. We rented a trencher from Home Depot for about $80, and after a few hours of pure hell we managed to carve a path through our root-filled yard.

We buried two conduit runs in the trench, one for power and another for an ethernet cable. On top of it, about 6 inches below the grass, we also buried some caution tape. Why the tape? Hopefully to prevent a future owner (or us) from accidentally digging into the cable.

Our panel was now installed. Our conduit run was now buried. Time to get wired. We first ordered the correct spools of cable online, saving a few hundred dollars over the local options.

Then we phoned a friend. Our neighbor Phil is a master electrician, and he was willing to help us in hopes of lowering the chances of a massive electrical fire burning down the whole neighborhood.

So, how do you drag nearly 100 feet of giant, heavy cable through a pipe? Easy: Tie a string to a plastic bag and then suck the bag through the conduit with a vacuum. We then tied our bundle of four wires (hot, hot, neutral and ground) to the string. Finally, we pulled the string-and our bundle of wires–from our house to our garage. Success! After a few minutes of Phil touching hot terminals just to show us how well his insulated shoes worked, our house’s panel was officially feeding our garage.

The Walls Are Electric


Our garage’s new panel had power, but those 100 amps were useless without circuits–the wires coming from each breaker to feed lights, outlets, compressors and everything else in the garage.

We hate popping breakers in the middle of a project, so we decided to use 12-gauge wire and 20-amp breakers for every 120-volt circuit. Is that overkill? Probably. Most people never need more than one or two 20-amp circuits, but we grew up in an underwired shop that blew 15-amp breakers every time we used a vacuum or a chop saw. We weren’t about to revisit those demons, so we overdid things this time.

Before we started installing those circuits, though, we made a wiring plan. No, not a diagram, just a plan. By mapping out roughly where each outlet would go–and which circuit it would be on–we could make our already oversized electrical system feel even bigger without any extra expense.

For example, we decided to outfit our welding zone with one 240-volt outlet and two 120-volt outlets. Putting each 120-volt outlet on a different 20-amp circuit meant we could run 40 amps of 120-volt equipment in that area. This would keep that angle grinder/shop vacuum pairing from popping a breaker. We also opted to put our lights on separate circuits so a blown breaker wouldn’t leave us in the dark.

With our plan sketched out, we bought a box full of boxes and outlets, a few hundred feet of Romex wire, and a pair of specialty wire strippers. Then we spent a few days crawling over every inch of the building, hammering down boxes, stapling wires and connecting outlets.

Don’t forget the ground fault circuit interruptors. Code requires that every outlet have GFCI protection, but that just means the first outlet in each circuit needs to be a fancy GFCI unit.

After running all of our wiring, we stepped back and photographed every wall, making sure to capture each circuit. This is a cheap, easy way to create a wiring diagram.


In addition to power for lights and tools, our shop needed enough electricity for air conditioning–a necessity down here in Florida. Our neighbor Phil showed us how to turn this daunting process into a relatively easy DIY project.

Condition Me


Next on the list: cutting a giant hole in the side of our new building. Adding air conditioning is cheap and easy if you don’t have any drywall to deal with, so we picked up a scratch-and-dent window unit on Amazon that’s also rated for through-the-wall use.

With $400 and some scrap four-by-sixes, we had a climate-controlled garage. The unit even has a heater, though we doubt we’ll need it much during Florida’s mild winters.

Insulating Feeling

Lights. Outlets. Insulation!

Now, we know what you’re thinking: “You’re going to waste time and a few hundred bucks insulating your garage?”


Why? There are plenty of benefits, but let’s start with the obvious: Insulation keeps the inside of the building a more comfortable temperature, whether it’s hot or cold outside. It also makes the a/c more efficient, which allowed us to save a few hundred dollars by going with a smaller window unit.

Next benefit: noise control. Insulation limits what your neighbors can hear. Instead of wondering if you’re building and test-launching a homebuilt spacecraft, they’ll get to enjoy the birds.

And finally, think of the cars! Insulating cuts down on temperature changes, which means it cuts down on condensation, too. As lovers of ’80s Japanese sheetmetal, we believe less condensation is always a positive thing.

Pro tip: Check Craigslist for insulation. We saved a few hundred bucks by buying someone else’s leftover building materials.

