Great Questions! Yes it can be installed horizontally.

Having said that typically, this requires more paper. It is important to plan where your seams are going to go, so they are not at eye level.

Thank you for the quick response. I ordered 8 rolls this morning for the entryway and stairwell. This quantity was given to me by the vendor doing the work. He said they can do it with 7 but if 8 means less seams, we're going with 8. I'll post pics once the project is complete.

Awesome! look forward to seeing your project all complete :)