"The rooms you don't see in the reveal, look just like this," says Joanna

Joanna Gaines’ real decorating secret weapon? Rows and rows of plastic storage bins!

In this exclusive first look at Chip and Joanna Gainesnew 30-minute series, Fixer Upper: Behind the Design, Joanna reveals everything that goes on off camera — and that includes a sea of clear containers, piles of pillows and rooms full of extra decor that never sees the light of TV.

“There’s a lot of planning that goes into a day like today,” Gaines says of the project she’s staging in the sneak peek of the series, which will air following Fixer Upper’s season four finale Tuesday night. “But it’s inevitable. I’ll need more books, I’ll need a certain vase. I always like to bring too much so that in the end I have what I need.”

The show also broaches one of HGTV fans’ burning questions: What’s happening in all the rooms we don’t see in the reveal.

“Most of the time when it’s the reveal, people wonder, what about the other bedrooms? Well, this is one of the bedrooms,” she says from a space that’s covered completely with rugs, tarps, tools, candles, galvanized buckets, and, naturally, more bins.

That doesn’t mean the unseen areas haven’t gotten the full Fixer Upper treatment, though.

“It’s finished, we’ve got a new light fixture in here, we’ve got all new trim and paint,” she continues. “It’s really pretty, except all of my stuff is in here. So typically 2-3 of the rooms you don’t see in the reveal, look just like this.”

See the full sneak peek of Fixer Upper: Behind the Design March 28th at 11:00 p.m. EST on HGTV.