The design world is obsessed with shiplap - the rustic material that's taking over America's homes

Shiplap is a building material made of wide wooden boards that fit together to form a flat surface.

If you've watched an episode of HGTV's wildly popular "Fixer Upper" recently, you know it well.

It looks like this (more below):

Shiplap has seen a resurgence in recent years.

On "Fixer Upper," Joanna Gaines (host and shiplap master) uses the material to give homes a rustic, comfortable feel. Older houses sometimes have shiplap lurking beneath drywall, and now homeowners are embracing it rather than covering it up.

Some people eschew drywall and use painted shiplap for interior walls:

Others put it on ceilings to give it a farmhouse look:

Some opt for just a touch of shiplap. Rather than deck our their entire house, they'll use it on an accent wall or maybe around a kitchen island:

It's shiplap all the time:

Shiplap is very much a thing.

Instagram is full of thousands of shiplap ideas.

On her blog, interior designer Holly Mathis wrote that it's a dominant trend right now:

"It seems I am talking more and more with new clients, both those remodeling as well as those in new construction, about where to use wood walls or 'shiplap' as it is commonly called.  It seems everyone is hot for this look and I love it too!"

It's only the beginning. In a post about the new season of Fixer Upper, Joanna Gaines says she has something new in store: skinnylap!

"Of course, I will forever love clean lines, neutral colors and shiplap, but it's also fun when a client comes into a design meeting and says, 'I trust you, just go for it,'" she wrote. "Lately I've loved incorporating 'skinnylap' (same idea as shiplap, but with thinner planks), wallpaper and bolder paint colors."