How to Insulate And Sheath Your Garage Walls Like a Boss

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When I moved into my current home, I had nowhere to set up shop. Coming from 2-1/2 bays of a 3-1/2 car garage, I was potentially – as they say – SOL (Dung Out of Luck). Fortunately, finances came through enough to lure a contractor into constructing a 24′ x 36′ building in the new back yard. But I could only afford bare studs and rafters, leaving the interior walls and ceiling up to me to deal with as my shriveled wallet slowly re-hydrates. I saved up enough to tackle the walls and spent several weeks researching and watching videos, learning how to properly do the job. And now I’m ready to share what I’ve learned. If you don’t mind a little manual labor, crack open a box of sweat rags and roll down your sleeves. Let’s insulate and start sheathing garage walls, all without drywall!

From Studs To Studly – Insulate And Sheath Those Ugly Things

Blocked by the mess
My first lesson was derived from the wisdom of ancient philosophers: “One must be able to actually get to the walls in order to work on the walls.” – unknown smart dude

Before going any further, take the time to research your local building codes. My research and experience was focused on my specific situation, but the rules and requirements of insulation and other details vary with respect to region and jurisdiction. Especially in basements, which should not be insulated with fiberglass, due to risk of mold.

At minimum, this will give you a good jumping off point. At most, I’ll recruit you to come help do the ceiling when the time comes; you are on my short list, after all. Oh no… you’ve already started reading; there’s no backing out of it now!

Move it all yet again
I should have just paid the extra month’s warehouse rent and finished the walls before moving my stuff in.

My first mistake was not doing the walls BEFORE filling the building with crap. Unless you enjoy moving everything you own multiple times, either take care of the walls before moving everything in or be sure to leave a 4-5 foot margin in which to work. Some things are learned the hard way. Truth be known, I’ve yet to do the front wall for this very reason. I must first move an 18” depth of sheet goods and the forest of lineal stock that’s leaned against the naked studs.

Insulation – A Cozy Blanket For Your Garage or Shop

20 rolls of insulation, waiting to be installed. Let the fun begin.

Your local building codes should be considered final authority on any construction protocol. I used rolls of paper faced R-13 insulation. You’ll probably want higher rated insulation for any walls shared with climate controlled spaces, such as your house. Note that basements have different insulation requirements than above ground walls and are not covered in this discussion.

Home Depot and Owens Corning’s nifty insulation calculator is a great resource to estimate how much insulation you’ll need. I figured I needed 19 rolls, but Home Depot’s price break was at 20. Buying that extra roll saved me a lot of money.

Whether you use batts or rolls, be sure to purchase insulation in the width that matches your stud spacing (16” in my case). Don’t use loose insulation to fill a wall. It will eventually settle, leaving open air space at the top and compressed insulation at the bottom, both of which dramatically reduce efficiency. Some alternatives to fiberglass include recycled denim insulation and products like Roxul, both of which have some useful sound-dampening characteristics and environmentally friendly traits.

It’s recommended to wear long sleeves and pants when working with fiberglass insulation. Naturally, I opted for a T-shirt and shorts. Sure, I itched a tiny bit but it wasn’t the end of the world. I did my best to avoid rubbing against the fiberglass, but some fibers will end up airborne. Therefor, gloves, goggles and a dust mask are a must. Fiberglass in the sinuses and lungs can be an unpleasant and hazardous experience, to say the least.

Insulation Laceration – Cutting To Length

Cutting to length
The 2 x 4 in the foreground was used as a measuring stick. I marked it with a line that shows me where to cut.

Roll insulation is easy to cut. Measure the length and use a framing square or other straight edge to squeeze the insulation flat against a scrap piece of plywood and cut it with a razor knife. Alternatively, the oversized scissors I used worked like a champ.

Your insulation should be cut the same length as the height of the opening. You don’t want gaps or bunching at the top or bottom. I chose paper backed rolls for both price and convenience. The Kraft paper backing has a vapor barrier coating between it and the fiberglass and should be installed with the paper side facing the interior of the garage. The paper also has tabs to prevent sagging.

Insulation Manipulation – Negotiating In-wall Obstacles

Mind the wires
Walls tend to have lots of electrical wiring and other obstacles to watch out for.

It’s a well known fact that the number of obstacles in a given wall is directly proportional to the severity of your wanting to just get the job done and over with. I think it’s a law or something. There may be wiring, outlet and switch boxes, water pipes and gas lines, and you’re going to have to work around them safely while losing as little “R-value” as possible.

