Hello,
Had a guy in the local hardware store recommend painting asphalt emulsion paint on the bottoms of fence posts (where post goes in concrete) to help maximize the post life.
Any concurrences or other thoughts on building a fence to last as long as possible?
Posts are 4×4 cedar….
Thanks,
Mac
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Replies
IMHO that is a waste of time and money--I say that because most post rot is just below the dirt line or in your case the cement line,
I am not going to get into the whole cement, rock, dirt , backfill issue here.
I have yet to see a post rot from the bottom up--It is from this subsurface rot that a post fails.
In dirt there are microbs that live just below the surface that thrive on wood to break down for nurishment, same microbs keep forest floor clean, which is why unprotected post rot just below the surface,
These microbs are arobic and therefore can't live on wood 3 feet in the ground, this rot happens from post in foot holes that hold water and the freeze cycle takes care of the rest.
Any protection that I would apply to the post would be in the form of a brush on preservative similiar to the "green treat stuff" The name escapes me but others may help you with the name.
second I would use a good post hole design that will pay off handsomely with a long lasting post.
Hope some of this helps and your project goes well , Mike
Sorry I wasn't clear, I didn't mean just the bottom of the post but the bottom 18" or so. My plan (after hearing this idea about asphalt emulsion) was to paint the posts up to 1" above cement line, angle cement away from post (for water runoff) and hopefully, have some additional protection at the point where post meets cement. Seems like that's the weak point in fences...Thanks for the quick reply.Mac
If you go to the trouble of ramping the crete then I would flatten the top 1/2 inch or so and wrap the joint between the crete and the post with Polyurathane sealant which will stretch as the post shrinks to keep the hole in the crete that the post is in dry and therefore saving the bottom of the post from the water that may get in. Go get em. Mike
Good suggestion - i've got a tube of poly sealant laying around in my garage somewhere. I'll locate it and add that to my to Do list.Thanks!Mac
Your'e welcome--be sure to snap some pic, and let us know how it turn out,Mike
Fence is finally done - we got hit with rain for two solid weeks and my truck's transmission took a dump which slowed me down a bit!I did set the posts in concrete, mounded the concrete up by the posts and angled it away, ran a bead of sealant around the concrete/post conncetion...we'll see. He's got a rainforest in his backyard and a pump that spews collected water from the basement right out at the fenceline. These posts are going to be wet no matter what. I set the concrete above ground level but the corner post floods everytime the pump shoots water out.Scared the crap out of me the first time the pump spewed. I'm walking down painted wood steps in the rain (a slippery proposition!) and I hear a gurgle sound by my feet and a rush of white. Thought the swamp rats were getting hungry!Thanks for the suggestions, guys. I've got a fence rebuild next week, guy used pt posts in concrete and buried the concrete 4" below grade. Every post was rotten at the concrete 5 years after it was built. And somehow, the HOs couldn't locate him. Apparently, he's not in business anymore...wonder why? I'll rebuild using pt posts and packed gravel. It's a much drier soil base than this one was!MacView Image
Looks like a nicely proportioned job Mac. I like the style of those little roofs.
Those of you who live in Appalachia - have you heard of or used split Locust posts for fencing? Tree is called the Black Locust. Locust posts take 50 years or more before they rot. I've seen some decades old without any significant signs of rot. No concrete, no treatments, no sealants - just stick or pound it into the ground. Walk away knowing they'll outlive you.
Edited 4/1/2005 1:29 am ET by Pierre1
HOs rainforest of a backyard was a Japanese styled garden - he wanted a fence to reflect that "look." I thought it worked in pretty nicely with his other structures.Thanks for the compliment, working in Oregon puts me out of range for the locust posts - they sound like iron wood!MacView Image
Nicely done--love the roof idea---was considering the same for a privacy fence at my house over the gate---Not only for looks but for a function as well, Ya see 2 years ago when I built my shed the phone line was in the way,I did the right thing and called the phone com. and they did the typical thing and never came out to raise the wire. so I cut it---ran it into the garage--around the perimeter and out to the house .Which is were the roof idea comes in --I need to hide the phone and sat wires in the fence roof to hide the route from the garage to the house.I see Why didn't you bury it? I word, Cement , a complete slab connecting the house to the detacted garage ( My kingdom)Thanks for the update on your fence--shes a beute. Mike" I reject your reality and substitute my own"
Adam Savage---Mythbusters
mac... i would never set a post in concrete.. it traps the water and keeps the base in the right conditions to acelerate rot
and i would not paint them with asphalt..asphalt will do the same thing.. water moving down the post will get trapped behind the asphalt
i'd use either Cuprinol Green #10.. or Bora -Care..
