Area that gets gusts of very strong winds - can a tarp canopy survive?

October 26, 2022 9:51 PM

My dwelling is in a mountainous area with very strong gusts of wind that literally come out of no where, and there is no knowing when or how strong. Want to secure netted tarps for shade and privacy, mostly for the wintering of my plants.

One side of the tarps is attached to the house with hooks and bungee cords. The other side is currently unsecured. I've been looking at various idea that would work, but sadly nothing is coming up for high wind gusty locations, only serene and green ones.

Am thinking maybe large planters or huge buckets filled with cement, with poles sunk in and to attach the tarps to that. My only concern is if this would suffice or would they get overturned in the winds? I can't really start digging and put them into the ground which would be ideal, have to think about an alternative for renters.

Am looking for any type of solution that has worked for other people in similar climate conditions. Maybe even that withstood hurricanes.

Also, formulas and ratios for the buckets, width of poles, materials, connectors and basically everything I need to know to make this happen on a tight budget.

Thank you so much.

posted by watercarrier to Home & Garden (11 answers total)

Honestly, it'll almost certainly turn out one of three ways:
- Something breaks and comes loose.
- Something lifts and comes lose.
- If you manage to keep it from coming loose, the tarp itself will get shredded to bits far more quickly than you would imagine.

I mean, maybe there's either expensive, new, or magic solutions I haven't seen? But pretty much everything in the higher-wind areas I've lived in that involved any kind of tarp or sheeting is going to fail sooner or later.

In the setup you've described, I've seen it fastened with bungees, rope, chain, wire, zip ties, just the closing metal hooks, on carabiners, and probably at least a dozen other things. They all fail, sooner or later. Things break, the hooks pull out of walls or wood or concrete, the tarps fray on the edge or around the eyelets... and in the really wonderful ones, it lands on the roof, or the tree, or the neighbors yard.

It's not really a question of "will it last?" but a question of "how LONG will it last?" or "at what point will it fail?"

Things I've noticed that can help increase longevity include:
- NOT having an edge for the wind to get under. If you're trying to make the tarp equivalent of those white shade tents, it's not going to last very long at all, and it's going to drive you (and possibly your neighbors) nuts with the noise in the meantime.
- The hooks into the side of the house are going to be a weak point, if you weight the other edge down with wood, rocks, concrete blocks, whatever enough to mostly make it stay. They will wiggle their way loose if they're just screwed in, and probably nearly as fast with reinforcement.
- When I've gotten both the outside edge weighted down, AND it fastened on the other edge sturdily enough, that's when the tarp starts ripping right around the eyelets.
- If that doesn't end up tearing it up enough to make the tarp worthless, the fraying and wear and tear on the edges AND the middle from the wind will make it much less waterproof and prone to ripping the rest of the way.

The only way I've seen a tactic sort of work well, is when none of the sides are "up high", but can be tucked in under the edges of whatever it is covering. For example, over a woodpile. And that's provided that the tarp (or heavy plastic) is long enough to go to the bottom on every side, and have at minimum a couple of feet extra. Then it can be tucked down under the bottom pieces, or with concrete or wood that doesn't have to stay dry sitting ON the plastic at the base. And then it's still sort of iffy and needs checked REALLY frequently, especially if it's essential that what's being covered stay dry/completely covered. The tarp or plastic needs to be sturdy enough to not get holes poked in it from what it's covering, too.

To improve the coverage a little bit more, my dad always used to things like plywood, pieces of lumber or pipe, etc, on top of it and up against the sides - anything to keep the tarp/plastic so that it moves as little as possible. Because the looser it is, the more the wind can catch it - and the more wind that catches it, the quicker it gets loose.

Another trick, with something like wood, is to start the tarp UNDER the item being covered, at the side away from the house, have it run under the item, then up the side of the house, then back over the item to the front, and down the front, where it's then held down by as much as possible. The sides need to extend enough to cover, but if it's long/wide enough, one of those can be wrangled underneath, too. (The hope in that case is that the open side is long enough to hang down enough, perhaps stay down and keep everything dry with something on it, but still have relatively easy access. And if that side gets loose, well, at least the tarp isn't going anywhere.

