4.2.2 Frame Design - Walls
The walls will need to withstand lateral forces; therefore a system to resist these forces is needed.
Unfortunately, glassy materials, like plastic, glass, or fiberglass, do not have the properties to completely
oppose these forces. Therefore, other methods to resist lateral forces have to be found.
One simple way to resist them is the use of diagonal posts. Using diagonal posts in between the studs on
the walls of the greenhouse ensure that the structure will hold the lateral forces by tension and
compression of these posts. Ideally, the diagonal posts are placed in between every stud. However,
most of the greenhouse is transparent, having posts in the middle of every stud would considerably
reduce the light transmission for the plants. Therefore, to be on the safe side, one option is to use one
post on every few studs, as shown in Figure 34 , preferable closer to the fish tanks where the lack of light
will not affect the growth of the ecosystem.
Figure 34. Diagonal Post on Walls
Normally aquaponic systems have beds that are a few feet above the ground. With this consideration
we can build wood walls until the height of the beds. From our structure design we can build a 4 feet
high of non-transparent material in three walls and an entire non-transparent wall.
The parts of the greenhouse where transparent walls are not required should also be insulated as much
as possible to diminish the heat loss. A cheap and effective way to do this is to use double skin of
plywood, one on the outer wall and one on the inner wall, and in between fill it up with insulating
material, like fiber glass. Figure 35 shows how the fiber glass is placed in the middle the walls.