Drying Out

It was time to close the walls, and we faced a decision: What size drywall should we buy? Sheets come in a few standard sizes, with 4×8 feet being the most common.

However, that size would require 1¼ sheets per wall in our garage, with a butt joint between each-in other words, a lot of extra time and drywall mud. Instead we went hunting for 4×10-foot sheets, which would stretch all the way from floor to ceiling.

We did end up having to drive to a Home Depot nearly an hour away to get the taller size. (We grabbed more than 2000 pounds of drywall on that trip.) Still, our math says that we spared ourselves about 15 hours of labor (and quite a few unsightly seams). We also saved a few bucks, as the 4×10 sheets were less expensive per square foot than the 4×8s.

We picked up a few drywall tools, too, like a three-in-one gadget that lifts the panels off the floor. The most helpful tool, though, was one we rented: a pro-quality drywall lift that cost us about $30 for the day. Instead of lifting and positioning each sheet by hand–not easy unless you’re 8 feet tall and built like the Hulk–we simply raised them with the crank of a handle. Then we screwed each sheet in place.

After about a week of evenings hanging drywall, we were ready to tape and mud. “That’s too much finish work for a garage!” the naysayers will cry. “Screw some plywood on the walls and call it a day.”

Fair enough, but we have a few good reasons to choose drywall. First, cost: Yes, installing drywall requires more labor, but the actual boards cost less per sheet than plywood. Drywall is also far easier to work with, as you can cut it by hand with a sharp knife.

Second: appearance. Hey, we can have some vanity, right? Plus, this shop will be used to photograph magazine articles, and we wouldn’t want our readers gawking at our rough, ugly walls.

Finally: safety. Drywall is actually a fairly good fire protectant since it’s basically made out of rock. Each wall covering has its pros and cons, but we decided that drywall fit our needs best.


It added a lot of work to the project, but installing insulation and drywall made the shop more comfortable and presentable. The rented drywall lift was money well spent, too.

Smooth Things Over

Time for the worst step. We needed to cover every drywall seam with tape and mud, let it dry, and then sand it smooth.

Is this job hard? No. But just like automotive bodywork, it takes a careful hand and expertise to do well. We didn’t do a great job, but over the course of a week or so we managed to get an acceptable finish. We also got pretty dusty–don’t forget your respirators for this step.


After hanging the drywall, we had to tape, mud and then sand the seams. It's a lot of work. Trust us.

Cover It Up

A lot of factors go into picking an interior paint color–how it reflects light, its ability to hide flaws and, yes, its aesthetics. Most people paint their garages white, and that’s a great idea: White bounces and diffuses the light, yielding a bright workspace. But it wouldn’t work for us: White walls show dirt and dust like crazy, and they make proper photo exposure difficult to achieve.

We decided to take a different approach. Light gray walls should cut down on overexposed backgrounds without introducing anything distracting, we figured.

How do we make up for the lost light? Easy: more light. We scored a dozen 8-foot fluorescent light fixtures for free from a friend’s warehouse that had just been converted to LEDs. We plan to hang them all. Yes, that’s overkill, but for garage photography it’s hard to have too much light.

We chose a satin finish for those walls, too; flat paint is harder to clean, but anything glossier is tough to photograph. So, how do you get gray satin paint? Sure, you could go to your favorite paint supplier and have it mixed, but that’s no fun at $37 per gallon. No, we took a different approach, rounding up 4 gallons from the mis-tinted paint rack at $9 each. After some time with the mixer and the drywall bucket, we got a slightly greenish gray. Total cost: 75 percent less than we would have paid otherwise.

We painted the ceiling white and then slapped the gray paint on the walls. Finally, we were feeling like our garage was almost finished.

We still had to paint the floor, though. Concrete needs protection to be durable, and we wanted a coating that would lighten up our dark floor, repel our abuse, and keep our concrete from literally turning to dust.

Back to the mis-tint rack! We scored 5 gallons of concrete stain and sealer for $40. The color wouldn’t have been our first choice–we’re not sure if Lowe’s was aiming for red or brown, or if they were actually trying to make pink garage floor coating–but the $100 discount looked beautiful in our eyes. We’re officially calling our garage’s color palate Zombie Video Game Hospital.

