Cement board attached to plywood or similar underlayment will only hold with corrosion-resistant 1 1/4-inch screws corrosion-resistant. For thick or heavy metal fixtures, use 1 5/8-inch corrosion-resistant screws.
Generally, 1 1/2-inch galvanized nails will hold the board firmly in place. You can also use drywall Bugle head screws that are especially coated against corrosion on cement boards.
While I can now answer what screws to use for cement boards in my sleep, believe me, I learned the answer the hard way.
Wifey had on several occasions accused and warned me of being too flirtatious with beautiful women. However, thinking it a gene she must have inherited from Eve, I had never paid any mind to her warnings-well until one day at the local hardware store.
So, there I was in the Screws aisle of my favorite local hardware store when from behind me a sultry, silky smooth voice asked me what I was looking for? I turned around and my eyes confirmed that it wasn’t old Darlene, the store’s usual shop floor assistant, but rather, a replica of Miss World. I decided to roll out some of my Southern flirtatious charm.
“Why, hello there most beautiful, it’s just as well you’re here…I am looking for a… SCREW,” I responded in my huskiest, sexiest voice.
Miss World gasped, blushing but also visibly shaken.
“Yes, little durling, a SCREW…. for my CEMENT BOARD,” I jokingly and flirtatiously continued, oblivious to the young lady’s initial facial reactions.
Anyway, to cut a long story short, to this day, I can still feel the sting of Miss World’s hot slap on my cheek and her shrill scream! It turns out she was a trainee saleslady and an engaged-to-be-PW (Preacher’s Wife), tired of male customers always making “tool passes” at her.
Were it not for my sincerest apologies and Darlene’s timely intervention, I dread to think where the matter would have ended. Fortunately for me, I ended up learning three very important life lessons-never, ever to flirt, what cement boards are and which screws to use for them.
So, What Are Cement Boards Anyway?
Usually, cement boards are used to cover walls, ceilings, and floors over which another type of material will be installed. Normally, other such types of material will be tiles. Since in such cases, the boards create a barrier between the frame or exterior of the area and the new floor, it needs to be strongly in place and firmly attached to prevent shifting or damage over time.
For flooring or wall installation, some builders will apply a thin layer of thin-set mortar under the cement board to prevent any shifting or expansion. However, even if you do use this extra adhesive, you will still need to use cement board screws. This is why using the right cement board screws is so important.
Cement Board Screws
Cement board screws are used to fasten a cement board to a substrate, usually a cement layer. They are also used for attaching other boards, such as plywood, to the cement layer under it.
Cement board screws are usually made from galvanized steel and are coated with a black oxide finish to prevent corrosion. They are sold in packages of 12 and come in a variety of lengths. The packages are available in quantities of 12, 50, or 100.
Given the importance cement board screws play in firmly attaching your cement board to your new floor or fixtures, the screws you use must be designed specifically for cement board installation. While most cement board manufacturers will include these all-important screws with your purchase, they are also readily available at most hardware and home improvement retailers.
Should you have the daunting task of having to purchase them yourself, however, then at least a description of what you need to purchase is always handy.
The size of cement board screws you require will largely depend on the fixture or base to which you would like to attach the board. Directly under the concrete screw head, are small grooves that enable them to dig into the cement board for the firmest grip.
Due to the alkali levels in the cement boards that can easily cause rusting, cement board screws are, more often than not, finished with a corrosion-resistant special coating.
Cement boards attached to plywood or similar underlayment will hold with only 1 1/4-inch screws. For thick or heavy metal fixtures, use 1 5/8-inch screws.
However, to attach the cement board to the studs, you’ll need special 1-1/4 in. cement board screws.
Like all cement board screws, these screws also come with a coating to resist corrosion. In addition, they have a special wide head with cutting flutes and hi-low threads for a strong grip.
If you can’t find them at a home center, call tile specialty stores. They usually have them in stock.
Cement Board Screw Alternatives – Nails
Should you, however, after searching both high and low, still fail to find cement board screws, then you should consider alternatives.
Aside from using cement board screws, there are some types of nails you can also use to install your cement boards. Used in outdoor decking and roofing installations, galvanized or hot-dipped nails are the best and recommended alternative should you decide to use nails.
Generally, 1 1/2-inch galvanized nails can hold the board firmly in place. They too have a similar corrosion-resistant coating similar to cement board screws. This enables them to resist rusting or fading from moisture exposure — or, as in the case of cement boards, from the alkali levels in them.
However, because the composition of the interior of drywall or Sheetrock boards is completely different from those of cement boards, it is advisable not to use drywall screws or nails.
The other reason why sheetrock or drywall screws or nails should not be used as an alternative is also that the fasteners designed for use with drywall do not have the corrosion- and alkali-resistant coating that enables the cement board screws or galvanized fasteners to last.
Cement Board Screws: Frequently Asked Questions (FAQs)
Q. How many screws do I need for the cement board?
A. Fasten a minimum of 12 screws into the board (4 rows of 3 screws). Keep fixings between 15mm from board edges and 50mm from board corners.
Q. How long should cement board screws be?
A. As mentioned earlier, a cement board attached to plywood or similar underlayment will hold with only 1 1/4-inch screws; for thick or heavy metal fixtures, use 1 5/8-inch screws. In general, 1 1/2-inch galvanized nails will hold the board firmly in place.
Q. Can I use deck screws for cement board?
A. There are deck-like screws made for concrete board. They are called Bugle heads and are like drywall screws but they are coated to resist corrosion and have sufficient strength to support the board. The heads are larger than deck screws or drywall screws, too.
Q. Can I use regular drywall screws on the cement board?
A. As mentioned earlier, NO! You shouldn’t use drywall screws. Drywall screws can corrode due to the presence of Portland cement and lime in mortar and CBU. Only use drywall Bugle head screws that have been especially coated against corrosion on cement board.
Q. How often do you put screws in cement board?
A. Fasten HardieBacker cement board with specified nails or screws (as listed in “Materials Required”) every 8 in over the entire surface. Keep fasteners between 3/8 in and 3/4 in from board edges and 2 in from board corners.