Tuck half behind
The insulation easily peels apart. Feed half behind and half in front of the wiring.

“R-value” is the insulation’s resistance to heat transfer. Insulation works best when it’s fluffy and fills the entire space. So, rather than crush it up against in-wall utilities, peel it apart and feed half behind and half in front (or whatever proportion matches the situation).

Insulating Around Electrical Boxes

Box cutout
The proper way to cut out for an electrical outlet or switch box.

It would be insulting to the insulation (and your wallet) to just cram it behind electrical boxes. Tempting as it may be, crushed insulation is highly inefficient. Work around such obstacles by cutting out for the box, leaving about half of the thickness to fill in behind it.

Cutout in place
The cutout tucks behind and snuggles around the box.

You’ll have to remove outlet and switch plates – and maybe a breaker box cover – in the process of this job. Use caution. Better yet, kill the main power so it doesn’t kill you.

Death's door
This is a deadly place to fool around. Be careful and tape off the opening for safety.

Be aware that flipping off the main breaker may not protect you from live bus bars in the breaker box. If you don’t know what you’re doing, consult a qualified electrician. This is no time for carelessness.

An Insulation Installation Situation – Insulating And Sheathing Garage Walls

Staple the paper tabs every 18” or so to prevent sagging.

Windows, doors and builder errors will undoubtedly create areas where you’ll need a wider or narrower strip of insulation. For wider pieces, you can cut a strip to fill the gap then use special insulation tape to join the pieces. Just make sure you have paper tabs at the studs.

For narrower strips, cut the insulation lengthwise, but leave an extra inch of width. Then peel and trim fiberglass away from the backing to create a paper tab on the cut edge.

Finally, use a staple gun to attach the paper tabs to the studs. With metal studs, spray adhesive can be used instead. The insulation will fluff up when unrolled. But, once in place, gently rub and pat the paper facing to fluff it even more.

Wall Sheathing – Insulate And Sheath Your Garage Walls

Weathered OSB
OSB is a lot more durable than you might think. These pieces have been outside – fully exposed as shown – through two Florida rainy seasons (rained on well over 100 times).

Nothing beats a wooden wall in a garage or workshop. Plywood and OSB (Oriented Strand Board) are both excellent choices, with OSB being less expensive. You can bump things into a wooden wall without fear of punching holes. And things can be hung with screws pretty much anywhere without having to locate studs (though studs are nice for heavy objects, such as cabinetry). The drawback is that the finish isn’t going to be as smooth or pretty as drywall; a minor price to pay, considering the benefits.

Particle board = junk
In contrast to the OSB above, some idiot (some other idiot, not me) threw this particle board on a street corner about two weeks ago and went from A-OK to WTF in about five rains.

I used 7/16” OSB, a wall sheathing I’ve been very happy with in the past. Some people falsely conflate OSB with particle board. But OSB is widely used to sheath roofs and to skin the exteriors of houses. It can handle a surprising amount of rain before swelling and breaking down. That said, it’s not intended to be exposed to the elements for any long period of time. My point is only that it’s a lot more durable than it looks. Particle board, on the other hand, will disintegrate and contort if you look at it funny; or feed it after midnight. Compare the two photos above.

Stud Finder – Points To Self

Standard stud spacings
Some OSB comes printed with lines showing where the studs should be. But don’t assume they match reality. Measure and verify.

Before placing each panel of sheathing, be sure to measure where the studs are. Don’t take for granted that the builder spaced them all perfectly. Odds are, they didn’t.

Plumb bob
In this split view, you can see how I hung a string from a nail above the sheathing. The bottom is weighted with a heavy nut. Now I know exactly where the center of the stud is.

To be sure you can find the center of the studs – especially if you find one that’s out of position – mark its location on the panel or hang a plumb bob so you know where to drive your nails. This is your last look inside the wall, so consider marking the center of each stud at the top and bottom of the wall that’s still visible once you have the sheathing in place.

The sheathing should be nailed at every stud. But be very careful to avoid wiring, gas lines and water pipes! In other words, know where the utilities run through the studs and avoid them like the plague. One ill-placed nail can open a huge can of worms.

Stud Gets Nailed – Recommends Eye Protection

8d ring shank nails
2-1/2”, 8d ring shank nails. Don’t use screws.

I used 2-1/2” long, 8d ring shank nails. Once they’re in they aren’t coming loose without a fight! OSB is usually used for exterior wall sheathing. In that application, it’s recommended to locate nails 6” apart around the perimeter of each sheet and 12” apart on the intermediate studs; and to leave an 1/8” expansion gap between sheets.

