Building a greenhouse is a logical step when having a vegetable garden for a few years. Mine is a 450 m2 rented allotment, with vegetables, lots of flowers and landscaping. It is located just outside my town, in Alkmaar, the Netherlands.

In spring, seeds have to be nursed, in summer, tomatoes, peppers, cucumbers, grapes etc. need extra warmth.

I winter, lots of plants need protection from the cold. In my attic it is too warm and dry - survival rates are low.

During about 2 years I have been keeping an eye out and been collecting suitable wood and other materials.

Everything is recycled and re-used, except nails, brackets, paint and the plastic roof cover.

Total costs for me were about E 200.

If used wood and 2nd hand agricultural glass would have been purchased, the costs would have been ca. E 800- 1000.

If new stuff would have been bought, the costs would have been over E 4000.

Companies selling greenhouses made from disassembled commercial large greenhouse complexes charge ca. E 10.000, assembled on site for this size.

If well built and maintained, it can last over a lifetime.

The greenhouse was built with hand tools and electrical hand saw, planer, router, belt sander and (battery) drill. In front, the allotment has 220 V.

Time: more than 2 months, almost full time (built completely on my own). Update: make it 3 months. (doors, gutters, and windows which can be opened). Building time can be shortened by using standard sizes of windows etc. (I made everything custom built)

The sizes are actually 5.20 x 3.85 m, with the roof reaching 2.75 m (not the decoration). For US: about 17 x 13 feet, with a height of about 8 feet.

Step 1: Materials

Everything collected on the bike, mostly with my heavy duty 4 wheel trailer.

Wood: Lots of large boards (beams), about 16x 6 cm (6+ x 2+ inches). Many about 2 m, but some over a sweet 5m!!! (learn metrics!- 6 to 16+ feet). Had to be cut (over length) in 2! Many smaller boards were found, as needed. Sometimes, it almost seemed like I ordered them: anytime I needed a certain size, a certain amount, a dumpster showed up, with just the proper wood required!

The 'glass': This part of my instructable is of course very specific to my own situation: I found beautiful, large, discarded acrylic sheets, but with nasty commercial plastic foil stuck to it. It was loads of work to remove the sheets and very sticky glue, but now I am the envy of everyone.

In the step about ' the glass', I will present some options to find transparent greenhouse covering.

Finding useful stuff in dumpsters works 2 ways: Giving nice things found, away; everyone will help finding that special bracket, the ways to stabilize the frame, or the address where to obtain the perfect roof covering material.

Step 2: Working the Wood.

Near our garden complex was a road construction. Their break room had a crude pergola of large beams, to provide some shade during hot and sunny days. When the viaduct was finally finished, all the stuff was thrown in the dumpster! A broken road sign, and many office and store re-modelings in town, provided additional material.

The large beams were cut (sawed) in 2, over length.

Everything was painted: first with 50- 20 % turpentine/ paint, then with regular paint. In our allotment, any color is OK, as long as it's green.....

Old and questionable quality wood benefits from a first layer of very diluted paint. It kills the bugs, and actually strengthens it...

The acrylic sheets were carefully measured. The top and corner boards were routed to receive the sheets, the rest of the vertical boards receive the sheets on top.

Step 3: The Frame

All 4 sides were framed (on the path in front of the garden). Everything was put together in place, resting on scraps of wood. First with nails, subsequently with brackets:

All connections were secured with brackets; these large surfaces are subjected to huge forces during storms, and can easily get airborne!!!

The frame is connected to 14 concrete bucket size foundation casts by means of M10 and M 8 threads.

Everything is painted at least twice.

Step 4: Design and Permit

OK, most material have arrived, there is some idea about what to build, the materials, the sizes...

1) make a preliminary design, a drawing. Find out what more to obtain, plus alternatives.

2) Check out the building codes and rules of your place: submit, in a casual way, the design to the board, the authority which has to approve construction (in my case, the allotment board).

3) Discuss and modify problems in he design. When everything is OK, submit the corrected design. Get the approval!, in writing!!!

Forget to take this step? prepare to rebuild!!!!

My first greenhouse was built without approval. I had to take it down!!!

Check if you can build!!!

Step 5: The Glass...

A greenhouse needs transparent covering. Traditionally: glass.

3 ways:

1) Use available, standard sizes of agricultural windows of your area. Cleaning might be needed. If a window breaks, replacement will be easy...

2) Obtain windows, sheets or other materials. If quality is sufficient, find a way to use them in the overall design.

3) Use the enforced UV resistant plastic: In my area: 2m wide: 6 E/ m. I used it for the roof. It lasts over 10 years.

Cheap plastic: Not even for one summer! Bad idea!

Step 6: The Roof

Actually not a true step... You can build all of your greenhouse during this stuff, If I would have chosen this option, the total costs of this transparent covering would be ca. E 200.

I did not have enough acrylic sheets for the roof, so for me, 11 m was sufficient ( E 66.-). The plastic needs to be applied without too much play. It means fixing it down at every support.

It can be done with strips of plastic, or aluminum, but I was able to secure plenty of high quality, food grade strips of conveyor belt. These belts are fabricated, and subsequently cut to size, leaving beautifully long, high quality strips, thrown into their dumpster!!! The company folks were very helpful, lending clippers and providing a large box to take the strips away!!!

Step 7: Other Greenhouses...

I decided to add some pictures with comments of other self built greenhouses on our allotment.

This way my instructable is less specific with regard to materials. After all, acrylic sheets are a rare find.

Some of the greenhouses are over 50 years old, with very traditional designs. Disrepair can be caused by design flaws or sloppiness, but usually the old greenhouses have been aging together with the builder, and 80 plussers are not that good at maintenance anymore...

Step 8: Use of the Greenhouse!

Of course this step begs for updates! For now, a small desk, a petroleum heater, some tables and a comfortable bench/ couch are in the planning. A large table for propagating seeds. I have no experience with greenhouses. Just have to watch it not becoming not just another storage of indeterminate junk!!!

A gutter/ water storage / distribution system has to be made, ventilation windows, etc. etc. (Just could not wait to submit the instructable!)

In an update, I will show how the greenhouse has been put into use, and how all the gadgets still to be made are employed...