Greenhouse plans to purchase

Kia Ora from New Zealand. Im a long time lurker first time poster here. Having finished our small house following permaculture design principles as much as possible, we are finally in a position to get a greenhouse going in a zone 9 area in New Zealand. I love the ideas I’m getting from this forum and the riffing off them we do ourselves. I’m interested to know if there are plans we could buy that we can easily tweak to our own footprint size? Any recommendations? Thanks in advance for your help!

Hello!

I'd love to try and help, but what do you mean by "tweek to our own footprint size"?

Haere mai! First of all, do you have a size in mind? Budget? What do you want to grow? We went to Redpath for a fully engineered kitset, but that was highly influenced by having some spare funds that year and being perennially time poor. I'm mostly growing nightshades and some tropicals in there, but will also do things like lettuce this winter.

R. Steele wrote:Hello!

I'd love to try and help, but what do you mean by "tweek to our own footprint size"?

Hi, ha ha, sorry, terminology probably lost in translation. I mean are there software programs  out there with plans that will adjust the size of the components based upon the size of our footprint. Rather than us having to draw it up in sketchup for example? We are still undecided about the precise size yet and we got to wondering if there is such a thing.

It’s not a going to be big - ever so slightly dug in (we had hoped to have it sunk a bit but the boys hit a schist seam and gave up). Probably max 7m by 7m. We have extremely hot dry summers and winters which while getting warmer generally get down to -5c for a week or so most years.

Digging in is an excellent plan. Sorry to hear about the schist. We went down about 70 cm for ours and the extra headroom is nice to have. Are you thinking about a timber frame and recycled windows? Strawbale or earth for the south wall is another thing you might consider. Thermal mass is nice to have and so is protection from the southerlies.

Kia ora,

In most districts you can call a greenhouse a temporary structure and do it yourself. If it's not in line of sight from the road all the better! My old 5x15m  pvc structure is still sound after almost 30 years, and has produced over 100,000 tree seedlings for a low cost. No serious design required with those things, just bang them up. Next time around I'll be digging in a bit for the thermal mass,  but it really wasn't necessary in my pvc hoop. I haven't even shut the door for over 20 years, which is the advantage of the NZ climate I guess. Intention is to build another one on a slope (for convective cooling) with hardwood framing and  50mm polypipe hoops to have another go with some more subtropical fruits.

Phil, did the 70cm pit  depth come from any specific design considerations? Pit greenhouse makes sense, but I've often wondered what the ideal depth is. I had an experimental structure 2.5m deep which grew great bananas, but only very short dwarf types could fit under the 4m roof.


Nga mihi,


Ben

Have you seen the PDF put out by Bob Oehler titled Earth Sheltered Solar Greenhouse?  It is one of the cheapest ways to build greenhouses, but I would classify them as more of a grow-hole.

Hello again!

Thanks for explaining that : ) Im not sure of any programs available that adapt the engineering of a spacific greenhouse design, to recalibrate for new dimensions; however, I'm no expert in that feild. If they do have them, they would be the expense toys of an engineering firm. Have you found a design you have in mind? Do you know the building materials you want to work with? Once you have decided on a spacific design, you could go a little smaller, if you dont mind being over engineered. Its going bigger that would require a engineers approval to make sure minimum structual requirements were met. Depending on the greenhouse style, you could probably do the conversion yourself with information found online, especially if you have building experience. If I'm following your post correctly, your space is 21 ft by 21 ft. You could without issue get a 20 ft by 20 ft hoop house, on top of a foundation of sorts. Going 21x21 ft is probably even do able without much issue for converting plans yourself, but the materials available would make it more efficient and cost effective to stay at least 20 ft wide, by 21 ft long, or at least using the 20 wide standard length pvc to create a 21ft wide hoop house, since you have no snow load, and extra head room from digging down. The underground opening dimensions would of course be determined by the materials used to retain the surrounding dirt. If you want a tall fancy structure. You will need to have someone in the greenhouse feild, qualified to draw up plans with the materials, you want to use. If you want to start off with a hoop house, it would be very easy to use the same materials already in common use for your dimensions, which means you can find all that information on line. If you decide on a fancy more permanent structure out of say aluminium and polycarbonate sheeting. Well some greenhouse manufactures will custom engineer it for you, then deliver the product for assembly. But knowing the building materials you want to use, and or the style of greenhouse build, is key to pointing you in the right direction.

Kia ora Ben -

The 70 cm depth was determined by two things. The first consideration: my nephew and I were digging it by hand and that was about as far as we were willing to go (and about as big of a pile of dirt as we could make in the driveway without completely stuffing accessibility for everyone). The second is that there happens to be a stormwater culvert under my driveway and a novaflow field drain emptying into it just a short distance from the glasshouse site. The invert of the novaflow is about 80 cm, so I was able to tee into that and provide a drainage outlet for the sunken area.

Unforeseen consequence: We had a gullywasher back around the first of the year. 72 mm came down, most of it in 45 minutes. The stormdrain pushed water into the glasshouse and flooded it to 30 cm depth. Pots filled with compost and biochar were floating. It all drained away an hour later, but it soaked the cob bench portion of the RMH. That made the first few fires into smokefests.