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How to build a garage from the ground up

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Need some workshop space, a fortress of solitude, or a place to house your beer fridge? A new spacious garage is the answer, and this is the Instructable to make it possible. As a new homeowner and avid DIY type guy, I was up against a big challenge when tackling a brand new construction of this magnitude. Let my mistakes and sage advice steer you clear of pitfalls and heartbreak. Read on for a step by step guide to building a new garage.

The general process can be summarized as consisting of the following steps.

1. Understand your local rules and make a plan
2. Get the appropriate permits
3. Get quotes and contracts from any subcontractors
4. Order materials (don't forget beer)
5. Begin construction. Getting periodic inspections as required.
6. Get more materials
7. Continue construction
8. Curse your incompetence
9. Get more materials
10. Repeat steps 7-9 ad nauseam

DISCLAIMER: While this Instructable details my experiences building a garage, your mileage may vary. Use your brain, at your own risk.
 
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Step 1: I love it when a plan comes together!

The key component of Colonel John "Hannibal" Smith's favorite saying, "I love it when a plan comes together!" is the plan. Take that to heart and you will spare yourself a lot of trouble when building a garage. You will need to plan the layout of the new garage within your lot, plan the size, shape, and look of your garage, plan the materials needed, plan the subcontractors, plan the permits and inspections, plan the zero-cost (beer compensated) workers, plan the timetables, plan the weather... well you get the picture. If planning is not your cup of tea, then maybe you should just write a check for ~$25k to get it done by a crew of folks who will do a fine job without you learning a damn thing.

So step 1 is simply this: do the legwork and get a plan together. Easier said than done.

Key areas to consider:
1. How big do you want the garage to be?
2. How big can the garage be (city ordinances!?!)?
3. Where and how many doors and windows?
4. What type of roof?
5. What parts are you going to subcontract?

The plan will depend on the rules in your local municipality. Since I undertook this project under the rules of a major metropolis, my example will be on the more restrictive end of the spectrum. If you live in the sticks, then you can probably build as big and awesome a garage as you like. Not me. :( So from this point forward I will be presenting the garage-building process from the point of view of a homeowner in the city of Minneapolis, which should transfer in large part to any city in the US of A.

The first thing to do is visit your city's website to learn about the permit and building plan process as well as any special restrictions in your area. Click here to go to the Minneapolis permit page.

Take the time to talk with your neighbors as well to give them a heads up on your plans for dominating the landscape with your new garage. If they don't like it then at least they can get used to the idea while you get underway. If you live in a neighborhood controlled by a homeowners association, you may need to talk to them as well. They really know how to put the ass in association. In general, as long as you do not require a "variance" or exception from city rules on such things as garage height, placement, and so forth you can build regardless of objections from neighbors.

In Minneapolis, we have alleys behind the houses in a lot of neighborhoods and very deep narrow building lots. As a result I didn't have room to expand the existing attached one-car garage. So I decided on building a detached two-car off of the alley in the backyard. The key municipal codes of interest were the required distances that must be maintained between the new structure and the property lines, adjacent structures, the alley right of way, and other urban features. Click here to read the relavant document (PDF).

You will want to draw up a sketch of your lot and your neighbors' lots so that you can get an idea of how things will fit in your yard in relation to the lot lines and other buildings. Get out a tape measure and a friend and take a walk around the yard to get accurate dimensions for the sketch. You also need to locate the metal stakes that mark the corners of your lot. These are often buried a few inches underground and are set 1 foot in from the actual lines. If you can't find the markers on your lot corners, walk around and find your neighbor's. It is permissible to use theirs as a reference point if you know your lot dimensions. I located my neighbor's corner marker two doors down which was very lucky. If you can't find these markers, you will have to commission an official survey ($$$) to locate them in order to draw up the site plan sketch. This sketch is required by the city in securing a permit, you will need to show this sketch and get the plan approved before a building permit will be issued. See my sketches below. The city of Minneapolis requires a top view building site plan with relevant dimensions as well as a series of detail and elevation drawings of the building itself. As you can tell the level of artistry involved does not need to be high.

