Hmmmm..... Not entirely sure, but probably 5.5" is most likely. Tightening that up to 4" is still a great look if the space has a more intimate scale than this master bathroom.

Thanks, for your interest in our project!

Pat Connors

The horizontal planks are 5.5" wide V-groove tongue & groove. We have also done this with a "nickel gap" appearance rather than v-groove