What You Should Know about Water-Resistant, Greenboard Drywall

greenboard drywall

via Actually Ashley

Whether you’re building a new bathroom in your home, or you’re remodeling a section of your house that’s exposed to humidity, it’s important to know about greenboard and where it’s appropriate to use it. It’s a product that’s good in several sections of the home, and something that you’ll want to use instead of standard gypsum board also known as drywall.

What is Greenboard?

Greenboard is a water-resistant gypsum board or drywall panel that came out in the 1960’s. The product is essentially a more durable gypsum board. It has the same gypsum core that you’ll find on standard drywall all over homes, but it comes with a thicker coating of paper that’s protected by wax for water resistance. The exterior paper has a green tint to it helping to separate it from standard gypsum board, and leading to the product being known by most people as “greenboard”

It’s Thicker

While standard drywall comes in ¼” and ½” thicknesses, greenboard is sold in ½” and 5/8″ thicknesses. That’s something that you have to keep in mind if you’re replacing ¼” drywall in your home with greenboard. It’s thicker because of the added wax that’s infused into the material, and also because it has to be. Studies show that greenboard is actually weaker than standard drywall when it gets wet and the added thickness helps compensate for this. When installed properly the slightly weaker material isn’t a problem at all and offers superior moisture resistance.

It Isn’t Water Proof

Greenboard drywall isn’t designed to line the inside of showers or for use in environments exposed to outdoor weather. It’s the type of stuff that you want to use down in your basement or another part of your home that’s exposed to more humidity and moisture in the air. Greenboard drywall isn’t water-proof, it simply resists moisture better than the standard gypsum board that’s on most walls in homes around the United States.

It Isn’t Fire Resistant

There is a fire-resistant drywall product known as Type X that’s sold in 5/8″ sheets for use around fireplaces and other high-risk locations in the home. This is completely different than greenboard even though they are both available in the same size. It’s important to realize that greenboard drywall isn’t any more fire resistant than standard drywall is. If you’re looking for a fire-resistant product you’ll have to rely on something like Type X or another solution like Cement Board instead.

Properly Installing Greenboard

Cutting Greenboard

When installing greenboard on the walls of your home you can install it just like you would standard drywall. Cut the pieces to size using a sharp utility knife and a metal straightedge. Simply secure the straightedge in place and score through the outer paper coating using a fresh blade. Once the paper is scored you can snap the board off changing its overall size to what you need.

Installing it on Walls

When put on the walls of your home you can install water resistant drywall just like standard drywall. Drive drywall screws into the board and the studs behind it. Take care to only go just below the surface of the drywall and try to avoid going through the paper coating entirely. The gypsum core doesn’t hold fasteners as well and isn’t as strong to rely on during an installation. If you have to go with multiple rows of greenboard on a wall stagger the material to keep seams from lining up. While it will be more difficult to cover up your seams when it comes time to tape and mud them, staggered joints are stronger and more reliable.

Putting it on Ceilings

Special care must be taken when putting greenboard drywall on ceilings. It’s heavier and a bit weaker than standard drywall which can lead to sagging issues. To compensate for these problems it’s important to fasten the drywall every 12 inches instead of 16 inches. To do this you’ll want to strap your ceiling first. To do this purchase 1″x3″ lumber and fasten it perpendicular to the joists in your ceiling. This is a good practice to use when securing drywall on a ceiling in general because it makes installations simpler and more secure.

With the strapping in place you can install the greenboard with drywall screws used liberally. Drive the screws to just past the surface but avoid going through the paper entirely. This makes covering the screws easy but preserves the strength of the installation.

Why it isn’t Recommended for Bathroom Ceilings

Many local building inspectors will tell you to avoid putting water resistant drywall on your bathroom ceiling, and that’s actually for your own protection, even though using it that way may not be a problem. Greenboard weakens more than standard drywall does when it gets completely saturated. Since bathroom ceilings tend to collect a great deal of moisture this is a common weak point for the material. When you consider that a ceiling installation provides the greatest chance for failure of this product it’s easy to see why many inspectors would suggest a different material. When installed on a ceiling without enough fasteners greenboard is known to fail. In order for it to function properly it has to be installed with fasteners no more than 12″ apart, that’s something that most ceiling joists won’t accommodate without some modification. If you do want greenboard on your ceiling you can accomplish the installation safely by adding on some blocking to allow you to nail or screw the material every foot, but it’s generally easier to just go with a different material like standard drywall with a paint finish.

