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I'm thinking of building a mailbox like in this picture

image

Problem is that I need to bolt it down onto concrete. Any suggestions on the best way to support 2 pieces of 2x10 at around 4 feet high?

  • The concrete that you're bolting to is existing? How thick/wide is it? – Daniel Griscom Mar 10 '16 at 15:43
  • I have not measured it but it is on a concrete walkway that comes off the driveway – reaver Mar 11 '16 at 18:10
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Drill baby drill. Drill 1/2" or a bit more for glue or epoxy-fill holes in the concrete & in the bottom ends of the boards, 4 in the concrete & 2 each in the boards. These would receive steel Rebar, big Rod, Threaded Rod, Bar Stainless Steel, etc. I'd guess 4" deep into the concrete & at least 6" into the boards. I haven't done, so you can let me know what works or doesn't.

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  • Thanks, I like your suggestion. I think I'll try to go this route but my challenge would be to make sure I drill straight 6" deep into the boards. I might do 3 holes on the board and go with 1/2" rebar to try and make it as sturdy as possible. – reaver Mar 11 '16 at 18:12
  • Sure, go to 3, the more the better. Drill upside down on a work table. You just set the top of the drill down & simply slide it in & out...since the top of the drill is usually flat. Depending on your drill, you'd build up the piece's side or the drill's side & let the bit do the work. Spade bits work best for anything over 2" deep, Straight bits warp & bind & Forstner bits cut way too slow & bind. Hammer (2 or 3lb mini-sledge) the Rebar into the wood first & then hammer the boards into the concrete...using the board weight to your benefit. Likely no glue needed...your call. – Iggy Mar 12 '16 at 3:02
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You could use a couple "post base" style anchors. Paint them and/or hide them with potted plants. To make it stronger, buy one for 6X lumber and sandwich the 2 x 10 between 2 short pieces of 2 X 10 (bevel cut at the top) before through bolting them.

Of course, the best way is to bury them or sink them in concrete.

enter image description here

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  • Thanks for the suggestion, I did consider this but I'm worried that the boards might sway because the post bases are not rated for lateral loads. I did see a post base that can handle lateral loads but its a bit pricey for this experiment. I might go with the hidden rebar suggestion and see how it goes. – reaver Mar 11 '16 at 18:14

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