Building Greenhouse Doors

November 10th, 2008 by David LaFerney Leave a reply »

<< Building the $50 Greenhouse

Welcome back Stumbleupon Gardeners!

If this looks like too much work – I did a much simpler door on the other end.

This weekend I finally got time to start on the doors for my 50 dollar greenhouse.  The design that I came up with is light, strong, simple, and can be built easily and quickly using only a circular saw and a hand drill.  I must admit that I did use a table saw to rip out the stock, and put it through a planer to accurately dimension it, but this was only a convenience, and isn’t at all necessary for a good result.  This polytunnel door design can be built on a set of sawhorses out in the driveway, but it will be a lot easier if you get someone to help you hold things while you saw, drill and fasten parts together.

Needless to say you can seriously hurt yourself with power tools, and you should follow all applicable safety rules for the tools that you use.  No kidding, a friend of mine lost an eye about a year ago because he wasn’t wearing safety glasses.  Don’t make a mistake like that.  Be Careful.

You will need enough 1×2 stock to make your door – two pieces to make the sides, and three pieces to make the top, bottom and middle brace.  The dimensions of these pieces will be determined by the size of the door that you are making to fit your polytunnel  hoop house.  The sides need to be the same length as the finished height of your door while the top, bottom, and brace need to be 3 inches less than the width of the finished door.

Pre-drill holes before screwing the frame together.  If you don’t pre-drill you will probably have problems with your wooden parts splitting when you drive the screws.  Use a bit that’s just small enough to allow the screws to get a good bite.  Try it on a scrap of wood first to make sure that you aren’t pre-drilling too loose or tight.

I used 3″ washer headed self drilling screws (I still had to pre-drill the holes though to prevent splitting) but any 3″ screw would work. If there’s a gap between the parts after you screw them together – back out the screw and re-drive it.  There is no point in gluing these joints because glue doesn’t hold very well on end grain – trust me, don’t bother – the finished product will be very strong anyway if you follow the plan.

Your frame should look something like this after you screw it together.

Now drill a hole in each corner to thread the brace wires through.

Thread a loop of wire diagonally both ways and secure the ends by twisting them together, and then twisting the tags back around the main wires. I used galvanized electric fence wire for this, but you can get a similar product called “utility” wire at any hardware store or home improvement center.  You can also use small rope/large string, but wire is really better because it isn’t as likely to stretch.

Clip the ends off and bend them neatly so that they won’t stick out and snag people, clothes, or greenhouse plastic. There has to be a better way to do this than I’ve done here.  Gotta’ look into that.

Check your frame for square by measuring diagonally across the corners.  If they aren’t about the same then tweak the frame a bit to get it pretty close to square. Although this is a pretty forgiving design and unless it’s really  out of square it probably won’t matter much – within a quarter of an inch is great.

Now use some scraps of wood to tension the wires.  You want them to be merely tight, but not like guitar strings – just without any slack.  This will pull all of the joints together so that they aren’t likely to come apart or sag.  Check for square again to make sure you haven’t torqued everything out of whack.

This is how the tensioners finish off.  You may have notice that I’m a fan of this kind of device – I used it on my polytunnel greenhouse for the same reason that I’m using it here – It’s strong, light, easy, and it works.

Now glue triangles of plywood at each of the frame intersections – the corners, and at the cross brace.  Notice the pencil marks to help keep the glue in bounds.  Use a water proof glue like Titebond 3, and secure the connection with screws or nails. I used scraps of 1/2″ plywood for this, but anything from 1/4″ to 3/4″ sheet goods would work, or even solid wood, but lightness is a virtue so mind the weight. I used what I had.

You will be amazed at how strong and light this structure is. You can certainly use other sizes of lumber instead of 1×2 to make your doors – 1x3s would also work great for the sides, and 1×4 or 1x6s would be fine for the other parts.  However,  your door will be heavier (although it might be stronger), and you will probably have to recess the screws that hold it all together so that you get enough penetration for them to hold – or find some really long screws. You will of course have to adjust the measurements to work with your door size and the lumber that you use. Keep in mind that if your door is very heavy it might be more than your polytunnel greenhouse frame can support without some beefing up.

When I turned my frame over I discovered that some of my screws were just a tad too long, and they poked through the other side.  This had to be fixed or it would cut the plastic covering and would probably cut me or someone else sooner or later.

Just a few strokes of a file on each screw takes care of this small issue.

Nice and flush.