Given that these are interior walls, I used 12” spacing around the edges (including top and bottom) and minimal gap between sheets. To determine your “nailing schedule”, don’t listen to me: check your local building codes.

Also, it’s a good idea to wear goggles or a face shield while nailing. It’s possible for one to come flying back at you as you try to get it started, especially with OSB.

Placing And Raising The First Full Sheet

Gap to be filled later
Because of stud spacing, to fit the first full sheet, I had to leave this space at the corner.

The sides of each sheet should land in the middle of a stud. But, often times – at corners, windows and other irregularities in a wall – some studs are going to have different spacing than the standard 16” or 24”. I started at a corner and figured out where the first full sheet can be placed. I also took window placement into consideration when deciding where to start.

In general, try to place any narrower sections at the ends of a wall, rather than in the middle. But every wall is different so you’ll have to play it by ear.

Spacers underneath
Temporary spacers are set under the sheet to raise it off the floor a bit.

When sheathing garage walls – especially on a concrete floor – use a temporary spacer (such as strips of plywood) to raise them off the floor about 3/8” – 1/2” while fastening them to the wall or measuring for cutouts. This prevents any ground moisture from wicking up and creating problems. For the same reason, the 2×4’s at the bottom of the studs are also not contacting the concrete. Instead, there is a foam barrier between the two.

Between The Sheets – and Your Garage Walls

Cutting guide
Clamp a straight edge in place to make a cutting guide.

Once the first sheet is in place, work outward from there. Get the vertical edges of that first sheet as plumb as you can. If it’s crooked, the rest will follow. Narrower pieces can be cut on saw horses with a track saw or a straightedge and circular saw or jig saw.

Measuring the offset
When placing your straight edge, be sure to account for the blade offset.
Cutting with a straightedge
If you don’t have a track guided circular saw, this method will yield excellent results.

Don’t forget to measure the offset between the edge of the tool’s base plate (or “shoe”) and the inside edge of the blade, then compensate when locating your cutting guide.

Cut it Out! Cutouts For Electrical Boxes

Perfectly placed access hole
Cutting openings for electrical boxes is easy if you take your time and measure accurately.

If you’re as unfortunate as I, you may have to cut access holes in more OSB sheets than not. But it’s really not that hard to do. Some careful measurements will ensure everything lines up just right. Stand the sheet on your floor spacer(s) so that it’s at the proper height and lean it against the wall, as upright as you can without it falling on your head. Then lay out the required height and distance from the edge.

Marking top and bottom
Use a framing square to draw lines where the top and bottom of the opening should be.
sheathing garage walls - measuring
Here, I’m measuring the distance to the sheathing on the right, which is already attached to the wall. This measurement will be transferred to the one (on the left) that I’m currently laying out.

Cutting Out The Cutouts – Insulate And Sheath Your Garage Walls

Layout lines
This one was laid out using the square and tape measure method described above.

To cut the openings in your sheathing, first drill holes at the four corners. Then use a jig saw to cut the opening.

Drill the corners
These holes are large enough to accept a jig saw blade.
Cutting with jig saw.
This sheet of OSB is leaned at enough of an angle so that there’s plenty of clearance for the saw blade.
The completed cutout.

If you’ve crossed your fingers hard enough and measured carefully, the cutout should be in the perfect spot. If not, well, you can always use that sheet to surround a window or to get any narrow strips you may need. That’s what I did! Luckily, I only messed up once.

Yay, it fits!
Ah, fits like a glove!

Let There Be Light – Sheathing Garage Walls Around The Windows

Half and half
My windows are framed with two separate sheets of OSB.

Rather than a patchwork of four separate panels, get cleaner results and two fewer seams by cutting the window surround out of two sheets.

Window cutout
The first half of the window surround, cut out and ready to hang.
Window half done
First half of the window surround in place.

The sheets are each notched to wrap around the window. Of course, your particular window and/or wall arrangement might now allow for this solution. In a pinch, you can always add an extra stud to attach to if none are appropriately located.

Corner Moulding – Insulate And Sheath Your Garage Walls

Corner moulding
3/4” x 3/4” PVC composite inside corner moulding.

Once the shop walls were sheathed, I pin nailed moulding to dress up the corners. You can buy wooden moulding, but this paintable extruded plastic was easier on the wallet and has no chance of splitting or cracking.

An Extra Special Electrical Panel Access Panel

Room for access panel
I left space for an access panel above the breaker box.

