Compost bin 'duvet'

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I have two large wooden compost bins and the contents used to dry out reasonably rapidly and also cool down quite quickly. So I made 'duvets' for them, out of rock-wool, bubble wrap and plastic sheet.

I knew that moisture would get inside but I wanted to seal them reasonably well so that they did not fill with water when it rained. So I wrapped duct tape[1] around the 'parcels' and used it to tape all of the openings.

[1. Not the genuine stuff. I looked on Amazon for duct tape and bought some silver tape that came up.]

I put them in place in autumn last year and well before the end of the year the tape had started coming off.

They do work, in that the compost stays wetter and gets hotter. However the tape had pretty much all come off by this spring and when it rained they did fill with water, so removing a duvet to stir the compost risked me getting covered in water.

I know it is asking a lot of the tape to stick when the environment is wet and hot (often >50°C) but I had hoped for more than a couple of months.

What should I do to make these hold together longer? Would genuine duct tape work? Is there something else that is better?
 
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You could make a wooden lid that fits onto the boxes? Just plain old wood. And you should have some sort of drainage at the bottom for the rain water? It would help to see a photo too, for suggestions.
 
I did think about wooden lids but they would not be as insulating as a 3-4" layer of material. Also the duvet lies immediately on top of the compost whereas a wooden lid would be above the top board and a lot of heat would escape because of that air gap.

The bins are on mesh (to keep out rats) on the ground so excess water will drain away. I'm going out shortly but I'll add photos later on.
 
Hi Stephen. I have some questions:

1) have you noticed a significant increase in decomposition by using the duvet ?

2) does the bottom of the heap drain into the soil? is this not needed to stop the heap from going anaerobic ? which is what results in putrid sludge and pathogenic activity.

3) what is the size of each heap?

4) have you considered moving the heaps to a sheltered spot, e.g. under a tree, or to the north facing side of a larger structure?

5) are the heaps currently exposed to full sun at any time of day ?

6) have you considered wetting down the heap and covering the entire thing in tarpaulin, watering say once or twice a week, and monitoring the temperature at the center of the heap from then on?

My composting is poor and needs much improvement so I'd like to learn something here as well. I also no doubt have a problem with rats and mice, who doesn't?

As for advice on tape - I've never seen it done in such a fashion. The closest I've come to what you're describing is someone having used old carpet draped over the heap with tarpaulin (or a sheeting material that excludes all moisture like DPM) on top.

Does this help you at all ?

p.s. you can get tapes that are designed for outdoor use on screwfix and toolstation, but they will likely stick so hard that it will be a nightmare to get them off. As Sod says, a lid may be an option, and what looks like a common solution judging by the compost heaps sold as flat packs. A piece of old ply-board or OSB with some of that insulation strapped to the underside?

There is also a tumble style compost station : https://www.ebay.co.uk/itm/70L-Tumb...051163?hash=item2ab10d159b:g:MbYAAOSw3dtan979

for the most pest-attracting stuff, like food waste. I've never used one of these, but would suspect they are fit-for-purpose judging by reviews.
 
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I did think about wooden lids but they would not be as insulating as a 3-4" layer of material. Also the duvet lies immediately on top of the compost whereas a wooden lid would be above the top board and a lot of heat would escape because of that air gap.

The bins are on mesh (to keep out rats) on the ground so excess water will drain away. I'm going out shortly but I'll add photos later on.
Fair enough. As am not sure any tape will last the elements for long, I was trying to think of something else.

I made myself a couple of compost bins out of pallets and lined them on the inside edges (not bottom) with thick plastic and used nails to keep it in place. I was wondering if you could do something similar, and nail your duvet to the inside of a wooden lid. Or at least a lid would stop the rain and wind mucking up your duvet. If you've the right mix of compost you'll get a fair bit of heat being generated anyway, enough to do the job well.
 
Some photos.
1. Duvet with the wrapping plastic unfolded IMG_20180817_192549858.jpg

2. View coming down to the bins, roughly south facing IMG_20180818_140223147.jpg trees providing shade, downhill steps to the left

3. Bins viewed from the slope down to the steps IMG_20180818_140342321.jpg

4. IMG_20180818_140540613.jpg RH bin, older contents, filled between end Dec 17 and mid April 18

5. IMG_20180818_140545937.jpg LH bin, younger contents, filled between early May 18 and end June 18

I made myself a couple of compost bins out of pallets and lined them on the inside edges (not bottom) with thick plastic and used nails to keep it in place. I was wondering if you could do something similar, and nail your duvet to the inside of a wooden lid.

I suppose that is a possibility. If I added a sheet of wood on top of the rock-wool & bubble wrap filling, then wrapped the plastic round this and nailed through the plastic into the wood.

Or at least a lid would stop the rain and wind mucking up your duvet.

