[RichardA]

After several years of quite good compost making using scrap doors, old pallets etc I have a chance to make some tidier looking compost bins. Books and internet articles appear to conflict on several points -- can I ask if anyone has the experience to settle teh following:
Q1 - are air spaces/breathing holes etc necesssary (lets air in) or undesirable (lets heat out) - I am using 6 inch wide planks set horizontally, they are one inch thick and I was thinking of a 1 inch gap between each plank
Q2 - is treating timber with preservative a waste of time or is essential or is it undesirable for reasons of toxicity. I have a large quantity of Wicke's shed and fence treatment available, wood is untreated softwood of a quite low grade.
Q3 - 4 by 4 by 4 is a recognised "good size". For best use of timber I am thinking of 4 foot 6 by 4foot 6 by 5 foot high. I have a good supply of usual compost makings plus a lot of duck enriched straw bedding all year round. I am tall so a heap 5 foot high is not too much for me. Also I have 4 plastic bins so all compost is collected in them first and only then transferred into the wooden bins building up quite rapidly as a final turning exercise of the partially rotted stuff from the plastic bins.
I would appreciate thoughts please.
Many thanks
R

[Trillium]

I built a series of square 4'x4' wood 'rings' with bottom corner pegs so a ring locks into the previous one against wind and large vermin damage. I can add or subtract rings as needed and it is working very well. There are no true air spaces in my system but there are enough small gaps between the rings to allow air. Plus, I turn this heap more often than I did with pallet type bins and I'm getting compost faster. If air worries you, simply buy a 3 foot or so length of 6" poly waste pipe, drill a lot of holes all around, attach an end cap at the base and stick into the centre of the heap or build the heap around this pipe.
I never found leaving air gaps in the wood sensible as we all cover the top of the heap to retain the heat. The more often you flip, the faster the piles heat up.

I could afford only cheap spruce wood which would rot quickly so I primed and oil painted mine with 2 top coats and they should last much longer. Mine are also very visible from the road so I wanted them to look neat. The base rings were all pressure treated wood as they'd take the brunt of all moisture. You can treat your main wood but do consider whether or not your product could leach out of the wood and into the compost, specifically carcinogenic elements in the product. Each set of my bins sits on a piece of 1/2" weldmesh which keeps out vermin and allows in worms. With your 1" thick planks you'll need to add more vertical supports for stability. And some sort of lid is always a good idea.

Size wise, you can build it 8x8, provided you can get into it for turning the contents. I personally find a series of  (2"x6") 4'x4's (approx) sturdy and easier to work from and good use of my lumber. By the time the season's first bin is full enough, I can leave it and start a 2nd. The first bin has time enough to break down and be flipped into the next where I can stack the now unneeded rings of the first. The 2nd bin is a bit slower due to the later season, but will eventually be flipped. The 3rd bin is our winter bin as its too late for much composting breakdown so it holds all our household winter offerings. Heightwise, if the bins are fixed, its better to have a front access panel of some sort. With mine, I simply take off a ring at a time which I find much sturdier than previous bins which bowed at the sides after time and front doors wouldn't stay in.

I'm finally getting around to building flip up lids for my bins, again a 'ring', one that's angled and will have sheets of metal shed siding which I got free from our local tip. Couldn't believe my luck that they were the exact size I needed. Lids will keep out excessive rain as well as climbing vermin.

[Ivor Backache]

Firstly trawl the internet. I found lots of information on composting-it is a huge subject. Read the university projects- you will get ideas from their findings.
Q1: You must have air. What you suggest will work. Compost can draw in air through itself upto 3' of thickness. That is why 4X4X4 is a good size to work with. Bigger than that you must have a pipe system. Make holes with a crow bar is the simplest otherwise use plastic pipes. I use gutter down pipe with half inch holes every six inches.

Q2: I doubt that you can buy toxic wood preserver. Creosote is not used and if it is an issue (read what it says on the tin) then just soak the ends overnight. That is where wood rots the most.

