Shiplap Walls- 5 Reasons to Use CDX Plywood Vs. Luan Underlayment

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, sometimes called CDX plywood, instead of luan underlayment when we were ready to shiplap our bathroom walls. Here are 5 reasons why. :

1. Texture- The difference in texture is the reason why time and time again we'll go back to using exterior plywood instead of luan. The wood grain is even more pronounced when you use a semi-gloss paint instead of satin like you see in the pictures
2. Humidity Resistance- The main difference with CDX plywood is that the manufacturer uses an exterior-grade resin glue to hold the layers of the wood together. Since we’re putting the shiplap in our bathroom, we wanted something that would withstand the humidity and be less likely to delaminate over time.

3. Cost- 3/8" CDX plywood is a couple dollars more per 4X8' sheet than 1/4" luan plywood. When you compare the cost of ripping down strips of plywood instead of using real shiplap planks, you're saving approximately $1.73 per square foot.
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. 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. 

I'd love for you to come visit the blog to see progress on our shiplap bathroom!

Tricia @ Simplicity In The South
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