Hi Anna and Mark,

The farmer I was working with, who just sold his farm, had 9 hoop houses. I watched him install 2 of them.

His comments were:

 Round top is best.

 Enough spacing between them to allow for snow plowing between them without damage by his tractor.

 One end door big enough (double door) to allow a real tractor inside. 

 One electric fan on one end to help with hot summer cooling.

 Roll up sides and continuous roof plastic.

 Wiggle wire to hold plastic at top of roll up portion.

 On a raised pad, cross wise to the prevailing wind so when the sides are up real air flow happens.

 Plastic long enough to seal well with the ground when the sides are down. 

 Sheet metal screws added to roll up pipe clips to keep them in place.

 Person door on one end to keep cold winds from shocking plants in early spring.

 Good luck,
 John

I would put it up ASAP, if only for tomatoes. I only grow tomatoes in hoop houses because late blight is almost guaranteed outside. Also good for chickens in winter.