Digging post holes and setting the posts.

[Gooner]

Over the weekend I will be erecting athe frame for a 2.4 x 2.4m cubby house that will sit 1.5 meters off the ground on six 100x100 cypress pine posts.

I have read various ways to dig and set the posts, but would like to get some feedback here from people who have done it.

As the posts will sit about 1.5 from the ground and I have relatively soft soil, I will dig the holes about 60-70cm deep. (I assume this will be OK for a simple cubby house on 6 stumps. I doubt it will sink).

Question 1 : Best way to dig the holes? I dont want to go hire an auger so I *was* going to dig with a shovel...... until I thought about it. Probably way too hard. how about a post hole digger? The ones with two handles and two shovel scoops on the ends. Does this simplify the job? How about a hand operated auger? Don;t mind putting a little effort into it, but don't want to break my back at the same time.

Question 2 : How to set into the hole? The guy I bought the timber from suggested using a "fencing method" of digging out the dirt, then mixing the dirt with cement and putting about 6 inches of this mix in the hole. Allow it to set a little, fill up the hole with more dirt (say about 10 inches) then pour in more of the dirt concrete mix, and then fill the rest of the hole up with dirt. He seems to think this will be OK for a cubby house and will save alot on concrete. I've never heard of it.

Question 3: Any special consideration for setting the post considering it is timber?

Question 4 : Best way to make it plumb? I thought about suspending the post so that gravity would do the job. Any other ideas?

I've never done this kind of thing before so any advice would be appreciated.

[Vernonv]

Question 1 : Best way to dig the holes? If you are doing a lot of holes, getting an auger in is worth it ... but for 6 holes I would just use a post hole shovel and crowbar (quicker and easier in the long run).


Question 2 : How to set into the hole? I'd just fill it with straight concrete. You want those footings to be as strong as possible.


Question 3: Any special consideration for setting the post considering it is timber? Put some batten screws into the timber that will be set in concrete, to prevent them from being pulled out and ties the post to the concrete. Personally I would use steel posts.:)


Question 4 : Best way to make it plumb? I thought about suspending the post so that gravity would do the job. Any other ideas?I would use timber stays on the post (two stays). Screw the stay into a peg and the plumb the post. Once plumbed, secure the stay to the post using a clamp ... check plumb again ... then screw the stay to the post.

[oohsam]

Steel posts can be expensive. Nothing wrong with using cypres pine. Make sure there is a bed of crushed rock at the bottom of the post hole for the post to sit on.

[ndaki]

Make sure there is a bed of crushed rock at the bottom of the post hole for the post to sit on.

crushed rock or a sole plate, try to make the plate the same wood type as the posts. i prefer sole plates over rock as it can help steady the posts when setting it straight.

[Vernonv]

Steel posts can be expensive. When I did a cubby house for our kids (maybe 2 years ago) the price of steel was only marginally more expensive than timber (much less than 5% if I remember correctly). So I ended up using steel for the posts and cypress for the bearers and joists.


Nothing wrong with using cypres pine. Absolutely, but gal steel will last a lot longer in ground and is less likely to have any structural issues than timber.

[rrobor]

For me its cypress pine. What I do with my poles is I paint them before they go in. I use any old water base paint under ground, then a top coat of that tarry paint. To keep straight you need your spirit level or plumb bob and a few bits of wood to brace with. Just tack a brace on with the other end of the brace in a hole a few feet away. You will find theres not much movement in a pole with wet mortar round it. If you are in clay, you might need to chuck some water down the hole to soften it for digging, just add some of the wifes wash up liquid, then start the next.

[Gooner]

Ok, thanks for the advice... Here is my current plan of attack....

1. not a bad idea to paint or seal the the bottom of the posts, so I may do that tonight ready for tomorrow. (May use some spare thinned down Feast Watson Spar Marine varnish I have sitting around).

2. Go past Bunnings on the way home and buy a steel pole type crow bar type thingy and a post hole digger.

3. String line the outer perimeter where it needs to be.

4. Dig holes to a depth of about 60cm, use a sole plate at the bottom and perhaps try and make the bottom of the hole a little bit wider than the rest of the hole for a better footing.

5. Hammer in some pegs ready for the supports to keep the post straight.

6. Place post in hole on top of sole plate, fill up with only cement. (What type of cement mix? Would quick set be good enough?)

7. Spirit level or plumb (I find a plumb bob is more accurate) the post and secure to pegs with some timber and screws.

8. Go back to step 4 and repeat for all six posts.

9. Have beer.

Sound good?

[Gooner]

crushed rock or a sole plate, try to make the plate the same wood type as the posts. i prefer sole plates over rock as it can help steady the posts when setting it straight.

why should the sole plate be of the same wood type? What does it matter?

[Vernonv]

(What type of cement mix? Would quick set be good enough?)Don't use quickset (ok for fences and TV reno programs) ... use normal concrete (like premix bags) for anything structural. My all round mix is a 4 all-in to 1 cement mix.