When making the drawings, be sure to use the wonderous series of tubes we call the Internets to check the city webpage for property line and lot size information as well as using your favorite satellite imagery site to get info on the placement of buildings in your immediate vicinity . While a 3D model is not required by the city, I found Google's SketchUp to be a useful tool for visualizing how the garage was going to look in relation to the rest of the house, trees, neighbors, etc. Download it here. A sample shot of my model is below.

Once you have a set of drawings to your liking you can take some time and head down to the Minnesota Development Review offices at 250 S. 4th St., Room 300, Minneapolis MN. As a first-timer this can be intimidating, but even though this bureaucratic organ qualifies as part of "The Machine" the people there are there to help you out. If you read and understand the rules, bring in a good site plan and drawings, they will happily inform you of any problems, give you time to correct them, and then take your money with a smile. For reference, our 440 square foot detached garage cost $300 for a building permit. I also had to lop off 2 feet of the width since the city of Minneapolis allows a maximum of 676 square feet of accessory building. My existing 1-car attached counted towards that total, a fact I had overlooked. On your way out of the review office, be sure to get a parking token. With the new permit in hand, I was ready to begin purchasing materials, locating subcontractors, and other details.

In summary:

1. Communication with the building permit office and your neighbors is helpful and important.

2. Take the time to know the city rules.

3. Take measurements of your lot and draw up your site plan on your computer. Experiments here are easier than moving foundations later.

4. Get your plan approved by the city and get your permit.
polarbytes110 months ago
I want to build a 24x24 garage but do it in two steps. Is it safe to use a 12 foot 2x4 wall with the ridge pole on top of that and install the rafters to just one half. I plan to build a second 12x24 section next summer. My concern is whether the roof will be strong enough with just one half built. I was planning on a 6-12 pitch. My roof framework is 2x6 roof joists on 24" centers and the walls are 2x4 on 12" centers.
That was very informative and I liked your humor throughout. I have framed a couple small additions to my cabin in the past, using a framing book for guidance. I feel very comfortable building a garage myself now. My only change to your instructions, will be to use PBR, rather then Miller lite. Thanks for your great instructions.
graphixv1 year ago
Just wondering if you had checked into metal roofing (like I've seen installed on primitive cabins). It seems like it would go on a lot faster, but perhaps I'm wrong.
danzo3211 year ago
Does rebar just lie there on the gravel or is it elevated to be surrounded by concrete? If lifted, what with? Does rebar have to be tied?
Hi
The rebar must be elevated enough so the gravel that is contained in the wet concrete will fit under it. The minimum is 1" and the maximum, for a 4" thick concrete, should be 1-1/2". If you've got old concrete blocks, you can break them and use the pieces as supports, but make sure you tie the rebar to these or they'll fall off while pouring concrete! Other items would be used bricks, pieces of concrete. NO organic materials that will decompose should be used! If you want to spend some $ and do it nicely, go to a contractors supply house and ask for 'rebar chairs'. These come individually and in 5' strips, which can be cut to short pieces.