Maybe, but I'm not sure. The sides mostly protect it from wind and I really don't know what has the most impact on the tape adhesive, large amounts of cold rain or much smaller amounts of much hotter water from the compost. Often the temperature, c. 150mm down, is >50°C but when I lift the duvet the surface underneath is steaming.

1) have you noticed a significant increase in decomposition by using the duvet ?

Yes, I think so. Of course it is hard to be sure as the exact mix varies from year to year, the weather conditions vary (temperature, rainfall before I added the duvets), how much I mix it varies.

The boards are 130mm wide so a full set (of nine) is 1170mm. When I filled the RH bin some of the stuff had been in a smaller compost bin (waiting for me to empty this one) and had broken down somewhat but I filled the bin up to the brim with that and new material. As you can see, the contents are now only c. 515mm high.

The LH bin I also filled brim full all with new material, then when that had gone down I topped it up (two? three? times) in order to include the last of a huge amount of shreddings. For that one the contents are now c. 1040mm high.

2) does the bottom of the heap drain into the soil?

As I said earlier, the bins are on mesh (to keep out rats) on the ground so excess water will drain away.

3) what is the size of each heap?

C. 1 cubic metre when full to the brim.

4) have you considered moving the heaps to a sheltered spot, e.g. under a tree, or to the north facing side of a larger structure?

Not really possible. The garden is large (by urban standards) but on the side of a valley so there is not that much flat space. In any case I doubt that this is particularly relevant. The contents are often >50°C and that is internal not external heat and (apart from a bit at the top) it stays damp.

5) are the heaps currently exposed to full sun at any time of day ?

No.

6) have you considered wetting down the heap and covering the entire thing in tarpaulin, watering say once or twice a week, and monitoring the temperature at the center of the heap from then on?

I am really not sure what you are getting at. As I said at the beginning with the duvets in place the compost stays wet and hot. The problem is the duvets coming apart.

As Sod says, a lid may be an option

I had already said that a lid will not help as it is not as insulating.

A piece of old ply-board or OSB with some of that insulation strapped to the underside?

Strapped with what? The same tape as I used before will come off just as quickly.
 
Hi Stephen, apologies about my late reply to your thread.

1 ) Question : are duvets essential here? Activity in the heap will slow as the colder days move in, so really what heat is that duvet offering? Yes it might trap in a bit of heat escaping through the top, but what about the lower reaches and the outside perimeter? The wood is not doing anything in the way of insulation is it ? Are you over-thinking this a little ?

2) As far filling and re-filling, I was under the impression that once a bin is filled it should not be added to. In other words it should be left to cook - you said you are topping up the bin? Is this an insufficient method ?

3) In terms of securing the insulation by strapping it - if you do want to go this route - put a piece of wood inside the plastic wrapping plastic so that it holds it's form and then push it down onto the heap and put heavy material (bricks/blocks) on top to hold it firm ? Then place plastic polythene over the whole heap, weighted down at the edges ?

4) Are you turning the heap ? This will aid decomposition

Sorry I can't be more help.
 
How about a sheet of PIR insulation board cut to fit inside? If the top of compost is flat you can put it on top with no air space, and the PIR board won't absorb water.
 
How about a sheet of PIR insulation board cut to fit inside?

If I had some of that spare (e.g. left over from work) I would have used it, but I didn't. I got all of the main materials (rock-wool, bubble-wrap & plastic sheeting) for free on Freegle. The only thing I paid for was the tape.

I think I will get some of this or this and see if that lasts longer.
 
A builder bag, upturned, will form a weatherproof (if ugly) shelter

They would be awkward to put on and off whilst filling a bin & when I wanted to stir the compost. Also, more importantly, they would offer precious little insulation.

And they're a cubic metre.

Some are sold as that but I don't think many actually are. I looked when I bought some a while back and most said they were 900 mm per side which is basically 1 yard. The ones you linked say they are only 850 mm per side.

Even if they were 1mm per side I'm not sure they would fit as the bins are 1 cubic metre inside volume. The boards are 19mm thick and the posts at the corner stick out further, so the outside volume must be quite a bit more than a cubic metre.
 
Ok.
But I meant for (an adequately-sized) bag to form the final weatherproof cover, and you could still put your rockwool on underneath that.

Failing that, rockwool mat, then impale with a cheap garden brolly?
 
But I meant for (an adequately-sized) bag to form the final weatherproof cover, and you could still put your rockwool on underneath that.

Thanks, that was not clear to me.

I may not have made this clear but I am not worried about keeping water out but about keeping water in. Excess water (e.g. from rain) will drain away but before I covered the bins the contents (well the top part) dried out quite quickly. With the duvets in place the centre of the top stayed damp throughout the recent hot spell.
 
Fill heavy duty black rubble sacks with rockwool, then fold over the open ends, and superglue / gorilla glue / frame sealant seal the end.
Effectively, rockwool pillows.
?
 

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