Once the coating was dry, we painted some one-by-fours the same color as our walls and nailed them down as baseboards and trim. A few outlet covers later, and our garage was move-in ready. We’ll cover that process–as well as our overhead lighting installation, our lift, our compressor and more–in future issues.


We're on the homestretch: Time to paint the walls, seal the concrete, caulk the gaps and install some baseboards.






Now it's really looking like a shop. Next installment, we'll discuss tools and equipment.


We built and finished our garage to code, but before you copy ours step by step, research your own building codes and stick to them. Every municipality is different, and what’s fine in our town may not be okay in yours.

Also, note that we didn’t tell you what size wire we ran through the backyard trench. That was intentional. If you’re going to take on this project, you need to do the math yourself, as there isn’t a one-size-fits-all answer. We found tons of free calculators and tables online that make properly sizing things quick and easy.


Master Garage Builders:
garage kit
(352) 369-3033

garage flooring
(866) 748-7940

Thanks, Everyone

Now that our building is complete, it’s time for some proper thank-yous. Without the friends and family listed here, we would have never finished. We especially need to thank our dad. He went above and beyond a father’s normal doghouse-building, lightbulb-changing duty, and instead helped us construct an entire building from start to finish. Thanks, Dad; we can’t wait to help you build your next garage.

Chris Tropea
Derek Bennett
Doug Buchanan

Kevin Rajkumar
Lise Forte
Nicole Tropea

Pat Tropea
Phil Lawing
Sam Votaw

Shane Samuels
Steve Eckerich
Tim Suddard

Read the Whole Backyard Shop Series:

Project Backyard Shop: Planning the Building

Project Backyard Shop: Building The Building

Project Backyard Shop: Wiring and Interior (This Article)

Project Backyard Shop: Moving In and Organizing

Project Backyard Shop: Solving Our Storage Problem

Project Backyard Shop: Walls of Specialized Storage

Project Backyard Shop: Installing a Lift

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Jerry From LA
Jerry From LA SuperDork
8/16/18 5:50 p.m.

A ceiling fan might help that AC.  I have garage envy.

CrustyRedXpress New Reader
8/16/18 8:23 p.m.

In reply to Jerry From LA :

Depends on ceiling height-I removed mine because it got in the way of raised hoods or cars on lifts. It wouldn't surprise me if they decided to insulate the ceiling with blow-in after a few years. 

Easy to nitpick-I'm really just as jealous as you!

Tom Suddard
Tom Suddard Digital Experience Director
8/16/18 8:34 p.m.

I actually insulated the ceiling right after finishing the garage. Now, even on a 90-degrees day, it’s cool and comfortable inside. 

Robbie PowerDork
8/17/18 8:32 a.m.

My garage is fully insulated too - 2x6 walls and 2x6 ceiling (the ceiling is pitched so there is no real attic).

I've only had it less than a year, but so far without any HVAC its been mostly comfortable inside. I have a really high ceiling, so maybe after I get my lift done a big ceiling fan would be a good idea!

maschinenbau Dork
8/17/18 8:48 a.m.

For only 100 amp from main house panel to the sub panel, you can direct-bury some mobile home feeder cable. It comes with 3x 2ga (2 hot 1 neutral) and a 4ga ground, is cheap, and available at most big-box stores. You have to dig 2 feet down, but don't have to worry about conduit which is nice for very long runs. I also put some direct-bury ethernet cable in the same trench, but you need separate transitions for service and ethernet into the wall. And it was totally to code, at least where I live. The caution tape is definitely a must-have. 

singleslammer PowerDork
8/17/18 9:00 a.m.

In reply to Robbie :

You also don't live in Florida.

Tom Suddard
Tom Suddard Digital Experience Director
8/17/18 9:01 a.m.

In reply to maschinenbau :

I looked into it, but it didn’t meet code where I live, and was only rated for 85 amps due to the length of my run. 

singleslammer PowerDork
8/17/18 9:01 a.m.

Tom, do you have a expenses list somewhere? I am potentially in the market for a shop in the next few years and have been trying to get a handle on what I should expect to pay. 

Tom Suddard
Tom Suddard Digital Experience Director
8/17/18 9:04 a.m.
singleslammer said:

Tom, do you have a expenses list somewhere? I am potentially in the market for a shop in the next few years and have been trying to get a handle on what I should expect to pay. 

