Friday, May 1, 2009

How I built my Poly Tunnel, Finally...

Here is the unveiling of the completed poly tunnel. I really like how it turned out and the velcro works great. The poly tunnel is made to almost fit one of the raised beds and it is 58" long x 36" wide & 31" high. For this project I used the following materials:
  • two 2x4x8 cedar
  • ten 2x2x48 cedar balusters (8 for the trusses, 2 for the center supports)
  • Gorilla Wood Glue (water activated)
  • 3 1/2" coated deck screws
  • 90 degree all weather angle brackets
  • flat all weather brackets
  • 1" truss head screws for the brackets
  • 11 mil super strong woven poly from Northern Greenhouse Sales
  • Velcro
  • Velcro Glue
  • 9/16" staples
  • two 1x2x8 finger jointed spruce (for weighting & rolling the poly)

I made the roof trusses by cutting the 2x2x48 inch balusters on 22.5 degree angles to form the full 180 degree roof frame. Once the angles were cut I glued the joints and then clamped them in a work mate. When everything was lined up I pre-drilled the joint and then screwed it together with a 3 1/2" deck screw. I then let it dry and moved onto the next joint, a total of eight 22.5 degree cuts per truss.

The base of the poly tunnel was simply fastened together with butt joints, gorilla glue & two 3 1/2" deck screws. Once the base was fastened together I attached the four roof trusses with the 90 degree brackets and the 1" truss head screws.

With all the trusses fastened on I then cut center supports to stiffen things up. The front and back center supports were fastened in place with a 3 1/2" deck screw on either end. Then the center one was fastened with flat brackets and the 1" truss head screws.

With all that completed here is the finished frame. It is very ridged and the cedar makes it surprisingly light to move around.

I then stretched the poly on either end, stapling as I went and then trimmed off the excess. I doubled up the poly on the base to reinforce it from staple damage, the top edge will be reinforce once the velcro is added. The corners were folded and stapled down much like you would do in upholstery.

After the two end pieces were stapled on I cut the top piece of poly to fit. This was done by stretching the poly over the frame, tacking it in place with common nails as I went.

With the top piece in place I then cut off the excess with a sharp utility knife. Here it is with all the plastic cut to fit, ready for its velcro.

After cutting the top piece of poly it then had velcro sewn along all the edges. I used the velcro to help with wind resistance and to make it pretty much air tight. It also makes for easy access. The velcro was sewn 1.5" up from the bottom edge to accommodate the 1x2 for rolling and weighting down the poly. The two corresponding sides had the velcro sewn about 1/8 of an inch in from the edge.

The other side of the velcro was then glued & stapled onto the frame to line up with the top piece. Now that everything is in place it is time to make the poly tunnel operable so it can be opened up. I accomplished by doing the following:

This view is the top side of the poly. The two bottom edges had 1x2's stapled on to aid in rolling the poly up. Then two strips of velcro were sewn on the top to correspond with the two center supports. These stripes of velcro will then be used to hold the rolled up poly in place.

I then stapled 4 stripes of velcro onto the frame loosely. Lastly I stapled a small piece of velcro to the frame so the stripes can be tucked out of the way when not in use. I think I will later add more fasteners to these stripes to stop them from ballooning out. Now when the poly is rolled up, these pieces will wrap around and hold it in place like in the photo below.

Well there you have it, One poly tunnel thought up and built by Dan.


  1. Dan - you have impressed the heck out of me with this design! Holy Moly.....What kind of poly did you use? It looks like it has fiber in it.....Way to go, man! Absolutely beautiful.

  2. Dan, you never cease to amaze.
    I've been visiting your blog for over a month now but have never left a comment. This time I couldn't resist.

    That's gotta be the prettiest poly tunnel in town !(almost too good ! lol). Impressive design. A true perfectionist.
    (I can't believe mom let you cut the poly on that lovely carpet, tho. he-he ! ;) )Great blog, btw - fabulous info throughout. (plants, recipes, wildlife, etc, etc, etc. and fantastic pics to top it off)

    Great stuff ! TY :)

  3. Very professional. It would look perfect in my garden! Ha! It will surely extend your season a LOT.

  4. Very cool. I can tell you spent so much effort on it. It shows! That will be a welcome part of your garden for years to come! Great work Dan. You never cease to impresse me! Congrats!

  5. EG - Thanks EG. The plastic is called woven poly, it is 11mil and is used on greenhouses. Not sure how they make it but it is really strong and puncture resistant. Pretty cheap too, they sell scraps for small project for $0.25 a sf. Their link is in the materials list.

    Miss M - Thanks for reading & commenting. PS, I did all the cutting in another room, I just took pictures in the office so I didn't have to use a flash. No carpet was harmed in the production of this poly tunnel, ha.

    Tina - Thanks Tina. I sure hope it works well into the fall for me.

    Sinfonian - Thanks Rich. It did turn out pretty well. I am going to start moving the tomatoes out into it tomorrow.

  6. WOW! I am impressed!

    Dan, you should sell those as kits! Have everything pre-drilled, and the poly cut with the Velcro'd soon be a millionaire! You'd better get a patent on that design.

  7. I am thinking I need me one of those! Great work and it looks very functional. You have my curiosity up though... you stated it "almost fit" the garden beds..??? Purposefully smaller? Fits over???

  8. Incredible project! and then all the detail you went into to describe what you did. So do you have a day job or is it gardening?

  9. What a great design! We need to make something like this for our beds so we don't have to keep all those seedlings in the house for so long. It would be great to get them outdoors sooner. How do you plant to store this when not in use?

  10. I am amazed at your construction skills. I wish I could build one of these. Hopefully, it can repay you into the care and precision you have put into it.

  11. Your poly tunnel looks smashing. Call you sister!

  12. I am such a loser!! I can't believe you do all these things. Who taught you how to do all of this??

    And how do you have the time? Do you work too?

  13. Great post and awesome plans for that poly tunnel. You and EG amaze me with all the things you both build. I wish I could build like that!

  14. Fantastic stuff! I might attempt a very amateur, girlie sort of cloche! That looks great!

  15. The tunnel turned out amazing... you really should try to sell them.

    Great Job .... !!!!

  16. How is it that EVERYTHING you build looks so awesome? Great work as usual. :-)

  17. This is an awesome idea and design. I'll have to try this out this fall as a greenhouse. Thanks!

  18. Very nice, do you need to use it during the summer?

  19. You could live in that! I think if you do have a day job, it must involve construction...

  20. I am drooling over this poly frame! Don't let my husband see it, it will inspire him to a new level of garden structure perfectionism! What a great project for long winter days before anything is growing.

  21. Thanks for all the comments.

    I made it a little smaller then my raised bed to reduce material waste & so it will fit though the door.

    I will store it in the basement or attic in the off season.

  22. Holy crap, that's gorgeous! I want a poly tunnel! It so esthetically pleasing and really appeals to the German side of me. Have you weighed it? Is it heavy? Great job on the tunnel, I'm SO jealous! :)

  23. Kathy - The cedar makes it really light. I have not weighed it but it is definitely less then 20lbs.

  24. So impressive! Inspirational!
    I just built my little portable poly tunnel today. I am taking notes.

  25. That is very well thought out and a work of art. I really think they would sell as a kit ready to assemble.