Thread: Setting posts for fencing

Originally Posted by Tiger

[snip]where the mixture is tamped repeatedly.

Tamping is where you are pounding on the top of the material, I don't know if there is a particular name for what you mean - other than "mixing"

I would like to know what the proportion of soil to cement should be

"soil" ?? DO you mean sand? 4 sand and one of cement is a good mix. You should also have some "bluemetal" in the mix (maybe 1 to 2 shovels full).

and how hard to tamp.

You only do this "mixing" to ensure that the sand/cement mix is properly settled, ie no air pockets or gaps. You do not need to pound it around the base of the post to gain "extra strength".

I have had a go at this before with a heavy crowbar but it was a lot of work

Try something lighter like a stick or the blade of your shovel. You are not trying to impact on the mix, only remove space or gaps in the mix.

and the post moved anyway later.

Most likely because the surrounding material ie the ground around the post was not firm enough to hold the post, or perhaps the post was not deep enough in the ground? I replaced a Jarrah (closed) picket fence not too long ago and used jarrah posts these posts were at least 2 feet in the ground.

Does the soil have to be dry orpartially wet?

It doesn't really matter, as long as the soil is FIRM. Wetting it can cause the hole to collapse and/or make the surrounding area soft. If the soil is damp it helps the concrete mix "cure".

Saw a guy put in a few posts in about an hour, he didn't seem to be exerting himself much and only did what looked like minimal tamping.

Sounds about right to me

For rigidity, you need to keep the post hole as deep and as narrow as possible. 12"/300mm square is a good size. Prepare the sand/cement/bluemetal mix BEFORE putting it in the hole. DON'T do it like they do on tv and pour the dry mix and water in the hole.

BTW a six inch hole surrounding a three inch post with the mix put in like on tv (dry mix / water in the hole) is almost no better than the post in the hole by itself.

Hi
I've used the tamping method before and to be honest I find it easier to simply concrete the posts in. If you want to ram them in here's what I did
make sure holes are 600 mm deep min
use poured concrete for all corner posts and gate posts
I never used cement with the mix, though I suppose 1 to 10 would stablize the soil.
don't use this method if the ground is too sandy
make the soil damp not wet
ram about 200 mm at a time with length of fence post or rail, it has to be flat not pointy like a crow bar
This is the way I've done it before but don't take it as gospel, and like I said I find concreting them in easier

to make it easier on yourself i would use rapid set concrete.
about half a bag per hole
just pour it into the hole add water
use shovel/stick/whatever is handy to help put a few 'holes' in the mix and you are done

cheers rackrussel

Hi Tiger, unless you have very sandy soil i wouldn't worry about mixing cement with your soil i was a contract fencer in western central queensland for a while and all we did was tamp the soil back in to the hole the secret is don't be tempted to tamp too much soil at a time ,a little soil tamped more often will give you a better result. I have my own property now and i still use that method works great.

With tamping you need to put only a little bit in at a time and tamp home. The back of a crowbar works best, but like the earlier posts soil type can vary the result. All the fence posts put in here are tamped soil only and solid as a rock, if you throw all the soil back in and just ram from the top you will only firm the top and leave the rest loose hence wobbly posts. Concrete usually hold moisture around the posts causing them to rot a bit faster, but its easier to just chuck the quick mix in dry and after a quick ram to firm the top flood the post with water or if really keen you can wet the premix first and after getting the post level wait for it to dry.

JohnC

All of the replies you have had so far have their merits. Believe me I have set too many fence posts to mention so here is my method depends on your soil type of course so I am presuming clay loam or similar: make the post hole 600mm deep and about twice the diameter of your post,ensuring the sides are nice and vertical. try not to disturb the surrounding soil too much.Set the post in position and brace temporaraly on two sides at 90 degrees to ensure vertical. Rapid set concrete is great but quite expensive, but 20kg bags of concrete mix do the trick (1 bag per post). It's best mixed in a barrow and tamped to remove air with a stick or similar. Tamping with a crowbar will push your post out of alignment. Try to use the minimum amount of water in the mix to ensure maximum strength.
Have fun

Concreted in posts = rot
Tamped in posts = lasts a lifetime
My brother and I farmed for a few years and we put in a few posts (low thousands) plus I've put in more than a few posts for pole homes, sheds, decks verandahs etc. Concreted inposts will generally rot off just where they exit the concrete. Dig a hole about 600 dia for fence posts, throw a bit of coarse gravel in the bottom to sit the post on, this will drain any water away from the bottom of the post. Stand the post in the hole and steady it (iether a helper or a few bits of timber. Throw a few shovel fulls of dirt in and tamp with the pointy end of the bar, continue till you've got about 1/3rd of the hole done, then swap to the spud end of the bar. keep throwing in a few shovel fulls and tamping, you should run out of soil before the hole is full. Get dirt from elsewhere and keep filling and tamping until you get above soil level and you build a cone shaped collar to shed the water. Fences and sheds that I put up 23 years ago like this are still fine, and we live in a very high rainfall, humidity and sunlight area (read: great conditions for decay)

Mick

Originally Posted by journeyman Mick

Concreted in posts = rot
Tamped in posts = lasts a lifetime

Mick

Please excuse my ignorance, but why do the concreted ones rot?