Yes, the rebar needs to be tied together. This helps to keep it in place while you're pouring the wet concrete, and it does give strength.
The rebar must also overlap where it is tied/spliced together. The rule for how much overlap is: 18 x Diameter (in inches). So if you're using 1/2" diameter rebar, 18 x 1/2" = 9 inch overlap. If using #6 bar (rebar is named in 1/8", so #6 = 6/8" or 3/4" diameter) the required minimum overlap is 18 x .75, or 12" overlap.
Building your own garage is tough. As soon as we got do the garage doors part of it I just let the pros come install it. garage doors
jmengel (author)  swinterscott1 year ago
Any home improvement store should carry or be able to order all the materials discussed. Shingles are typically special order, outside of a very limited selection of style and color. The key limitation to my instructions is the lack of discussion of flashing since my garage did not require any. Roof penetrations or intersecting faces are where roofing gets more difficult as you need to ensure water-tightness. Be sure you understand how to flash and waterproof all areas where there are vents, pipes, skylights, joins, etc before you begin.
graydog1112 years ago
I have a 50' x 50' steel building divided 2/3 is a shop with a concrete floor, 1/3 is storage room with dirt floor. It was built before I bought the property. I would like to suggest three things :........... (1). Put your big air compressor as far as possible from work area to lessen noise when compressor is on ...................... (2). Make shop floor 2 inches or so higher than driveway so water will not come into shop. We had a deluge of rain and water came in......................................... (3). If shop is a distance from house, consider installing security alarm system with loud siren on building and hard wired small siren inside house. You will not hear alarm on building if it sounds at 3:00am, but you will hear small alarm inside house. I bought a HoneyWell with 6 zones on eBay for about $150.  It adds a lot of peace-of-mind. 
jmaloney22 years ago
I actually paid a guy $500 to shingle my garage when I got to this point. The roof had an 8/12 pitch and it was worth the money to have it done in 5 hrs vs 3 days
wakojako3 years ago
very good.
did you use sketchup BTW?
PS like the a-team reference!
jmengel (author)  wakojako3 years ago
Sketch-up yes.
thanks for the reply
rhombus003 years ago
I have a 24' x 24' garage. The walls studs are 16" on center, but the ceiling joists (2 x 6) only run along every 3rd stud (48" on center). I would really like insulate and drywall the ceiling and use the new "attic space" for some light storage. I was thinking that doubling the number of joists would give me 24" on center. My questions are:
1. Would that be enough to support some light weight storage?
2. The rafters sit right over top of the studs, so my existing joists are ~2 inches off to the side. The new joists would rest in middle between studs. Would that be putting too much load in a bad place?
jmengel (author)  rhombus003 years ago
The joists as described are not up for bearing weight. Not sure of the code requirements in your area but it sounds as if you have a hand framed as opposed to trussed roof. Even so, it sounds as if the 48" on center joists are not to modern code. Is there a central beam that the joists tie into? I would guess there must be since we're talking only 2x6es.

1. If there is a central beam so that the joists only span 12 feet, then getting 2x6 on 24" centers would support storage in my opinion, but your local inspector may be of a different mind. 24 feet is a long span for a 2x6, so without a central beam I would be hesitant to put much weight up there. I don't have my span table on me but that would be a good place to start for maximum span as a function of spacing and lumber.

2. The new joists in the middle between studs should not be a problem if you have a double top plate which is one of the main reasons a double top plate is required, if not it should still be OK for storage. Again your local inspector would be the end authority. You could put joists on 16" centers over each stud to be safe. This would only be 6 extra joists, so not much money. Tougher to get big stuff into the "attic" though.

Good luck.
Thanks for the reply.

There is no central beam. They were able to span the 24' distance by using two 2x6. They are each about 13' long and are fastened together with several screws at the overlap. They are then fastened to a vertical 2x4 running from peak of the roof. Kind of scary, huh?

I don't know much about framing, but it doesn't sound like the joists should be able to support anything on their own; all the support would come from the 2x4 tied into the roof.

I'm going to have a framer come by and check it out for me. Hopefully, I can get away with replacing the existing stuff with 2x10 on 16" centers.
jmengel (author)  rhombus003 years ago
The roof doesn't sound up to code, at least here in MN with our snow load. But with the 2x4 tie in to the roof the 2x6s are probably surprisingly strong. The key will be the strength of the attachment between the 2x4 and the overlapped 2x6s and the 2x4 and the roof up top. A simple overlap with nails or screws is not ideal as the load is carried in shear on the fasteners and the wood they are piercing. There are specific hangers and "mending plates" designed for this, which you can see in commercially made trusses. None of which use overlapping with screws/nails.

Replacing the 2x6s with 2x10s without increasing the bending strength would be a waste of money. If you can get 2x10s long enough (and can fit them in the building!!) to go the full span from wall to wall, and tie them into the roof with a vertical 2x4 using a suitable hanger then you should be in good shape. If you can't get full span lumber, then I would just fill in between the existing 2x6s and 2x4s with duplicates to make them 16" on center and call it good. Use hangers or mending plates if possible. Throw some plywood up there to bridge the joists and you'd have some light storage. I wouldn't walk up there though.

Good luck
Yeah, I was surprised when I tested the strength of the existing joists. They used some kind of plywood as mending plates to join the vertical 2x4 to the 2x6 joists.

In any case, I ended up going to Home Depot and speaking with someone at their Pro Desk. He thought I would need a center beam and referred me to their LVL manufacturer. After I spoke with them and provided the dimensions and the live/dead load and they recommended four 1 3/4" X 16" LVLs.

