How to Build a Greenhouse Using Secondhand Windows — A Tutorial

How to build a greenhouse using secondhand windows — a tutorial by John at Old Redding Farm.

Transcript: The following is a transcription of How to Build a Greenhouse Using Secondhand Windows — A Tutorial.

Follow John at Old Redding Farm: Instagram @oldreddingfarm – Youtube

[Robin:] Today, many peoples’ standard response when they need something new is to go to the store, or go online, and buy it. You can buy cheap, junky greenhouses made out of plastic that will fall apart in a matter of a year or a couple of years. So, today I am excited for John at Old Redding Farm to show you how to build a greenhouse out of doors and windows that were being thrown away. You are able to build a greenhouse nearly for free, or for free, that is sustainable and will last a long time to help you grow more of your own food.

[John:] What’s up, everybody? My name is John and I am from Old Redding Farm. I live here in southwestern Connecticut with my wife, Catherine; our two dogs, Pepper and Peanut; our five alpacas, Mocha, Marshmallow, Pumpkin, Linda and Macy; as well as our flock of chickens and a few honeybees. And today, I am here to show you about how we built this beautiful greenhouse. It sits right on the edge of an old stone patio that we have. It is a 12-foot square, mostly. I am not an expert at anything, so I did my best to make sure this was as square and even as possible, but sometimes I can’t do that.

So, all of the windows that you see along the walls here are recycled. We didn’t purchase any of these brand new. We were able to source a lot of it online through either Craigslist free or the Facebook marketplace. Our local ‘buy nothing’ group had them also. In fact, the only windows we actually paid for were the stained glass ones on the front and those are reclaimed from a church in Texas that was being torn down for some reason. So, we purchased all of the lumber and the things used to frame everything out. This is all 2′ x 4’s and 4′ x 4’s because we wanted to make sure that the structure was sound. Windows don’t provide any structural integrity, so we had to make sure that the whole skeleton surrounding it was strong enough to support the weight.

We also used Tuftex corrugated plastic roofing for the roof. Again, we thought about using windows, or even recycled greenhouse glass, but because we live in an area with such a high concentration of trees, and because we need to support a snow load, we decided to go with something that was designed specifically for greenhouse roofs. So, we built the frame around our three biggest windows. This one right here, which is made up of three is almost eight feet long. So, we have 4′ x 4′ posts on either side, right here, and right here, and then there’s another corner post over here. But that way, the weight of the roof and, if we have a snow load on there, gets transferred to the 4′ x 4′ posts instead of sitting on the windows.

Like I said, windows have no structural integrity, so it is important to support everything as opposed to having a bunch of windows sitting on top of each other. So, when we put this all together, the first thing we did was put in our large windows. We have three windows all approximately the same size on all three sides. And then we took a 2′ x 4′, and we got it in here, along with a cripple stud right here. Which again, it takes the weight away from the window and puts it on these two 2′ x 4’s. And then on top of this 2′ x 4′, we have, let’s see, four windows sitting on top of here. And we had to play a game of Tetris to see which ones fit where.

There were several instances where we had to add things. Like this is a 2′ x 4′ that we added to block the gap, but once we got the windows sitting on top of this 2′ x 4′, we would use thinner strips of a 2′ x 4′ to secure them in place. That also serves as a means of closing the air gap. Because when you have a greenhouse like this, it is important to keep all the warm air in. Because what happens is the sun will heat the air inside the greenhouse during the day, but if it is all drafty you are going to lose it all. So our goal was to make sure this was as airtight as possible. They are old windows, so that is not always a feat that is easy to achieve. But, that is why we have these little blocks here. These little furring strips to cut the airflow.

As far as sealing up the roof goes, there are these little foam pieces that fit right in the ridges there and again that seals everything up so that no air escapes and you save all your hot air. So, the whole reason why we wanted to build this greenhouse is because we live in southwestern Connecticut, which is zone 6B. It is a relatively short growing season, so we wanted a chance to be able to start our seeds early. Especially with things like tomatoes and peppers. And we wanted to also extend our growing season. It also afforded us the opportunity to build a lot more growing space because we ended up planting a lot more seeds that we had room to actually sow. But we would rather grow food over lawns any day so we will take it.

So, overall it took us probably about eight months to build this thing from start to finish and that includes picking up all of the windows, which was the most time-consuming part because we weren’t buying it, so we had to wait until the opportunity presented itself. And then, I am sure some of you know, if you are on the free Craigslist section, some things are only up there for a few minutes and you have to nab it as soon as possible, so we were on there checking a few times a day and sending messages as soon as we possibly could.

We started building this in November of 2019. In October of 2019, we were getting our alpacas, so the first thing we had to do was build our alpaca barn. It was tough because we had to build this thing in the winter months and there was a lot of time where we had some trouble with ice and, in general, it was cold and sometimes it was miserable to be out here. But we wanted to make sure we had it ready for February so we could start our seeds, so that was a good motivation. So about eight months’ time, including the time to procure all the windows, and then three or four months to build.

So again, this is a 12′ x 12′ structure, and I think we had about 35 windows, so it all depends on what sizes you get. We were lucky. The largest windows came from a local contractor who was remodeling a house. We were driving by, saw there was a bunch of windows in the dumpster, we did not jump right in. That is dangerous and inadvisable. We saw that the house was for sale, so we called the realtor. The realtor hooked us up with the contractor, and he was so happy to get rid of them, he even loaded them onto our truck for us, which was nice because they are giant and heavy.

So again, it was 12′ x 12′ and it suits our purpose well. If you are planning out your own greenhouse, I would suggest remembering to plan for the tables. They take up a good amount of space in here and you are going to want to have easy- to-use working space. All in all, I am proud of this greenhouse. I am happy with how it came out. I think it looks great. It makes me feel nice to have kept a bunch of stuff out of the landfill. I’m glad we were able to use a bunch of recycled materials and I hope that this inspires you to build one of your own.

If you feel like you’d like to try to build your own greenhouse made out of recycled windows, I encourage you to do it. I am not a carpenter. I am a graphic designer and I have a full-time job. We built this in our free time, over the weekends, and I learned a lot doing it. There is a lot of information out there on how to build these types of things, whether it is recycled materials or not. And only good things can happen by trying. That is how you learn.

[Robin:] I hope that you found John’s example as inspiring as I did. I know the first time that I ever heard of the concept of building a greenhouse out of windows and doors that were being thrown away I was pretty excited about it. So I hope that many of you will actually put this into action and use it to grow more food.

Now if you were inspired, make sure to subscribe to John’s channel. The links are in the description to follow him. And make sure to subscribe to this channel where there are many more educational and inspirational videos to come. And if you want this video to get out into the world, make sure to ‘like,’ comment, and share it with people. I love you all very much and I’ll see you again real soon.