Either is acceptable, although butt-seams require a high degree of skill to line up the panels. Because this product is going on uneven surfaces and is thinner than a normal wall vinyl, an overlap should be the default way to install.
GF 285 RoughMark™ is a 3.5 mil matte white opaque polymeric vinyl film coated with a solvent acrylic high-tack removable (HTR) pressure sensitive adhesive on a 90# layflat liner. Its thick HTR adhesive is designed to aggressively grip onto textured substrates such as brick or block, yet cleanly remove without leaving adhesive residue on the contact surface. The 90# liner provides excellent dimensional stability for digital printing. GF 285 accepts a variety of solvent-based, eco-solvent, latex and *UV curable inks common to wide format digital printing systems. *For UV Curable inks, please consult with the ink manufacturer for specifics on ink flexibility.