Finishing the Drywall

Once you have it all locked in place it is time to finish your greenboard installation. To do this you have to mud and tape it completely and put on a layer of protective paint. Coat every seam and all your screw holes with joint compound (also called mud) using a putty knife. Now use the putty knife to press drywall tape into each of the seams in between your panels and go back over them with another layer of the compound to cover them and really stick things in place. Allow this coating to dry and apply one to two more subsequent coatings evening the coatings out so it all blends well. With the compound covering the walls and ceiling you can begin painting. Before you start sand down any rough spots that you see, though there shouldn’t be many, and wipe away the dust with a damp cloth. Now prime and paint the walls using a durable paint designed for bathrooms and other damp environments. This completes your installation.

Greenboard Versus Cement Board

While greenboard and cement board are often compared to one another they are very different products with different purposes. Cement board is a better solution for use around showers or other locations that are going to get very wet, but it needs a moisture barrier behind it which takes more time to install and is more expensive than greenboard.

Greenboard is the faster and more affordable solution for sections of your home that are going to get damp but not really saturated. Greenboard doesn’t need the moisture barrier behind it that cement board does, but it can’t be relied upon to hold up to shower conditions either.

Greenboard isn’t good for every application, but when you know how to use it properly it can be a useful tool to keep your home functioning properly. Add it in the damp areas of your home to help prevent mold and mildew and you’ll have fewer problems later on.

8 Responses

  1. Shirley Blair

    I really enjoyed reading the information on how to use green board and standard drywall and cement board, I’m trying to redo my bathroom; so it’s been a very good help to me outside of some of the training that I’ve had with drywall in construction. I think you doing a great job on this instruction written material, so keep up the good work, I will be visiting you more often. Getting involved in your website will help me a lot on remodeling my bathroom.I really enjoyed reading the information. I got a clearer understanding on what’s needed around my bathtub. Thanks a lot.

  2. Paul Neeley

    This was very helpful and clear to me, a novice in this area – thanks so much, Samantha! You’re a great writer.

  3. Nick Caraway

    As someone in the waterproofing business I can safely say that many consumers that purchase this product for basement remodeling are greatly disappointed in the representation that basements are a great candidate for green board. It is typically sold as moisture resistant, however never explained that only one side is resistant. Over and over I find the reverse or backside is still as moisture absorbant as standard drywall. Home owners and many contractors finish basements without taking proper precautions to avoid moisture or condensation from the walls, leaving the drywall backside to grow mold. Actually very common.
    I’m not referring to actual leaks in the walls but condensation, humidity, and dampness. Homeowners continue to blame the store at which it was purchased for not explaining this and steering them in the direction of the product. When in reality the manufacturers don’t properly educate the vendor of the product.

    • Perhaps you (or someone) can help with this rather unusual problem. I just bought a house in the “hot springs” district of town, where the home inspector’s moisture meter said a high of 22 % in one location along an interior wall. In pulling up the old carpet, we are finding what appears to be 3/4″ particle board, then linoleum (and ostensibly concrete substrate under that). I am wondering about whether to use 3/4″ greenboard to replace that particle board, which side to put up, and whether we can then just lay our 6 mil moisture barrier on top of the greenboard before putting down our click-lock laminate (which we’ve used 3 times prior with great success, but never in a higher moisture area such as this). Do you think this would work? We have to put something down to bring the floor height back up to that 3/4″ that will be missing once we pull our this old (stained and partially crumbling) particle board. Thanks for any ideas!

      • Doug Weber

        You may want to consider Tyroc Subflooring. It is easy to install. Impervious to moisture and provides a substrate for any finished flooring. The issue may be the required thickness as Tyroc is 1/2″ thick. The main thing is to avoid any plywood or OSB in this assembly with that type of moisture issue. I would also avoid GreenBoard as well, since over time it will absorb moisture and break down just as the particle board did.

  4. Drew

    I have a 7 ft by 3 ft tiled shower. Three walls are tiled, the fourth wall is 30 inches high with a piece of glass that runs to the ceiling. The door is glass and that has about a 4 inch gap to the ceiling, The result is the steam stays in the shower. The problem is that every 6 months or so the drywall tape cracks. We tried different tapes but always get the same result. Do you have a suggestion on how to fix the ceiling permanently?

    • without looking at your bathroom I can’t really what to recommend. if there is room to tile I would cover the wall in question with 1/4 ” cement board, a skim coat of tile morter. and tile..I can assume that if the covering you have on there now is wet ,it may be a mold magnet. I recently did a job where the roof leaked and when I removed the drywall, which looked perfectly fine, the back paper was black with mold. .Another way to go is with blueboard, a coat of plaster weld, and a veneer plaster, but you might want a pro to do this. plaster is mold resistant.

  5. UBS

    Green board is still widely used almost every state in the U.S. However one has to have it planned properly when being use in areas that get wet a lot such as washrooms.

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