you can google on either
to set the posts.. dig your hole.. but crushed or graded stone in the bottom.. tamp the stone.. set the post... backfill with tamped coarse gravel.. plumbing the post as you go.. the stone and gravel will allow the hole to drain.. and the tamped gravel will give you the support you need..
and.. it makes repairs easier also
you could go to your homeowner and tell them the concrete is the old method... but research shows it is not the best method
Mike Smith Rhode Island : Design / Build / Repair / Restore
Edited 3/24/2005 7:20 am ET by Mike Smith
My question regarding tamping the gravel and plumbing the post as I go is...how would you keep the posts in alignment throughout this process? In the end you'd have a plumb post but with the battering the gravel will get, it seems like it would throw the post base off a bit. Your fencline wouldn't be totally straight.I don't think water will get behind the asphalt. I painted them up and it looks and acts like paint. It's secure to the post. Do you think the exposed asphalt will peel?I appreciate the info on the board treatments, I'll look them up and see if I can't get them locally. I've been using end cut treatment (can't remember the brand off hand) on all my cut pt, I just wanted to try something beefier on these fence posts. I heard about this asphalt emulsion technique and thought that might do the trick!Thanks again, guys,Mac
Last Fence we built... We set Galvanized Fence Posts in Concrete.. and then built a cedar box to go over the post. Galvanized bolts keep the post square and in place. No heaving and no wood in contact with the ground to rot. A bit more work... but it will probably outlive me...David
you set your posts to a stringline , the same way you would if they were in concrete,
i set all our posts this way.. fence posts, rail posts, stair posts.. all exterior posts
as for trapping water with the asphalt coating : the posts are cedar.. they will check and split... the water will get in.. run down and be trapped behind the asphaltMike Smith Rhode Island : Design / Build / Repair / Restore
Hey Mike,I just finished a fence repair (replacing posts only) because the previous builder used concrete but buried it 5 inches under grade. All the posts were rotten at the top of the concrete.I took your suggestion and installed the replacement posts using 3/4"minus gravel instead of concrete.4x4 pressure treated posts sitting on 4" packed gravel
hole is 20" deep, 16" diameter at bottom, 24" diameter at top
dropped in 3" gravel, packed it down, repeated with 3" increments until hole was fullThese posts wobble. The fence wobbles. Will the gravel mix stiffen up as it gets wet and dries or is that just a signature of using gravel instead of concrete?Do you do anything different to reduce the "wobble factor?"Thanks,MacView Image
mac... our posts are about 30" deep.. the bottom of our hole is about 40"
we get excellent compaction with a tamper..
these columns are slipped over 4x4 posts set on a concrete footing with tamped gravel surrounding them
View Image
Mike Smith Rhode Island : Design / Build / Repair / Restore
Edited 4/6/2005 9:36 pm ET by Mike Smith
Tamper...I used a 4x4 shorty post and beat on the gravel until it was compacted. You're refering to a metal bar with a small flat plate on the end? I'll need to pick one up and see if I can't beat down this gravel some more.Reading your measurements, I went too shallow on the hole depth.I appreciate your sharing the ways you build. There's no structured school for contractors to learn how to do the job right. That's why I started hanging out here. I want to learn the best ways of building.That's a real nice looking lattice wall you built!MacView Image
Usually any noticeable wobble is a result of the amount, inches away from the post and depth being inadequate, the use of gravel that won't lock together because it has too much fines or crud or it isn't angular enough or inadequate tamping.You need enough gravel to go completely around for the full depth and a few inches underneath. Width is a judgment call but something like an extra three inches all the way round is usually good. The gravel should be clean, free of excess sand mud or organic materials. Foreign materials can keep the gravel from packing and locking together and can hold moisture. The gravel should be crushed stone about 3/4" works well. Avoid river rock or any gravel that lacks sharp points and edges. It is the edges that wedge together and lock when packed.I usually pack with just the handle on my shovel but a tamping iron does a better job. If the ground is soft expect to add more gravel. Idea is to center the post in the hole after pouring in some gravel and packing the bottom. Then pack in the gravel in 6" lifts or so. When the handle, or iron rings instead of penetrating the pack is tight.
