Greenhouse From Old Windows




Introduction: 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.

Step 1: 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

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

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

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

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

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

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.

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

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

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

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

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

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

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.

3 People Made This Project!


  • Metalworking Contest

    Metalworking Contest
  • Creative Misuse Contest

    Creative Misuse Contest
  • Water Contest

    Water Contest

198 Discussions

Maybe a solar panel. I've been told harbor freight carries inexpensive ones.

Someone commented that a cement floor should be put in, but as was stated in the directions - City approval is required in most places, to put a structure on a cement floor so he used cinder blocks to put the posts in. I suppose he could have also put some cement into the bottom of the blocks, so wood would not touch ground.
As for the lead paint - that was only used on windows of a certain era, correct? Getting windows of a later era should stop that being an issue.
I like the up-cycling of the windows, stones, and old greenhouse parts - what an Awesome amount of re-purposing items that others no longer want/need. Talk about "one man's trash is another man's treasure"!!!!

6 replies

That's what I was thinking. Sink the cinder blocks in the ground a bit, place your 4x4 posts in (square them up) and pour cement into the hole. I think I'll lay ground cover then grab some patio stones that come on sale and use that as a floor. Maybe use 4x4s along the bottom outside edge of the structure as well, be a good, solid base I should think? Then frame away...I'm still trying to figure out what to use for 'glass' as old windows seem to be all the rage now, they're expensive!

Hello,experience told me that wood doesn't like to be cast in concrete, unless you're absolutely sure that it will always be dry ... If you pour small stones, Peebles around the post and squeeze them (stamping), they'll keep the post in place safely, but will drain every drop of water away. Put a round shaped stone at the bottom of the post hole, firmly stamped, so the post doesn't touch the soil. The shades I built with this system are over 10 years old ... It also works for bigger structures : for holes until 3 feet's deep, and posts over 7 inches diameter, and 12 feet high ! In this case, fill up the hole with stones that you smash down with an iron bar, for example, one after the other. So, ready to start your salvage home ? ;-)

yes - as new windows get more expensive, more & more people are turning to recycling companies to get their windows. And if they have an older house these would keep the "flavour" of the older home. Triple paned windows are not only expensive but don't match homes of older eras.
I would want to know where the recycling companies exist that don't charge an arm & a leg for old, recycled windows! They're becoming increasingly rare!

....or you could do what we did. There is an abandoned (repo'd by the bank actually) house next door that was built in 1900. We bought it to demo for the lot. I'm scraping EVERYTHING I can out of that house before the bulldozer and backhoe come. Windows, doors, (for a greenhouse build project) brick basement walls (for a grill pit, later) Anything I don't use and is worth $ to get out, i'm having a reclamation company come get it and pay me for the pleasure :)

to reply only to the foundation part of this convo. My guy poured an 1' wide x 2' deep footing of my footprint and put the future 4x4 post braces in. Done.

and, you are so right about the trash to treasure. My Windows were all donated and boy! did I Dig through peoples barns at their "garbage" and I now I have wonderful,local,vintage windows!

Beautiful! So appreciate you providing updates and your innovation sir :)


1 year ago

How could I do this with a bunch of half round windows ? I got a bunch of the half round ones given to me. Looking for a plan to use them for a greenhouse.


Please know that the cover photo of an all window greenhouse is not the one I, OnaFarina, built. Scroll down and see mine after it was built. It is stick built and large and awesome with a tall roof, but is still wrapped mostly wrapped in plastic and there are photos of what windows I had installed when I wrote the post.

Lead paint can be contained with a good double coat of exterior paint or exterior grade clear "varnish" this will keep your shabby chic look

Waw, well done! It looks fantastic & beautiful to have in the garden too! :)

Occurs to me--> Do you really need to seal the cracks if you always want to keep some air flowing? Perhaps without sealant you get close to the airflow necessary? To get air flow out you can have a centrifugal fan blowing IN which distributes the air out the cracks?

5 replies

The primary purpose of a greenhouse is to modify the ambient temperature to benefit your plants.

The "greenhouse effect" is to allow visible light to enter the structure and warm the interior surfaces. They, in turn, will radiate light in the IR due to that surface being so much cooler than the sun. Window glass allows visible light (that's a good thing) to pass; but it blocks IR. That traps heat in the enclosure and makes it warmer for your plants.

This is all good for those cool days, but can cook things on a warm sunny day. THAT is why there needs to be a way to vent the hot air. Ideally, you can have an automatic opening (at some cost) or you can be diligent in doing it yourself. In my experience, I will forget to open or close the vent at some time during the season and lose some plants. Watering falls under the same category. So all the auto features are great but add to the cost.

While I agree with the statements you're making, as they're generally correct, I don't see how that is a response?

I did indicate airflow. I'm just saying that what is the point of *sealing* your greenhouse windows, and then proceeding to make a hole for ventilation. Why not just ventilate using the holes that exist and positive airflow?

Granted, I think the answer is obvious, that my suggestion is much harder to control and requires slightly stronger fans. Still, it seems worth asking if anyone has tried that. Especially if it makes eventual greenhouse disassembly and reconstruction much easier.

I think the point in the original post was to re-glaze the windows to hold the glass in place and to avoid cold air getting in. It is not necessary to provide air flow through the structure. Venting is important when it gets too hot. In that case, convection is enough and does not require a fan.

just turn the windows around so the inside is facing outwards.

my greenhouse will be heavily sealed at every window. I need to control the temperature, breeze, etc. just like a "real" house.

I have a high vent that is chocked open 24/7/365. I have a fan installed diagonally across from it on a thermostat. I keep it's vents propped open during growing time. I open the door EVERY morning during Spring/Summer growing season and shut it every night. I also have 2 pop-up roof vents that also stay open all Spring/Summer.

Do not go cheap on vents, fans and thermostats in a "real" greenhouse like mine. They are THE most important items in there!