Board fixing screws Lost their heads (Ed.)

[Wazap]

Hi fellas/girls, I have, perhaps, an unusual problem. Could you give me an answer or two?
I've used N & C for doing a bathroom, except that, when attaching the super strong tile backer boards to the studding I decided I wanted to use stainless steel screws and washers. I used Timco's stainless steel set and, in the process, three screw heads came off. I replaced them. Now I'm beginning to worry that the four by two porcelain tiles might just bring too much weight to the screw heads when I think the bathroom finished.
Has anybody had this scenario before?
What should I do.
I've made the problem a little worse because I've already taped the joints.

What the hell should I do?

 

[opps]

Stainless steel screws are easy to snap when tightening them, but shear load wise you should be OK. I suspect that you didn't drill pilot holes first.

 

[Wazap]

Thanks 'opps;' ah, the delicate ways of success. I wonder if the wood being over thirty years old may have contributed, as well.

 

[opps]

Thanks 'opps;' ah, the delicate ways of success. I wonder if the wood being over thirty years old may have contributed, as well.

Whilst I don't use them very often, I have snapped SS screws when drilling into softwood fencing. I didn't have a freakishly long drill bit and didn't want the chuck on my drill to scuff the panels. On reflection, I should have used regular screws to make the holes and then removed them and used the SS screws after.

 

[JohnD]

most cheap steel is made in China, and often contains 0% nickel in the alloy.

Nickel greatly strengthens it, but is an expensive metal so is omitted for customers who want a cheap product.

You can get away with it if you treat it as gently as brass.