Hey there! If you’re gearing up to install outdoor wall panels—whether it’s for a new build, a backyard refresh, or replacing that beat-up old siding—I get it. Rushing the measuring part is a super easy mistake to make, but trust me: skip this step wrong, and you’ll end up with too few panels (or way too many wasting space and cash) before you even pick out the style you want. I’ve been supplying outdoor wall panels for years, and I’ve seen so many folks stress over miscalculations that could’ve been fixed with a few simple, no-fuss steps. Let’s break this down like we’re grabbing a coffee and chatting, no confusing jargon or fancy equations here. Outdoor Wall Panel
First off, let’s get one thing straight: outdoor walls aren’t perfectly flat. Even that “smooth” side of your garage has tiny dips, bumps, or a wonky corner that’ll throw off a lazy measurement. So, what do you need before you even pull out a tape measure? Grab these basics first: a heavy-duty measuring tape (not that flimsy 10-footer that curls up mid-measure—invest in a 25 or 30-foot one, it’s worth it), a notepad and pen (or your phone’s notes app, but write it down anyway—trust me), a level, a pencil, and maybe a friend if your wall’s big. No need for a laser measurer unless you’ve got a huge commercial job—for most residential decks, patios, or small exterior walls, a good old-fashioned tape works just fine.
Now, let’s split this into two types of measurements: linear feet and square feet. Wait, I know, those terms sound like middle school math, but they’re dead simple here. Linear feet is just the total length of your wall, and square feet is length times height—this is how you’ll figure out how many panels you need, since most of our panels come in standard sizes (we’ll talk about that later).
First step: Measure the length of your wall. Stand at one corner, stretch your tape all the way to the other end—but do it three times. Yeah, three times. First at the baseboard level (if you’ve got one), then mid-wall, then up near the top edge. That’s because walls often curve or shift a little as they go up. If the numbers are off by an inch or two, take the average—add them all together and divide by three, easy peasy. Don’t round down here, either. If your average length is 124.5 feet, write that down as 125 feet to be safe.
Next, the height. This is where a lot of people mess up—they just measure from the ground to the top of the wall, but wait: are you mounting the panels directly on the existing siding, or do you have a trim line, a roof overhang, or a fence post top that the panels need to fit under? Measure from the exact bottom mounting point to the exact top mounting point. For example, if you’re installing on a patio wall that starts 6 inches above the concrete (to avoid water damage), measure from that 6-inch mark up to the bottom of your roof fascia. Again, do this three times too—near the left corner, middle, and right corner. Walls can have a slight slope (called a “bathtub curve” in construction talk, but don’t overthink that), so taking multiple height measurements will keep you from being short on panels at the top. Write down those numbers, average them, and again, round up if you’re at a half-inch or more.
Now, here’s a pro tip no one tells you: add 10% extra for waste. Wait, waste? What’s that? Let’s be real—when you cut panels to fit around windows, doors, outlets, or those weird little nooks on an old exterior wall, you’re gonna have offcuts. Even if you’re a pro installer, a 10% buffer is non-negotiable. Let’s say your wall is 10 feet long and 8 feet high. Square footage is 10 x 8 = 80 sq ft. 10% of that is 8, so total you need is 88 sq ft. That way, if you mess up a cut around a window, you’ve got extra panels instead of running to the store last minute (and who wants to do that for outdoor panels?).
But wait—what if your wall has openings? Like windows, doors, or vents? You don’t want to pay for panels that go where a window is, right? So measure those openings too. For each opening, calculate its square footage (length x height), add all those up, and subtract that total from your overall wall square footage. For example, if your wall is 80 sq ft total, and you have a window that’s 3ft x 4ft = 12 sq ft, subtract 12, so you need 68 sq ft of panels. Still keep that 10% extra on top of that adjusted number, though—cuts around openings also create waste!
