Coops Built from Stokboard Plastic Sheeting

[DanHibbert]

Hi everyone,

This last week I have been considering the design of plastic coops. Before I get started let me make clear that I am not after a debate of timbre construction vs plastic but rather a discussion on plastic coops such as the ones put together by Green Frog and Solway. I guess this would also cover the carefree coops first posted about back in Jan.

http://poultrykeeperforum.com/viewtopic.php?f=3&t=5546

http://www.greenfrogdesigns.co.uk/

http://www.solwayrecycling.co.uk/recycled-shop/pig-poultry/hen-houses

As far as I am aware all use a recycled plastic material sold as stokboard which is sold in black, grey or black with a colour laminate on one side. I am not so sure on how many UK suppliers there are as I can only find information on the Solway stokboard material that is available to purchase online and/or through agricultural merchants.

For an individual to buy a few sheets of material for their own self build the price of this stokboard can be up to 3-4X the price of exterior ply or tongue and groove alternatives depending on the thickness of the stokboard used and quantity ordered.

I am interested to know if there is anyone out there with a Solway, green frog or carefree coop product who would be able to comment on the thickness of the material used. Using Solway as an example, they sell stokboard in thicknesses of 3,6,9,12&18mm and also 18mm ecoboard (cheaper, lighter, rigid board made from mixed plastics) and agriboard (A rigid, more expensive version of the stokboard).

When I talked to the supplier over they commented on the flexibility of stokboard. Obviously the thinner the board the more flexible it will be and looking at some of these product, the curved chicken arcs in particular, I do wonder about the thickness of the material used in these coop as I doubt it will all be 18mm sheeting - and probably does not need to be.

So, if you own a plastic coop or have experience or view with them I am interested to know what you think. I know there are a few green frog coop fans on this forum so there must be merit to some of their designs to get your recommendations.

 

[Marigold]

Hi Dan, nice to see you back on here.
Recently I contacted Green Frog because i was thiunking of making some quail cages from some kind of plastic material but the choice seemed bewildering so i asked them what they used and whetherthere was an alternative whoich would be more easily available for smaller purchases. The reply was this;

''The board we use is called Ekosheet, but it is very hard to find in small quantities in the UK, especially retail. Much easier to find is a board called Stokboard made by Centriforce. It is not quite such a high quality board as ours, but is very similar and a fair buit cheaper. It has a diamond pattern on both sides. You should be able to find 8x4 sheets in black at any agricultural merchant (e.g Mole valley Farmers here in the SW).''

So Green Frog isn';t made out of Stokboard, and I do know it's entirely recycled material and they even recycle the offcuts when making the coops. In the morning I will go out and measure the thickness of the Ecosheet. No problems at all about it flexing, it seems very sturdy and is pretty heavy as well.

 

[DanHibbert]

Thanks for the info Marigold. I can see what they mean when they say Ekosheet is very hard to find. I have one phone number I found which I will try tomorrow as I am curious to find out if it is at all available in the UK.

Centriforce do indeed make stokboard that I can actually locate to purchase. The agri merchant I rang last week, CWG in Melton Mobary, stock the Centriforce stokboard. Both Centriforce and Solway make their stokboard from Low Density Polyethelene (LDPE) recycled polymers (recycled shopping bags are one example) which make these boards flexible.

I will have a ring around tomorrow as a few suppliers offer recycled High Density Polyethylene (HDPE) or recycled Polypropylene (PP) sheet which are more rigid. This could be more like green frogs Ekosheet.

I remember reading a comment made by Tim that green frog use off-cuts of medical grade polymer, this has been backed up by your comment today on GreenFrog's recycling. It would suggest that their board is not LDPE like the stokboard.

This dip into researching recycled polymer materials is proving to be interesting, but also very tricky to get my head around. I will let you all know what I find out tomorrow.

 

[chrismahon]

Plastics fall into two catagories, semi-crystaline and amorphous. Semi-crystaline resists fatigue failure by dislocation of the molecules in the crystaline regions. Amorphous can just snap like glass. PP is semi -crystaline. Just binned my plastics reference material (to reduce shipping weight) Dan so I don't know which catagory the Polyethylenes are in. But it may help with selection of material in lower temperature applications when under stress.

 

[DanHibbert]

Yeah, the amorphous regions in polymers will turn to a brittle glassy state when they are below their glass transition temperature. This Tg is specific to each type of plastic and is related to the crystalline content, chain alignment and side group structure of the polymer. (With your experience in polymers I am sure I am preaching to the choir).

The recycled polypropylene is a more rigid board compared to the stock board so I am thinking it would allow me to use a sensible thickness of sheeting (e.g. 12mm) over 18mm board and save weight and costs whilst keeping a rigid structure compared to the stokboard. Or I could build a frame and clad it with the thinner board.

PP polymer has a reasonably high crystalline content which make it more resistance to fracturing but its Glass transition Temp is only around -10-0 oC so it the amorphous content in the polymer will become more brittle when it starts to freeze in the winter months.

I believe the stockboard is made from Low Density Polyethylene (LDPE) which has a more favourable Tg of -110 oC making it more resistant at lower operating temperatures. I think I need to find some figures for the failure forces as, to be honest both materials would probably suffice for the use in a chicken coop. I think it's just the case that the PP will be more rigid than the PE stokboard. Hence the earlier post about sheet thickness.

In reality each manufacture of polymers, and in this case recycled polymers, will vary their processes, additives, pigments etc so there is no real way of knowing the exact figures without testing samples.

 

[chrismahon]

Just so you are aware Dan. You'll be marked on material selection. The recycling process is the key as you can lose 90% of virgin polymer properties. Which is why I don't belive it's all recycled, no matter what they say. Going to be incredibly heavy if you used 18mm -tried to lift a sheet of it once at CWG.

Went through a load of paperwork few weeks ago. Discovered I qualified to be a Chartered Design Engineer about 12 years ago, because I met the full criteria for years of experience and responsibility at that time. Don't think I'll bother applying. Won't help with breeding chickens, planting foodstuffs or re-building a house at all!

 

[cammie]

Thanks for sharing such informative post on plastic sheeting.

---------------------
http://www.american-plasticlumber.com/

 

[Margaid]

What did you use in the end Dan? I'm still dithering about whether to use exterior ply or a plastic boars to build a house. I have a Solway house (up at my friend's) - the one that looks like an American mailbox, andit's made out of a single 8' x4' sheet bent over. From memory it's either 6mm or 9mm, I'm pretty certain it isn't as thick as 12mm.