Screws work themselves out of gate?

[markchamness]

I built a gate for my fence last year using pressure-treated 2x4's for the frame.  I fastened it together with exterior grade pocket-hole screws (NoCoRode PLUS PocketMax)http://www.mcfeelys.com/product/1025-PMT/10-x-2-58-NoCoRode-PLUS-PocketMax

Unfortunately, every three months I have to re-tighten the screws.  They seems to work themselves out of the wood.  Maybe it's because the gate is exposed to temperature changes and rain.  Any suggestions for a better fastener that will stay in place?  I thought screws would be better than nails.

 

[Qwas]

Is it possible to drill holes through and put bolts, lockwasher, and a nut in there?

 

[Eli]

or even a nylock nut. Otherwise back out the screws and dip them in epoxy before re-driving them?

 

[dltflt]

Why not countersink them and put as plug in the C.S. hole with some exterior glue.  That should hold the screw in place.

 

[JimRay]

Mark:

Without knowing the construction method used it is difficult to difinitively tell you whether a different fastener would be better. However, having had some experience with Square Drive Screws, I'd say that the choice of screws is not the problem. I suspect that the wood has been drying out since the gate was constructed, and as it shrinks, the screws are loosening. Pressure treated lumber is most often extremely wet when purchased. My other thought is that the gate is shaking enough to cause the screws to loosen - most likely the result of depending upon the screw for structural support rather than as the clamp that secures a joint. If you are using a Butt joint, for instance, and the Pocket Hole Screws are drawing the joint together as well as providing the structural integrity, the banging of the gate could certainly cause loosening. I would not expect that plugging the hole would help this problem. I would suggest that a better construction method would be to use Domino tenons (or a similar tenon type joint - slip tenons, loose tenons, etc), and use the Pocket Hole Screws to lock the joint mechanically rather than relying soley upon an adhesive.

Hope this helps.

Jim Ray

 

[markchamness]

Jim,
You are correct about the wet pressure-treated wood and the Butt joints I used.  You are a mind-reader.  Thanks!