composit decking as guardrail cap
handydadtom
| Posted in Construction Techniques on
Used Evergrain 2×6 composit decking as a “decorative” guardrail cap over doug fir 2×6 top rail. It’s on my deck that I built about 15 years ago. Needed some post maintenaince so had to take off the old top rail. Almost all the deck screws which I used to attach the Evergrain had sheared off due to expansion and contraction of the Evergrain in relation to the doug fir 2×6 that it was attached to. Length of the caps are about 16′ long. I paid attention to the proper gap between the 2 pieces per manufactures specs
I’m rebuilding and thought this time maybe just a perimiter bead of silicone for attaching the composit to the 2×6? Any thoughts would be appreciated on the best approach.
Replies
Tom
Can't say as I've run into this problem with composite decking b/4. Perhaps the screws were overdriven? The density of composites is greater than wood. To flush up or countersink in the rail, it's possible to put too much strain on the screws.
did the screws show any rust at the break? Today, there are screws meant for composites that have a thread change up near the head. Not sure of the science behind it, but I'd go that route.
Permanent bond using silicone won't work for long.
I did use the composite screws with the double thread and didn't see any rust at the junction. I suppose I may have overdriven but I just went flush with the heads. I live in Central California and it can get to 100 degrees + in the summer and 30's in the winter and know that the junction of the two 16' pieces would seperate almost a quarter inch in the cold weather and close on hot days. I assumed they probably were sheared off or at least stressed so they broke at the junction as I withdrew them.
Possibly inferior screws. I can recall about 15 years ago getting a box of deck screws from HD and having about half of them break while I was driving them