Looking Closer at Polytunnels

 

Looking at the Crocodile Trading website at the PT0008 - 4 Arched 25mm Galvanised Frame with full Ground Bar Kit web page and the photo of the bracing I noticed a couple of things.

1. The horizontal (longitudinal) brace is fitted to the outside of the framework. This I knew had to be wrong as I know that they sell tape that goes over the framework to stop the heat affecting the cover. 

2. That the diagonal brace is fitted on the inside at the bottom and on the outside of the upright members at the top. 

So I downloaded the four page Assembly Guide from their web site for the PT0008 shown below.  

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You will notice that the advice to "Fit all horizontal and diagonal bars on the INSIDE of the tunnel arch" is repeated on each page of the Assembly Guide. 

This really begs the question, why did Crocodile Trading not erect the framework as their own instructions and why show an image on their web site that is contradictory to the advice in the Assembly Guide? 

Bracing consists of only two diagonal bars one for each row of frames. I have contacted Crocodile because as a structural engineer I will want to place the bracing in opposite directions in the same line either end so they act in compression and tension depending on the direction of the wind.

So I will be requiring to buy two additional 6 and 6A members to install as shown above in a red dashed line.

Greenhouse V Polytunnel

 

With the wet weather and no internet connection for over a week I have been toying around with the idea and cost of getting a larger greenhouse to replace the two high entry ones on each plot or a polytunnel to place over the three beds to the right of SFG1 rather than just replacing the framed beds with smaller raised beds. 

I'm considering the 4m x 2m (13' x 7' approx) Pro+ Green Poly Tunnel from Crocodile Trading.

PT0008 - 4 Arched 25mm Galvanised Frame with full Ground Bar Kit, increased added bracing, rip stop cover, front metal hinged door & rear zippered roll up door.

The additional bracing consists of only two diagonal bars one for each row of frames. I have contacted Crocodile because as a structural engineer I will want to place the bracing in opposite directions in the same line either end so they act in compression and tension depending on the direction of the wind. 

They didn't have the additional braces at the moment but said they would have them next year.  

I have been reading a lot about how people have reinforced their polytunnels and installed them to survive longer and have joint a Facebook group called Polytunnel Growers UK and have been reading what people have done to offer more stability. 

My plan is to install a timber base with 600x600 raise beds in the corners and mid point on the length and to use my existing Quadgrows in between and buy another one for the end with the zip door. This should assist in resisting uplift and and lateral movement.