# Please help,I need advice from greenhouse experts



## a1Jim (Aug 9, 2008)

Hi Gang
I have posted this on garden tenders also. I was hoping I could get some advice on Green houses ,I have a customer in southern Oregon that wants a 10' x 40 greenhouse and I've been doing research on line and there seems to be two schools of thought what's best polycarbinate vs glass as to whats best and hold heat best. I also seem to be getting conflicting stories as to it's best to use fans or automatic vents. Lastly I would like to know a good source for buying a kit that large and perhaps companies that are not desirable to purchase from.
.

Even though I'm a contractor with 25+ years experience I have never had a greenhouse nor am I a gardener so I really could use your help.

Thanks Jim


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## Jim Jakosh (Nov 24, 2009)

I'm not a greenhouse builder either, but I found this link for you:
http://www.wvu.edu/~agexten/hortcult/greenhou/building.htm

Cheers, Jim


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## a1Jim (Aug 9, 2008)

Thanks a lot Jim that looks very informative,I'll look it over very closely .


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## CalgaryGeoff (Aug 10, 2011)

Jim sounds like a big project. What do you think you will use glass of polycarbonate windows?


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## a1Jim (Aug 9, 2008)

It's hard to tell at this point Geoff,that's part of why I asked for help here .


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## MtnMystic (Feb 2, 2010)

We have a greenhouse that was built before we bought our property. Some things we would recommend: Keep with a dirt floor not concrete as concrete sucks the greenhouse heat away in colder weather. Use one of the plastic woods where there is contact with the dirt to avoid rotting wood. Automatic vents with fans are important and enough are needed to actually circulate the air so there must be an adequate outside source for air to come in as well. Our greenhouse was insulated and green wall board used with plastic between the wall board and insulation but the wall board should have never been placed near the ground or concrete. Double or triple wall corrugated polycarbonate instead of glass (Tek Supply), and a door that lets in light plus a screen door so you can use it for cross ventilation. If it is used year round and heat will be needed to supplement in winter, plan for that and add lighting into the design plus lots of wall outlets. Don't make the whole building polycarbonate, just the south wall and add a some windows to the east and west. The south wall can have a short solid wall for the first two feet but if you insulate it, use plastic wall sheeting at that lower level. Then start the polycarbonate. Another layer of corrugated Polycarbonate on the inside south wall rafters above the short wall will create an air pocket that keeps the greenhouse from getting so hot and will reduce it losing heat when it is cold. We installed a greenhouse bubble wrap (Tek Supply) to reduce loss of heat but would have rather had another layer of the polycarbonate. It was just to hard to do since it wasn't designed for that. We use our greenhouse year round at 9,400 ft elevation. It can be above 90 degrees in the winter so venting must be a year round option. At night in winter when it is 30 degrees below zero and with high winds, the challenge is keeping it warm enough that it is above freezing. We have used some oil filled heaters to do the heating but would like to install a 220 electric heater. We have grown banana trees, tomatoes, grapes, an olive tree, pomegranate, citrus trees, a fig tree and many vegetables year round in the greenhouse with success. In fact the banana trees grew so well they got too big, so they had to go so we could have more space for other vegetables. Keep the roof a solid shingled roof as you won't gain enough light to warrant the heat loss from the polycarbonate if it is placed up top. They made that mistake with our greenhouse. You sunlight is lower in the winter and you gain enough sunlight in the summer like a sunroom. Hope this helps.


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## a1Jim (Aug 9, 2008)

Wow that's great info many things I might not of thought of, Thanks Mtnmystic


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## donwilwol (May 16, 2011)

Jim, I built 2 green houses about 25 years ago about 200' x 300' each. We used Russian glass. (I don't remember why) The structure was all glass and steel with drip tubes approximately every 6" apart. The building inspector decided we needed a sprinkler system. I had to go to the state to get a variance so we didn't need a sprinkler system in a building were absolutely nothing was combustible.

I'm sure it doesn't help, but just something else to think about.


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## a1Jim (Aug 9, 2008)

Wow those were some big greenhouses Don,sometimes those inspectors can make it tough. Thanks for your input.


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## Elksniffer (Feb 5, 2009)

Hi Jim. I just built a greenhouse 16' by 40' using 2" PVC for the hoops. I purchased a ventilation package(fan, automated louvres, thermostat control) and film from Greenhouse Megastore and they were very good to deal with. Vents might be nice as primary cooling, because you won't have to listen to a fan, but if you have very high summer temperatures I believe a fan would be necessary. I don't think the heat holding value of glass or polycarbonate is enough to keep much heat in the greenhouse at night or winter months. Mass that can absorb heat during the day and release it at night or a heater of some sort probably would be needed depending on ambient night time temps and what temperature you want to maintain.


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## a1Jim (Aug 9, 2008)

Thanks for your advise Elksniffer


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## kdc68 (Mar 2, 2012)

*a1jim*....I have nothing pertinent to add about greenhouse building, but am looking forward to seeing this as a project post when completed…good luck


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## exelectrician (Oct 3, 2011)

Hi Jim,
Our green house which is on a much smaller scale uses both auto vents and a fan, here in the Seattle area. On hot days we leave the window and door open. Pollinators need access to the plants!

Regards Vince


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## steliart (Jan 15, 2011)

cant help on your quest but i can wish you all the best


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## teejk (Jan 19, 2011)

Please keep us posted on this one. Dad always said "mow it or hoe it" and I have a spot for a small greenhouse. And when you get done with the greenhouse, let's move the discussion to smoke houses (the old fashioned ones where a small pile of green wood smolders for days with meat hanging overhead). I have room for one of those also.


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## a1Jim (Aug 9, 2008)

Thanks everyone.


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## Boxguy (Mar 11, 2012)

If your beds can be rolled outside as a unit it will solve several problems in moderate weather. Rails are nice.


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## Paul2274 (Nov 17, 2009)

Hey Jim, 
You may have seen this site before but I think they have a great selection of building materials and double and triple pane material as well. Keep us posted with pictures as you build please.

Paul

http://www.charleysgreenhouse.com/


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## a1Jim (Aug 9, 2008)

Thanks again everyone.


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## tomd (Jan 29, 2008)

!http://i248.photobucket.com/albums/gg166/TomD5895/DSCF0015.jpg!










This is one I built 10 years ago, since then I have replaced the glass with polycarbonate, it is designed as a solar greenhouse. The south wall is glazed and angled at the same degree as your latitude, this provides maximum heat and light collection. I'm sorry I don't have a picture of it finished.


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## a1Jim (Aug 9, 2008)

Thanks Tom that looks great.


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## Lumber2Sawdust (Jul 22, 2010)

I have a LJ Project with some pics of the greenhouse I attached to our garage. We ended up with a triple-wall poly roof and glass on the front/sides.

We are at 8,000 ft in the mountains of Colorado. My wife says it is harder to keep the greenhouse cool in the summer than it is to keep it warm in the winter. That seems to surprise a lot of people.

We grow lots of tomatoes, peppers, squash in the summer then switch to crops that prefer cooler temps in the fall so we have fresh spinach, cilantro, greens, etc in the winter. Colorado gets lots of sun so the greenhouse usually warms up nicely even on cold winter days. During a cloudy and cold spell it will get cold in there but we don't use heat except for the coldest nights.

When you build, consider adding as much thermal mass as you can. Our greenhouse is 2 levels. The wall between the 2 levels is 55 gallon drums filled with water. They help to store head while it is sunny and radiate it back into the greenhouse at night. The lower level also acts as a cold sink so the cold air settles in this lowest point.

Like MtnMystic said, keep it a dirt floor. We put down rigid foam insulation then covered it with a crushed gravel. That helps with keeping the heat in but still allows for drainage.

Good luck with the build, give us some updates as you progress.


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## a1Jim (Aug 9, 2008)

Thanks for the help Lumber2sawdust ,lots of good tips. That's one super looking green house you built.
Do you recall where you bought the triple wall poly ?


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## teejk (Jan 19, 2011)

Water source? In Wisconsin I would have to bury a line if I wanted to come from the well. Seems like a rain-water collection system would work but how do people determine that? Polycarb the choice solely because of resistance to breakage? And then just one more question…if fully loaded in the winter time, is there a way to pipe off the excess heat into other areas (I built the house and shop new and didn't qualify for any of those renewable energy tax credits…I think enough time has now passed where I can let the government pay for some solar).


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## sandhill (Aug 28, 2007)

I don't have a vast knowledge but this is what I feel. I love glass and I could get so much glass from about any glass shop on their screw-ups but we have hail storms now and then and the glass just does not survive like the polycarbonate. I think having vents that open on the ridge is extremely important but I have never seen one that did not fail. So just know somewhere down the line you will have to replace the mechanism that raises and lowers the panels. They almost always leak in heavy rains, but who cares! Even with the vents you still have fans on one end and evaporative coolers on the other, if you can afford an evaporative cooler. If not you may have to put up shade cloth that cuts UV rays 10% to 90% in the summer so you don't burn every thing up. You will need a heater in the winter. Normally, gas with a blower in an upper corner. Most people put down gravel for the floor. I have seen many problems with white fly infestations due to gravel and they had to use very strong chemicals to kill them out which I am against. I prefer a concrete floor with drains. I would investigate companies locally for a kit. They may be able to show you working ones in the area. The greenhouses that I like the most are brick or block on bottom( about 30" to 3') then glass starts. No real reason, they just feel nicer. Best advice is take a class at a Vo-Tech or Agricultural school. You will learn so much about what pots to use, how to make your own potting soil, different ways to propagate plants.
Hope this helps.


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## a1Jim (Aug 9, 2008)

Thanks for your help Bob.


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## Lumber2Sawdust (Jul 22, 2010)

Jim, we got the poly from Charlie's Greenhouse, online. the shipping isn't cheap because of the size of it, but I think it was a good way to go. We started with a roof made from glass panels recycled from patio doors that had been replaced. The glass was free, but it was pretty painful and stressful framing it, installing it (walking on a glass roof!) and trying to get it sealed well. All of the glass was tempered, but we had a couple of them break. One was my fault during installation, and another broke for an unknown reason. At that point I decided it would be safer and less painful to just replace all the glass with poly. It was a hit to the wallet, but I have no regrets about doing it. I just wish we started out with the poly.


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