I’m not necessarily suggesting you do this, but this is in my workshop. And there are two things a woodworking shop never has enough of: clamps and wall outlets. I figure I may some day need to add more electrical lines. To avoid the possibility of having to later destroy the wall, I decided to make a removable access panel above the breaker box so it’ll be easier to add more lines if/when the time comes.

Access panel in place
The access panel is screwed in place above the breaker box.

Unlike the rest of the sheathing, which is nailed in place, the access panel is screwed to the studs for easy removal. With screws, you’ll need to pre-drill and counter-sink the OSB. Use good wood screws; not drywall screws, which are prone to snapping when torqued.

Painting The Newly Sheathed Walls

Ready for paint
Whew, that was one heck of a job! Now let’s paint this thing and move on with our lives.

And now, the moment we’ve all been waiting for! Actually, I hate painting walls. I seriously do not enjoy it at all. But I got a huge feeling of satisfaction when that first coat went on. Even more so after the second.

Taped to block paint
With all the switch plates, outlet plates and panel box cover removed, tape up everything you want to keep paint out of. Be careful around exposed wiring!

Personally, I find the look of bare OSB kind of sexy. But painting helps to protect it and brightens up the room quite a bit. We’ve made it this far; we might as well grab a paint roller and rightly finish the job.

Painting in progress
With a roller, I first painted horizontally, along the top and bottom. Then went back and painted the entire wall vertically.
Two coats
After two good coats of paint, this job is a wrap.

OSB is thirsty and has tons of crevasses to fill. No matter what paint you use, it’s going to require two medium to heavy coats.

Welcome To The Wonderful World Of Sheathing Garage Walls


Granted, this isn’t the most fun project one can take on, but doing it yourself can save a lot of money and give you bragging rights too. Not to mention, you’ll finally have walls! It’s hard to appreciate just how nice walls are until you go eight months without. And now that I have walls, I can finally start setting up my new shop. It’s about stinkin’ time!

I’m not going to lie; this was an exhausting job that leached gallons of sweat from my now glass-fiber-filled pores. Failure to enlist help – and the maniacal laughter of a million Florida suns – may have contributed to my self-inflicted desiccation and backache. So did having to first rearrange everything in the building to even get to the walls. But at least I can say it did it all by myself. You know, me trying to be a hero and all. Let us know your tips and tricks for insulating and sheathing garage walls in the comments below!

Photo of author

About Steve

Steve made his first woodworking project at age 9 (in 1982) and whittled his first wooden chain at 18. He was also a consumer electronics repair tech and shop owner for a little over 20 years, until his impending obsolescence became impossible to ignore. Since then, Steve has focused passionately on manipulating his wood... in his workshop. Don't judge him.

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20 thoughts on “How to Insulate And Sheath Your Garage Walls Like a Boss”

    • Lesley Ann Roberts – I used several coats of regular indoor wall paint; nothing special. You can still see the grain and texture of the OSB. I knew that would be the case and am fine with it. I wouldn’t sheathe the walls of my living spaces with OSB. But for a reasonably dry garage or workshop, it has its advantages.

  1. Great post, appreciate you taking the time to write it.

    Question, do you need special plate covers to accommodate for the 3/4 inch thickness of the OSB? Or do the outlets and plates sit well?

  2. This was a truly useful post and I picked up lots of new tips and tricks from it. My son and I are in the middle of sheathing a 770 sq ft garage/shop with 1/2″ plywood. The idea of using a plumb to mark the studs has been very helpful, fr example.

    One thing that we found when doing the first long wall, though. It’s difficult to get the panels to be square so that the top is even all the way across by just putting spacers under the bottom of the panels. In my case, the concrete slab has a slight rise to the middle of the wall so we ended up with a problem when moving from a panel set square to the floor (we thought) on the left end as we got further to the right using the floor spacers as the guide. The first panel was slightly off because of the floor tilt and that got increasingly worse as we butted panels next to it on the right.

    The solution, I think, is a level chalk line across the top. Make sure it’s at least 96-3/8″ above the floor at all points. My garage is about a 98-1/2″ from floor to the bottom of the trusses. I am running a 2″ strip of plywood along the top to fill out the balance. So there’s plenty of room for a chalk line at the top. Wish I had thought of this before running into the problem but at least it was a minor issue and we will use chalk for the rest of the walls. Aligning the panel to the chalk line is easy by using the wide end of a curved demo bar to lever the panel up in position while your partner sets it.

