Thread: Setting posts for fencing

You got it stylesy, It paid off to pay attention in class after all . The same concept applies to the base of retaining walls, drainage lines etc. I agree the text is boring but makes enormous sense. Handreck and Black is more readable.
Cheers, Micro

Just had another thought on the adhesion/cohesion/capillarity concept. How about using crushed basalt fines under and around the post, right to the soil surface. If well tamped the capillary attraction of the tiny pore spaces in the surrounding soil should keep the timber post relatively free from water. Any thoughts Craig? and if it works we should take out a patent

Cheers, micro

Ever thought of a nice brick wall..... or a hedge.....or better get your neighbour to put the fence up

How about using crushed basalt fines under and around the post, right to the soil surface.

Micro,

While this should work to draw water away (and I remembered the reasoning - all to do with increased surface area within fine particle soil profiles), the increased particle size such as basalt fines would not provide the support needed. I guess it would act a bit like sand - you can compact it, but only to a point - the spaces between will always be dictated by the size and shape of the particles. This means you may end up compromising too much stability, as even when compacted the fines may move over time, more than standard soil (even finer particles) would. :confused:

And I'm thinking too much today, but it still beats working

Cheers, Craig.

OK Craig, I think you are probably right about the stability. The fence posts might be rot free but a bit wonky in time. Ah well, forget about rags to riches then.
Cheers Micro

it's interesting what Mick said about rot (god knows I speak enuff of it). Having watched several hundred American home renovation type shows, I have seen maybe 30 fences put in and none of them had concreted-in posts. I guess we think we need it to stop the fence from falling down, but tamping is pretty bloody tough! My next (front, picket style) fence will not be concreted in..... in fact, I have toyed wit hthe idea of making it in sections but doubt I will.....seems an unnecessary strain on the body to lug the things down the front after making them.

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

Make it even easier on yourself and don't waste your time with "half a bag". Unless it's a VERY BIG bag, such a small amount of rapid set concrete does nothing for support, it only adds a little extra mass at the base of the post.

Using this method of adding the water to the dry mix ALREADY in the hole prevents a PROPER mix being done (unless you add too much water to enable easy mixing).

I was stunned when I saw this method first used on the various "backyard" programs. A "piddly" little hole surrounding a post with a "skin" of rapid set concrete around it! What a waste of time and effort and money. THAT amount of concrete is just a waste as it does very little for support!

Journeyman Mick says that posts will rot when concreted in the ground because of the small gap which occurs and water gets in....my question is - can you fill this gap when it occurs with "no more gaps" to keep the water out? "No more gaps" should expand and contract with the gap. What do you think?

I believe it is the concrete that stops or retards the water getting OUT from around the wood that is the culprit...... and I believe also that water will get in no matter what is done

Hi Journeyman................one question......is the tamping method still good for the posts that have to support the gate, especially the longer driveway gate? Or should these be concreted in? Is there a more long lasting timber post than cryprus? Thanks

Neddy,
tamping is still fine for a gate post, but depending on the size, weight and length of the gate(s) you may need to use an oversize post, go really deep, brace it back to another post or corner or all of the above. And sorry, no I don't know any formulas for determining the sizes or bracing required, it varies with the soil type, we just did it by experience/local practice.

Mick

Ned,

An early way of bracing around here was to put a cross at the base of the post out of 2" x 1" or thicker and brace it at 45 degrees back to the post. Any I pulled out seemed to only come out about 6" from the post and none seemed to shift under the weight of the gate. I could never get excited about the method, and simply braced back to near the next post in line. Generally timber that does not break the surface is very slow to rot, you need both water and air to create rot and in tightly compacted soil there should be little air and if a well drained soil not a lot of water. As for no more gaps to stop water, even if it did work it would not prevent moisture building up in the gap as water will draw through concrete and expire through timber to penetrate the cavity between post and concrete.

JohnC

Thanks Jonnyc......has anyone ever heard of using scoria to support the post....ie. sit the post in the hole and simply tip in the scoria, as you wiggle the post around the scoria compacts untill the post is as solid as............a farmer told me this but I'm a little bit wary of the method.

Originally Posted by neddy

has anyone ever heard of using scoria to support the postme

Scoria, if you get it as its forming it sets as hard a rock
mind you the post might not last.





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