Hi, I am happy that you were able to recover most of your panels. You were pretty lucky!

I just wanted to comment on your question. "Would any greenhouse kit have survived these winds unscathed? I don't know"

we had a front come through this past week and we had gusts at least 50 mph. When I went to bed I think the gusts were at 52. During the night I awoke and the wind was howling so I think they increased during the night.
Anyways, I just bought a home attached solar grow greenhouse and everything was fine. I checked on it when I awoke in the night because I was worried. I didn't even hear any Polycarbonate moving. All I could hear were the trees and wind and debris tinking on the greenhouse.
Granted, my greenhouse is more sheltered, being a home attached. However I just wanted to answer your question!

I just wanted to post about this so other people can read it. This seemed like a suitable thread, as you brought the question up.

Anyways, hope your repairs go along smoothly. I know some other people had similar problems and were able to fix things so the greenhouse was sturdier. Maybe they can offer you some suggestions.

My greenhouse is a cattle panel hoop house. It sits in the open fully exposed to winds. The storm that hit both of you (Thursday to Friday) hit us too. My GH had zero damage to it. The film didn't budge an inch. Inside the plants were safe from the elements and the temperature held at 57 which is fine for my daylilies. Guess I built this thing right after all! I've been seriously tempted from time to time by the HFGH (I like the way it looks) but each time I'm almost on the verge of getting one I hear one of these horror stories. I've been looking into Solexx. Does anyone know how it compares to the twin wall that comes with the HFGH in terms of insulation value and longetivity? The company says that Solexx is good for 8 years. While I'm happy with my hoophouse my problem is head space. I can't hang lights easily in there so I'd like to go to a more traditional box like shape for next year.

MollyD

russh_nepa Sorry to hear about your loss but you are not the first and you won't be the last to loss a 10x12 HFGH.
What is just as sad as your loss is that many will take this opportunity to start bashing the GH.
I ordered mine before they were even available so I didn't have the benefit of someone building ahead of me to warn me about the flimsy framing but when I started building
mine I posted about the problems and how I modified it.
I posted several times about these problems and later put all the modifications and pictures all in one post for anyone who was going to build one could see what I did to it. Since then some have build them and posted here that they thought the GH was very strong and did not need any modifications. That means those people will not have their HFGH after the first big storm and all who believed them and did not make mods will also suffer a loss.
My GH went through 60 mph winds last week and 80 mph wind last spring.
I have stated many times on this forum that as it is it will not survive but with less than $ 100.00 you can make it as good as a $3000.00 greenhouse.
Maybe others will benefit from your loss and start making the necessary modifications and I'm sure that some will be scared off and buy a GH that will cost several times as much.
In one of my posts last spring I described how I made a latch for 50 cents that holds the doors secure.
With your loss and that of some before you we can hope that others will start doing the mods so we won't have these kind of posts in the future.
I admire your attitude you are right the panels are worth what you paid for the GH.

>I admire your attitude

Yeah I agree; thanks russh for telling your story. Last Thurs. my new 10x12 was put to the test by a serious cold front that blew big-time from about 3am to well after 5pm. Not sure but prolly gusts to 50mph, and lots of "swirling" and turbulence where my GH is located. Over the course of the day first one panel was blown-out (I replaced it), then another, and even a third (and AFTER I'd added a couple clips to it). With a panel out the thing was acting like a bellows and I feared for its ability to stay together. Note: it is SCARY to try to deal with panels when they are threatening to blow-out! At least one needs to have eye protection!

But mine did hold and I've since made some mods, tho I won't know how well they work until the next comparable blow which may not come for weeks or even months.

It's clear the 10x12 has to have the cross-bracing (I think oraylawson was the first to do this), but also that the cross bracing needs to pull the walls-in so the panels have the absolute least amount of slop in them. Taping the panels where clips are not possible is also advisable.

I think most every precaution has been mentioned here somewhere before--hopefully owners will get-after their HFGH installation before "the storm of the season" arrives to challenge it...

I am still waiting with mine; I have just about every reinforcement on my Greenhouse that has been mentioned in these forums.

I also have a NOAA Tested weather station approximately 20 feet away from the Greenhouse (Yes it is my Weather station, but it's Data is used nationally by many weather and News services.

Since I put up my Greenhouse, the highest gust we have received was 30 mph, with sustained winds not exceeding 20 mph. (Usually it is sustained winds that cause the damage)

The most severe winds I have recorded at this location were gusting to 65 MPH, with Sustained winds exceeding 30 mph.

