How About a PVC Greenhouse?

Have you ever thought about a PVC greenhouse? I’ve heard about rebar and PVC greenhouses, but never thought about building one almost entirely out of PVC.

What a great idea for frugal living and vegetable gardening.

I’m here to tell you that it is possible, and you can do it for less than you might think possible.

The construction techiques are basic, and it seems to require few if any specialized tools and fasteners. This is a do it yourself greenhouse if I ever saw one.

Jeremy and Wanda Manley were gracious enough to allow me to visit with them about their 17 by 32 foot greenhouse made from PVC.

It was built in the spring of 2008, and they have had lots of success with it.

Located just southeast of Cheyenne, I know these folks see much the same windy weather that we do here northwest of town.

The structure seems plenty sturdy to hold up in the wind, and I can tell you that it gets plenty warm inside too.

Let’s dive in now and learn about this greenhouse structure made primarily from PVC.

I’ll try to provide sufficient information so you can make a determination if this might be right for you.

I think it might be a good design for a beginner, as it certainly doesn’t look technically challenging.

a pic of greenhouse pvc entrance
The basic design of the structure is similar to what’s known as a Gothic Arch.

It isn’t the rounded shape of the quonset hut, nor does it have straight sides and sharp angles like one would expect from a garage or shed.

I rather like the shape of the structure. It provides good room overhead without being wasteful, and it makes good use of the side walls.

They don’t go straight up, but they don’t curve in much either to where they might interfere with the gardener.

The primary materials are 2 inch PVC tubing and fittings.

These materials should be readily available at your home improvement store.

I understand that the Manley’s built their structure out of 20 foot long pipe.

This was important because the walls of the PVC greenhouse are made from 5 foot sections, and the rafters are made from 7.5 foot sections.

It makes the construction work out well with little wasted material.

apicoflathonpurlinandendrafterThe PVC greenhouse is constructed mostly of PVC, with some wood elements.

Sole plates and purlins are made from painted wood, and are mounted on the outside of the PVC piping.

Painted wood lath is also used to hold the greenhouse film to the structure as shown to the right.apicofoverheadsprinklers

You’ll note on the left that the ridge piece is 3/4 inch PVC mounted on the inside of the PVC piping, using conduit clamps that screw into the 2 inch PVC ribs.

It also doubles as a header for overhead sprinklers or misting nozzles.

The nice thing about this arrangement is that when you shut down the water system for the season, the positioning of the lines overhead promotes draining to prevent freeze damage.

When you build your PVC greenhouse, even if you aren’t going to use overhead watering, it’s a good idea to have some sort of ridge piece to keep the ribs from wiggling and rubbing on the poly film.

apicofspigot
There are 3/4 inch PVC water lines that run alongside of the purlins on both sides of the structure.

These are headers for water lines that have spigots and hoses attached. If you would rather hand water, this is a good way to do it.

apicofrollupdevice

This PVC greenhouse also incorporates roll-up sides.

A long PVC tube with a homemade crank is positioned on either side of the structure and attached with wood lath to the clear film used for glazing.

After removing the weights that hold down the ends of the poly film, the sides can be rolled up to help vent the heat of the summer.

Ends and doors are made from wood, and the ends are anchored into the ground as a precaution against the winds we are famous for.

Idaho is famous for potatoes, and we’re famous for wind.apicofrebarandsoleplate

The sole plate of the PVC greenhouse is attached to the ends of the ribs, and then the sole plate is anchored into the ground as well.

See photo on the right.

Earth anchors are rebar pounded about 2 feet deep. The above earth portion is bent into the shape of a hook to grab the sole plate.

External anchors as used for fastening rope that keeps the poly from picking up off the structure in high winds.

If lath is used to secure the poly to perhaps every other rafter, and you use woven poly, you probably won’t need to use rope to secure the top.

If you do use rope, be sure that you attach some wooden guide piece to avoid damage to the poly as shown in the photo below left.apicofropetearonfabric

The amazing part of this structure is that it has no cross bracing on the walls.

Usually a cross brace is necessary to keep the structure from swaying lengthwise.

The way cross braces are avoided with this PVC greenhouse is by using two screws, spaced far apart, to fasten the purlins to the sides of the building.

