This is a tub removal changed to shower project. The contractor enclosed the shower area with blue board; no prep under the board. I was told it would be green board. Should it be replaced or another board laid on top or membrane rolled onto blue board for the tile to be placed on?

Not familiar with Blueboard.

I think I would have used either Durock or WonderBoard.
There are a couple different shower water proofing systems.
Ask contractor about what system is going to be used.

Blueboard vs Regular Drywall Paneling | DoItYourself.com (http://www.doityourself.com/stry/blueboard-vs-regular-drywall-paneling)
https://www.usg.com/content/usgcom/en/products-solutions/products/tile-and-flooring-installation/backerboards/usg-durock-cement-board.html
WonderBoard Lite BackerBoard | Custom Building Products

https://prosupplycenter.com/browse/832/kerdi-shower-kits-waterproofing-kerdi-shower-kit/?gclid=CMrB4tiWxs4CFQsehgodOusOEA (http://www.custombuildingproducts.com/products/surface-preparation/cement-backerboards/wonderboard-lite-backerboard.aspx)
http://www.schluter.com/schluter-us/en_US/Shower-System/c/SS

Blue board is a better material for your shower as opposed to green board.

Greenboard vs Blue Board | DoItYourself.com (http://www.doityourself.com/stry/greenboard-vs-blueboard)

Blue Board Vs. Green Board | eHow (http://www.ehow.com/info_8694897_blue-board-vs-green-board.html)

Talaniman

Your reference

Green Board for Moisture


Green board's paper has a moisture-resistant coating and may or may not have moisture-resistive additives in the gypsum core. Green board is suitable for walls that may be exposed to occasional moisture and condensation, such as standard bathroom walls (not shower walls) and kitchen backsplashes. It is often used as a backer for tile in these applications. However it should not be used in showers, bath enclosures and other areas that are frequently wet, and it is not suitable backing for floor tile. Tiled walls in wet areas require a backing surface of cementboard or other panels designed for wet applications, such as gypsum panels with fiberglass facings.

Yeah, I think the answer depends on the material going over the board.

Are you having a wall surround installed? Perhaps, a terestone wall system installed? Or, maybe you are having ceramic or porcelain tile installed? Each of these requires a different wall board material.

Back to you...

Mark

In my house, I would put Moisture Barrier over the studs first ( asphalt paper ). Then some kind of cement backer board that is designed for wet locations and taped the joints. Then set tile on Thin Set over it. I would not use Blue Board.

Moisture barrier is the key word here as it prevents condensation from entering wall cavity, creating damage to the framing of the house

If you plan on installing granite or marble ( tile or slab) on the walls, than the walls should be floated as blue board is not strong enough to hold the weight of the stone. However, such board, designed for wet locations, will hold regular tile.

If nothing, your contractor should - at least - coat the blue board with RedGard type material to prevent deterioration of the board due to moisture. However, if I run the job, I would take that Blue Board down and do it right way.

Now, it begs a question: What did your contractor do to water-proof the base of the shower ?

Back to you

Milo