Now for the Plastic – After building the greenhouse I discovered that condensation and rain will collect at the bottom of the plastic if it can, so don’t fold the plastic around the bottom of the door just staple it flush so that water can run out the bottom.  On the sides and top leave a little extra to fold it around and double it up…

Like this.

Plain old (recycled) loose pin interior door hinges are fine for this application – be sure and install them right side up though so that the pins don’t work loose and fall out.  With regular gate hinges the pins would be attached instead of loose and you couldn’t remove the doors as easily (by tapping the hinge pins out) when the weather turns warm next summer.

Another recycled item.  You could also use a cabinet knob, or just a piece of 2×2 for a handle, or even a strap of leather from an old belt.

Ready to go…  Wouldn’t you like to explore that shop?  I used to love the “Mister Wizzard” TV show when I was a kid, and my life is now complete that I have a shop like his.  Now all I need is a box on the shelf labeled “Dinosaurs” – I always wondered what was in that box.

Because of insufficient foresight  I have this “situation” that I had to deal with before I could hang my door. The door frame needs to be unobstructed all the way to the ground.

I took the quick and dirty route of shoring up the problem spot with plastic and a scrap of galvanized metal after trimming the wood off flush.

Now that you’re ready to hang the door put a scrap of lumber under the door first to space it off of the ground.  Since my polytunnel greenhouse site slopes, I only needed to do this on the high side.

Now just set the door down on the spacer and screw it temporarily to the greenhouse in just the position that you want.  Stand back and take a good look for obvious problems before you continue.

I made my door about an inch and a half wider than the door opening on the greenhouse and a couple of inches taller because I want the door to close against the greenhouse itself instead of using a door stop.  If you have much snow you might want your doors to open in – think about what your needs are, and adjust the design to do what you want with the materials that you have readily available.

Now, hold a piece of lumber that will be the jamb right against the side of the door and mark about a quarter inch above the top of the door.  Cut it off at this mark, and do the same thing on the other side.  Then screw the two resultant side jambs securely to the greenhouse leaving about a quarter of an inch of space between the jambs and the door.

The 2x4s that I used for jambs are 1/4″ thicker than the actual door – this turned out to be a good combination because it left enough space between the door and the greenhouse for the door to open and close easily, but because the polytunnel plastic is a bit poofy there isn’t really much of a gap for air to leak through.  Serendipity I guess. If you do have problem gaps you can weather strip with scraps of foam carpet pad (or even carpet) and your staple gun.

Once you’ve attached the jambs you can screw the hinges to them, and remove the temporary screws that have been holding the door in place. At this point the door should open and close easily – if it binds or rubs excessively, back up and adjust before you go on.  A common error would be to make the space between the door and the jambs too tight.

Now cut a piece of lumber to use as the head jamb.  I ripped an angle on mine so that it would shed water better.  I stapled the strip of black plastic to the back before attaching the head jamb.

The strip that was ripped off is then attached to the front to extend the jamb and give an overhang so that rain won’t run over the door. You could actually accomplish the same thing by just using a 2×4 that lays flat for the head jamb and letting it stick out.

Then, just staple and trim the plastic strip thusly.

Add a simple turn bolt both inside and out and your door is finished.  Almost finished – I shoveled a bit of dirt in to close up the gap under my door, and I will probably add a simple sweep to the bottom later.  But for now it works great, and looks fine. It’s easy to open and close even with just one hand.

On the other end of the hoop house I did something much simpler – basically a well secured curtain.

Secure two or three pieces of string at the top of the door opening – these will be used to tie the curtain open when you have it rolled up in warm weather.

On both sides of the door opening apply two strips of wood leaving a gap between them.

Hang the curtain by wrapping the top of it around a stick and then screwing it to the greenhouse.

Put two or three turn bolts on each side

To fasten the curtain shut push a stick into the gap on the sides..

And secure it with the turn bolts.

And that’s it.  It isn’t as convenient to open and close as a hinged door, but it gets the job done.

Now that the doors are up it gets pretty warm in the polytunnel on a sunny day even when it’s cold outside – I have the same problem with my cold frame.  Next time I’ll give you the scoop on some really easy automatic vents that you can make for about $10 – $15.  Subscribe to the DoorGarden RSS Feed and you’ll never miss a thing.

Thanks for coming by! How about a thumbs up if this is helpful?



  1. Elizabeth says:

    I don’t know if my reply worked. I can’t see it so I’m going to redo my reply. I apologize for the redundancy if it is duplicated.

