Table Of Content
Chapter 1. Introduction
After we have installed the aardwarmtekorven we should start thinking about building the greenhouse. We are very fortunate to have a back yard with a garage in the back. Additionally the side of our house, which is the outside wall of our kitchen, faces the side of the garage. The depth of the back yard is approximately 11.5 meters while the full width of the yard is about 8 meters. We’ve considered building the greenhouse from side to side but this may run into problems with permits. The side of the garage however is about 6 meters and has a pointed roof which starts at a height of 2.5 meter. In the center it’s about 3.6 meters tall.
In the above picture we see the garage in the back while on the right we can see the wall separating our yard from the street. Having the side of the house facing the side of the garage makes it very convenient to build a strong basis for the greenhouse. Essentially it comes down to attaching 5 wooden beams between the two walls.
- The top beam will be supported by 16cm wide PVC tubes. PVC is not only a strong yet inexpensive material, it also has the nice property in that it’s hollow. We want to use this property in order to create vertical strawberry towers.
- The diagonal going up will be approx. 3.6 meters long as we were able to purchase very inexpensive polycarbonate plates that are 3.60 x 2.10 meter. However, the wooden beams we were able to purchase inexpensively as well are 2.5 meter long. This, and the fact that we also want windows in the top despite the goal of building a ‘closed greenhouse’ made me decide to put two beams in parallel to the top beam. The polycarbonate plates can be cut right on the top of the two parallel beams so the windows have a support to lean on.
- The two top-side beams will be the attachment point for the walls plus additional support beams, and the sides of the roof.
Chapter 2. Wood
I was able to purchase a bundle of 8 x 12 x 250 cm used wood beams. They’re beams that have been used 1 time which is why they’re pretty cheap. These cost 3 euros per beam but this is the unprocessed price. I asked houthandel Smetsers if they could treat them for me which they will also do at an additionl cost of 1.25 euros per beam.
All in all, including delivery, the material totals 553 euro, not a bad deal at all for 225 meters of sturdy, treated wood!
Chapter 3. Polycarbonate
We’ll use polycarbonate plates to cover up the frame. I found a good deal on marktplaats.nl, a Dutch auction site, for used polycarbonate plates. They’re 360 x 210 x 1 cm plates. Each of them weighs approximately 12 kilograms. They will cover the roof with one on each side, so every 2 plates cover 2.10 meters of roof. This means we will need 6 plates to cover the 11.5 meter yard depth, or 12 plates in total. With a combined weight of only 12×12 =~ 150 kilograms, the wooden beams should be plenty to hold them up. In fact I believe the 8×12 beams to be almost excessive for this purpose but I also love the idea of having a ‘wood atmosphere’ to the greenhouse.
These plates do not look fantastic as they’ve obviously been used but new plates will look like these in no time and the price difference is significant; Buying 20 of them, I even got a nice discount from 5 euro/m2 to 4 euro/m2. At 150 square meter that totals 600 euro.
Chapter 4. PVC
For the supports for the center beam we’ll be using 16cm wide PVC pipes.
Through making openings in these PVC pipes we’ll be creating planting space for strawberries so we’ll have 4x3m planting space for strawberries built into the structure itself!
UPDATE January 22nd: Meanwhile, Smetsers Houthandel has delivered the wood. They’ve also been very helpful in getting the polycarbonate plates here. The plates are very large (3.20m x 2.10m) and apparently I would not be allowed to rent a tandem axle trailer with my B drivers license, so it became very difficult to get these plates here in Almere. Fortunately, for a very reasonable sum extra, Smetsers picked up these plates and the PVC tubes and delivered it all yesterday morning at 7am. My backyard now looks like a construction yard!
Chapter 5. Concrete
For the foundation we need something pretty heavy so the greenhouse will not fly away with the wind. At first we’ve been looking into buying cell concrete blocks but these are actually fairly light. Another possibility that’s affordable are retaining straps. Not sure if this is the right translation in English but these are often dug into the ground as separator between soil and pavement.
The best and cheapest solution so far however popped up as we were working on the rainwater collection. As a few IBC containers have to be dug into the ground for this, a rather big volume of soil and sand was dug up. As from previous digging in the backyard, we also have a fair amount of gravel buried in the location where the fish tanks will go into the ground, we already have a reasonable volume of the two most important components of concrete.
After stumbling on an advertisement for a free concrete mixer the decision was quickly made; We will use our home-made concrete for the foundation. This serves two purposes. We will be much more flexible in deciding on the shape of the concrete blocks but we will also clean up a sizable volume of sand and gravel which otherwise we would have to pay for to get rid of.
Chapter 6. What’s Next?
Well, in parallel to building the greenhouse my brother Ron is working on making solar panels, you might want to check out the progress!