Vermicomposting, worm bin, composting with worms community and forums

04/14/2011Update- Well the new FT is finished and I am very happy with the outcome. Pictures can be found at The first pictures are what happens when you use spray in foam insulation in a wall - bad idea! The rest of the pictures are of the new bin during and after construction.

Other than a few small mistakes (corner of plexi-glass snapped off when I drilled it – always have something to drill into when drilling plexi-glass) everything went well. I would build some, talk it over with my 13-year-old daughter, take some time to think about the next steps and the next day did some more. The lid fits very well but not airtight. The corrugated plastic I used for the liner on three walls worked great for the top surface as well. Since it is corrugated is has small holes that will always let air in from the sides.

I was able to add the front door/window and insulate everywhere else. I am especially happy with the way it is currently holding the temp. I use a 40-watt light (the Christmas lights I used all burnt out) in the drawer to produce heat (hooked up to a plant mat heater thermostat). The light went off as the target temp was achieved and the temp has only dropped .6 degrees in the last 5.5 hours. That is with a 20-degree temp difference between the compost and the outside air. Trying to insulate better was reason this whole situation started in the first place.

I managed to find on old cabinet hinge in the garage and used it for the front door/window. I built it a little high though – I thought that the height of the compost would get that high, but it just misses. I might have made it if I hadn’t decided to take the opportunity to harvest before putting everyone back in the bin J

I know Larry had commented on the loose blow in type insulation foam absorbing moisture, but I am hopeful with the plexi-glass/plastic corrugated between the worms and the insulation that it will stay relatively dry. If not I am sure I will see it through the front wall. At that time I can remove the cedar outer planks and use the foam board as suggested.

I hope someone will read this and learn from my mistakes but mostly I hope this is the last bin I ever have to build (my wife is beginning to think I am nuts J).


Original Post

Before I say anything, you have to know that I am a bit of a perfectionist being the first born, so read this keeping that in mind.
OK, people have said that they were impressed with my FT bin, but now let me tell you about the issues I had with it.  The walls were created in the following layers:
   Outer layer – cedar planking
   Middle layer – standard fiberglass insulation from a roll
   Inner Layer – A very tough landscaping fabric

The first problem is that the middle area of the wall where the fiberglass was had gaps. The role was not the exact same size as space in the walls. The inside of the bin kept losing heat quickly. I ended up wrapping an additional role around the outside of the bin, but still not an air tight seal and it only helped a little. Oh and don’t forget the mice … I got em and I think the little buggers got some of my worms.
So now that the weather started to warm up I decided to readdress these issues.  I removed the worms and placed them in a tote and holy cow – just a tone of castings. These babies ate a ton over the winter. I have a full tote of 90% castings weighing at least 50 lbs and it is relatively dry (just not soaking).
Then I removed all of the landscaping fabric and noticed the next big issue – a lot of wet fiberglass – what was I thinking! I immediately ripped that out.
Now what to do about insulating and keeping it dry. I found some corrugated plastic sheets that one might use for a large garage sale sign. It was fairly rigid and seems strong enough. Now … should I insulate? I came up with the single worst idea ever – an insulating spray foam called Great Stuff. DO NOT EVER USE THIS PRODUCT BETWEEN WALLS OF ANY KIND!
At first it seemed to fill in the gaps nicely but then it kept growing and growing and growing – all night long! The next morning I went to begin work again and the walls had blown out and yellow foam was everywhere.  I pulled the corrugated panels off and the center was still wet and growing – 8 hours later!
Guess who started building another bin yester day …that’s right me.
At least now I can make some subtle changes that wanted to. I have opted to make the box the same size in order to re-use the cedar planks. I will be using the corrugated for 3 interior walls and a pane of plexi-glass for the front interior wall. I will be using a very green (80% recycled) blown in (or gingerly placed in?) insulation between the interior walls and the cedar panels. I am spacing my PVC grate bars a little further apart.  I will also be incorporating a drawer. I am hoping to have a little window in the front that has a hinged flap (cedar panel) cut so that the worms can be viewed from time to time. I have several curious neighbor children. I think this would be a nice teaching aid as well possibly at schools etc…
So far the frame is complete and the 3 inner corrugated panels are installed. I will try and finish up this evening and keep everyone updated.

Views: 75

Comment by Don Dillon on April 11, 2011 at 10:56am

Excellent info, Larry.  My first thought when you wrote about wet fiberglass was "hmm, I wonder how that spray-in foam would work"... then in the next sentence, you answered it.  That piece of info gold for anyone who is about to try and insullate for winter.



Comment by Sharon Hollars on April 11, 2011 at 2:00pm

Have you looked into getting some rigid foam insulation board?  I would think this would be a much better option than any kind of soft insulation (and more predictable than foam).  I'm not sure how strong your corrugated plastic panels are, but as you know, worms/bins weigh a lot and the plastic panels are likely to distort if not supported very well.  The rigid foam board seems like a better bet all around.  You can even get it with a vapor barrier.  You can get it different thicknesses (R values) and you could layer it to get as much insulation as you want.  I love the window, if I build another bin I'm sooo doing a window.

Comment by Gardener Larry on April 12, 2011 at 7:04am
I had already purchased the blown in insulation prior to posting the last message. It is surrounded by wood with no entry points so I am hopeful that I won’t have any critters. I also stuffed it in fairly well and braced the plastic corrugated with 1*3s and use plastic corner protectors to hold the corners in place. I should have pictures in the next few days. I just have to complete the lid and drawer. I have come up with some better ideas for ventilation than my last FT as well.


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