With a few spare days in the blazing sunshine (May 22nd – 25th inclusive and May 29th & 30th 2012) I helped RBWM and St.Mary’s School Maidenhead to build their Eco Greenhouse and new Chicken run with coop. The following is a shot by shot of the processes we used and there is a lot of cross over between the two structures so I will illustrate both builds in tandem. For further information or to request amendments or corrections please email me. This blog entry is intended as a public resource for people to refer to and to inspire, please ensure all people are supervised and competent if using tools and any necessary permissions and insurance is in place if required. Seek professional advice if unsure of any process. Regarding images used they are taken by me and if there are any objections or sensible reasons for amendment please email me, this is an educational resource.
Eco Greenhouse outline and Manual/Instructions:
This consists of a timber frame structure that uses recycled and salvaged fizzy drink bottles with bamboo cane support to create the glazing instead of glass. It is a great way to have the entire school or organisation help create a viable useful greenhouse for teaching purposes. I am an experienced carpenter & designer (www.rgproduct.com) and having reviewed the original documents provided by RBWM (from an existing project) we amended the process to suit our needs (please note I do not claim ownership or authorship of these documents, if there are any rights issues please contact me).
The Moray Council/REAP original instructions are very good and obviously have lots of useful info and should be read before commencement. I have combined it with some simple Chicken Run plans/elevations also supplied by RBWM and converted to PDF. If there are any download issues relating to the manual please email me.
In choosing site, consider exposure to sun, shade and wind throughout the year as well as any windfall from large trees (leaf/sap and bud toxicity for example). The above manual suggests concreting in your posts and this is a perfectly good option, however for various reasons I selected to create a slab base and bolt the main verticals down via foot mounts. Chiefly for ease of repair and to prevent rotting of ground timbers etc. There was much discussion on this in relation to Chickens scratching for food etc but we felt having a solid base to clean back to, with a good layer of soil and grit would allow our birds to scratch yet keep the site cleanable and usable in diverse conditions.
For slab bases we did the following: Mark out your base extent with wooden pegs and remove turf to the compacted soil level, giving a good level base. Scrape and rake level to suit your personal tolerances. (Michelle and Stewart doing a grand job via RBWM) - Eco Greenhouse base:
The same method will be used for both the greenhouse and Chicken run. Once the soil is ready, lay some water permeable plant stop membrane on the soil and sprinkle a good measure of sharp sand across this area and level. The best way to do this is to set up some levelled timber guides and run a long strong timber across these to give a smooth sand finish.
Add more sand and re-level Thanks Jo and Chris. Eco club parents:
Start to lay slabs from a chosen edge or point, we used 600mm square slabs at 50mm thick. Mind those fingers and your back! Once your base is complete at some point you will add cement powder and water to it, brushed/broomed in and across the slab joins creating a cohesive base. There is the option to add cement powder to your sand to make a really tough base. Depends on your time and budget issues, ground work can be as simple or comprehensive as you like and is not fully explored here. Google is your friend.
Greenhouse frame construction:
Having chosen to mount our posts on the slab surface and not into cement there is a fundamental structural issue to contend with; rigidity. As the posts are not held rigid, ready to rot in concrete we have to do this with the carpentry. It is assumed an experienced maker knows the basics to achieve the build as follows. Basic process list below, expanded thereafter:
Create mitre cornered wooden frames to accept the bottle walls (Free ranging frames allow children to assist with bottle wall install and creation).
Make main structure that is rigid and allows the wooden frames to be inserted later, once the bottles are attached.
Bolt down main frame to site via post foot mounts (we literally lifted it from the build area to the install site)
Install doors, internal shelving etc
Install completed bottle walls and start growing and seeding stuff!
1/ Bottle prep
Allow for a month or two bottle collection and store them safely, once enough have been collected you will need to have your troops carefully cut the bottoms from the bottles (under supervision, an adult will need to pierce the plastic to allow children to use safety scissors and cut of the base of each bottle), clean, rinse and dry them for cane mounting. I think these are standard 2 litre bottles but choose your preference:
Arrange your helpers and set up bottle cut, clean and dry stations and an area to cane them up.
