Before I share our post on how we installed shiplap walls using plywood in our bathroom, I wanted to go over the reasons why we chose exterior plywood instead of luan (aka underlayment). After using this type of plywood, I’ll never go back to luan!
If you’re a fan of Fixer Upper, then there’s a 75% chance you’re also a fan of shiplap walls.
I know this girl is.
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Very few of us are blessed enough to find authentic shiplap under our existing wall surfaces like you see on the show. And not all of us can afford to buy actual shiplap (the kind that has a special notch cut on the edges of the board)…that’s if you can even find it in stock at your local home improvement store.
Most DIY shiplap tutorials I’ve seen use 4’ X 8’ sheets of 1/4″ luan underlayment ripped down to 6” to 8” wide planks. We’ve used 1/4″ underlayment as faux shiplap before and were happy with the results.
Regardless, we knew we wanted to use 3/8″ exterior plywood, also known as CDX plywood, instead of luan underlayment when we were ready to plank our bathroom walls.
Update: Someone asked a good question about the safety of using this type of plywood inside a home. From what research we did before installing, the CDX plywood is safe for indoors since the layers are bonded together with wood glue (which can withstand a little moisture). The glue is between the layers so sanding the surface wouldn’t release the glue into the air. It wouldn’t be safe to use pressure treated exterior plywood since it’s treated with chemicals.
So, what made us choose to use exterior grade plywood to shiplap our master bathroom instead of luan underlayment (or even authentic shiplap)?
Here are 5 reasons:
1. Texture
The reason we’ll go back to using exterior plywood to shiplap walls in our house time and time again is that it has so much more texture than the luan which makes it look more like the real thing. You can see in the comparison photo above the difference in the wood grain but it’s even more noticeable in person. We used a satin finish paint for our bathroom walls but a semi-gloss would show off the texture even more.
2. Humidity Resistance
The “X” in CDX means the plywood can withstand exposure to the elements over a short period of time before it’s painted or sealed. The main difference is that they use an exterior-grade resin glue to hold the layers of the wood together. Since we’re “shiplapping” our bathroom, we wanted something that would withstand the humidity and be less likely to delaminate over time. After putting the boards up, we covered the planks with primer before we painted. Speaking of humidity, it’s important that you have an adequate exhaust fan. We used this calculator to see what size fan we needed and ended up ordering this one.
3. Cost
The cost difference between exterior plywood and luan underlayment was only a couple dollars per sheet…$13 for luan and $15 for plywood. Either way, you go, it’s inexpensive. When you figure the cost of real planking at $2.20 per square foot, using exterior plywood at $0.47 per square foot will win my vote every time.
4. Durability
The 3/8″ exterior plywood is less likely to warp over time compared to 1/4″ luan. It’s also less likely to split when cut or nailed.
5. Thickness
The thicker the plywood, the more noticeable depth the gap is between the planks. This makes the faux planks feel more authentic. Also, having 3/8″ thickness of wood compared to 1/4″ gives more wood for the nails to hold onto. But, you can also run into problems if you go too thick.
Actual shiplap planks are usually an inch thick which means you’ll have to take off the window and door trim. The 3/8″ thickness is a good compromise although we did had to remove the trim below the window sill because the profile would’ve been hidden.
There are some drawbacks to having shiplap walls using plywood that you need to consider too:
Exterior plywood needs a little bit more prep work. Even though it comes pre-sanded, the surface of the CDX plywood is what I would call “hairy”. The fibers tend to stick up a little bit. Fortunately, sanding gets rid of the hairiness.
Also, you run into the occasional problem with having knots on the surface. The knots can be filled with wood filler and then sanded.
It’s really important to spot prime over the knots with B-I-N Zinsser shellac primer. This will seal the knots and prevent the from sap bleeding through the paint. Then, use an all-purpose interior/exterior primer for the rest of the walls before you paint.
Our favorite interior/exterior primer is Sherwin Williams PrepRite ProBlock.
I can’t imagine this bathroom without the shiplap.
* Update: Here’s our tutorial and tips post on faux shiplap
If you have any questions about how to shiplap walls using plywood, please feel free to leave a comment. If we don’t know the answer, we’ll research it for you.
We also used exterior plywood to plank the walls and ceiling in our cottage shed guest house. Click here to see the reveal of our guest house or click the picture below.
Catch up on all the posts and projects that went into our master bathroom remodel here:
So Long, Spare Bedroom…Hello, Master Bathroom, Walk-in Closet and Half-Bathroom
Eclectic Farmhouse Master Bathroom Inspiration and Mood Board
Progress with the Master Bathroom Remodel: Up Goes the Drywall. Down Goes the Popcorn Ceiling
Shiplap Walls- 5 Reasons to Use Exterior Plywood Instead of Luan Underlayment
Shiplap Walls for the Master Bathroom: Tutorial & Tips
The Modern Farmhouse Master Bathroom Reveal: Turning a Bedroom into an En Suite Bathroom
Master Bathroom Source List, Paint Colors & Budget
Knockoff Restoration Hardware Bristol Flat Mirror
6 Ideas for Organizing the Master Bathroom Vanity, Cabinets, Shower & More
Cristina says
I’ll be giving it a try in my next shiplap project! I’ve used the 1/4″ Luan and also think it’s too thin, many times the nails just go thru, and I hate to use adhesive.
Kate Hollingsworth says
I’m definitely trying plywood for our bedroom. Thanks for the comparison pic – I had no idea the plywood would show so much grain. I love it! Cheers, Kate xx
Pamela-FromMyFrontPorchToYours says
Looks great! We have planked our walls in our previous home. Cant wait to do it here at the new house.
Gloria says
I will be trying this in my kitchen and I really appreciate this post. Pinning it for later use. Thank you!
Warmly, Gloria
Moses says
Interesting and I may follow your advice. Two questions:
1. I’m assuming the exterior plywood is safe for indoor use?
2. How would you apply a beach weather finish to the ship board?
Thanks!
Tricia @ Simplicity in the South says
Hi! From what research we did before installing, the CDX plywood is safe for indoors since the layers are bonded together with wood glue (which can withstand a little moisture). The glue is between the layers so sanding the surface wouldn’t release the glue into the air. It wouldn’t be safe to use pressure treated exterior plywood since it’s treated with chemicals.
To do a beach weather finish, first lightly sand and remove the dust. Then, seal the surface of the wood with clear shellac. Shellac is smelly, but it will prevent yellowing from wood tannins of your final coat of paint but still allow the wood to show through. It will also protect it from moisture if you’re using this wall treatment in a bathroom. Then water down latex paint. You can start with a 1:4 ratio of paint to water. I like doing a test sample on a scrap piece of wood. Brush on the watered down paint, then quickly wipe it off with a damp rag. Do small sections at a time. I hope this helps!
MaryLee Kersten says
I’m so glad I found your post. I will be using the exterior plywood rather than the 1/4″ underlayment. In a different post that I have read, they say to paint the boards before putting them up. I noticed you didn’t. Do you have strong feelings either way about this? Also, any other suggestions/tips would really be appreciated.
ML
Nick says
Hiw much of a space is between each plank?
Tricia says
Hi Nick,
We used a nickel as a spacer between the planks. I hope that helps!
Judy Hamm says
Have you done the shiplap over walls that have not been sheet rocked?
Tricia @ Simplicity in the South says
Hi Judy! Yes, when we put shiplap up in the guest cottage, we didn’t have sheetrock under it. After we insulated the walls, Jason stapled 15-pound tar paper to the studs. It serves as a vapor barrier as well. This is a trick we learned from watching This Old House. You can see the post here: https://www.simplicityinthesouth.com/orc-week-3-the-cottage-guest-shed-shiplap-walls-painting-lighting/ And the timelapse video can be seen here: https://youtu.be/cabyD1lj7lM
Paige says
Hi! We are planning on doing this in a shed much like your guest cottage. We will probably use the tar paper behind the plywood like you mentioned in another comment. When painting, did the spray get in between the gaps and cover the black tar paper or do you just not notice the tar paper between since it’s such a small space? We may end up rolling everything, and I’m wondering if I should just quickly hit the tar paper with a paint brush as we put each board up. Your space looks beautiful!
Tricia @ Simplicity in the South says
Hi Paige, thank you! I’m so happy that you guys are planning to do a guest shed too. I just double checked to see if the paint sprayer made much of a difference between the gaps and I’d say no. You’d be just fine rolling the paint on. There’s such a small gap between our boards that I can’t even see if the paint got on the tar paper. The space between them is about the width of a penny. I hope that helps and have fun making over your shed!
Paige says
Great! Thank you for taking a look! I’m so glad you’ve shared such a cost-saving and beautiful tip 🙂
Tricia @ Simplicity in the South says
You’re welcome 😊 Glad to help out any way I can