Picture of Greenhouse From Old Windows
This is a brief guide on how I took some old windows from houses they where tearing down in my neighborhood and turned them into a small greenhouse in my back yard. I collected the windows over the course of a year and a half and the build took about 3 months, spending one day a week on it. I spent about $300 for the lumber for the frame and screws, caulk, latches, etc. That's almost 10% of what a greenhouse kit would cost. The size I built was 7 ft high x 10 ft deep x 6 ft wide. But the size of your greenhouse will depend on your windows and the time you want to put into project.
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Step 1: Collect Windows and Plan Two Pair of Equal Sides.

Picture of Collect Windows and Plan Two Pair of Equal Sides.
Look for old windows and save every one you get. After you have many, lay them out and play a game trying to make two pairs of "walls" both the same height. Two to three inches won't matter as you can cover the difference with wood. Smaller holes will need to have glass cut for them or filled with something else. Keep in mind that one end will need a door and the other a hole for a fan.

Step 2: Create a Frame

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Using the windows you chose as a guide, construct a frame for each wall. Use good lumber for this, as it is the structure that holds all the weight. I used all 2 x 4s for the studs and 4 x 4s for the corner posts. Choose a length that allows at least 14" of the stud to be placed in the ground for support.

Step 3: Brace Walls

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Start placing the walls up, bracing well so they don't fall over. Be sure to check that they are level.

Step 4: Make the Foundation Secure

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To avoid certain problems with pesky city building permits, I built the structure shed height and did not pour a concrete foundation. Instead I buried cinder blocks to stabilize the 4 x 4 corner posts. They keep it from moving an inch.

Step 5: Screw on Windows

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I used some nice coated deck screws to affix the windows to the frame. This will allow for easy removal and replacement if any break. This side facing the camera has the empty window for a fan.

Step 6: Get a Floor

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I was able to find someone who needed rocks removed from their yard. Using rocks or stones is good for two reasons: good drainage and heat storage.

Step 7: Build the Roof

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This was tricky. I ended up getting siding from an old shed someone had torn down. Any material you use, look for lightweight and waterproof material. Be sure that you have some that will open for ventilation, at least 20-30% of your floor space. You can get by with less if you use a fan for ventilation. Also build the slant roof with at least a 4 degree pitch, otherwise rain may not sheet off well.

Step 8: Add the Shelves and Fans.

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I found an old picnic bench table and this fan and shelf in the garbage. I figured I can use them in my greenhouse and save them from a landfill.

Step 9: Caulk and Paint

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Use a good outdoor caulk and seal all the cracks and holes between windows. Paint the wood to protect it from the weather.

Step 10: Update: Spring 2009

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The winter this year was especially bad near me. We had several feet of snow weeks on end. Luckily, I had already emptied the greenhouse and removed the roof panels in late November. I live in a zone 5 area. During the last month I brought out an electric heater to keep the temperature more consistent overnight.

This year I was able to obtain a large picture window and decided to install a windowed roof this spring. It will allow much more light in and therefore heat. I used the same deck screws to affix the windows to the roof frame I already had built. For the roof vents, I took two windows and screwed them together. I found old door hinges and used a piece of PVC as a brace. I added a screw holding it to the frame as a cotter pin. Lastly, In case a huge gust of wind came along and tried to yank open the windows, I nailed a small chain to the frame and window to prevent the window slamming backwards onto the rest of the roof.

I also modified the south facing bench. It connects to the frame on one end and still uses cinder blocks on the other. This will hopefully allow me to utilize the space inside better. It's filling quickly!

Now that the roof will allow so much light through, cooling will be a greater issue this summer. I may place some of the old panels back up in July/August to reflect some of that light. I also have obtained some reflecting fabric.

Lastly, I think in the future, I will completely rebuild the roof, using the windows for a gable type structure. It will force me to use some sort of poly material to cover up the gable ends. The current pitch of the roof is not enough to slope water off the windows completely.

Step 11: Edit: Fan Window

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I was unhappy with having to remove the fan/vent window and having to prop it against something while cooling the greenhouse during the day. The frame was already designed to fit the window into it. I decided to have it slide up and be held in place. I started by salvaging some hinges from an old entertainment center. They are the kind that sit completely outside the door. Plus these had a unique shape that fit around a right angle. This allowed the wooden "stops" to swing in place and hold the window up while I was venting or when the fan is in place. Across the frame I nailed some boards to hold the fan window against the frame. Lastly, I found an old pulley and fastened it to the window so I can pull it up easily.

Step 12: Spring 2010 Roof Vent Upgrades

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Had a major score! A local community greenhouse was torn down and replaced. I was able to get some great parts. Here is a picture of the new window system. It originally opened the windows on the side of the greenhouse. The wheel is turned and rotates the gear attached to the pipe opening the windows. Makes opening and shutting easy. While every window now must be open at the same time, I can control the angle at which they are open.