I live in an area of expected high winds, so some of our building codes are a bit stricter than others.

However when I recorded the 65 and 30 winds, it was during a Microburst that damage my roof. I have actually had roof damage on two occasions this year about 6 months apart, both times were with 60/30 winds....

Now with that said...
OK, Now I am going to say something that may offend some people.
I am not trying to offend anyone.
If you are easily offended, please stop reading
This is not intended to offend anyone, or as an attack on anyone, nor is it meant do diminish anyones experiences.
. .
. People are not good judges of wind speed.
People tend to over estimate the speed of winds
The local paper is not a good estimate for the wind speeds in your back yard.
Knowing this it is going to be very difficult to say which brands, which styles, which reinforcemnts, etc, are the best.
One exception of note as mentioned earlier in this post would be a single location with multiple types of structures.

With that said, when I had the damage done to my house, especially during the Micro burst, I would have written down a sworn testimony that the winds were exceeding 100 MPH, especially when I saw the lid for my 10 foot by 12 foot Jacuzzi Clear my Roof without touching it, and then slam down on my car causing several thousands of dollars of damage to my car (This lid weighs in the neighborhood of 150-200 pounds...

I ran inside to check the data from my weather station after both storms, and was very disappointed to see that the gusts were to 60 with sustained winds around 30 :(

So with that said, I wanted to post Beaufort scale of wind speeds, with visual descriptions.

FORCE SPEED DESCRIPTION SPECIFICATIONS
0 0-1 Calm: Calm; smoke rises vertically.
1 1-3 Light air: Direction of wind shown by smoke drift, but not by wind vanes.
2 4-7 Light Breeze: Wind felt on face; leaves rustle; ordinary vanes moved by wind.
3 8-12 Gentle Breeze: Leaves and small twigs in constant motion; wind extends light flag.
4 13-18 Moderate Breeze: Raises dust and loose paper; small branches are moved.
5 19-24 Fresh Breeze: Small trees in leaf begin to sway; crested wavelets form on inland waters.
6 25-31 Strong Breeze: Large branches in motion; whistling heard in telegraph wires; umbrellas used with difficulty.
7 32-38 Near Gale: Whole trees in motion; inconvenience felt when walking against the wind.
8 39-46 Gale: Breaks twigs off trees; generally impedes progress.
9 47-54 Severe Gale: Slight structural damage occurs (chimney-pots and slates removed).
10 55-63 Storm: Seldom experienced inland; trees uprooted; considerable structural damage occurs.
11 64-72 Violent Storm: Very rarely experienced; accompanied by wide-spread damage.
12 73-83 Hurricane: Severe and extensive damage. Roofs can be peeled off. Windows broken. Trees uprooted. RVs and small mobile homes overturned. Moving automobiles can be pushed off the roadways.

Once Again I want to reiterate, that I am not trying to belittle anyone, or anyoneÂs experience

I appreciate everyone's comments. My wife was in tears. She thought it was her fault, that she should have "done something". One of us had to keep some perspective. Once the storm started it was much too late.

I agree that there has been a ton of information on this site regarding reinforcement of the HFGH, but I still considered mine a "work in progress". I was planning reinforcement once I saw what it actually looked like. The roof needs simple trussing, and the doors need latches.

I am absolutely not knocking the HFGH. It is what it is! Be prepared on the day you build it to with extra materials. Don't think you have a week, as I did.

Regarding wind speed, I don't have a weather station on my property. I am not offended in the least. I should not even have quoted a speed for it is irrelevent. The damage occurred, period. My quote was based on television weather broadcast the following day, and from a neighbor who has a "Radio Shack" type wireless weather station on his roof. My point was that this was clearly not the tornado that was reported doing soooo much damage in NE PA. This was a simple common everyday storm front. Be forwarned.