Spacing the screws farther apart provides a little “shear wall” effect on each of the ribs, and this is enough to keep this do it yourself greenhouse from swaying back and forth.

The photo above left shows the wooden purlin on the outside of the PVC piping, but inside the poly covering.

The photo lower left shows how the purlin is spliced together to span this 32 foot long structure.
apicofoverlaponpurlin
While I’m at it, I should mention that the fasteners for this project are almost exclusively drywall screws.

The PVC is soft enough that the screws penetrate it easily.

Care must be taken not to over-tighten the screws that bite into the PVC as this will risk stripping through the soft plastic material and making a weak connection.

The poly covering on the structure is UV protected greenhouse film.

It is held in place at the purlins with painted lath that is screwed through the poly and into the purlins.

The same approach is used at the bottom of the end, but not the sides (since they roll up).

The poly at the top of each end is also secured in a similar manner, except instead of wood purlins, the lath and film are screwed into the end rafters.

apicofanchortobottomendwallsThe photo to the right shows how the lath on the outside of the ends is screwed through the poly film and secured into the 2 by 4 on the inside of the end walls.

Nothing fancy, but it works just fine, and that’s what you want with your PVC greenhouse – effectiveness at a low cost.

The poly film at the ends of the sides overlaps the ends a bit so it can be wrapped around the corner of the end wall and held in place to provide a seal for the greenhouse.

The seal can’t be secured much because it needs to allow the sides to roll up. This will naturally makes the PVC greenhouse a little “leaky”, but it shouldn’t make any difference at all in its performance, especially if you’re not going to heat it.

Note: I suggest not heating any greenhouse unless you have double walls on all sides. Without double wall glazing, you’ll have poor insulation, and you’ll just end up tossing your money away.

Another part of this project involved making raised beds. Of course, something like this is optional, but I find raised beds to be a nice feature for organizing plants and more convenient gardening.PVC Greenhouse

The photo to the left shows a raised bed right and left, and one on the far side of the PVC greenhouse.

There was also a very nice work bench constructed of 2 by 4s with a hardware cloth (hail screen) top that would be ideal for a garden work bench.

Dirt and water fall through the metal screening, so the bench top stays clear of debris. What a great idea!

I certainly appreciate Jeremy and Wanda letting me poke around, ask questions and take pictures of their greenhouse. It’s a great way to start with greenhouse gardening, and it certainly is an inexpensive way to go.

You might get some of that purple primer and glue on your hands, but that beats splinters and sore thumbs from nailing up a wooden structure, and metal cuts and filings associated with a metal structure.

I think building a PVC greenhouse will be far less challenging than other methods, especially if you are a beginner.

I understand that these structures can last quite a while. The longest lasting one I have heard of is 8 years, and that is impressive for plastic pipe that costs about 65 cents a foot.

Background and credit is in order here. This particular PVC greenhouse idea is the brainchild of Del Jimenez of New Mexico State University.

Del is an energetic and knowledgeable man who is busy helping farmers and gardeners get the most from their efforts using organic means.

He put on a program for the Cheyenne Master Gardeners Club in May of 2008. I attended the lecture portion of the workshop.

As part of his visit, he orchestrated the construction of this PVC greenhouse with the help of more than a dozen members of the club.

It required a good two day effort as well.

For pictures of the greenhouse under construction, estimated costs and material data, and instructions for assembly, see: the program summary from the Laramie County Master Gardeners.

As with any project, building a PVC greenhouse goes quickly and more smoothly when you have lots of help, and everything is well organized from the start.

If part of your plan for frugal living is a do it yourself greenhouse, then this might be a low cost solution for you.

2 thoughts on “How About a PVC Greenhouse?”

  1. This is difficult to follow because the structural components are called the incorrect names. Mainly the use of the word “Purlin” There is no purlins used in this from what I see in any of the photos. A purlin is a ROOFS structural component that runs perpendicular to the ridge and parallel to the side walls, and used to provide support for roofing panels in-between the rafters so there is no sag in panel (not the only reason).

    I’m not trying to be picky just try to understand so I can build a version

    Reply

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