Also pictured  is a gutter claimed from the trash. The hinge side of the roof windows always leaked profusely. The gutter catches the water and stores it in a bucket for easy watering.

Step 13: Spring 2010 Shading

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Bought secondhand some rolling shades which are working great. They easily roll up and down the south facing wall while not taking up too much room.

Step 14: Winter 2012

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Here is the greenhouse in a mild winter.  I overwinter many potted perennials inside. To insulate the roof, I stretch a sheet of poly across the top to keep out the drafts. Last October, 2011, I repainted both the inside and out. All the wood is doing well. I hope that, with care, the greenhouse will last over 10 years. It has changed the way I garden, making my back yard much more productive.
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Just scored a few big windows today for my own version of this. Thanks for all the tips!

tina.denning8 months ago

Okay, I see there is more directions...(duh). So you are saying you exchanged the roof for windows for more light. I like the gutter idea..I have a bunch of them so its great I can use them.

tina.denning8 months ago

Cheft: could you be more explanatory about the foundation. I see in the pic, you have two boards attached to the 4x4. Did you leave them Both in? How did you attach the windows? Hinges? Screws? I have been collecting windows and want to do this, this summer. I am going to attach it on one side to a garage...any suggestions?

Akin Yildiz made it!10 months ago

i kind of made one ? :)

cheft (author)  Akin Yildiz10 months ago
Nice! Great looking cold frame!
Conquest10211 months ago

ABSOLUTELY AWESOME !!!!!!!! Love the reuse aspect.

brensullivan11 months ago

Another good source for old windows is - you join one of the online groups that's in your own community - I moderate the one for Storrs CT. It's free. On these sites, you ask for/offer items. Always free. I see old windows offered on my site every month or so. And if you post a "Wanted" - you might just inspire someone to part with old windows sitting in their garage, barn, etc.

CurlyQue1 year ago

my husband and i have been collecting glass doors and old windows in hopes to build something very similar to this!! awesome inspiration!! absolutely love it! can't wait for spring so we can start on ours! woohoo! (wow - sorry about all the exclamation points, but this kind of stuff gets me excited. LOL) :o)

Great idea my wife mentioned this earlier tonight and look what pops up while browsing. Well I started collecting window tonight and hop to be able to get some better weather to work on this in my project garage and have it ready to go by spring. Living and gardening in MN make for some tough to do winter projects but I always mange to pull it off. Thanks for a good set set of plans and how to's they may come in handy.
Madrigorne1 year ago
Look, you're an inspiration!
See how awesome you are?
desoi1 year ago
Inspirational stuff! I want something similar but smaller and probably a fair bit simpler in my own garden and this has given me lots of ideas. Many thanks
twighahn2 years ago
i seen these here but i think i would like all the windows to be the same size and use a pole to open and close the top vent and have a closable window where the fan goes so when we have a bad winter i can close it.
alicemartin2 years ago
Are the screws affixing the windows to the frame on the outside? Great glasshouse by the way: )
flyingpuppy2 years ago
Genius! Will favorite this one.
corcutt2 years ago
That's AWESOME! I commend your ingenuity and helping to save the planet by recycling! Kudos! Thanks for sharing!
makalove4 years ago
When our local community gardening group was offered a bunch of windows by a guy who was remodelling an old house, we were told by our local county extension office that building a greenhouse from discarded windows was a bad idea because of the possibility of injury due to broken windows. Greenhouses should be paned with shatterproof substances because regular household window glass could break badly and seriously injure someone inside the greenhouse. Just a caveat.
Stofax makalove2 years ago
that is why many use clear corrugated plastic sheeting for the roof, and windows for the walls. This also helps create moddled lighting as most plants prefer that to full sun and it will greatly decrease the odds of them burning, especially in a higher ambient humidity. :)
I have three greenhouse, and used regular windows for the construction. They have been in use now for more than 11 years, and with only five broken window panes. One from Hurricane Opal, the other four normal accidents that would have broken just about any window.
A warning about single pane ordinary glass hazards is warranted, BUT...

There should be no regulation preventing the use of used windows with single pane, single or double strength glass.

I to am in the process of trying to collect enough old windows to build a greenhouse of a reasonably usable size.

In the meantime, I got really lucky when a couple of neighbors replaced their large "patio" sliding glass doors.  They each consisted of TWO glass panels [one fixed and the other sliding], giving me FOUR large double glazed [insulating] panels.

And the REALLY good thing about them is that they are both made with TEMPERED glass which is genrally much stronger, AND IF broken, shatters into hundreds of small "pebble-like," pea gravel sized pieces which are not as dangerous as the shards from broken ordinary glass.

Not yet having enough windows collected to build a greenhouse, I used the 4 double insulated panels to make four COLD FRAMES,  which work great.  Because of being double pane insulated panels, they each are very heavy, but with proper [ergonomically speaking] handles and automatic [gravity-pendelum action] prop rods, they are managable.

