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How many grip-clips do I need to hold up 6 mil polyethylene  (3 pieces 10 x 25 ft) inside a 20′ dome?

On Mar 17, 2007

Bob,
How many grip-clips do I need to hold up 6 mil polyethylene  (3 pieces 10 x 25 ft) inside a 20′ dome?
The geodesic dome is 3V 10′ radius and about 19′ diameter at ground level and about 8.5′ high; it’s
made of 120 struts each 3.5′ to 4′ half inch EMT.  There are 15 joints at ground level and 31 higher up.
Each joint has a 5/16 bolt through the center.  Based on what is typed here it looks like I need 46 plus
maybe a few extra.
This site may help illustrate–http://www.desertdomes.com/dome3calc.html
(note, the drawing is of a 5/8 dome, mine has one less row of triangles at the bottom).
See attached picture;  the door will be the large triangle in front.
At this point I am using 3/4 inch rocks with wire wrapped around them to attach two pieces of plastic
or to make something to hook a bungee cord to.  Not too elegant but I guess I got the theory right.
Eventually I want to insulate this greenhouse–two layers of poly with practice golf balls as spacers. (One
ball per triangle)
BTW, the frame will support 200 pounds (me) at any joint but not between joints. And, it’s almost 30′ from
ground level over the top to the other side.
Feel free to make any suggestions especially about the door (it seems sturdy with one strut removed).
Thanks,
Dan

Hi Dan

I would use one Heavy Duty Grip Clip at each joint. Get a few more to attach to a door flap. Make the flap bigger than the opening so that it overlaps it by about 6″. attach clips on this flap and attach out side the dome covering so that your door will be tight and shingled.

Sincerely,

Bob Gillis

Bob
My order arrived yesterday and I put some of the grip clips to use this morning.
I can definitely see that putting the film, tarp, or fabric on the inside of a frame is the way
to go– nothing is chaffing against the hubs and it’s easier compared to trying to fasten
two pieces together that are already installed and under some tension. So, I will be
putting the poly film on the inside sooner rather than later–I still plan to install two layers
but the second will go on the outside.
I appreciate all the ideas for how to use these things you have on your website.
Dan

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