you will be alot happier if you purchase a tubing bender and build your greenhouse if finances dont alot buying a kit

Herb lover, I worked in a commercial greenhouse for 7 years but when I wanted a hobby greenhouse for the backyard, I couldn't afford to purchase a kit. (No purchasing power? Maybe because I worked in a greenhouse for 7 years. ;o)

I used 5 storm windows and a storm door. First I build a short wall with 2x4's and plywood about 6 feet from the south wall of my garage. Then I built 4 window frames on top the wall and attached wall and frames to the garage. Then I framed in the door at one end and one window at the opposite end and hung the door and all windows. The roof was built of 2x4's and corrugated fiberglass roofing panels.

Construction was made a little more difficult because I knew I would need to move the structure in a few years. So, walls and roof were built as units and bolted together. It worked but was long-ago replaced at my current home by what is essentially a sunshed - 9 by 20. (You can do a google image search and look at sunshed models.)

Over the last 20 years, I have built various plastic tunnels made out of pvc pipe and plastic film. Two were 10' by 20' and used framed-in doors and windows for access and ventilation. On the simpler one, the pvc pipe was held by short lengths of rebar driven into the ground. I used 15' pipes to form the arcs and just tied them with plastic rope run along the apex and to the tops of the window and door frames. The rope holds the pipes in place and rope is also used across the top of the structure (from opposite corner to opposite corner) to keep high winds from blowing the plastic off.

Since I'm over 6 foot and this tunnel is only about 5, I've excavated a pathway about 16 inches deep. I framed the pathway with cedar boards  thus giving me raised beds on either side. This structure allows me to start cool-weather vegetables in the beds very early each season.

The sunshed is used to start plants in flats on shelves. When I run out of room - flats are taken into the tunnel and laid across the boards that frame the path. Putting flats on the beds is not acceptable since I'd both limit what can be grown in the ground and make a fine home for slugs under the flats.

I use construction grade 6 mil plastic film (20 foot wide) on the tunnel and discard it each summer. The sunshed's south wall is covered with UV resistant 6 mil film. It is actually cheaper to buy the more expensive film and leave it up but the tunnel would be too hot if left covered thru the summer - I grow warm-weather plants in the open beds at that time.

Steve

my plans are to use some angle kits from charley's greenhouse supply....they're made of galvanized steel, and simply require that you insert the end of a 2x4 and fasten....3 kits, at a cost of about $180 will yield a 10x22' structure...i then plan to use corrugated polycarbonate for glazing...i estimate that the whole thing will run me about $750 for materials....doors will be home-made, and ventilation will be rigged until funds are available to upgrade....i plan to heat it with a basic used wood burner until i can get a wood-fired boiler....good luck to you...

have a very peaceful day,

doug

Herb,
Depending on the size of greenhouse you want and the amount of cold weather you get, the link below has plans and photos for a very inexpensive greenhouse that might give you some ideas.

Here is a link that might be useful: hobby greenhouse design

Go to the bottom of this page and type in homemade greenhouse in the search box. You'll be amazed at the wealth of information from previous posts!!

Make sure that any wood that you use will stand up to a moist environment.

For heating, consider attaching the greenhouse to your house so it can share your heating system on cold nights. I wouldn't want to have my AC cool my greenhouse in the summer, though -- a combination of shade cloth and/or vents/fans should be considered a must (just a warning: passive venting takes very big vents).

To stay cheap but still have reasonably good insulation, you can't go better than double layer polyethylene. Note that if you get construction grade stuff, you'll have to change it annually. Better is to get treated PE with a UV-resistant coating; that'll greatly slow down how fast it degrades. Other useful coatings will provide things IR absorption (really helps with insulation) and fogging resistance. Also, you want airspace between the layers. If you're trying to stay cheap, you probably won't use a blower; just put spacers every six inches or so to keep them apart, and it'll do fine.

To have it retain heat better, have the inner layer be PVC instead of PE, or add a layer of PVC inside. PVC lasts longer than PE and absorbs IR reasonably well (unlike uncoated PE). I haven't tested them in a greenhouse environment (and probably won't have a chance to for another couple years), but if you can get some mylar or kapton film, they should be even better than PVC in this respect.

I am replacing three sliding patio doors and will soon have six large sheets of tempered glass surrounded by an aluminum frame, sizes 5 feet by 6 feet eight inches and four feet by six feet eight inches from the old doors. Any ideas? I was thinking of making several large cold frames out of them with a cement block foundation and walls sloped towards the south and just lay the glass on top of the cement blocks. Should be quick and cheap. I would just tip the glass up when I wanted to get to the interior of the cold frame.

karenrei,
Could you please provide a reference where any greenhouse, in the universe, has used "PVC instead of PE" as a greenhouse covering?

you might check for old sliding door windows from your local glass supplier--my local store sold them for about $10-15 each

cuestaroble,

"Could you please provide a reference where any greenhouse, in the universe, has used "PVC instead of PE" as a greenhouse covering?"

Quoting from this source, Greenhouse Covering Systems, on pages 8 and 9:

"Modern plastics have become the only alternative to traditional glass for covering the greenhouse. Plastic glazings include rigid plastic structured panels, such as fiberglass reinforced polyester (FRP), acrylic (PMMA, polymethylmethacrylate), polycarbonate (PC), and polyvinyl chloride (PVC) panels. Thin film coverings include low density polyethylene (LDPE), polyvinylchloride (PVC), and ethylene vinyl acetate copolymer (EVA). These materials have been used in single, double and even triple layers to cover the greenhouse."