BTW, now that you mention it jimmydo2, I lost a half dozen shingles from my roof, and also need to repair them before the next rain. Thanks, soemthing else for the old honeydo list. LOL

I would like to thank your wife for the observations while the GH was actualy failing, I am sure it will be very helpful for those that are still reinforciing their greenhouses. Usualy we just hear about the damage, not how it happend

One person who lost their 10x12 HFGH said the door was open and the wind blew inside and started blowing the panels off. If I'm going to leave home I latch the door but my theory on the panels is that while adding the stronger clips is good it will not keep from blowing the panels out because the wind will bow the panel in the center and when it bows out it becomes shorter pulling the panel out from under the clips. I used self tapping screws with neoprene washers and put then at top and bottom and in the two #30 horizontal braces for a total of 4 screws per panel plus the heavy clips. The bracing on the corners plus the mod to stop the base from flexing will go a long way toward saving your GH. If the storm is bad enough NO GH will survive but it is possible to make them pretty strong. I would suggest placing the GH where it had a wind break even if it means that it will not get all day sun.
I still have work to do to mine but plenty of time it will sit empty until late Feb.

gardenerwantabe: I agree, that's why my lightly built greenhouse using single layer corrugation has survived at an least level 10 wind (blew trees down across the road, removed a neighbour's garage roof). The reason is that my roof uses screws that actually penetrate the skin and stop it from moving, and I use a lot of them (24 per panel). In that storm I saw the whole wood frame bouncing up and down 20cm in the middle, yet nothing broke.

So if you want to increase the strength of your panels, you should seriously consider using bolts all the way through the panels to transform the problem from stiffness to tensile strength (which is always greater). Remember to insulate your bolts on the inside to prevent cold bridging.

>the wind will bow the panel in the center... two #30 horizontal braces...I would suggest placing the GH where it had a wind break

Not sure what the "#30" braces are but am thinking here about how to further prevent panel bow-in. Oops, I get it, these are the HFGH parts you are talking about. Maybe I will add a slat between the panel and the brace to take-up the gap/space between.

I commented to the wife today that while our HFGH is protected from the North wind, the wind last Thurs was swirling such that it was being buffetted unlike anything I'd have expected.

jimmy I asked Santa for a deluxe weather station, but dunno if I've been a good enough boy this year!!!! Is yours a Davis? Other? Need one that will accomodate extra sensors (for the GH of course).

laserfan
The screws are to hold the panels if the wind blows in through a open front door. One person lost his panels from the wind opening the roof vents and blowing in the vents.
When a storm is expected I put tarp straps on my roof vents to prevent them from blowing open. A strip up the center will not help if the air gets inside and pushes the panels outward.

Laserfan:

My station is a Davis Vantage Pro. When I bought it I needed the faster updates/refresh. If I had to d it over, I would probably go with the Oregon Scientific 968. I like the fact that you can view the Temp/humidity at the remote sensors, as well as at the console. There is however the drawback of only three additional remote sensors, however the floating pond one is nice.

at $310 for the whole caboodle, with the usb adapter, 25 foot pc cable, and pc software, and at 25-40 each for the remote sensors, you can get every thing for under 400.

The 968 can also become NOAA Certified as well (Usualy takes 1-2 years of data being submitted online (The big clincher is the uptime required to be considered certified...well of course with accuracy as well)

There is however the 1-wire solution for the most versatility.

There have been a couple really good threads in this forum, regarding the various weather stations

gardenerwantabe thanks for the reply. I have been researching plastic clips for an easier solution than screws--thinking maybe arrow plugs or canoe clips which would push-thru the polycarb and then I could nylon tie-wrap to the #30. If not I'll do screws w/washers as you, with some sort of spacer (horiz, not vert at the #30) to un-bow the panel.

I've actually wired my vents shut for now--these are not very easy to use/secure are they. Well, it'll be windy again tomorrow so I'd better get after those panel mods.

Thanks jimmydo for the station info. I have looked at the 968 as well and appreciate your candor vs. the Davis which are 2x the price.

For what it's worth, the pool cover I use to provide a bit of insulation for my GH seems to make it much more stable in the wind.

laserfan
Don't forget to do the roof panels also.
I screwed the roof panels down just like the wall panels.

When you put screws through the panels don't you have to worry about cracking if you restrict movement of the panels due to changing temps? If not, then I'm surprised they don't use screws up front. It would be quicker, easier, and more secure than the clips.

Any thoughts?

PS: Can I still be a member of the HFGH club? I did buy and build one after all. I even sacrificed it in the name of product safety testing. You know, like they do with crash test dummies. Now that is a club my wife thinks I belong to! LOL

Is your resting-in-pieces HFGH still under warranty? If so, you could get another and reinforce the heck out of it, or use the refund to buy different building materials for a new gh.

Alia

I didn't figure wind damage would be covered under any GH warranty, unless it had load specs. I guess I should call harbor freight and find out. I'm not hopeful.