Q3: Make your compost to suit your supply of material. Making a compost 4X4X4 is fine but not if it is half full- better to make one 3X3X3 which would be full. 5' of compost will be very heavy and the weight of the material will force out the air.

If you do fill your bin there will be 80 cu ft of compost which will weigh in the region of a ton. Are you really going to turn that by hand--every two weeks!
I have 3 bin system: (1): 3X3X3 which keeps mostly full and which I turn often. (2)Transfer the compost to a larger 4X4X4 to finish and then (3) to 'ton bag' for storage (Bags used to deliver bulk sand and gravel and cost £5 each) I make two such bags each year. You must monitor the moisture content and therefore you will need a  cover which for me is a heavy polythene sheet.

Mix the ingredients to give a carbon/nitrogen ration of 30:1 and you will have lots of good quality compost and a lot of satisfaction. Good luck with your project.

[RichardA]

I am grateful to you both, Trillium and Ivor for the level of detail and the trouble you have both gone to in sharing your experience. I have considered the wooden ring design and also use the crow bar method of aeration. My thoughts are to build four panels that will stack easily when out of use and just wire up into a square at the corners. Much as I did with old fence panels upto now.
Turning the big heap is not my strong point but by filling upto four approx 3 foot high and 3 foot diameter plastic "dalek" type bins first and then turning them out and adding all four to a bigger bin I can aearate and achieve the small bin filled quickly starting phase and also the big heap standing longer sort of sequence whilst staying tidy as volumes coming available flucuate and contents change with the seasons. Luckily I do have a lot of duck muck and straw. I buy 20 small bales a year of straw.
I then turn once more from each big bin into its neighbouring bin and of course when emptying I can select what is ready into the barrow and reject what is not back into a convenient bin or a bean trench.
I note from Ivor's note that he uses "ton bags" by which I take it he uses the bags that sand and gravel get delivered in from the builders yards. Never thought of that -- does it work well??
Again many thanks
R

[Ivor Backache]

I use two ton bags. One for leaf mould which does not require air, and the other for storage of completed compost. I would not use them for compost making because the sides and floor would inhibit air and drainage. (but you could always cut holes in them)

[compostqueen]

I'm making compost in a builders rubble sack at the moment and started it off with twigs with a layer of lawn mowings and am using them in alternate layers. It only got off the ground last autumn so too early to say how successful it will be. Once I get near the top I'm going to plant squashes or courgettes in it  

I prefer to keep heat in and with my pallet bin I used a tack gun to pin flattened out fertiliser bags to the insides of the bin, plus I keep the top covered. If it gets dry I water it
I also keep it turned as best I can (being only little  )

[solway cropper]

I have 2 daleks and an open heap about 6 x 4 x 4. I aerate the daleks by making holes in the compost with a crow bar. The open heap is never turned, just added to and it produces the better compost, presumably because air can get to it all round. I think the main thing to remember is the right mix of brown and green material.

[BostonInbred]

If you do fill your bin there will be 80 cu ft of compost which will weigh in the region of a ton.

Composted waste on average has a bulk density of around 400 Kg/Cum,  80 cu ft = 2.2 cum, so i agree it will weigh about 1000 Kg.

If it get very wet, the bulk density can rise to 800 Kg/cum. We had this situation during the winter, where raw peat coming off peat harvesters was so wet, 24 cu/m was making a 26 ton bulk lorry overweight.

[sunshineband]

Richard, although I can see why you might want to consider a kind of fold away version of a compost bin, in reality theyare never out of use. I have three made of pallet wood and covered with heavyweight corrugated cardboard to keep the heat in.

One always seems to be 'ready' one being filled and one in between. I don't turn mine as often as Trillium (although I probably should do tbh) but I find that the slats (which slide up and out) make it easy to unload the compost either to use or to turn before reloading the bin. 

[BostonInbred]

I just nail together two 1 metre pallets and two 2 metre pallets, line it with old holey black plastic, fill it up  and leave a sheet of black on top loosely weighed down. In the spring  i knock the  thing apart, leaving a nice easy to shovel pile and reassemble the pallets on another spot.