I just have to figure out how to tie it into the walls. I plan on running it under the existing joists, but I will have to cut into my top plate so the top of the LVL will be on the same level as the bottom of the joists.

Thanks for your help.
jmengel (author)  rhombus003 years ago
One more thing to clarify, the 48" on center joists as they are function only to keep the A-frame side walls from spreading under the roof load. The "king" post 2x4 would nominally transfer some of the vertical roof load to the spanning joists but with a screwed overlap is probably only supporting the 2x6s with the roof and any storage load you put up there. Six of one, a half dozen of the other I guess. And regarding mending plates, they are also called structural truss plates.
bit_bucket3 years ago
Your a great help but I need to self install a 4 way switch for a man cave (3 switches one light) any help?
jmengel (author)  bit_bucket3 years ago
Google.
tnnv3 years ago
When setting the walls on the concrete slab (with anchors all in place, etc) does the framed out wall set even with the edge of concrete or overhang slightly, say 1/2 inch? Reason I ask is the company that is building my trusses asked and I had assumed they would be flush/even with my concrete edge. Is one way better than the other or what is the preferred method?
jmengel (author)  tnnv3 years ago
I really don't know if there is a reason for one approach over another. I had a course of block around the perimeter on my garage and I set the sill plate (bottom treated 2x4) back from the edge of the block by 1/2" so that the sheathing was flush with the outer edge of the block and concrete. Your mileage may vary.
rzook3 years ago
what software are you using for your cad drawings? is it free?
jmengel (author)  rzook3 years ago
As discussed in Step 1: http://sketchup.google.com/
zra3 years ago
Thanks for taking the time to put this together, what did you use as a moisture barrier? Did you insulate the walls?

Thanks
jmengel (author)  zra3 years ago
I did not use a house wrap moisture barrier.  I did insulate the walls with a craft faced fiberglass and sheathed the interior walls with 1/2" plywood.  I'm not sure the insulation does much since there is no ceiling and the roof is uninsulated, but the plywood was a great idea since it allows me to screw in mounts, cabinets and other gear just about anywhere and it has allowed me to unscrew the plywood panels at will to make changes to the electrical systems as needed.  This came in handy a few weeks ago when I had to run wiring for a photovoltaic system that I installed on the garage roof.

Maybe I should write that process up...
zra jmengel3 years ago
Thanks so much for the quick response.

Yes I'd like to see any additional work you've done.

I'm planning the same sort of garage thing, but I want to insulate the roof and walls. We get no ice here in So Cal, but it gets roasting hot in the summer. I have been told to make sure to use a moisture barrier and weep screens at the bottom of the walls to avoid mold problems.

On another note, was there a reason you chose this type of roof construction over what is called Type 5 which has a central beam and provides more open rafter space?

I'm in the research phase, I'm right on the fence between trying to build one myself and just buying a Tuff-Shed brand garage as I don't have a bunch of framing experience.

Thanks again
jmengel (author)  zra3 years ago
Well the solar install is mainly a RTFM on the panel, inverter, and racking.  Along with a sprinkling of local electrical code errata, so I haven't spent any time writing it up.  I'll tell you though that having the panels on the south facing roof do keep the garage cooler.  Basically functional shade.

Using the moisture wrap and screens are a good idea, I just didn't feel it was needed on our install.  Time will tell, and at least I know where to find the builder for rework.

I chose this type of roof construction because of low cost, ease of build and permit approval.  Getting a plan approved and passing inspection is easy with pre-fabbed trusses but takes a lot more work on a hand built roof as you describe.  I just didn't have the confidence in getting a ridge beam hoisted 20+ feet in the air.  Those LVL beams are heavy as heck, and getting them in position at the peak would require a crane that I did not have or desire to rent.  An attic with more storage room is possible with that type of roof, but I am able to store a fair amount of stuff in the trusswork so I can't complain.  The main reason I would go that route would be to allow an insulated ceiling in the main garage room, and a separate attic with access hatch/ladder.  That would allow the garage to be cooler in summer and warmer in winter.  However, the attic would be hot as all hell and limit what you could store up there.

