The next step will be to install the anchor cables. There are 6 cables. My original plan was to put three on each side. The greenhouse vendor agreed that they might be necessary. The greenhouse is going to be sheltered on three sides by our privacy fence and our tractor shed, but the western end of the greenhouse is exposed to winds, with little protection being offered by the chain link fence about 200 yards away. Shortly after we moved in, a windstorm blew over some partitions in our kennel area, so there is precedent for strong winds coming from the West. So far I have only put four anchors in the ground, two on each side, grouped close to the exposed end of the foundation frame. I may put two more in on the end that is exposed most to the wind, but haven't yet decided on that.
The second photo shows one of the cables threaded through the side of the foundation metal. A steel rod is provided as part of the anchor kit to drive the metal anchor cup at the end of the anchor cable into the ground. The other end of the cable forms a loop that is closed by application of a small bracket with two small set screws. This seems to be the weakest "link" in the anchor cable system. I just hope that it has been engineered sufficiently to hold in strong winds. I don't think it is very likely that there would be strong winds tending to lift the Eastern end of the greenhouse, since it is protected by the tractor shed that is only 10 feet away, and that end is submerged in the ground, preventing lift from wind that would get underneath the greenhouse. Therefore, I plan to install the anchors distributed more toward the western end of the greenhouse.
When I opened the anchor kit, my frist guess was that one should fasten the anchor cable to the foundation and then pound the anchor into the ground until the cable was taut. The illustrations that comprised the instructions indicated otherwise. Then, I saw that if the bracket with the set screws was subjected to a large force during the pounding, it would fail. The correct way, apparently, is to situate the anchor in the ground sufficiently deep that one can draw the cable taut while it is attached to the foundation structure.
The way that the anchor cables will be attached to the foundation pieces was not covered in any instructions. I thought at first that I would drill two holes in the midsection of the aluminum pieces of the foundation for each cable. Then, I would thread the cable into one hole and out the other and complete the loop by joining the end of the cable to the main portion of the cable with the bracket that has the set screws. However, Andrew at Exaco Trading (http://www.exaco.com/), the company that imports and wholesales the Riga greenhouse in the U.S., suggested that I drill just one hole and loop the cable under the foundation in each case. If I went with the idea of drilling two holes at each cable location, a pull on the cable would be resisted only by the inch or two of aluminum material between the two holes, but by using a single hole and looping the cable around the bottom of the foundation, there is much more aluminum resisting the pull of the cable. Andrew was very supportive and was willing to talk at length about his greenhouses. He also appeared in the DVD provided with the greenhouse kit. In the DVD, he shows step by step how to erect the greenhouse. The support and encouragement provided by Andrew is a terrific reason for choosing a Riga greenhouse over the other brands I looked at. Of course, I didn't know this when I made my choice, but if you are reading this and want to erect your own greenhouse, Andrew's availability is a very important selling point. Exaco is the exclusive U.S. distributor of Riga greenhouses. I also received excellent support from http://www.4seasongreenhouse.com/.
After I install the 6 anchor cables, I will have about two weeks to assemble the front and back ends of the greenhouse in the garage, to be ready for the final assembly on Memorial Day weekend. Once the ends are constructed, I will have to connect them to the foundation. The pieces that comprise the aluminum frame are called profiles. Aluminum straps are provided to attach the curved vertical profiles to the foundation pieces. However, Andrew says that the straps aren't needed. It is better to drill holes into the floor profiles and connect the floor profiles to the foundation using self-tapping metal screws. I assume that I will have to use rust-protected metal screws for this purpose. How many screws needed for this purpose was not explained, but I guess one screw per linear foot of floor profile should do it. The heftier the screw, the less screws will be needed. The screws will go into the sides of the floor profiles from the inside, so they won't interfere with sliding of the glazing panels.
I have had to modify this text after it was published to reflect what I learned afterwards about the self-tapping screws and the foundation. Alan, at Exaco, told me that the foundation frame will have to be loosened, because the floor profiles have a larger perimeter than the foundation pieces, if they are fastened as closely as they can be. There has been some wasted effort, since I will have to remove some of the soil I filled in around the outside of the foundation, so I can loosen the foundation pieces. I don't see that as being very difficult or time-consuming.
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