But if you're wanting to put it up as a shade canopy or rain canopy, like I always tried... don't bother intending to keep it up. It'll just get ruined. Instead, put the effort and money into setting it up so you can quickly and easily take it down when a windstorm is coming in.

And if someone suggests one of those white tents or a car canopy... no matter what you try to do with it, you've got really good odds of it ending up at the neighbor's sooner or later. (My ex-husband finally gave up and intends take his down every year. I think he's had three destroyed now?) Last year, he thought he could put it off one more DAY. Nope, storm came in early and it was in the neighbor's yard again. Terrible thing is, the sturdier he fastens it down, the more it seems to bend the legs/poles. He just can't win.

So... good luck?
posted by stormyteal at 12:17 AM on October 27, 2022 [7 favorites]

A short article which explains how the root system, trunk and leaf structures of palm trees allows them to survive hurricanes OK. Taking that idea a little further - 18 of the Best Wind Resistant trees offers some other options. In brief: one or more trees might be a better solution to your problems than a tarp.
posted by rongorongo at 12:58 AM on October 27, 2022 [3 favorites]

The only system I've seen work with this is a VERY tough shade cloth we have in NZ, but it also needs to be very well anchored, and might still damage the building it's attached to. Snow will destroy them

You also need some kind of quick release for emergency wind conditions, otherwise there will be damage.

You can use ground anchors to tie down to - helical screws (we build houses on them here), ideal for renters, but only with non-rocky soil.

I often use a hired marquee for tradeshows in a very windy place - what I hire uses a scaffold frame that is pegged very securely to the ground, sometimes I turn up to my turn and find most of the others flattened or damaged. So if I had to do this reas. cheaply I'd start with a scaffold frame.
posted by unearthed at 12:59 AM on October 27, 2022

I have previously considered using camouflage netting, in a somewhat similar situation (strong, unpredictable gusts of wind, and reducing flapping noises) but ended up not using it because of moving.
At the time i my reasoning was that the camouflage netting will acct less like a sail, as the wind can penetrate it and will not be "trapped". When i looked at set up camouflage netting (eg in a River beach restaurant garden with a constant wind exposure), the shade provided seemed sufficient to me. And several colours are available not only military green.
Of course no rain protection is possible.
posted by 15L06 at 1:33 AM on October 27, 2022 [2 favorites]

In march/protest banners when they’re very large and you need them not to act as a sail, I’ve seen regular semicircular slits cut so that wind can pass through. Lines not half moon shapes.
posted by lokta at 3:17 AM on October 27, 2022 [2 favorites]

Get very sturdy bungee cords and use them in line with any rope. Elastic will absorb some of the wind energy. Bungees won't last long outdoors in use. A friend did this with camping tarps.
posted by theora55 at 6:37 AM on October 27, 2022 [1 favorite]

I have a canvas cover for my 28' sailboat. It has stood up through 20 winters each of which has had numerous windstorms with 50 knot gusts. I did get it re-stitched a couple years ago.

It's made of a strong canvas, and cut and sewn to match my boat's shape at least loosely. It's closed on each end which greatly lessens the amount of wind that gets under the cover, but it still billows in a wind. Along the edge there are strong grommets about every 18 inches. In my case, I can tie each grommet to the rub rail, but not all boats are made to facilitate that.

Some boats have covers that go well down the boat's side, and are held down by weights from each of the grommets. You can see a neat example here (6th picture down). I've seen it done with bags of sand and bags of water. It helps that the "skirt" comes well down the topsides and can probably be cinched a bit to help keep it place.

The lessons are strong tarps well fitted and many ties. It's pretty dim under my cover. This may be bad for your plants.