[rrobor]

Hey Gooner you must by flush. Big pinch is $70 and a digger thing, who knows. you dont need both. Personally one of those hand powered post diggers I found absolutely useless. If you are fit, 60 cm with a sharp spade would take half an hour, with a big pinch as well, even less.

[president_ltd]

+1 to post above... :wts:

another variation on it is to dig the holes (with post hole digger), set up your first bearer at the right level (typically on bricks) and 'hang' the posts from the bearer into the holes then add your concrete mix into the holes.

when concrete has said, remove bricks holding up bearer, bearerr should not move. :)

[watson]

Paul..don't forget to keep your fluids up tomorrow. :roll: :roll:

[Gooner]

Hey Gooner you must by flush. Big pinch is $70 and a digger thing, who knows. you dont need both. Personally one of those hand powered post diggers I found absolutely useless. If you are fit, 60 cm with a sharp spade would take half an hour, with a big pinch as well, even less.

Mate, this is one of these off-the-cuff projects that has turned into a mega budget blower. Site leveling, tons of crushed rock, $1K worth of timber, $2K cubby, $150 worth of paint, tools, and it still isn't over.

Well I went out and bought a post hole digger for $55 and a 5.5ft crow bar at $85 for a grand total of $120. (?? They must have stuffed up the count to my advantage).

I generally agree with Henry Ford when he said something along the lines of;

"If you need a tool today and do not buy it, you pay for it tomorrow but do not have the tool."

I have found this to be true in many of the jobs I have done. Not buy a tool, struggle without it, compromise the job, only to go out and buy it a few months later.

Anyway I gave the post hole digger and the crow bar a test run tonight and the pair work a treat. By itself the post hole digger is cumbersome. The crow bar does a good job of loosing it all up for removal with the post hole digger. Should get it done relatively quickly tomorrow methinks.

Thanks for the replies so far.

[blonk]

Are you speaking from experience, Mr Watson............:?

Just be careful with the fluids that you use to hydrate yourself.

From personal experience I can tell you that excessive consumption of the wrong type of fluid has the tendancy to make a bad job look tremendously good...............untll the next day......................

Good luck


You know that beer is 90% water. :U

[Gooner]

My next "issue" that I am kinda ignoring and hoping it won't bite me is that the cubby is elevated 1.5 meters off the ground and the cubby total height is 2 meters. Therefore the cubby will be 3.5 meters high in total. It it over 1.5 meters away from the fence, but I think the council code allows no higher than 3 meters. Hmmmm hope the neighbours don't complain.

The issue is compounded by the fact that after leveling the site the cubby is now much higher.. add another 30cm of bark and the thing is going to look more like 4 meters high from the neighbours yard......

[president_ltd]

My next "issue" that I am kinda ignoring and hoping it won't bite me is that the cubby is elevated 1.5 meters off the ground and the cubby total height is 2 meters. Therefore the cubby will be 3.5 meters high in total. It it over 1.5 meters away from the fence, but I think the council code allows no higher than 3 meters. Hmmmm hope the neighbours don't complain.

our neighbours built a cubby exactly like that, close to us, <1m from fence looking straight over into our pool. not only broke rescode but all those rules & regs around "climbable fence" for our pool too...

anyhow a word or two with said neighbour, we worked out that they would 'extend' their cubby and put a wall up the back of it where it had a platform such that its no longer a platform facing towards the fence. no longer climbable, we get our privacy back.

mind you in the meantime planted some screening in the meantime which has gone great guns.

[Gooner]

The cubby will be tall, but will be tucked on the back left hand corner of the property and be about 1.8 meters away from the left and back boundary line. The left wall has no window and neither does the back. The cubby does have a verandah, but that looks into our backyard. It will look into the neightbours on the left, but behind his shed, so probably no big deal there. Will certainly be able to see better into the neighbours on the right, but from the opposite side of the property.

I am going to do all I can to respect my neighbours privacy just as I would hope they would do the same for me. May put up a screen/sail on one side of the verandah and maybe some trusses on the fence next to the cubby.

[bpj1968]

I did a job in the back yard almost identical to yours. 2.4 x 3.0m, and 1500 high at front 500 at back (sloping block)
Dug 3 1/2 by hand and a neighbor with his dingo for the rest. (I only dug by hand waiting for him to have a free bit of time.)

All holes about 600 deep and cypress posts braced and set with a bag of quick set in each, then back filled. Once set, trimmed to length and bolted on bearers. The cubby floor just sat on top, and was a wedge fit between the posts, which were a little higher than the bearers.

You are only building a cubby to hold a handful of kids and maybe 1 oe 2 adults, not a deck to hold a family, so the stresses are much less.

Many cubby companies sit the posts on the ground and tie all together with 240x45 treated pine to make edges for the sandpit and the weight of the cubby to hold it all down