    My garage was originally 440 sq ft and we added on. New stucco was applied to the new walls, and a thinner stucco coat was added to the old walls to match the texture and color. YOU DON’T WANT TO NAIL SHEATHING TO THE STUDS when you have stucco walls. The stucco will crack…a lot. I don’t know this from experience, fortunately. The stucco guy warned me about it and I confirmed it online, as well. We are using 1-1/2″ GRK trim head screws instead of ring shank nails. Expensive but provide a neat appearance and allow for panels to be easily removed in the future if needed. If a panel is warped a bit you may need to use a deck screw here and there to ensure the wood doesn’t pull over the slim heads on the GRK screws. We are using a 12″ by 16″ fastener field.

    If you can swing it nothing beats a Festool track saw for a job like this. Just a dream to make long straight cuts in plywood.

    Thanks again!

    • We appreciate your input, Robert. You made some great points.

      Frankly, I would have preferred to have screwed the OSB in place. I mainly wanted to avoid the added expense, as the project was already stretching me beyond my budget and it would have required a substantial number of screws. I did, however, screw the access panel about the electrical box to make it a little easier to add more lines in the future. That said, I love GRK screws. Those and Spax are my go-to’s whenever possible. The self-drilling tips and heads are worth the price.

      As for the track saw, some time back I had the good fortunate to review Makita’s Track saw here on Home Fixated. You’re right, a track saw is a dream come true. I love it so much I purchased extra track for longer cuts and have used it more than a handful of times since then.

  3. Thanks Steve for the article. I’ve been wanting to do this to my garage. Do you prefer nails over screws? Did you sheath the header above the garage door also? I’m glad you mentioned the spacing the sheets above the floor as I’ve seen people doing it differently.

    • Rick, I apologize for not seeing your comment until now. I actually prefer screws. But with hard sheathing, such as plywood and OSB, screws would require the extra step of drilling counter-bore holes through the sheathing to ensure it draws tightly against the studs. And that would have added a lot of extra time and effort to the process.

      I did sheath above the man door, but not the roll-up door. None of the exterior sheathing is exposed above the roll-up. Also, the terrain is just too craggy there, with multiple layers of header and mounting framework that would be better treated with paint alone. But I’m afraid sheathing would just look like cobbled-together patchwork.

      Though the area would be more feasible to sheath if the walls were sheetrocked, so that the seams could be hidden with tape before painting. Speaking of, I also have not painted that space. But some day I likely will mask it all off and have a go at it.

      Finally, It’s good practice to elevate wall sheathing above concrete floors. Where the gap is an eye sore, cover it with moulding, which is a lot easier and cheaper to replace than wall sheathing should condensation ever become an issue.

      Thanks for the support!

    • Fantastic, informative article, thank you!

      I have a question about the paint. What kind did you use? I’ve read that water based paint will raise the grain, so I was wondering if that is what you used. Did you use a primer first?

      Looks great!

      Thanks much!

  4. As a female diy learning as she goes, I enjoyed your sense of humor along with useful information. After researching and researching online tutorials, it’s a relief to have some comic relief, too. 🙂 good work.

    • Hey Heidi, I’m glad you found it informative. We want readers to be educated and inspired. But we also want you to enjoy the time you spend with us. And sorry for the delayed response; sometimes we miss notifications of new comments.

  5. Can you sheetrock the ceiling now? How do you get around the lighting? I have a situation where the ceilings are set for recessed lighting but I’m not sure is I want to sheetrock yet. Is it possible to just have an electrician finish putting in the cans and then put sheetrock up at a later date?

    • Sure, they do it all the time. They’ll install the cans to allow for the thickness of the drywall. Later, when you hang the drywall, just make your cutouts around the circular edge of the cans.

  6. Oh man, great article. I’m in the midst of finishing up my studio myself and onto wiring now and wanted to research the insulation and wall boards a bit more. I’m sure this will save me hours of heartache and lead to a much better finish. Thanks so much!

  7. Nice job, as usual, Steve! My first shop EVER, for which I have waited many decades, is going up right now, and I plan a similar treatment for the interior walls. And despite the fact that I can’t wait to get my stuff moved in and set up, I do plan to hold off until the walls are all squared away. Since you’re such a pro at it now, check your calendar and let me know when would be the best time to come up and play. And bring those big honkin’ scissors!

  8. Thank you for your wonderful article! You have now convinced me that i can put back up a wall in my converted garage all by my female self!

  9. Thanks much for the detailed and humorous report. Sounds like a well thought out and executed plan! I prefer drywall screws and have not had many cases of them breaking under the torque of the power drill. But both work fine.


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