  2. Kyle says:

    You mention that you’ll post another article about automatic vents in this article but it doesn’t appear that it ever made it up. I know this is years later but I’ve made your pollytunnel only to find out I am in dire need of vents. I’ve looked around online and they are all the side vents that can’t really be incorporated with this design. Please post your article about the $10-$15 automatic vents! My garden thanks you in advance!

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  4. Jonathan says:

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  5. Did you ever make the vents discussed in some of your articles? I am interested in how to make them, may need them for the climate I live in. Would like to be able to use year around.

  6. Sam says:

    Had a second thought on useable venting.

    By adding a clean out trap to the ridge pipe, only limited by size and amount of day heat needing to be removed or even circulated. A pc style muffin fan could be rtv’d to the trap and one of the small $<40 solar auto battery chargers could be used to run the fan. Thus it would only run during the day. A sealed battery like those used in kids toys or Uninterrupted Power Supplies could be added for night support and lighting. Using the LED light strips nice effects could be added for totally green holiday lighting.

  7. Sam says:

    Where you have used the timber to brace the sides and ridge have you considered using a union and cotter/quick pins to produce the same effect?
    2″ x 3/4″ Sch 40 PVC Reducing Cross Tee and similar for the sides would allow for limitless building of your green house. The use of pinning rather than gluing would make for easy tear down and maintenance. The small scale truck farmer would also gain the added benefit of getting crops to markets year round in southern climates. The use of the foam strip a contractor secures beneath walls on cement slabs would also provide protection to plastic rubbing against the piping.
    Rather than a scraptamate pricing on the project. How about a redo at current costs to include all of the pertinent changes suggested, important to house function, per 5′ segment. To include the end wall and door wall. Then we builders would only have to work out how many segments were needed and how thrifty we are at shopping.
    Thanks for a truly inspiring project.

  8. Zsuzsanna Evensen says:

    I found Your blog really handy!

    In Hungary (where I am from) is quite common to build such greenahouses for privat use, but in Norway (where I live now) not at all. People here rather buy one made of glas or polycarbo plates. Since they are rather expensive I decided to build one like Yours. Since I`ve never done anything like that before, Your instructions are much appreciated.

    But I was wondering if you considered to devide the door into two parts so that you`d have a kind of “window” on the upper part? You could open the two parts non simultaneous (or simultaneous if you want). This way you could avoid cats un unwanted visitors inside, and by opening the window you`d still have ventilation.

    I also Wonder if it would be possible to use metal pipes and bend them? What do You think?

  9. Tomi Inglis says:

    Did you ever write an article on adding vents to your $50 greenhouse and if so, how can I access it. I followed your plans to build a greenhouse but before I finish putting it together, I’d like to add the vents.

  10. Damian D says:

    THANK YOU FOR POSTING this it is by far the best one i have seen. Started on it this weekend i got both ends built and they turned out very nice. hope to finish it tomorrow with the help of my 8 year old daughter who kept coming out side today giving her dad a cheering section.She said dad it looks great i am so proud of you lol i am blessed to have such a fan DADS ARE A SONS FIRST HERO AND A DAUGHTERS FIRST LOVE I BELIVE THAT.WELL THANK YOU IF YOU READ THIS I WOULD LOVE TO ASK YOU A FEW ??s please email if you have time

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    visit the web page, that’s what this web page is providing.

  12. Dolo says:

    Awesome! I’ve been looking for a design for our 10′ by 16′ garden and I am going to take your design and run with it. Thanks!

  13. Catherine H graham says:

    I have wanted one for years! Now with your design I may be able to have one at last. I live in Quebec Canada and we have cold winters here. I would have to do extra work to make it strong enough as our winds have become pretty wild in the last few years.. I like your design! I had thought of buying one of those put up yourself car garages but to buy one strong enough costs a fortune and then one would have to buy the plastic for covering. Thanks so much for your greenhouse design. It was great and I followed it right through

  14. gene holman says:

    DID you build it already, Im now in the process. Good luck Gene

  15. Mande says:

    Do you open both doors?

  16. Iain says:

    I’m just a little confused onthe curtain door… Do I add two strips of wood in addition to the one that is already a part of the greenhouse?

  17. tombstone barrier says:

    Corny jokes make me laugh… I feel depressed. I shall not continue this series. I don’t enjoy comedy. I’ll attempt the next episode though… Might take a week or two though.