My existing deck has a railing system that has no posts - just wooden ballusters secured to doubled-up joists on the ends and to the rim joist on the edge.

I'm interested in switching to a composite railing system, but would obviously need to install posts to do that. The easiest posts to work with my existing decking would be surface mount ones - they all include documentation on how to install them into blocking - but on one edge of my deck I have a somewhat odd situation.

There are four joists very close to that edge of the deck. An edge joists butts right up against two normal joists, and then a third joist sits not far from those ones.

I'm not entirely sure why the original builder decided to put 4x joists in this 12 inch section - but it would make using normal blocking for the posts problematic.

Would using lag screws (or structural screws like ThruLock etc) into the vertical joists be an ok way of anchoring a surface mount post? Obviously if one of the bolts was going to be going into that gap between the joists I'd put some blocking in there

View from under the deck1

  • Sounds like you have the support to bolt a 4x4 along the outside rim joists, this would save on the cost of the surface mount hardware. Do you like the looks of the surface mount better or you just feel it is easier? – Gary Bak Sep 11 '18 at 23:41
  • Yeah, bolting a 4x4 along the outside rim joists would be another good option. I didn't see a lot of good examples of that. I eventually settled on a fascia-mounted aluminum railing that I liked the look of and will be similar to what I have now, but better looking and more code-compliant – Ryan Oct 15 '18 at 14:06

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