Why not use what will work with a lifetime warranty? I'd use 3" deck screws.

DECKMATE #9 x 3 in. Tan Star Flat-Head Wood Deck Screw 5 lbs.-Box (365-Piece) 115985 - The Home Depot

Get your desirable level of performance and durability by choosing this excellent DECKMATE Star FlatHead Wood Deck Screw.

www.homedepot.com

 

The problem with coated deck screws is when you drive them in with an impact the head's coating gets partially removed. Then whenever it rains (which is almost every day where I am) water sits on the screw heads constantly and I don't know what metal is under the coating. To get maximum corrosion protection I am going with SS especially since these coated deck screws are only rated for ACQ treated lumber I don't know how it will do with copper azole treatment lumber at higher concentration.

 

2x4 decking over water? I wouldn't waste time or money on screws. Exterior grade ring shank gun nails will be 10 times faster to install and will hold just as well as any screw.

 

For this project saving install time is not an objective. Serviceability (allow easy removal of decking whether it's one piece or ten pieces) and corrosion resistance are most important.

 

My company uses exclusively SS hardware and always screws for decking. We have screw guns so it's not too much slower than a nail gun. We do prefer composite decking though.

 

I am so glad the pro deck and fence carpenters use some sort of nails… it makes removing them later so muck easier than screws.

 

I don't want to use nails for multiple reasons, one of them is not being able to remove them without destroying the decking. In my experience with shooting ring shank nails to fasten 5/8 to 3/4 wood pickets to the horizontal rails, to date I have not been able to remove one picket whole by removing the nails first. Usually the pickets break first, or the process of trying to dig under the nail heads destroys the material around the heads.

But more importantly if I need to remove one piece of deck for replacement, screws will allow me to back it out. I cannot use a pry bar due to the presence of joist tape on the joists.

 

Size matters. #10 if possible, #9 is ok. #8 are very common because they cost less, but they are thinner.

The kind with the little nubs under the head tend to self-bore a little better, bugle head can split the board at the last few turns.

 

Size matters. #10 if possible, #9 is ok. #8 are very common because they cost less, but they are thinner.

The kind with the little nubs under the head tend to self-bore a little better, bugle head can split the board at the last few turns.

I think I will be using #10. I thought bugle heads countersink better because of the concave on the underside of the head like drywall screws but I looked at one bugle head next to another one with "flat head" and I can't tell the difference side by side. Hence I asked what the difference is.

The one I am considering is CAMO 3 in. #10 316 Stainless Steel Premium Star Drive Bugle-Head Deck Screws (350-Count)

CAMO 3 in. #10 316 Stainless Steel Premium Star Drive Bugle-Head Deck Screws (350-Count) 0348174S - The Home Depot

 

Use the ss screws if you can.
Deck mate screws are junk. They rot out in less than 10 years

 

Be aware, SS screws are weak at the head and you will cam out really easily. One cam out and the screw is toast. Choose SS strength and head design well.

Another thought is to use Trex screws with T-20 heads. They don't cam out easily.

FORTRESS HULK Torpedo Tip Brown Composite Deck Screws (350-Pack) 172565351 - The Home Depot

HULK fasteners 350-pack brown surface mount deck screws are designed to be compatible with Fortress Infinity I-Series and Apex deck board collections, as well as many other brands. Our screws use an advanced

www.homedepot.com

 

I will be drilling pilot holes, yes yet more install time but I am willing to do it for this project so it will last longer. The last install went from 1992 to 2022 so was pretty good but the treated lumber in 1992 was much better and today's.

 

I use ss screws in ipa with no problems .

Need a small pilot hole but never had an issue even with Treated.

 

I hate nails for the most part, and use screws for almost everything. Definitely for this.

3" is the right length, but the problem I see with the screws you picked is that the bare shank isn't quite long enough for screwing in 2x material. What you really want is something that looks like this.

Amazon.com: #9 x 3" Bronze Star Exterior Coated Wood Screw Torx/Star Drive Head (5 POUNDS - 395 Approx. Screw Count) - Multipurpose Exterior Coated Torx/Star Drive Wood Screws : Industrial & Scientific

Shop Amazon for #9 x 3" Bronze Star Exterior Coated Wood Screw Torx/Star Drive Head (5 POUNDS - 395 Approx. Screw Count) - Multipurpose Exterior Coated Torx/Star Drive Wood Screws and find millions of items, delivered faster than ever.

www.amazon.com

Or at least has a counter thread in the shank area, like this.

Amazon.com

Alternatively I guess you could predrill a hole a little bigger than usual in the plank only, so your screw threads don't catch on in the plank.

The reason for this is that if the threads are stuck on both pieces of wood, the screw won't pull the plank tight. You can never get two pieces of wood really tight if the threads are catching in the top piece.

 

This is another option from Amazon. 316 stainless steel marine grade 3" deck screws.

#10 x 3 Inch 316 Marine Grade Stainless Steel Wood Screws 350 Pack T25 Star Drive Type 17 Point for Docks, Decks, Jetties, Fences or Any Coastal Marine Construction by Eagle Claw Fasteners: Amazon.com: Industrial & Scientific

#10 x 3 Inch 316 Marine Grade Stainless Steel Wood Screws 350 Pack T25 Star Drive Type 17 Point for Docks, Decks, Jetties, Fences or Any Coastal Marine Construction by Eagle Claw Fasteners: Amazon.com: Industrial & Scientific

www.amazon.com

 

Yeah, those screws look closer to 50% shank, which is the optimal number. (Did a quick nerdy calculation and got something like 38% for the first one, and 45% for the second one.) I also like the head design better - should countersink a little easier in theory.

 

Above tried it which is endorsement that's more than none at all. Though i would verify by testing the screws with good magnet. Some stainless from china had enough steel for magnets.

 

Above tried it which is endorsement that's more than none at all.

Huh?

 

With 2x decking I would use 3” screws. The unthreaded shank is long enough to virtually go through the deck boards. That lets the screws pull the decking down tight.

 

The unthreaded shank is long enough

Which screw are you talking about?