Now, a quick note on panel sizes, because this is where measuring can go sideways fast. Most of our outdoor wall panels come in standard sizes: common ones are 4ft wide x 8ft tall, or 2ft wide x 8ft tall. But wait—make sure you’re measuring to match the panel’s actual coverage, not just its stated size. Some panels have a 1-inch “lap” where they overlap the next one to keep water out—so a panel that says 4ft wide actually covers 3ft 11 inches when installed with the lap. That’s why it’s so important to check the specs of the panels you’re planning to buy (we list this clearly on our product pages, fyi). If you’re mixing panel sizes (say, smaller ones around a door), adjust your measurements to match how they’ll overlap.
Let’s run through a real example to make this concrete (pun totally intended, and I’m not sorry). Say I’m measuring a small accent wall by my back patio: it’s a new wall, no openings, 8 feet long and 6 feet high. First, length: measured 7.9ft, 8ft, 8.1ft—average is 8ft exactly. Height: measured 5.9ft, 6ft, 6.1ft—average is 6ft. Total square footage: 8 x 6 = 48 sq ft. Add 10% waste: 4.8, so total needed is ~53 sq ft. If I’m using our 4ft x 8ft panels (each covers 3.16 sq ft when installed with lap), wait no—wait, 4ft wide x 8ft tall is 32 sq ft per panel. Oh right, I’d need two panels here, since 32 sq ft is less than 53, so I’d get three (which gives 96 sq ft total, but I’d have extra for a future repair—never a bad thing).
Another thing to watch out for: odd angles. If your wall is not a straight rectangle (like a gable end on a house that slopes up to the roof), that’s a little trickier. For sloped walls, measure the height at the lowest point, the highest point, and the halfway point along the length. Then calculate the area as if it’s a triangle plus a rectangle: (length of base x height of rectangle) + (0.5 x length of base x height of triangle). Or just add all those areas together—don’t try to guesstimate this, because sloped walls can throw off your numbers big time.
Oh, and a super common mistake: forgetting the trim or the edge pieces. Most outdoor wall installations need trim pieces to finish the edges, seal around openings, and make it look polished. Measure the linear feet of trim you’ll need too—run a tape along the top of the wall, both sides, and around any openings, then add a few extra feet just in case. We carry matching trim for all our panels, so once you have your measurements, we can hook you up with that too.
Wait, should I mention if you’re working with an old wall? If you’re replacing old siding, pull off one small section first to make sure the wall is flat—sometimes old siding is uneven, or there’s a layer of insulation underneath that’ll change the mounting depth. That’s why measuring after removing a small test spot is a good idea, instead of just measuring the old siding.
At the end of the day, the key here is to slow down. Rushing to measure one time and then ordering the wrong number of panels is way more work than taking 15 minutes to measure three times, add the 10% buffer, and account for openings and trim. I’ve had customers come back to me months later saying they messed up measuring and needed more panels, and it’s such a hassle for both of us when they could’ve just taken that extra step.
If you’re still stuck, no sweat—we’ve got a team that can help you double-check your numbers, or even walk you through the steps over a quick call or email. We know that not everyone loves measuring, and we’re here to make this as easy as possible for you. So if you’ve got your numbers sorted, or you just have questions about what panels work best for your space, reach out to our team to chat. We can help you make sure your order is spot-on, so when installation day comes, you just have to hang those panels and enjoy your new outdoor space.
PVC Foam Board References:
- Construction Mathematics and Science, Volume 2, Linear and Area Measurement for Exterior Finishes, National Association of Home Builders, 2021.
- Outdoor Sizing and Installation Guide, North American Building Products Association, 2022.
- Waste Factor Calculations for Exterior Cladding, Residential Construction Journal, Issue 4, 2020.
Linyi Xingang International Trade Co., Ltd.
We are one of the most professional outdoor wall panel manufacturers and suppliers in China. With abundant experience, we warmly welcome you to buy high quality outdoor wall panel made in China here from our factory. If you have any enquiry about quotation, please feel free to email us.
Address: 13th Floor, Building B, Central Times Square, Beicheng New District, Lanshan District, Linyi City, Shandong Province
E-mail: vincent@cnxingang.cn
WebSite: https://www.xgdeco.com/
