A contractor apparently did not a good job on rebuilding my deck and after a couple of months caulking in between wooden moving deck railings doesn't provide any sealing from water dripping into the half-wall underneath.

What's a good way to seal those corners? Assuming those wooden railings continue shrinking and expanding.

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1 Answer 1


Miter joints are almost always susceptible to expansion issues like this. It's worse when exposed to direct moisture and heat. Caulking isn't going to entirely stop that from happening--may make it worse if it clogs the joint and leads to worse separation.

Some ideas:

  • Fabricate a metal wrap and drip ledge for the corner, if not the whole rail.
  • Rebuild with a different wood that's more stable.
  • Rebuild out of a composite material that'll never move.
  • Rebuild with a different joint maybe a simple butt or lap. In either case, consider sealing the end grain with epoxy or spar varnish to inhibit moisture wicking up the grain.
  • Thank you. Well, rebuilding is not an option. Building this one took them forever and I don't want to deal with that anymore. I'll take a look into the metal wrap idea. I was also thinking about a T-shaped piece of plastic or other material to insert there that would prevent leaking into it.
    – Nikita R.
    Commented Sep 25, 2015 at 21:10
  • I'd pull up that 1x1" square molding and tack down a metal sheath under it then put the molding back -- kinda like flashing. I'd imagine a gutter or siding specialist could knock it out for you. The corner will be the trickiest bit to bend/cut correctly and someone who knows what they're doing will save a lot of time and possible lacerations.
    – evantish
    Commented Sep 25, 2015 at 22:01

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