I'd also like to mention screw-in anchors. I've seen these used in Florida to tie up boats, despite the sandy soil that I would think would have little holding power. Chances are that in the mountains, the ground is too rocky (as it is here in Connecticut due to the ice ages). There are quite of variety of styles.
posted by SemiSalt at 7:11 AM on October 27, 2022 [2 favorites]

Buckets of cement will be a liability. Can you sink anchor bolts into the ground and/or pour a cement post foundation that you anchor into?

Your tarps will do fine but they'll age quickly and need replacement sooner than you expect, or they'll get tattered and loose. I used tarps attached to bolts sunk into decking material and used a strap lever to continually adjust (tighten) the tension on the (heavy duty canvas) tarp. The main things I'll point out: wind is strong, and a tarp is a force-multiplying sail. Anchoring to a bucket is asking for that bucket to be flung across your property, or onto a neighbor's property. Tarps are noisy as hell and, if you're not able to adjust tension, will get noisier and more irritating. THey will pull and tug at their anchor, they will flap in the wind, occasionally the forces will align and they will snap (both loudly, like a belt, and structurally, as they rip apart).

Maintenance is the answer, as is comfort with tarp failure and replacement.
posted by late afternoon dreaming hotel at 7:44 AM on October 27, 2022 [3 favorites]

It's hard to tell exactly what you are trying to do. It sounds like you want to make a 'lean-to' like tent structure off of the side of your house. One edge high up attached to the structure, the other edge sloping down and out until it hits the ground. How do plants get light under that unless it's like the camo-netting sort of thing that has a bunch of holes in it.

It's more the attachment to the structure that I worry about, ground anchoring is the easy part.

I would firmly attach something like a 2x4 with 16" spaced counter sunk eye hooks to the building,then dig a narrow trench a bit from the outer edge. Cut narrow sloping channels every 16" to match up with the structure mounting. Loop around a pipe or rebar some stainless steel cable, drop that into the trench and feed the cable up the slope to a U-bolt. Fill in the dirt. Do the same from the eye bolts on the structure, meet about half way. Connect the two parts with a turnbuckle to adjust tension. Put a tarp or whatnot on it, go through and secure it along the cables every 12" or so with zip ties or something along every 16" cable-beam from ground to house.

Over Engineer's Anonymous.
posted by zengargoyle at 8:26 AM on October 27, 2022 [1 favorite]

I have a tarp setup over my south facing deck that I use for shade in the summer. I also live in the foothills and have seen hurricane force winds roll off of the hills and then get amplified by the local topography.

As others have noted, it is one thing to let a tarp cover an object. It will generally stay if it wraps the item. But a tarp that provides shade and thus is subject to having the wind get under and lift it is tricky at best.

For some basic back of the napkin numbers, a small 10x10 tarp with a "gentle" 10mph wind will be looking at about 40lb of stress. By 20mph we are up to 160lb which is enough to toss a popup that is using "only" 50lb of weights per leg. 50mph? 1000lb. At this point the anchor bolts and the rest of the system is typically at their limits. 75mph? We are up to 2500lb of force and the anchor bolts will typically rip out or the system will otherwise self destruct.

My solution was to design a system I could quickly put up and down. Some lag eye bolts along the house that the tarp attaches to via a carabiner. Then a few 2x4 uprights along the edge of the deck with an eyebolt that accepts a rope that gets tied off. The 2x4's also act as a dampening spring of sorts to reduce the shock from a sudden gust. Above 10mph the system is taken down since it is not a nice place to be anyway.

If you want something that is always up, I suspect that you don't need a tarp anymore. You need a well built pavilion. My deck sits 12' off of the ground and has no shelter from the winds. It uses hurricane ties that are rated to 4000lb each on every joist. It does not move, even with sustained 90+ mph winds.
posted by SegFaultCoreDump at 9:53 AM on October 27, 2022 [1 favorite]

Would making a low hoop structure (plastic sheeting over PVC bent into little hoophouse) be an acceptable alternative? You can get UV-resistant greenhouse plastic that will last a few years and potentially make this cost-efficient vs. tarps. More light for your plants, too. There are lots of instructions for these online.
posted by momus_window at 10:56 AM on October 27, 2022 [2 favorites]