The base of the structure is a wider pressure treated lumber that anchors the structure to the
foundation (described below) and serves as studs for the corners of the structure.
For the base, the pressure treated wood that goes inside of the sonotube (sonotubes are a foundation
component explained in section 4.2.4), and they will also serve as studs on the corners of the structure.
This structure would be stronger against lateral forces, what is a major requirement for places with
strong winds or storms. Another options to connect the upper body of the structure with the foundation
is to replace every stud that would go on top of the footed sonotube with these long pressure treated
wood studs planted in the sonotubes. This design would give the maximum resistance against the lateral
forces but it would also significantly increase the cost of the greenhouse.
For more information of the area, volume, and other dimensional aspects of the greenhouse refer to
appendix A.
4.2.1 Frame Design - Roof
The roof of the greenhouse is an important piece to be considered, the roof has to support the heavy
weight of the wet snow, have enough light transparency, and has to be made out of a good insulating
material in order to reduce the energy costs since most of heat loss happens through the roof.
Other aspects that were considered are height of the roof and the quality of the materials that will
compose the frame of the greenhouse. The flatter the roof gets, the stronger that frame has to be in
order to support direct weight for longer periods of time.
As for the structure, it has to be strong enough to hold the wait of the roof plus the weight of the snow.
While talking to Professor Alamos, structural engineer, three types of roof came up: the Collar tie roof,
pre-engineered truss, and diagonal bracing. More information about the styles of roof can be found in
appendix D.
We recommend the pre-engineered truss, because it serves as a reinforcement for the roof. The
triangular shape is known to have little to no deformation over the time because in every corner where
stress is applied there is reinforcement on the other side to distribute the load.
A pre-engineered truss is shown in the Figure 33.
Figure 33. Pre-engineered Truss
(Engineering)The draw backs of this roof is that it takes more material to build, thus making the structure more
expensive, and it also takes more space inside of the greenhouse, which might affect light transmission.