This has got to be a crazy people idea: Cover a whole bunch of plants with a plastic roof, that keeps the rain out, and then, pump water in to them. Or in my case, carry water. When you think about that, it just doesn´t make sense.
Last year I emptied a well into my greenhouse, by hand (off-grid), and it could have happily absorbed two more wells worth.
This can´t go on, I thought (dreading another summer of schlepping water).
So, I figured out how to put eavestrough on a greenhouse, to catch the water, to put it back into the greenhouse. Slightly less crazy. Easier than taking the skin off every time it rains, which honestly would be my first choice, if it were practical. Until they invent one-way 5 mil plastic.
I doubt I´m the first to think this up , but I didn´t google it because I preferred to figure it out for myself (go ahead and google it now). I didn´t want to know how other people´ve done it. Much as that might have made it easier or faster. This is how I did.
First unsecure the bottom of the long side of plastic and undo the wiggle wire up the side.
In my case I redid all the wiggle wire on the side/gables in order to take a layer of plastic off. In my style of off-grid, I´ve got no business having an inflated greenhouse. Although I made it work, it just never made sense. Most of the time it wasn´t inflated. Now I´m saving the second layer of plastic for when my greenhouse needs its next skin.
Essentially I installed a lip part way up the wall, creating a drip edge to catch the water from.
I ripped 2x4s (all rough cut for me) with a bevel and screwed them on to the top of a 1×6. 2″ screws, from the 1×6 side into the beveled strip. I did this in advance- measuring the overall length, so that I could lift each piece into place.
I cut through the exposed wiggle wire track on the side- only had to remove one screw, and cut out a four inch gap.
It´s four inches because the top track comes down over the 2×2
When I measured each end, I made a four-inch overall drop. 35″ inches from the base on one end, 39″ at the other end.
So I lifted my prepared 1×6 piece into place, propped it up to attach the end, and then secured it, and its mates, to the ribs of the greenhouse with plumbing strap, eyeballing for a nice straight line.
Plumbing strap is a bit hokey; I´ll get some of the proper brackets next time one of us in the area is ordering greenhouse parts.
My three pieces of 1×6 (36´overall greenhouse) were set up to overlap, so that on install, I could attach them. Then I didn´t have to think about where the ribs landed.
How it looks from the inside.
That´s the bulk of the work- the wood.
Back to the outside, I put 1×4 strapping under the drip ledge and screwed that down. I chose 1×4 to have 4″ of surface to mount the gutter on, and to have some room to play with the slope. Hence 1×6 behind the plastic.
This tightened up the skin quite nicely. The wiggle wire goes back in now too.
Then the base securing goes back in:
The addition for gutter uses up about 2″ more of the plastic, but if you have less than 2″ of plastic at the base, you´ve got bigger problems (unless you trimmed it, oh well).
When I built this, I dug a shallow ditch and buried a strip of hardware cloth against the base. Some squirrels and chipmunks have dug around my barrier, but it´s holding up very well. I haven´t seen that since I built it.
Install the gutter, and voila!
I used vinyl gutter with brackets that you can lift off of their little mounting hook. I´ll definitely be removing the gutter before any snow comes!
The greenhouse has never looked so good, now the plastic is more taut.
I´ve got two downspouts (with two elbows each side), to direct water into a stock tank, with has a threaded plug, which with a pipe-hose adapter I can put a garden hose on, and then put the water back into the greenhouse. The guineas are inspecting.
Doesn´t that look good? I thought so too.
I felt good and smug for about two hours until the rain came. I´d been racing the forecast, determined to catch all the mm that were on the way.
I got up in the night to go check on everything.
The water was running the wrong way! That is, what little water it was catching. Slope could be fixed (I do need the 4″ of the 1×4 to play with), but there was a bigger problem- the water coming down the plastic wall was turning the corner of the lip, following back (as water does) and soaking into the 1×4, not falling in the gutter. I should have seen that coming. I should have seen that coming.
I stayed awake for at least an hour until I could figure out how to fix it. Not simple, but it should work.
The only way was to take off that ripped 2×2 and change the angle on it.
This time the base didn´t have to come off, just the gutter, and the 1×4, and the wiggle wire on the ends.
Significant wrinkle- on the inside, I was using 2″ screws for the plumbing strap, through the 1×6 into the 2×2, for strength. But now the 2×2 had to come off. All 13 ribs!
Clamps came in handy, I backed out the screws, and I marked the wood against each rib. I took the opportunity to adjust it all for more slope while I was reinstalling.
Also because I didn´t undo the bottom (the better to keep curious chickens out), once I got all the 2x2s detached, I had to pass them out the end. And back in.
I put them all through the table saw again and put a bevel on the second side, creating an acute angle for the drip edge.
Slid them back under the plastic and reinstalled.
Now the business edge is sharp and angled down.
Waited for rain, now with less confidence. Still didn´t work.
These pictures don´t quite show it. There is a full inch of overhang on that lip, and then the gutter mounting holds the gutter out 1/4″, so there is 3/4″ of lip hanging over the gutter. Not enough.
The water comes down, turns the corner and travels for about 1/2″, now neatly dripping on the back edge of the eavestrough, or right behind it. Don´t underestimate the power of surface tension.
One more tackle. I thought about cutting ditches in the wood to recess the gutter mounting into, to suck the gutter right against the wood, but opted instead to screw on a strip of aluminum flat flashing, to kick the water farther out into the middle of the gutter.
Adding the flashing was the easiest part of all; took, like a blink. I got a roll of 6″ flat stock, cut it in half lengthwise (to 3″ wide), and I meant to put a bend in it and screw it into the 1×4, but instead I left it flat, and in one length, and tucked it between the plastic lip and the top of the 1×4, and put in just a few screws, pointed up, into the twice-ripped 2×2 component.
My conclusion is that this is pretty ideal, and despite having made it up along the way, I wouldn´t do it over differently (except putting two angles on the 2×2 on the first pass- definitely do that). It´s usually much more straightforward to cut the wood right in the first place.
With the wood alone, it would be next to impossible to get enough lip protruding to shed water well – wood is heavy and that would get too bulky to hang off the greenhouse ribs. The flashing is essential, and the 2×2 is perfect for adding it to.
Cost of about $400CA for gutter, wood, and flashing.