Can I use deck screws with Hardibacker?
 

I ran out of the green "backer screws" that are recommended with the Hardibacker sheets. I'm close to finishing up the area I'm working on in the bathroom I'm remodeling, and I hate to make a run to the store for a dozen more screws, and I'm wondering if I can use the coated deck screws I have laying around.

The hardibacker I'm laying in is not going to have any weight on it. I have a glass block window in the wall in the shower, and I'm lining the area around that window with strips of hardibacker so I can tile over top of that.

Sooooo since the most weight that will be applied is a bottle of shampoo or two sitting on the ledge of the window, is it okay to use outdoor deck screws to install these strips of backer?

Deck screws will work fine.Did you use Hardi for the entire shower? If so,did you put a vapor barrier behind or do you have liquid waterproofing planned for the surface of the Hardi?

........

No vapor barrier. I was under the impression one wasn't needed with the hardibacker (recommended by some, but not needed). I did seal the joints with mesh tape and thinset.

I was asking because you need a vapor barrier or waterproofing product such as Redguard that's applied to the Hardi.

The Hardi needs a moisture barrier attached to the studs behind the Hardi,
or, waterproofing on the surface of the Hardi but not both.:)

Weight on the wallboard (Hardi) isn't the issue with using the proper screws. The screws should be alkali resistant, galvanized deck screws don't qualify.:) The issue is corrosion from the cement products.:)

Okay, I went out and got the backer-on screws. But I have to ask about the vapor barrier. I thought the whole purpose of hardibacker was to provide moisture-proof wall and floor panelling?

No the hardibacker will let moisture through so you will need to protect the wall studs or put red Guard or similar on the surface. Dennshield is water proof.

Hardibacker is not damaged by moisture but it is in no way a moisture barrier.:)

Listen to Bud and Jim.
Drywall or gypsum products will turn to mush if they get wet. The paper on them is a favorite mold food. The purpose of hardibacker or CBU is to provide a stable surface that won't do either of the above if it gets wet.
However hardibacker can and will absorb water. Try it on a scrap.

deck screws are fine.

Deck screws have never been "fine" and technically are contrary to building codes. The Hardi company makes clear recommendations for the installation of their products. Always follow the manufacturers recommendations.:)