Do I need to screw down both sides of a composite deck board at each joist?

Question

I'm going to be using 6" composite deck boards to redo our front porch. I'm going to use a hidden screw system where you screw it down diagonally along the edge. The typical screw pattern looks like this:

| |          | |          | |          | |          
-*------------*------------*------------*------

-*------------*------------*------------*------
| |          | |          | |          | |   
-*------------*------------*------------*------

-*------------*------------*------------*------
| |          | |          | |          | |   

I was wondering if I could get away staggering them as such:

| |          | |          | |          | |          
-*-------------------------*-------------------

--------------*-------------------------*------
| |          | |          | |          | |   
-*-------------------------*-------------------

--------------*-------------------------*------
| |          | |          | |          | |  

My thinking is that the main reason to screw each side at each joist is to prevent deck boards from twisting. However, AFAIK, that's not an issue with composite decking.

The pros of this plan is half the hardware, half the time to screw down.

But are there cons to my plan?

Answer 1

As Michael Karas has stated follow the manufacturers' instruction for clip placement. If, for any reason a warranty claim is needed and it is found that directions weren't adhered to it will be hard to file for reimbursement. From my experience with composite decking the more fasteners the better. I've repaired a couple of hidden fastener deck jobs were they had worked themselves loose from the decking allowing the boards to become misaligned. FYI: heed the joist spacing. Depending on the composite thickness you may need more than 16 inches O/C.

Answer 2

My experience with composite deck boards is that they flex more than similar sized solid lumber. I would not take the quick way out and instead fasten the deck boards in the manner recommended by the manufacturer. Most certainly the manufacturer directions will also have something to say about the joist spacing as well.

Overall my take is that the more points you secure the deck boards to the joists the less flex that will be felt in the floor as you walk around on it.