Use concrete to set wood post?


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Old 08-15-10, 11:40 AM
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Use concrete to set wood post?

hi folks Ė

Hope this is correct forum. I want to replace the roadside mailbox at my house. I want to use either a cedar wood post or a pressure treated wood post. Are you supposed to avoid concreting in a wooden post? Seems to me I remember people saying donít ever cement a wood post in the ground because the hole will retain water and thus accelerate wood rot.

Instead dig a hole, put 4-6 inches of gravel in the bottom for drainage, place the post in the hole, and then tamp the dirt down and make sure the post is straight. But seems to me Iíve also heard people say cement the post in.

Any thoughts would be greatly appreciated!
 
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Old 08-15-10, 12:35 PM
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Concrete (not cement) is often required as support for decks and such...but they sit on top..not in it.

For a mailbox..I'd do exactly as you suggest.
 
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Old 08-15-10, 12:41 PM
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Since it it not structural and not under a lot of stress, concreting them in the ground is what we do. Just dig a hole 1 1/2 times the diameter of the hole, fill the bottom with gravel, set the post, tether it off with stand off support, pour the quickcrete in the hole, dry, hose in some water and poke it with a rebar to get the water down in the concrete. Much faster and easier than mixing the stuff up.
 
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Old 08-15-10, 01:19 PM
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From what youíve heard or read, youíve gotten mixed opinions. Iím sure youíll get them here too.

I think either method youíve outlined have pros and cons. The main reason for concreting in a post is to help stabilize it, and prevent blow down if a fencing structure is involved, especially a solid one that doesnít allow air flow through it. The concrete does not prevent the post or pole from rotting although it may slow down the process (I havenít seen convincing evidence suggesting it accelerates rotting) . . . a royal pia, however, having to pull out concrete embedded posts from ground when they do rot and need to be replaced, and main reason I donít concrete most of my posts. Some exceptions are end posts on fence lines, a post under stress due to weight of a gate, or a tensioned guy wire.

The original owners of my property installed a 4Ē x 4Ē PT post . . . it was showing evidence of rot after about 5 yrs., and suspect it was caused by them using an Ďabove-groundí PT post (marked as 0.25). It didnít matter as a girlís foot slid off the accelerator of the truck she was driving, and took out all of the mailboxes for the small community. Being a Sunday, and no marine lumber yard being open, I went to HD and replaced the broken post with a Ďground-contactí 6Ē x 6Ē PT post (marked as 0.40). Had one been available that day, I would have at least used a Ďpermanent wood foundationí 0.60 PT post or possibly a Ďsalt waterí 2.50 PT depending on price difference. Thankfully, it was not concreted in the ground making it easier to replace. I installed it 3í in ground so that if kids were purposely trying to knock it down with a vehicle, they would have to work at it. Where I reside, the water table is shallow and sometimes hit water when digging only 2 or so feet down and reason why I prefer higher PT rated lumber that may not be necessary in your area.

You should search the U.S. Postal Service guidelines for installing mailboxes as it may prevent having to re-do if youíre not in compliance . . . Iíve lived in areas where the postal carriers are extremely strict and other areas where they donít enforce the guidelines if out of compliance in a reasonable manner. Since there is a range of acceptable heights, you might want to measure a comfortable distance from window of your vehicle if picking up mail from car or truck . . . low range makes it difficult to reach if having a larger sized truck and visa versus if you have a small car.
 
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Old 08-15-10, 03:07 PM
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For a mailbox I probably wouldn't bother with concrete, mostly because I'm to lazy to hump those 80# bags. The advantage of filling a hole with dry concrete and hosing it down is that the chances of the post ever falling over is minimal. I would probably just dig a hole and put a few inches of gravel in the bottom to help drainage. I would make sure the backfill is compacted.

IIRC the post height should be around 42" +/- a couple. That means a post nearly 6' long.

If you decide to use cedar make sure it is heartwood. Sapwood cedar in the ground won't last much longer than pine. If you use PT, make sure it is rated for ground contact.

I don't think a PT post set in concrete is any more susceptible to rot than one set in dirt.
 