PVC film is included in this listing of greenhouse film products.

These Greenhouse Plans list PVC film as a covering option that is difficult to keep clean.

Plasticulture in the Global Community - View of the Past and Future has some interesting information on the use of PVC use as greenhouse covers.

The advantages and disadvantages of PVC on greenhouses are discussed in this greenhouse article.

It seems that PVC as a greenhouse cover is much more popular in Asia than it is here in the US.

MM

Cuestaroble: I thought you were an "international specialist in greenhouse vegetable production". You haven't heard of PVC glazing? Just google for it, you'll get tens of thousands of hits.

It's big in Japan.

It's more expensive than PE, but it's more durable and absorbs IR better.

Some here may remember when I was using vinyl on the south side of my greenhouse. (that post and thread is long gone)

It performed very well, I could see outside.That was my goal, I like to sit in my greenhouse and see outside.

It was only 4mil and was damaged by wind blown objects. However my new 6mil PE is suffering mechanical damage too.

It would be more convincing if they didn't make blunders such as "Polyvinylchloride (PVC) has a very high emissivity for long wave radiation (similar to glass), which creates slightly higher air temperatures in the greenhouse during the night."

They of course mean it has low emissivity in thermal IR.

So that no one gets the idea that using PVC film for greenhouses is either a good idea or widely practiced, the following is quoted from the reference given by a prior respondent to this thread. Note that it is based on over 20 year old information, from one country, and mentions that PVC film after one season results in "significantly reduce(d) transmission", and is only available in less than 6 ft widths.

"PVC film has been used mostly in Japan as a single layer cover, and in 1985, there were more than 34,000 ha (84,000 acres) (Takakura, 1988). The film has a transmissivity of less than 0.45 for a single layer, which is the best IR barrier properties for commonly used films. At first, PAR transmission compares to glass, but the surface of the PVC film attracts sufficient dust and dirt within one season to significantly reduce transmission. It is only manufactured in relatively narrow widths (approximately 1.8 m (5.9 ft). Pieces can be joined by heat sealing or by using a special tape."

Sorry, but that quote does not prove it is a bad idea, only that current implementations are poor. It could be made in wider strips, and it could be coated in a conductive film to make it antistatic. These things are all possible, and doing something wrong 100 times does not show it can't be done (something mythbusters still haven't clued onto).

Here in Melbourne I can buy a 4m wide roll of 4mm (160mil) water clear PVC at the local hardware store. Very clear, very tough. It is popular as a roll up window for outdoor eating areas.

The big argument against PVC for any use is the production of dioxins in its manufacture, and the difficulty of safe disposal.

I am in the process of building one of those 10 x 22 garden structures using the metal flanges from Charley's greenhouse and other places. I thought it would be the greatest thing since sliced bread. But in my humble opinion, they are crap. The flanges are very thin and in order to get better holding power, I had to cut the ends on an angle, and install all sorts of bracing to keep the structure from yawing one way or another. While you are erecting the frames, if the 2 bys move one way or another the flanges bend and the whole thing collapses. Also my studs are a full 8 feet tall, which means the roof is up there a bit to high for me to comfortably move around while trying to manuver ply wood and shingles, and still hold on. My wife says I am to old for this, I am 68. If you build one get a lot of help to work with you and consider making it shorter. Just my opinion from experience. I was sheathing it this afternoon.

Cuestaroble:

I just grabbed the first three links that I ran into. I'm really surprised that, with your reputation, you would write something like:

"Could you please provide a reference where any greenhouse, in the universe, has used "PVC instead of PE" as a greenhouse covering?"

without googling it first. There are countless references to it being used out there.

The quote that you excerpted demonstrates that untreated PVC exposed to the environment becomes dusty. Personally, I'd rather scrub my glazing than replace it due to UV damage, and I'd wager that anti-dust (assumedly anti-static?) coatings are cheaper than the anti-UV coatings needed for PE. If PVC were so problematic in natural environments, you wouldn't see things like skylights, clear roofing, awnings, etc. Oh, and rigid PVC is rated as self-extinguishing in a fire, while PVC sheeting burns poorly. PVC is one of the more fire resistant plastics. Of course, if you do burn it, its fumes are pretty nasty.

Yes, it's not a wonder plastic. But it is an option. The properties of untreated PVC are generally favorable to those of untreated PE.

But, anyways, I hope this answers your request for someone "in the universe" who's used PVC.

I know you probably don't have any cattle panels laying around, but they can make a nice greenhouse. They are 4' wide and 16' long. You bend them into arches and use however many you want for the length of the greenhouse, and cover them with plastic sheeting. You can anchor them to the ground with treated 4x4's or railroad ties. Do a search for "cattlepanel greenhouses". Good luck.

I am planning to make a greenhouse using treated wood framing, glass and fiberglass on S side and an insulated wood/plastic N wall and a shingled N roof. S roof to be fiberglass covered. Thinking of lining the inside( all sides) with poly film. 6' tall walls, and a 10' span. Length about 14'. Auto open vents top and bottom.
Have area filled to make a flat spot for it.