I need to make up some 90 x 20 treated pine screens this weekend and am wondering about the best way to fix the horizontal slats to a vertical piece of the same timber behind, ie fixing through 2 x 20mm TP, outdoor application.

I thought about a heavy duty staple gun, but would they fix through 20mm and how would the staples hold up in the weather??

The only other options are to nail using a paslode, with 35mm braids or use short screws and fix by hand (uurrgghh).

Any thoughts on the most efficient method ?

cheers.