Home>Discussions>EXTERIORS>What is the proper way to wrap 4x4 columns so they'll last?
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What is the proper way to wrap 4x4 columns so they'll last?

Hello, all. I want to wrap the columns of my new patio but I'm not sure how. They are pressure treated 4x4's & I'm thinking of "wrapping" them with clear pine 1x6's, but at the base I'll use PVC base board 1x6 or 1x8 so no wood will be touching the concrete patio. Let me interject here that I'm sort of a hack carpenter. I know enough to make it look right but maybe not enough to make it so it will last. I was thinking of using miters & biscuits or maybe "locking rabbet" joinery I found on the internet that seemed ultra secure. The joinery - I can do that. But here's my issue: From my research most people think it's critical to install the wrap in such a way that it "floats" on the 4x4. In other words, I've read where guys have glued & screwed wrap to there posts, only to have the joinery split several months later due to wood movement. I'm in Georgia, south of Atlanta so we have plenty of humidity, heat & yes, sometimes pretty cold (a few winters back it hit 7 deg F). So...how should I "secure" my wrap to the 4x4 to allow for proper ventilation & movement? I want to do this project only once! Thanks for your time!

Re: What is the proper way to wrap 4x4 columns so they'll last?

i do quite a few post wraps for decks and porches. the last few years i have been using nothing but azec. when i do it i simply use butt joints because of the amount of expansion and contraction that the azec has. if the post is 3 1/2" x 3 1/2" ill make the first two peices of azec 3 5/8 and keep them flush to one edge, then make the 2 larger peices 1/4" wider than the overall width, i do this so i can make a 1/8 reveal on the joint as opposed to keeping it flush. this is because of the expansion. the first post we mitred after about a year the 4x4 moved so much that the azec literally split from the tension

as for fasteners i simply run a light bead of white poly butyl caulking along the joints and nail it with stainless steel gun nails though hand nails will do just fine. teh problem with galvanized nails is that they will "bleed" which leaves streaks running down the trim (no good) we found this out on a job which took $40,000 in azec alone

Re: What is the proper way to wrap 4x4 columns so they'll last?

We use 1" spanish cedar and a simple rabbet joint at the corners. Two of the boards get rabbets down both sides, and the other two boards have straight edges. Of course, they are different sizes so the end result is a square box. I like leaving a theoretical 1/4" gap inside for the 4x4 to do its own thing.
In my experience the fancy lock-type joints are not worth the aggravation. They may be great in a factory where you have setups and hydraulic presses to clamp everything together in an instant, but in the field where you're fighting gravity, clamps, and drying glue they are a needless hassle. A glued rabbet joint is amazingly sturdy, and provides he needed alignment aid.
Backprime everything especially the bottom end grain. Clamp and nail them together with glue. Then sand or plane the joints until smooth. You plumb them up and tack nail the wraps in from all sides. Once it's all plumb, anchor with some screws. Do yourself a favor and use all stainless fasteners.

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