I made the cold frame bases of treated 2x4 framing, with the cavities filled with discarded Styrofoam sheeting [picked up wherever found discarded], covered with 1/2 inch treated plywood on the outside, and 1/2 inch untreated, but exterior grade, plywood on the inside.  I then lined the interior walls with a construction water barrier film to give some limited protection to the plywood.  To facilitate replacement of the interior plywood wall panels if it should ever be needed, I assembled the entire structure with Galvanized drywall screws.

Before varnishing, I carefully caulked all exterior crevices that might allow entry of weather [wind or water].  Finally, ALL outside wood exposed to weather was sealed with a properly applied [per label directions] triple coat of Polyurethane Varnish.

Unfortunately, I have no photos, AND have sold both cold frames a few years back.  A "out-of-towner" guy made me an offer I couldn't refuse [$500 each], and so I've got to start over in the process of collecting tempered glass double insulated panels.
my sisters inlaws had a green house two people used for years and such problems except weather and age...breaking windows...They even had dogs and cats around.
, you gave me associations to some thriller movie now. Can't remember what it was called, but a lady got "murdered by greenhouse"... I just love the greenhouse here, it is just sooo beautiful! Make me want a mini version for my balcony! Mine wouldn't be a walk-in model though, but rather a "closet" version... :)
BuckyH peapeam4 years ago
I'm sure the name of the movie is "The hand that rocks the cradle."
Gotta love the Nanny State....
[shrugs] not saying we didn't still use the windows! but people should have all the information when looking at a project so that they can make an informed decision.
cheft (author)  makalove4 years ago
They shouldn't have scared you like that. In Chicago we have many turn of the century greenhouses still in operation using mainly mainly single paned glass.
jmccallen3 years ago
"Choose a length that allows at least 14" of the stud to be placed in the ground for support." in buried in the ground like a post? standard non-treated 2x4's?
cheft (author)  jmccallen3 years ago
Yes, bury it in the ground for support. Any wood in contact with soil should be pressure treated, otherwise you'll be replacing them in just a few years due to rot. Good Luck!
jmccallen3 years ago
nice touch with the dutch door...easy to convert from any existing door you might have around..
trish3303 years ago
this is exactly what i have been saving those windows for in my garage. I will be clearing some area near my compost pile.... what a great idea and thanks for the step by step!. I live outside of Chicago...
denebrock3 years ago
Love this idea!
You have given me such inspiration. Our local court house was having their windows replaced. We scored 10 windows 35"'by38" and 10 windows 33"by35" and several more assorted sizes. All are double paned and we got the gasket around them. Couldn't get the channels. If we use 2" by 4"s and put a 1/2 inch channel in each to secure windows, would this give me enough structure safety? Don't know construction but really am inspired by you.
neuronical3 years ago
We have hundreds of windows in our barn and I am getting ready to start the design and structural planning of a very large greenhouse. I will trade windows for expertise, project help or ???
ibarnett523 years ago
thats awesome im collecting windows right now gonna build a big one
kruegekm3 years ago
This instructable is awesome! Such good description that makes it seem possible. Also, I like how it evolved over time with the various materials scores. Inspiring!
katerlyn3 years ago
This is great. I have a lot of extra windows I got half price of very low prices, at the local Habitat for Humanity Restore....that would be a good source of reasonable windows.
A neighbor made a green house of windows, he set it on concrete from an old barn that was on the property years before.
davyR5 years ago
Very nice, also a good idea with the rocks. I used to have a similar setup in my garden, but it didn't last very long, because the wooden foundation was standing in mud and water during autumn and spring all the time, which resulted in it rotting away very fast. (I think we had to fix it after only 3 years)
peapeam davyR4 years ago
Wouldn't old railroad sleepers be an idea then, if you can get hold of some? Those does not rot easily...
If you decided to use railroad ties be careful how you use them. If they are separated from the greenhouse entirely (with non-porous floor) they probably won't be a problem. But they coat them with chemicals to prevent them from rotting and also they regularly spray pesticides on the tracks to kill the weeds. You probably don't want those chemicals near you or your plants, especially if you are growing anything edible. Just something to watch out for.
chmisc4 years ago
Great Instructable.  If you need windows, check with your local window/glass supplier/installers.  Most will let you have the old windows they remove from home renovations, especially if you give them a wish list.  Otherwise they have to pay to take them to the landfill.
peapeam chmisc4 years ago
Our local landfill has a recycle section. When you go to toss something, if it is recyclable, you get to leave it there for free (you get to do that with some other things too, but you have to sort them into different bins yourself). It's a big building, and people come there to leave all kinds of things for the home they don't need anymore and others come to find free furniture etc. etc. Think I'll have to go to see if there are any windows there. If something hasn't been claimed by somebody else within a week, the landfill people remove it and discard it. It's just like a second hand store for things for the home, only it is free for all. :) All landfills should do that, what a wonderful way to reduce the amount of garbage and great for those with little money... :)
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