greenboard or cement board?

Discussion in 'Remodel Forum & Blog' started by amys, Aug 11, 2005.

  1. amys

    amys New Member

    Messages:
    2
    Hi, I am looking for some advice. I am wondering whether to use 'greenboard' or cement backerboard for the ceiling above the fiberglass tub/shower unit in the bathroom my husband and I are remodeling. Our ceilings are only ~6'6" tall, so the ceiling material will get a lot of moisture, maybe even some splashing, though we're both under 5'6" tall :) . Would greenboard be adequate, or is water*proof* material necessary? If backerboard is the only good option, is it possible to join the seams as would be done with greenboard/drywall to make a decent-looking ceiling? Or could we put a coat of waterproof joint compound over the whole surface of the backerboard?

    Also, would you recommend greenboard in general for the bathroom, or is normal drywall adequate everywhere else (walls around sink, toilet, etc)?

    Thanks for your advice!!
    Amy
  2. thezster

    thezster New Member

    Messages:
    251
    Location:
    Fort Collins, Colorado
    6ft 6inches high? That doesn't meet code where I live.... Maybe folks are shorter where you come from.....

    Greenboard is not that much more expensive than plain old drywall..... splurge a couple of bucks and buy it for the bathroom...

    As for cementboard seams.... you should join seams with cementboard joint seaming material.... and it comes out nice... For the ceiling - I would put up cementboard "backwards"... smooth side facing you.... it should finish nicely...
  3. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Cement board is generally used as a substrate for tile. I have not seen it done as a finished surface, but no reason why it could not. I would check over on the johnbridge.com tile forum for advice on how to smooth coat it.
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,145
    Location:
    New England
    Greenboard is usually not allowed on a ceiling unless it is supported at 12" rather than the 16" of normal joist spacing (16" spacing is okay on a wall). Regualy drywall, properly painted is sufficient for all of your bathroom except behind tile in the shower/tub area. There, you should use cbu (cement backer unit) such as Hardibacker or one of the other brands. My unprofessional opinion. Go to the manufacturer's website and you'll be able to verify my comments. I highly recommend www.johnbridge.com
  5. amys

    amys New Member

    Messages:
    2
    Thanks

    Thanks for your kind and helpful replies. We'll take this input into consideration and hopefully have a functional ceiling surface in the end! Thanks again.
  6. plumguy

    plumguy New Member

    Messages:
    192
    Location:
    MA
    Regular sheetrock or blueboard is fine on the ceiling. You should be more concerned on the paint that you choose. Make sure you use a high quality bathroom paint, I used Zinnser(sp) years ago on my bath remodels and it was excellent. Not only was it scrubbale but it also very durable and long lasting.
  7. alhurley

    alhurley Guest

    that would be Zinsser Perma-White, right? Excellent choice - have used it myself. :D
  8. plumguy

    plumguy New Member

    Messages:
    192
    Location:
    MA
    That's correct!!
  9. decisions decisions!

    decisions decisions! New Member

    Messages:
    29
    Location:
    California
    Where do you find Zinsser Perma-White paint-I've never heard of it? Thanks!
  10. alhurley

    alhurley Guest

    try the boxes - they carry some Zinsser stuff. If not, try a paint store - shouldn't be that hard to find. Or call Zinsser and they may be able to tell you.
  11. toolaholic

    toolaholic General Contractor Carpenter

    Messages:
    874
    Location:
    Marin Co. Ca.
    using green board above the shower

    is wrong . use 5/8" reg sheet rock
  12. BellevuePaul

    BellevuePaul Seasoned DIYer

    Messages:
    16
    Location:
    Bellevue, WA
    no greenboard, huh? redguard instead?

    Interesting comment about 16" centers for normal ceilings...it seems like I'd heard that many truss built houses might even have 24" now.

    Anyway, I was wondering if the posters could explain *why* greenboard wouldn't be a good idea for a ceiling, in particular right inside a show surround.

    Assuming one doesn't do that, and uses regular sheetrock (5/8 I guess...is 1/2 out of the question for ceilings? I heard sometimes 3/8" is used to reduce weight on ceilings...) do people typically use something like RedGuard to block moisture?

    The Zinsser that people are talking about, can that be tinted, or are people using it as a primer, or does everyone out there have super white bathrooms? :)
  13. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    I think code might require 1/2" min, thickness of drywall, but check locally.

    I believe the consensus was that cement board is probably not recommended for ceilings. If it is uses, proper fastener pattern must be observed. I do agree that it is probaly over kill. I do think greenboard is recommended. If there is code against that, please help me out on this!

    The PermaWhite is a finish coat. I guess 99% of bathroom ceilings are white. Check with your paint store as to whether it can be tinted.

    As with all new drywall, a first coat of PVA primer is the best, and I would follow this with a coat of the best general purpose undercoat your local store carries. Any paint store or box store will have something. Then apply your topcoat. I prefer gloss in bath and kitchen, but a good semi-gloss will certainly perform well.

    On the RedGard, I don't think it goes on smooth enough to be an undercoat for paint.
  14. finnegan

    finnegan New Member

    Messages:
    250
    Location:
    CT
    3/8" is generally used only as a veneer over existing plaster or drywall. 1/2" is code except when 5/8" is needed for fire rating. Greenboard is fine on 12" centers for a ceiling. If you have 24" or 16" oc, you can strap the ceiling, which is a good idea anyway. 1/2" drywall is fine for a painted shower ceiling.
  15. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,145
    Location:
    New England
    Greenboard's surface isn't as strong as normal drywall...I'm told it will sag noticeably if not supported at 12" on a ceiling after time. Also, regular drywall is much stronger along its length than it is across the width. So, if you have a choice, install it horizontal on walls and across the joists on a ceiling, adding blocking as required.
  16. BellevuePaul

    BellevuePaul Seasoned DIYer

    Messages:
    16
    Location:
    Bellevue, WA
    Makes sense

    Still wondering about toolaholic's comment though about greenboard being "wrong." Is he referring to the strength issue someone else mentioned?
  17. alhurley

    alhurley Guest

    I believe the sag issue on ceilings is due to the added weight of greenboard over drywall. If you are doing anything where the span exceeds 16" you should consider using "ceiling" drywall - it's stiffened to resist sagging.

    As for the "wrong" comment he's probably referring to the sag problems. 5/8" is stiffer, but also heavier. Get the "ceiling rated" 1/2" and good paint. :D

    (you may have to go to a real lumber yard for the "ceiling-rated" stuff. trust me - it really exists. I just bought some.) ;)
  18. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

    Messages:
    4,434
    Location:
    North Vancouver, BC
    Green Board - No : Concrete Board - YES

    Make sure when building your shower you do not use any drywall on the wet walls.

    We use a product called Green EBoard which is a wonderful backer board but not drywall or gypsum based.

    I found an excellent online bathroom specification guide which covers cement board and drywall for California construction. California is a very progressive state and their building codes are some of the best in North America.

    Here is a link to the data sheet. It is a nine page report from the city of Palo Alto.

    [​IMG]

    [​IMG]

    There is more information on backer board selection here.

    JW
  19. lynnbrwn

    lynnbrwn New Member

    Messages:
    7
    Location:
    Washington, D.C.
    In my opinion, cement board would be best. let me know how it turns out.
  20. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,145
    Location:
    New England
    Since John likes to dig up ancient threads...this one is 7-years old, the OP has long since done his thing, and unlikely to respond!
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