I'm going to replace my old tub surround with a new 5-piece glue up model. Can I just glue it up over the 1/8" tile board that is currently there?

Hi Shippbc

Of course, removing the old walls would give the bbest result here, but it could also require you to have to redo the wallboard behind the shower and since you are only installing a tub surround there should be no real reason you can't install your tub surround over the old walls. Just be sure to use the TUB SURROUND ADHESIVE caulking they sell for this exact job. These adhesives will NOT Bleed through the surround over time as some of the regular construction adhesives can, OK?

Good luck!

Mark