Framing is pretty easy if you can measure and mark wood, make consistent square cuts to length within 1/8" of desired, have access to a pneumatic framing nailer, and if you have fairly straight lumber.  Sizing and design of the door and window openings and headers can be an area where experience is helpful.  That said, building it yourself is more fun than a Tuff-Shed any day, at least once you are finished.
zra jmengel3 years ago
I'd like to do it myself, after reading all of this I'm considering very seriously. The project is about as complicated as yours except for demo of the existing structure. I have an existing garage that is the New Orleans of garages, it's 8" below grade on all sides when it rains hard I get 2" of standing water inside and after 60 years some of the sill plates are rotten and the stucco is peeling off. I'd need to knock the whole thing down, though I could probably salvage a lot of the lumber, pour more slab on top of the existing slab to raise it up with rebar to hold it in place and then build a new one on 1' stem walls. This would also give me a chance to make the garage 10' longer. I'm thinking of a Hybrid approach, a contractor to prep and pout the slab and stem walls and maybe a roofer to do the shingling and perhaps a pro for stucco. I read through your piece again, some details that seem to be missing are the actual building of the trusses and the block stem wall.
brichins4 years ago
Stacking your trusses that way makes it much harder to roll them into place. Also, the way you show it here, your last 3-4 trusses will be impossible to roll upright, since the placed trusses would be in the way.

It's easier to lay them flat, with the peak (tip) laying on the cross wall (over your garage door in this case). After the first truss, spread the others out a little, like a spread deck of cards, to distribute the weight. Keep the bottom chord of each truss on your top plate.

If you do this right, you can just stand each truss and wiggle it over into place, rather than flipping each one completely over. Safer and easier.
jmengel (author)  brichins4 years ago
Good tip.  We had to bring one end of the truss down into the garage below the wall to get clearance to rotate.
Bet that was fun! :)

Forgot to mention, for the last few trusses you have to move them up against the completed trusses and work from the other end. Be sure to follow your layout (you DID mark a layout, right?) or measure off the places trusses so your sheeting lines up with your trusses.
brichins4 years ago
Exactly right :) Putting the strips on in this pattern drives any water towards the outside instead of to the wall.

Great instructable, by the way. Looks like SketchUp for the visuals?
jmengel (author)  brichins4 years ago
Yep. SketchUp is great for this.  Once you have the model you can generate as many views as you want.  Thanks for reading and commenting.
brichins4 years ago
Starting on one end actually makes this a little easier. By cutting a few shingles in half and using them to start/finish a row, you will have less waste.

You'll also save time by doing 3-4 rows at a time and working all the way across, so you don't have to move around as much walking back and forth cutting and filling the ends.
jmengel (author)  brichins4 years ago
The last pic shows this approach, I found that the ease/speed of each depends on how many people you have on the roof.  With more than 2 on each face, starting in the middle is faster, otherwise at one end.
jpb2804 years ago
Hello jmengel!  GREAT write up.  Love the sarcasm and jokes throughout.  As everyone else who is reading this, I too am in the planning stages of building a garage.  How big is your garage door?  Is that a 2 car or 1?  TIA!
jmengel (author)  jpb2804 years ago
The garage door is a standard 16 feet wide door, a two car.  This winter was the first time we had two cars in it, and even with all the tools and other stuff it worked fine.  If we had SUV's I would say an 18 foot door or larger would be really nice to have.  So take that into account. 
fcruise4 years ago

Great site!!!   My roof will be 7/12 pitch.  I've seen others nail down 2x2's or other size strips on the roof to use as footholds while on steeper inclines.  Seems to me this would damage the felt---- or would you start at the top and work down in this case, removing the strips as you go?  I'm in the southeast so I don't have to worry about ice barriers (thank goodness)...

I'll have the same issue with shingles....

jmengel (author)  fcruise4 years ago
Any holes you put in the felt should be covered by the shingles.  The ice barrier is a membrane that seals around nail holes so water backing up under the shingles will not get through.  If you don't have ice concerns then holes in the felt due to nailing foot strips will not impact the waterproofness of your roof if you overlap and nail your shingles properly.  With no nails showing, the shingles will keep the water from the holes in the felt.  The felt is more of a vapor barrier and last line of defense than an integral component of the waterproofness of the roof.  Good luck.
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