Common Questions When Building a Low Tunnel

All right everybody, this is Ross. Today I figured I'd do a video for you guys just answering a lot of common questions that I think you will have if you inevitably decide to build one of these low tunnels. I know some of you guys out there have contacted me and are actually interested in doing one of these things, and I had a lot of questions during the building process, during the construction process, even before in the planning process. I just really wasn't exactly sure how this all was going to work out. Inevitably, I had to do just some testing, right? I had to just go with one method and go with one direction, see how it all worked out, learn from those mistakes, and then correct it. I would have saved myself some time and money, and that's really what we're doing here on this YouTube channel. I think I save you guys so much time and money with these videos, but I think it's really nice regardless to have all the answered questions in one place. So let me give you guys first the dimensions and how everything's laid out in these tunnels. We're using a standard six mil plastic. It's clear. You don't have to go fancy with this. You just want something that's affordable that's going to last for a long time. You don't want to have to be replacing this plastic every year. There are some plastics out there that you will have to replace every year, every other year, which is kind of insane. So get something that's affordable and that's going to last. The dimensions of this is pretty simple, is that we have the PVC, these hoops. We drive the rebar into the ground six feet apart. So that means the tunnels are six feet wide. The PVC, the hoops themselves, are 10 foot long, and those just go into each side of the rebar, again, six feet apart. Now what that does for me, having them six feet apart like that with the 10 foot long PVC pole, is you get a height at about three feet, and you can do the radius there. I think you could take the width of the bed, so it would be six feet. Man, I forget exactly how this all works. I think maybe the three feet height, I have to get my calculator out and figure this out, but basically you take one of those numbers, either the height or the radius or the width, I don't remember, and you multiply that or divide it by pi, 3.14, and that's going to get you, I think it's actually the width. So maybe six feet times 3.14, that doesn't make sense either. Maybe it's divided. Maybe it's six divided by pi will get you the height. I don't know, but the point is there is a calculation. You could figure this out if you really wanted to figure out how far apart you should space the rebar to then figure out the height. Okay, so do that calculation. Sorry, I couldn't help there. Okay, so that's kind of mostly the dimensions. Now what that does for me is the fact that they're six feet apart allows me to plant in the low tunnels three rows of figs. So I have three rows width-wise going down this entire length of the low tunnel. They're spaced two feet apart on center. I have them spaced that close with the figs. It's an experiment. We'll see just how close I can space these trees. I have a feeling because they're under low tunnels now, it's probably going to be a headache and it's probably going to be too close. But we are playing around with the spacing, either two or three feet, even a foot and a half with some of these under the low tunnels. So we'll see what the right thing to do here is, but for now they are spaced two feet apart. Now what is the difference here in temperature between outdoors and inside this low tunnel? Can't really say for sure just yet. The greenhouse that I have in an environment that's not really all that sunny, it gets about five hours of light per day. Let's say it's 60 degrees outside and it's a sunny day and it gets five hours of direct light, you'll see a 30 degree jump in temperature. So it'll go from 60 to 90. Here in these low tunnels, it's way more sun. It seems to be less insulation because it's plastic versus polycarbonate. Also they're really big structures compared to a very small structure. So I don't know the exact science and I can't really say for sure just yet, but I would venture to guess that these low tunnels are 40 degrees, up to 40 degrees warmer than the outdoor temperatures, which is actually pretty nuts. And I think a lot of that has to do with just the amount of sun they're getting. So it's really important to be able to roll up the sides because if it's 60 degrees out like it is going to be today, we're going to find out, I think it's going to be like 65 today. So it theoretically could be 105 under these low tunnels. I have the thermometer set up in here. We need to be able to roll up the sides and it's really, really simple. If you just very simply take off some of these cinder blocks I have here, you can roll up the sides and with the tension that you've created with the paracord, this creates a very easy system to be able to roll these up and have it stay up. You can see how it's just staying up here without really any assistance because of this paracord. And you can do that all the way across if you really wanted to, but mostly you're going to be able to do that in the center. On the ends it's going to be a bit more difficult because of how this is all built, but you may want to get yourself something that will hold this up as well, which would be nice. And I should probably invest in some kind of something here that's going to hold up the sides for me on a day like this. All right, so now onto the construction. Some of the questions I think you guys are going to have on the construction itself is that we need to have really, really important is the length and the width of the plastic. Okay, so if we have ourselves 10 foot long PVC poles, that means we need to have at least 10 feet of plastic width wise. However, if you don't leave extra plastic on the sides, you're going to regret it. And I did that actually with this tunnel here. I had some leftover plastic. This was the first tunnel I constructed and it became really a mess. So you need to make sure that you leave some on the sides and also a lot on the end. So if you have a 10 foot width, you need to have at least an extra two to four feet on the width. Don't get cheap with this stuff. All right. Two feet is the minimum. Also, and the length, this is a 20 foot length here from this PVC to the end PVC hoop at the end. That means we need to have an extra eight feet minimum because what the difference