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Old 08-15-10, 03:54 PM
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I think I've heard of people putting a pipe in the ground fiurst and then the post for their mailboxes. It makes it much easier for them to replace the post when needed. I think it also allowed them to spin when the plows drive by and hit them with snow.
 
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Old 08-15-10, 03:55 PM
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Thanks a lot guys. A wealth of information here. Very good to see the different pros and cons. I afraid to see how hard it will be to get my old one out. Looks like itís on just a short wood post. It has one of those hard plastic formed mailboxes with the formed leg that slips over a post and is bolted to it. (Hope that short post isnít in concrete.) I will in fact check the U.S Postal Service guidelines.

(My neighbor has a funny mailbox. Itís on some kind of springy curly pole that you would think should be connected to a punching bag. Have to ask him if he did that because of previous knock-downs.)

I did not know at all about the PT rating system until you folks mentioned it. Glad you did. Good to learn that. Didnít know about heartwood and sapwood also. I think Iím in good shape to tackle the project.

Thanks a lot folks for your time and the very good information.
 
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Old 08-15-10, 04:05 PM
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Originally Posted by drooplug View Post
I think I've heard of people putting a pipe in the ground fiurst and then the post for their mailboxes. It makes it much easier for them to replace the post when needed. I think it also allowed them to spin when the plows drive by and hit them with snow.
Just saw this one too drooplug. Thanks. Sounds like a pretty good idea.
 
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Old 08-15-10, 07:22 PM
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Since you are in SE PA, you may have some real snow. - Snow plows do not slow down for mailboxes and they can easily destroy them.

I lived in newer suburban area that required 2 car garages and no overnight parking in the winter. The speed limit was 30 mph, but the plows usually went 40 mph during the night. If you submitted a claim for damage to a mail box and it was set back as appropriate, the city paid. If it was in the "snow war zone" or too close, it was the owners problem and cost. In rural areas, the speeds are much greater.

Dick
 
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Old 08-16-10, 03:52 AM
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Dick, funny you mention the setback. I had a friend who was in a snow zone who set his mailbox perfectly at 34" on the right of way. Snow plows deep sixed it first winter. He set it back a little. No problem with the snow plows, but the Postal service refused to deliver since it was set too far back for the carrier to not have to reach.....poor baby. Sort of a Catch 22.
 
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Old 08-16-10, 08:43 AM
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We do get some real good snow storms around here (think there was some kind of all time record set for the deepest snow ever seen around here last winter). So far the plows havenít hit mine - but thatís a good thing to keep in mind. But the plows do push the snow up several feet around my mailbox post and also create a big snow-wall where the driveway meets the road. They are extremely rude (just kidding Ė they do what they have to do.)

(I dig myself out by hand. Sometimes takes me 8 hours to do 90-100 feet plus area near garage. My late sister thought I was nuts since Iím 65+. But I donít need no stinkin plows to do my driveway!)

I think Iíll check with my neighbors to see what kind of problems they have had in the past with plows. Good thing to consider when doing a mailbox. Never even crossed my mind until drooplug first mentioned it below.

Thanks folks!
 
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Old 08-16-10, 11:04 AM
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Mail Box Post

I saw this idea in farm magazine:



The brown frame is made from round pipe and fits loosely over the round blue post so it can swing out of the way when struck.
 

Last edited by Wirepuller38; 08-16-10 at 11:06 AM. Reason: Added last statement.
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Old 08-16-10, 04:45 PM
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You don't even need much snow to have your mailbox taken out. An inch or two of slush on the road with a fast moving plow would do it. Some of those guys try to knock down the mailboxes with the snow.
 
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Old 08-16-10, 05:45 PM
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Originally Posted by Wirepuller38 View Post
I saw this idea in farm magazine:



The brown frame is made from round pipe and fits loosely over the round blue post so it can swing out of the way when struck.
American ingenuity is alive and well. Thanks.

Originally Posted by drooplug View Post
You don't even need much snow to have your mailbox taken out. An inch or two of slush on the road with a fast moving plow would do it. Some of those guys try to knock down the mailboxes with the snow.
I can believe that. Sometimes we have real immature people doing jobs they shouldn't be doing.
 
 

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