Greenhouse Snow Buildup

West and East Side Snow Buildup on Greenhouse

Our new greenhouse is 38′ wide by 96′ long and 21′ high. To prevent collapse from winter snow buildup on the peak we have a center line of posts supporting a ridge pole. A big question I’ve wondered is how much snow buildup would there be to the east and west of the greenhouse down along the foundation where it slides off.

We built the greenhouse up on a wooden foundation to give some room for snow banks to build up along the sides of the arch. I often see these sorts of greenhouses right on the ground, and this one came with steel ground posts to do it that way. We had to order the feet to sit on the foundation separately.

By putting the ribs up on the foundation there is extra room for snow to build up and not press in the greenhouse fabric. This continues to allow the snow to slide off by itself during the winter saving us the effort of having to manually clear the snow.

The foundation varies from 3′ tall at the north west corner to 5′ tall at the south east corner. This is because we had the plateau very carefully bulldozed the to that slope. This allows for drainage. There is also a berm around the foundation to redirect water away from the interior.

The top of the foundation is within an inch or so of perfectly level so that while the land slopes the greenhouse itself is level. That helps with the structural engineering making the building stronger. But, that creates a challenge with the foundation and snow drifts because I could not economically get posts long enough to make the foundation as tall as I wanted. The result is I went with 8′ posts. At the south east corner where the foundation is tallest the 8′ posts are about 3′ into the soil.

So we have a compromise of a foundation not quite as tall as I wanted but the real question is: “is it tall enough?

The answer based on this year appears to be yes, the foundation is tall enough. It’s plenty tall on the east side and tall enough on the shorter uphill west side.

Much of the snow blows off the greenhouse so it never settles and has a chance to slide down the sides. We get a lot of wind. Even though the greenhouse is built down in a lee of the mountain its plateau does not end up with the deep snows of other places because much of the snow is carried away by the wind. This is an advantage for siting of the greenhouse.

What does settles onto the arch tends to slide right down. The opaque billboard tarp we’re using as a covering this winter is not as slippery as real greenhouse film but it is slippery enough to dump the snow.

The complication with the answer is we didn’t put the tarp on until mid-winter so not all the snow had a chance to be part of an experiment. Had the snow buildup been a problem we would have plowed down the longwise sides of the greenhouse with the tractor to remove snow. So far it has not been an issue. More data next year.

Outdoors: 34°F/24°F Sunny
Tiny Cottage: 66°F/62°F

Daily Spark: Being a farmer and not believing in evolution would be like being a baseball player and not believing in physics. It’s possible but it would be a major league handicap in the big leagues.

Note that the middle of the photo is missing.

About Walter Jeffries

Tinker, Tailor...
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9 Responses to Greenhouse Snow Buildup

  1. Pam R says:

    Being so early in the AM, I didn’t notice the cross for the note, and wondered what had happened to the greenhouse!! LOL Glad it worked well and the door isn’t only 4′ wide. LOL

  2. Bob says:


    I am so much appreciating following the greenhouse story. Thank you for taking the time to allow us to do so.

    One question I have is about the composting wood chips inside the greenhouse. Are they 2 feet deep against the posts? If so, do you see a potential of early rot starting in the posts on the inside? Or….?

    Thanks again.

    • It is a good question and something I considered carefully. The woods are two different types. The foundation posts are cedar which lasts a long time in both theory and my real world tests. The bedding chips are hard wood, pine and spruce which compost much faster. Next over the course of years we’ve been doing this same test in several other places with the composting bedding up against both spruce posts, red pine posts, cedar posts and 2x studs. The bedding composts and does not make the thicker pieces of wood rot out. I suspect this has to do with surface area. Large chunks have relatively little surface area so they last. Small chips have a high surface area to volume ratio so they compost away more quickly. I don’t expect the wooden foundation to last forever but based on all this it will probably last a decade or two. Built into the design is an easy way to replace posts.

  3. Thomas Lunde says:

    Hi Walter:

    I’ve been following you faithfully for three years. I live in a very area with weather slightly better than yours but still extreme. Enough history for now as I have a question I need some advice on. I’m raising barnyard Large Blacks and I had a couple of litters in Oct. I am trying to sell them as growers at about 80 lbs each for $150. However I have one little boar, I hesitate to call him a “runt” but he is a little smaller than the others. He has developed what I could call a cyst on his side, it doesn’t seem to affect him in any way and I have done nothing but just be aware. In the last couple of days he has developed a second bump very close – almost touching the first bump.

    I spent some time on the Internet but could not find anything that seemed directly explanatory or remedial and the information was all over the board. With this little information could you take a guess and is there anything I should do or just let nature take it’s course?

    Another little story, I have two large boars 450 plus with one being dominant. Anyway I moved the second boar into electric fenced area adjacent to the dominant on. After snorting at each other and foaming at the mouth. the dominant one went right through the electric fence and the fight was on. They were shoulder to shoulder with both of them trying to tusk the other. Sadly, the dominant boar had dragged a bunch of wire fence with him and they could not get separated. Risking life and limb I got the wirecutters and went in cut the wires enough so they could separate but bit by this time the dominant one had inflicted 8 or 9 gashes on the other boar. Two of them were very long and deep, like 14″ long and a couple of inches deep. I thought I might have lost the injured boar but after about 3 days of lying the dirt and me bringing him food and water the wounds started to close up and by the 4th day he was at the trough for dinner. the point I want to make is my amazement at the healing and recuperative abilities that pigs have. Anyway it was quite an experience.

    Any thoughts you have on the cysts would be greatly appreciated.


    Thomas Lunde

    • The bump could be a hernia, a cyst, a hematoma (blood pooling under the skin) or cancer. I’m not a vet and can’t see it so it is hard to tell but if you go to they have some excellent pig health information including a disease diagnostic tool that I highly recommend. That may help narrow down the possibilities. The pig may raise up fine. Keep an eye on it and if the problem worsens then slaughter early. You’re very right about the healing abilities pigs have evolved. They recover from some amazing cuts.

  4. Anonymous says:

    “The complication with the answer is we didn’t put the tarp on until mid-winter so not all the show* had a chance to be part of an experiment.”

    *I presume that it should be snow instead of show.

  5. Jonathan says:

    My family has had greenhouses/high tunnels for decades in Northern Minnesota. To keep the snow from collapsing them or breaking the poly coverings in extreme cold weather we plow the snow away from the sides to keep it from building up. The poly gets very brittle in -30 degrees temperatures and the snow load will cause them to shatter. These structures are not used in the winter. Your cover material isn’t poly that is used for these structure so it will react differently but something to consider.

    • That is my thinking too, thus we left paths for the tractor to plow along both sides of the greenhouse where we can keep the snow from building up. Originally My intent had been for the foundation to be higher but between the cost of the taller posts, dealing with setting the taller posts, our shallow soil depth and the slope we ended up a little lower.

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