is, yes, it's 20 feet in length. However, there's a three foot height. So now you need not just three feet to cover this section here, but you need an additional foot at least to then be able to tie this whole thing down. And ideally I made the mistake from the beginning is I should have even more length. I should probably even have, if it's 20 feet long, I shouldn't have 28 feet. I should probably have somewhere around 34 or 36 feet. And the reason for that is I can get this ending here and I'll kind of show it to you here is I can get the end piece, both sides, and I'll be able to really bring this whole thing together, really get it all into one little piece here. And it's going to be out probably to here rather than this close to the frame. And I can actually get myself some sort of crank and these cranks and different things that have that ability is that you can attach the crank to this, anchor the crank in the ground, and then the ends are really, really sturdy and strong. The way that this thing fails in the wind, it feels like not just the wind, but also maybe even a lot of rain. You can see there's a lot of water on my structure right now because it rained last night, but snow as well. You got to beef this up. We got to make this thing sturdier. If we can get this plastic really well anchored on the ends, this whole thing just becomes a lot more simple to really beef it up. Another thing we can do, and we haven't done this yet, is we can get ourselves a line that's also anchored in here, which then goes up into this, anchors this into the ground, but then also is attached all the way down to all the different hoops, which then connects each hoop to each other, creating a really, really solid and rigid structure that can support itself because now all the different hoops are now connected and they're going to be able to support each other. It's kind of like, I don't know, actually a good comparison for it, but if these two hoops are now connected and supporting each other, if this one's bending this way, this one will then be able to pick up some of that slack, right? Now, what about the distance between the hoops? Because this is something that comes up pretty often and I was really struggling with this. I don't remember. I think this is about a six or seven foot spacing here with the hoops. Ideally, you should go at a minimum or at a maximum is four feet. If you really want to have this thing really heavy duty, really strong to withstand anything, you want this four feet. In the wintertime, as an example, when I really need to, let's say, beef this thing up, I'm probably going to add in an extra hoop right in the middle. I'm going to probably move this one four feet here, add one in the middle, and then move this one over a couple feet to get that four feet spacing that you really, really need, especially in the middle of the structure. You can see on this one here, I really need to fix this and kind of get this thing straight now because this is not really ideal compared to some of these other ones here. And it really just comes down to the tension that you're putting on this plastic on all sides, the ends specifically. Now, here's the big one that if you don't do this, you're really going to regret it no matter what time of the year it is, I think, is that you need some sort of wind protection, which comes in the form of this paracord. And I know it's a little difficult to see on the camera, but this paracord, we've done it in our construction video of how we built this. This is so, so important for weighing down the plastic and making sure this plastic is well attached to the frame. What I did just get, hopefully I can open this box. We got a box here from Home Depot because I ordered... I should be able to get this open. I ordered some clips and this is ideally what I probably maybe originally should have had. Oh, these clips are very small and this is not anywhere near the amount I ordered. Very strange. I'll have to order bigger ones. But essentially I got myself these clips and these clips are, you can see here, probably not all that big. This is, I think, a half inch clip. You can order this from Home Depot. And what I'm going to do essentially with this, particularly on the ends, is really help strengthen this and then clip this plastic to the PVC. It doesn't even go over. It's just not big enough. But this is ideally how it would go, is clip this then down to the frame, to the PVC, and that would really help my issue here. Clearly that's not the case. That's not happening today. But that's another method, I think, of beefing these things up that is worth looking into at least, you know, at least during this time of year when it's not really, I guess, that crazy out. You know, it is windy right now, but once the leaves start forming on some of the trees, the wind will die down. But in the wintertime, for sure, helping clip this down and making this whole thing more secure is key. I'm also using the cinder blocks and you could use sandbags or even bags of soil or bags of rock and make sure that in between the two poles or between the two hoops here, you got yourself something to weigh that down in between. But this paracord, I'm telling you, really makes a huge, huge difference in terms of the success or failure of your hoop. And you can really tighten this with slip knots, loosen it with slip knots. This is really the key of holding this whole thing down, and I didn't really understand that at first. I thought these clips that I ordered would be enough. I thought the cinder blocks would be enough. It's just not. You can have a lot of weight on the outsides, but inevitably, there's going to be some air that gets underneath the frame and pushes it up. And that's how the plastic is going to come off and come loose and cause you some issues and headaches. The paracord is what is really driving that stuff down and holding the plastic in place. So that's, I think, roughly what I wanted to cover in most of the questions that I sort of had going into this. But again, I think what I've been saying to you guys all this time now is that this is just so beneficial that I would just get out here and try it and do it. I have myself here some extra PVC, extra rebar. I want to be building more of these if I can. I just wish I had more plastic at this point. So yeah, that's kind of the video here, guys. I hope you enjoyed this one. I hope this really helped you out there. So if it did, let me know down in the comments. 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