Would the problem be solved if the concrete is allowed to finish above ground level and tapered?

Interested to know because I am going to build a cubby house with 6 poles (H4 treated crap stuff) about 1800 off the dirt. I was going to concrete them in so I like to know how to avoid the rot you speak of.

Boban,
even if you mound the concrete up above ground level you'll get rot. the timber will expand and contract with moisture changes and there will be a small opening in the conrcete around the post. Water will get in here and not dry out very quickly. Add to this the fact that your timber will probably be a bit green to start with and shrink over time which will give you a bigger gap for water to get into. Materials wise it's cheaper to just ram earth around the post, but it's more expensive when you factor in the labour. Yhis is why most contract fencers (of domestic not rural type fencing) use concrete. Cheaper and quicker.

Mick

I agree with micks method on heavy soils with wooden post, bang em in right & they'll stay firm.
The big advantage is that you end up with a compacted gradient arround the hole which is more secure than concrete.

I've found with skinny metal posts ramming dry premixed cement mix does the trick. Moisture in the ground will set the cement off in a couple of days but the post is firm anyway. If the ground is dry sling a bit of water in the bottom of the hole. A wet mixed collar just at the top helps with corrosion.

There are as many ways to set a post as as ther are days of the month, But I know micks methosd works.

You do need a bar with a big round disk on one end.
Don't kid youself, it is hard work.

cheers

It is as Mick said they hold water, it gets into the gap between the post and concrete and cannot get away. If you really must use concrete sit the post on the ground in the hole and place about 75mm concrete in the hole, tamp with soil up to near the top and make a similar concrete collar up there coned so the water will run away from the post, the condensation still gets between the post and the concrete but is wicked away by the soil. Like Mick I've done a fair bit of rural fencing before the days of the post hole rammers and if you are carefull you do not get your square town posts out of level, simply check levels as you go and tamp a bit harder on the side you need to push away from, those post levels make life easy these days . To give you some idea four blokes with a tractor auger and crowbars could do about 1km of posts per day, you simply run one post out about four from your last and then sight between the posts to fill in the gaps, the fourth bloke coming up behind with the wood borer for the wires does the sighting. Hard work and something I never missed I might add.

JohnC

Originally Posted by johnc

...........Hard work and something I never missed I might add........

Yep, same here, avoid anything like it like the plague.

Mick

You didn't say what you are using for posts but if possible on the section of the post that will be underground affix two battens at right angles to the post and each other using treated pine etc... you can do this by flattening two arears at the bottom of the pole And nailing the battons on , I usually use galvo nails.
Once in the ground it dosn't matter if you concerte or tamp the braces give the post better strength in all directions but as previously get them straight and brace them dont try ot align straighten them later espically if you concrete





Don't take life too seriously; No one gets out alive.

Originally Posted by journeyman Mick

Concreted in posts = rot
Tamped in posts = lasts a lifetime
My brother and I farmed for a few years and we put in a few posts (low thousands) plus I've put in more than a few posts for pole homes, sheds, decks verandahs etc. Concreted inposts will generally rot off just where they exit the concrete. Dig a hole about 600 dia for fence posts, throw a bit of coarse gravel in the bottom to sit the post on, this will drain any water away from the bottom of the post. Stand the post in the hole and steady it (iether a helper or a few bits of timber. Throw a few shovel fulls of dirt in and tamp with the pointy end of the bar, continue till you've got about 1/3rd of the hole done, then swap to the spud end of the bar. keep throwing in a few shovel fulls and tamping, you should run out of soil before the hole is full. Get dirt from elsewhere and keep filling and tamping until you get above soil level and you build a cone shaped collar to shed the water. Fences and sheds that I put up 23 years ago like this are still fine, and we live in a very high rainfall, humidity and sunlight area (read: great conditions for decay)

Mick

Interestingly and contrary to popular opinion, placing coarse aggregate at the bottom of fence posts will create a perched water table above the aggregate, thereby increasing the chances of wet rot.(refer to p. 92, Drainage For Sports Turf and Horticulture, Keith McIntyre and Brent Jakobsen). The proven theory is that water will not move through a soil profile from a fine textured soil (surrounding the post and above the aggregate) into a courser textured medium (the aggregate) until the profile is saturated. It is therefore preferable to have the base of the post in direct contact with the soil. Treating the below ground part of the post with creosote or sump oil can greatly increase the longevity of the timber.
Cheers, Micro