I thought about my homeowners, but one problem with such a value oriented purchase, it cost me less than my deductible. I guess I should have spent $3000 so I could have claimed it. ;)

russh: You're right, I forgot to mention you have to drill larger holes in the PC than the bolt diameter (add an extra mm to the dia). This is standard practice, and as discussed in another thread, there are even special screws that cut the holes for you (when afixing to wood)!

Thanks Nathan. Guess I missed that thread. Makes sense though. Just like in woodworking, allow for expansion and contraction.

Posted by russh_nepa (My Page) on Wed, Dec 6, 06 at 13:54

When you put screws through the panels don't you have to worry about cracking if you restrict movement of the panels due to changing temps? If not, then I'm surprised they don't use screws up front. It would be quicker, easier, and more secure than the clips.
Any thoughts?

Good question. If you are securing the panels to the frame all the way around this may be a problem but on the HFGH the panels are held on with clips.
With screws in the center they can be held secure because the panels can move at both sides under the clips.
I don't know how much about 22 inches of polycarbonate will move due to temperature change but it would not be much.

>Posted by gardenerwantabe (My Page) on Wed, Dec 6, 06 at 18:18

>With screws in the center they can be held secure because the panels can move at both sides under the clips.
I don't know how much about 22 inches of polycarbonate will move due to temperature change but it would not be much.

I agree with this, tho I should qualify as I live in So. Central TX where the temps only dip into the twenties for a few days a year.

I had (as I tend to do) over-thunk the whole panel-securing situation. Went to Ace Hardware and bought a box of "Lath screws" today. These are self-tapping sheet metal screws with a wide head, kind of an integral washer. The 9/16" ones are about 1/16" too long (!) but if you are careful they don't poke-thru to the other side of the #30 supports. Using my HF spring-loaded center-punch and a variable speed drill/driver made short work of all the panels, though the roof panels are harder to get at. Then I re-positioned the spring-clips.

Our GH is clearly much more secure for these; thanks to gardenerwantabe for making this point (again).

Laserfan Do you have the base plates installed to stop the flexing.

Yes thanks I'm good there--the base flexes not at all!

Sorry to hear about the greenhouse being destroyed. Ours are being built now (we bought two). The first one is finished and with the help of Gardenwantobe and others suggestions it is a lot stronger than it would have been. Our location is close to the ocean on the west coast and the winds can be strong. Our greenhouse hasn't had a good test yet and before it does I want to get some cross bracing for the rear wall. That is the weakest wall and also the one which takes the most wind on our site. I was thinking of getting some galvanized metal strapping and taking it from the upper rear corner across diagonally to the lower rear corner and attaching it to the 4x6 pressure treated foundation and doing this on both sides making a big x. I'm wondering what others think of this idea and if there are any other suggestions. I like the strapping because it can bend and be screwed down into the wood but it won't look as nice as using aluminum angle or square tubing. Mary

If I picture your "X" properly this would keep the wall square, but not from flexing in-and-out?

I built some shelves which greatly stiffened the back wall so it will not flex at all--you might want to look at my pics to see; the last pic in the link below, then click on the DETAILS button at the top of the page for more...

Laserfan your shelves look great. I had planned to build mine our of redwood but I like the way your shelves attach to the frame of the green house. And I am thinking about making a shelf (two foot deep) running along the back wall using your system. Yours looks like it gives a huge amount of strength to the wall. I'm not sure we could build all the shelving using your system as I'm planning to set about 11 rectangular flats on each long wall of shelving and we use a very heavy, sandy soil. I wonder how much weight your shelves can support? I'm also a little worried about putting too much weight on to the wall studs.

To build the pipe structure, did you use one inch galvanized pipe and how did you attach it to the wall studs? I couldn't tell from the picture but it looks like you had a part that holds the pipe and can be bolted to the frame. I'm trying to think of how I could use your system instead of the redwood. I had planned a 10x2' roll of shelves along each side with a 10x1' shelf resting on top. Your shelves also look nice. My greenhouse is in a farming community and I'll see if the cattle panels are available. I already purchased a roll of hardware cloth and I suppose we could build the pipe shelve supports and set the redwood frame with the wire on top of the pipe structure.

Thanks for your response and the pictures - it was very helpful.

Mary

Mary, note my 4x4 base structure--there are 2 galvanized pipe "trees" that are floor-flanged to it (it's 3/4 inch pipe). Then the horizontal members (3) are 3/4" EMT conduit flattened at each end (about 116" wide), drilled, and bolted into the back-side studs at 6 places. Finally, there are Qty 12 approx 22.5" EMT conduits projecting backwards into the wall studs. So the whole structure is tied-into the 4x4 in the floor, and at fully 18 places into the wall studs.