Gravel's ok, 3/4"minus. Good angular pieces, no earth or foreign crud in the hole when I'm compacting.I'm thinking now I didn't get the gravel packed tight enough. I can fix that!Thanks for the reply - MacView Image
If your interested and do a lot of this sort of thing a good tamping iron is a useful tool to have. Every GC should have one just for bragging rights.The one I like is a 6' solid length of 1" hexagonal steel extrusion. One end has a flat chisel edge that is nice for busting rock in the bottom of a posthole and general prying. Especially concrete when you break a slab. The other end has a shape like the bottom of a wine glass. Quite sturdy and about 3" in diameter. A 3" disk backed by a large chunk of steel and as much shoulder as you can manage. The sharp in is good for prodding the gravel in place and settling it. Flip the unit over and pack it until it rings a bit. These bars are brutes. They run near 20 pounds. Real jobsite aerobics and weightlifting in one go. Wear gloves as the steel is unpadded and will slip and rapidly draws blisters. Feel the burn. A good one runs about $25 or so.Of course a shovel handle, blade still attached of course, is good enough for most small fence posts. You just have to make smaller lifts and a lot of strokes to get a similar effect. And save the heavy artillery for the corner and gate posts where it counts.
I have a cedar fence.. Posts in cement.. Only post that did NOT rot over many years had the cement ABOVE ground level and were crowned to roll off the water..
ABOVE ground level and were crowned to roll off the water..Which is exactally what he said he was going to do and what I said would work well if he was going thru the trouble to crete them I suggested he make a Small flat spot on top to give the sealant a base to adhere to.Maybe we are splitting hairs but when you read something and don't get the visual feedback Ideas don't convay very well.MikeP.S. Sweet ---Chicago---My home town,
Before I respond, I need to know which one of you in your profile photo is you. I'm working on behaving and getting my words right in mixed company, you know.
;)
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we got a guy here that will heat up a vat of use motor oil, to almost a bubble and cook his fence post in them.
I'm the grinning fool on the left! My far better half is in the cowboy hat. I do the heavy lifting, she provides moral support.
Take some roof cement and thin it a bit to allow it to soak in better. Slather it on thick 6" or so above and below the ground level and you will likely will increase the life of the post. I have installed a lot of posts and power poles and I have never seen one rot out from the base. They always fail at or near ground level. This is also where the stresses are greatest.
If you do tar the posts wrapping the tar in newspaper helps keep it off your hands and clothes. No need to remove the newspaper, taped in place with a bit of masking tape, disintegrates after the first few rains.
My preference is to avoid using cement. Cement holds water against the wood and accelerated rot. Old timers used gravel packed in place with tamping rod. A shovel handle works well enough. The gravel drains and dries after the rain.
When I was a kid we used to run a lot of fence for pasture.
Did my share of creosote, did some charring of the fence post bottoms, did some concrete, did some just set in gravel. I prefer soaking in creosote and setting in gravel.
Except for the time I got a splash of creosote up the nostril...
If you're set in putting them in concrete, I have one recommendation. Set the post in the hole, then backfill and tamp a few inches of gravel to cover the bottom few inches of post. Then place your concrete. This will create a concrete collar around the base of the post instead of a concrete pocket.
The collar will allow water that gets between the crete and the post to drain. The pocket will hold the water.
As to your other question, it's not ucommon to dip the post bottoms in a 5-gallon bucket of foundation sealer and then set them in the hole. Sorta the same as your asphalt emulsion.
I don't figure Eugene gets too many freeze/thaw cycles, so heaving shouldn't be too much of a problem, or will it?
Thanks for the tips guys-No - frost isn't a real issue here. it's a pretty mild climate in the winters. Just a lot of rain!I'll do this fence in concrete - I've already spec'ed it out on the contract and I don't want the HO thinking I'm pulling a shortcut to save cash. The next one I'll try using packed gravel like some of the suggestions here. You think I'd need to get deeper than 18" - 24" when using packed gravel w/o concrete? Is it a less stable base than a concrete-filled hole? I can't be building wobbly things now!Gravel being 3/4" minus or 3/4" plus? - Rocks and sand or rocks alone?I'll take some pics and post them next week. It should look pretty cool, it's boxing in a Japanese garden and the HO wanted an oriental-themed fence.Thanks for taking the time to provide some suggestions - I appreciate your input. I may not take and use every suggestion but I'll read 'em all!I've attached 2 pics of the old fence - I demo'ed it today...it came apart like paper! It was definitely time for a new fence.