I don’t have a full list, but do know that the entire project cost me about $35k start to finish, which includes everything from site work to some of the bigger-ticket tools, A/C, etc. 

Where I live, that’s a bargain: I was getting quotes of $50k before any insulation, finishing, etc. 

Robbie PowerDork
8/17/18 9:46 a.m.
Tom Suddard said:
singleslammer said:

Tom, do you have a expenses list somewhere? I am potentially in the market for a shop in the next few years and have been trying to get a handle on what I should expect to pay. 

I don’t have a full list, but do know that the entire project cost me about $35k start to finish, which includes everything from site work to some of the bigger-ticket tools, A/C, etc. 

Where I live, that’s a bargain: I was getting quotes of $50k before any insulation, finishing, etc. 

I think that's a bargain regardless. Mine is 840 sqft and 9-13 ft ceilings. Concrete (including the local village required 42 inch deep fully formed concrete footings under the 36 inch foundation walls), 2x6 construction, 100 amp service with 3 220 circuits including a 50 amp one, fully finished with drywall, insulation, paint, vinyl siding, asphalt shingles, etc. All I did was sign checks, but it was more like 50k.

Robbie PowerDork
8/17/18 9:46 a.m.
singleslammer said:

In reply to Robbie :

You also don't live in Florida.

True, but I haven't been too cold yet either.

Robbie PowerDork
8/17/18 9:50 a.m.
singleslammer said:

Tom, do you have a expenses list somewhere? I am potentially in the market for a shop in the next few years and have been trying to get a handle on what I should expect to pay. 

I'd be happy to go through my experience with you. I think you could do WAY better than me both on building materials and on the type of structure. If you don't have the ridiculous concrete foundation requirements and if you can consider a metal building you could do really well.

At least that is what my rural Illinois friends tell me.

maschinenbau Dork
8/17/18 10:26 a.m.

In reply to Tom Suddard :

Due to my run, I breakered at 90 amps in the house and it's been more than enough. Including 2 pottery kilns and an air conditioner. 

Randy_Forbes New Reader
8/23/18 9:46 a.m.

Good job Tom!  I know you're already enjoying the fruits of your labor.  Lets get some more of those how to articles out there, we're hungry for your projects!

I like doing things myself as much as the next guy, but other factors can influence your decision (like time, distance, AGE__I'm probably 3X your age, lol).  So for my latest garage, built separately, but in conjunction with building a house nearer the west coast of Florida, I used the same builder.

The detached garage is built of the same materials (typical of Florida, block walls and trusses) and the finished appearance same as the house.  Talk with a builder, but when mine offered to do the entire shell, with finished/painted interior ceiling and walls, with minimal lighting package at "cost plus ten percent (+10%) I was all in!  For a 30 x 35 x 12.5 shop, they only charged me $42k.  Granted, I still had to add a/c__Florida, YOU know__plus circuits for welders, compressor and service outlets, so my total cost goes a bit higher than yours.  Point is, I don't think it was any less cost effective, as it allowed me to "hit the ground running" as soon as we arrived (from Ohio, >1100 miles away).  I also wanted to get all "my stuff" out of the three (3) pod-like 8x8x16 containers** as soon as possible, saving some rent money there.  Besides, I don't have near the number of friends willing to help as you did!

An "apartment unit" HVAC

Your Bud' in the act of reloading the red car (conveniently blocking the fact that there's no rear wheels...)!


** Getting back to those "pod-like" containers: I shopped around, like all good car enthusiasts do (why waste good money when it could be put to better use buying car parts or tools?) and found that the moving company Mayflower has a subsidiary pod business.  Not only were the Mayflower containers considerably less money to rent, ship and store, than the Name-Brand "Pods", there was No Weight Limit!  That latter feature is a Big Deal when most of your stuff is made of steel (and have lathes, mills, welders, hydraulic stuff, etc., etc.) and also a Full Library of hardbound books and magazines__including some going back as far as a little known publication out of Florida called Auto-X.  Just passing along the pod-savings as a PSA; car guys helping car guys.

Jerry From LA
Jerry From LA SuperDork
8/24/18 4:30 p.m.

Hey Tom,

it looks to me like you went for individual GFIs on outlets.  Why did you decide on individual GFIs instead of one or two big GFIs in the breaker box?

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