2/ Mitred wall frames:
Decide your dimensions for the overall structure and allow for the corner posts, bottle dimensions and quantities, mitre frame sizes and sketch up a basic plan. I suggest using a proper chop saw with RCD for 240v use or 110v site protection to accurately cut your 90 and 45 degree cuts. I chose 2m clear vertical height in the frames below and allowed for a multiple of 95mm width for each bottle cane and a rough vertical multiple based on a test bottle cane. An few cm’s here or there on the width across the frame is no issue. It is not an air tight thing.
Mitre frames cut from tanalised (rot proof) 2 by 2 timber, mitre joined and screwed together with 80 or 100mm long pozidrive pro wood screws. Do not buy cheap screws, the heads are rubbish and will not drive in. Suggest a decent drill driver to drive screws etc. Good value screw selection.
3/ Main structure
Timber used either 2 by 2 inch, 2 by 4 or 4 by 4 tanalised rot proof, 3 m lengths ideal generally.
To simplify things I used my bottle mitre frames to dimension my actual structure. Literally clamping/screwing my vertical corner posts to them to give final dimensions (NOTE: use a thin spacer between your frames and the corner posts so they do not seize in there once you stiffen your corner posts, lolly sticks are perfect):
From here you may add your roof structure, to any given height. NOTE: use long thin timbers to add triangulation to this frame to keep it accurate and stiff for moving if required. Below a very useful image shows the structure having been lifted into position by 4 strapping guys/gals. Notice triangulated timbers, these can be temporary until final fit is done or left in position. When finished it does NOT want to wobble, mine doesn’t.
4/ Bolt down frame:
(further images to follow, an apparent glitch with my BB)
Regarding post foot mounts and overall height I chose to keep all timber 50mm off the floor and away from any rain splash/pools. This was achieved by simply having 50mm of slate layers carefully shaped and placed in each of the 4 foot mounts to lift the posts and therefore whole structure 50mm from the slab base, Jamie from RBWM “knapping” slate to suit:
Layers of slate are simply built up to the required 50mm:
With your happy helpers, lift each corner and drop each post into the foot mount and onto the 50mm of slate, this should leave 100mm of post inside the foot mount. you will probably need to loosen the bottle frames a little to allow for this. Retighten frames before bolting down foot mount. Using a SDS drill to make the holes, bolt down your posts in situ; measure across the ends and sides to ensure they are the same (within a few mm) and check your diagonals too. Coerce the posts to suit before final bolt positions. I chose the very useful threaded bolts for concrete, image links to Screw fix:
5/ Install doors, internal shelving etc
This is where the real carpentry starts, I reused the fence panels to create shelving and other elements across both projects, note the triangulation timbers still in place, some temporary and some in final position:
The potting shelves allow for ages 5 to 11 and are at heights approx 600mm and 900mm from floor (650mm and 400mm deep respectively). The top shelf is shallower to prevent the younger kids bumping their heads!
Door uses solid brass hinges with a wooden latch, part of a bottle cap used as latch bearing washer for ease of use:
As mentioned this ran in tandem with the above and the following is a selection of images showing the team at work (under my supervision). Chicken run basic frame with triangulation timbers in place to allow accurate construction, this was built in situ. 6m long 2 by 4 inch tanalised timbers ordered to strap full length of run, top frame corner mitred onto vertical corner posts I Eco Greenhouse frame in being built in background prior to lift move):
Wide shot showing start of elevated coop (12mm far eastern WPB weatherproof plywood) and also base edge, the sand layer now has a rough wood gravel board edge to gold in some dry cement/sand mix, this will harden over time and contain the sand and allow for roots/natural consolidation of the sand over next 12 months. It can crumble away after that having done its job:
The very helpful Jo learning to mesh staple, doing a terrific job too!
Detail shot of coop and slung ramp for Chicken access, ramp planks are the gravel boards from the base surround cement. The steps are to help the smaller children access the coop and are made mostly from recycled fencing and built to highest “Tonka” standard!: