Greenhouse construction

[bullsie]

I've been looking at greenhouses and all the materials used to build them. For those who own them, can you help with the pros and cons of materials, in particular, structural parts made of aluminum/wood/? . Thanks!

 

[Ray]

I have built greenhouses using treated lumber, but the galvalume steel frame that came with my Turner Greenhouse was far cleaner and blocked less light.

There are several good options for the covering, but I think multi-wall polycarbonate is the best bet.

 

[bullsie]

Thanks Ray! I know you had mentioned Turners before, which look tempting, but I worry about our harsh winters of heavy snow and cold temps. And now, we seem to be affected by high winds and hail during the 'warmer' seasons.

I agree with multi wall polycarbonate, especially for the roof. Do you remember the durability of the treated lumber? I understand wood can be 'warmer' than the metals many greenhouses are constructed of?

Thoughts?

 

[Ray]

I had the Turner when I was in Bucks County, PA, and we had some pretty harsh weather there, and the greenhouse held up beautifully for 25 years before I sold it. In the case of any structure, but especially a greenhouse where the majority of the materials of construction are the glazing, the covering can be a significant part of the structural integrity. The steel frame plus polycarbonate yielded a stronger structure as a result.

Treated lumber is fine for probably 25 or more years, but being porous, will become saturated and a great home of molds and algae in the surface, providing a "bank" from which it can be shared. If I were to do wood again, I'd paint it with bright white paint, sealing it and helping scatter the light hitting the struts, and making them easier to clean.

Yea, a metal frame will conduct more heat than wood, but if you glazing is sealed (it must be), I really doubt there's a significant different in heating cost, as the vast majority of the heat loss with be through the glazing and leakage through openings.

Use multiwall PC on all surfaces; greenhouses don't only lose heat through the roof (your circulation fans spread it pretty uniformly), and heating will be your most significant cost. I had my GH oriented north-south, so my north wall was foam-insulated plywood, again painted white, saving me quite a bit.

 

[TyroneGenade]

An interesting read: https://www.lowtechmagazine.com/2015/12/fruit-walls-urban-farming.html

 

[Ozpaph]

great read. thanks

 

[Hardwood]

I think the most important concept in a greenhouse is energy conservation. Use triple wall poly-carbonate for the roof not just double wall. Seal the air leaks. I used 2x6 treated southern yellow pine for the rafters (2 feet on center) and the wall studs (4 feet on center). My knee wall is 36 inches high and insulated with foam. The walls are double pane slider windows. 4 feet wide and 5 feet tall.
Poly-carbonate will expand and contract with temperature changes. I used Sun dance supply for the roof. Quaker windows for the vinyl sliders. I have a tile floor with a center drain. if you use gravel, it will grow weeds and bugs and disease. Your mileage may vary. The most important thing for ease of growing orchids is potting them for the way you water. The second most important item is water quality. I use RO water and it solves so many problems. Then get Ray's fertilizer and Kelp and you are all set.
I use Aluminet for the shade cloth and cool cells for the wet walls. My greenhouse never gets warmer than 92 degrees. 72 degrees coming off the wet walls. My two speed exhaust fan on high will change the air every minute if needed in the summer.
I used wood because I could do all the work my self. My 20 x 20 foot greenhouse cost $12,000.00 fifteen years ago. It uses 300 gallons of propane to keep it above 60 degrees in the winter. It is attached to the end of the house so I can go into the greenhouse any time I want and also if (when) I get old I can still take care of the greenhouse.
Plan for the future and do it right the first time. Good growing.

 

[abax]

Are you building your greenhouse yourself or buying
one to construct? My 12x28 greenhouse is self-built
and is 21 years old and holding up extremely well.
If you'd like more info. on how we did it, please
PM me. My energy bills are quite low as well.

 

[bullsie]

Thanks abax! It's six of one half dozen other whether to buy or build 'myself'. Having limited funds, I want to do as much 'right' as possible - I more than know there are always changes or wish done different once up and running. But durability and moderate running cost are biggies for me.

A lot of good info everyone has provided and given me lots to think about. Will probably PM you later abax when I have the time to really concentrate on your information. Appreciate!