Re: strength, I wouldn't worry about downward pressure on the wall studs themselves--the weak links are the bolts that slide in the channels, but even there if one bolt slips it won't cause a big problem. I've never used hardware cloth, but cattle panel is 1/4" diameter stuff (I use an angle grinder to cut it though a bolt-cutter will work albeit less cleanly) and will support anything in my guesstimation.

You may want to lay your hands on a few 3/4" galvanized fittings and some 3/4" EMT conduit and the pics and captions may make more sense to you. Gotta run now but if more ?s ask away...

Laserfan, thanks for the new info. I really like the way the shelves tie into the structure. Our shelves will have to support a lot of weight and I'm not sure about having all the weight on the rear bolts. Maybe there is a way to add rear supports as well. I'll give it some thought and after Christmas I should have a chance to check out the galvanized pipe. Sure hope we don't have a bad wind storm before its reenforced.

Thanks a lot. Mary

>...after Christmas I should have a chance to check out the galvanized pipe. Sure hope we don't have a bad wind storm before its reenforced.

Mary at a MINIMUM you need to screw-down all your polycarb panels, and also install a cross-beam from side-to-side as oraylawson and I did (actually I did two). And tie-down your roof vents with wire or something.

Ya just never know about Mom Nature's moods these days.

The shelving is a good way to strengthen the back wall but if you lay out the shelving like I did their is not room across the back but you can use 3/4" EMT tubing and U clamps attach them with T bolts across the back then in order for the back to bow it would have to bend the tubing also. I also put two in the roof the same way that makes it much more unlikely that a snow load will cause a failure of the roof rafters.
All of these things may not be necessary but I would rather have it stronger than what is needed than go out and discover it had been ruined in a storm. I"m confident that if my GH blows down the house will go with it because anything less than a category 3 tornado will not damage it.

Hey Gardenerwantabe,

Do you have any puctures that a person could see of what you did?

Thanks

If you are talking about the roof braces I have not taken any yet but I will take some and add them to the other photos on the site where my GH pics are.
My GH is a work in progress Today I wired a thermostat and a speed control to the exhaust fan. During the summer months I didn't work on it but I got to get it ready I have about two months until I will start growing plants from seed don't want to have to do anything to it then.
When March gets here I will start getting my Show Car ready for another season so I won't have time to work on the GH

We are having a big wind storm and I'm worried about the greenhouse. This morning my husband drove down to see it and frankly I was expecting to hear it was destroyed but it is fine so far. The winds at our house which is about 20 mile away are very strong and luckily the greenhouse hasn't been hit as hard. The wind gusts last night are reported to have reached 51 mph. I was working late and felt the house shake as the gusts hit so you can see why I expected the worst for the the greenhouse. We did screw down all the panels with stainless screws including the roof vents. The corners are all firmed up using Gardenwantobe's brace system but the rear wall has some flex in it and it needs immediate help. I'm thinking of putting in the bench framing using the galvanized pipe - just not sure how to attach the pipes to the greenhouse frame.

Lazerfan I looked at your photo of the cross beam you added to your greenhouse and I'm wondering how you attached it to the frame. I read that you welded L brackets on to some of the pipe and I'm trying to think of how to install the pipes (for both the cross brace and bench frame) without welding. I guess I could bolt an L bracket to the wall stud, drill the pipe and attach the pipe by bolt to the L bracket. If there is a better way please let me know.

Our neighbor who is building the greenhouses is out of town until the 3rd and I want to be sure there is something left when he returns. It is so cold and windy out that it is hard to get myself motivated to deal with all this - for now I think the worst part of the storm is over. I live in Pacifca, CA (hence my name) and you may see us on the news as the surf here is very high and the local news stations keep coming down from San Francisco to film the waves.
Mary

Mary the 10-foot EMT conduits that go from side-to-side are flattened on each end and drilled (yes, it's hard to do accurately).

Your idea of attaching the L brackets to the shorter pipes by simply drilling the pipe (and using a sheet metal screw thru the L bracket into each pipe) was actually what I was going to do before my brother-in-law loaned me his MIG welder. Should be very doable.

I don't think that flattening-and-drilling those shorter members (into the back wall) would be very fun to do (unless you have a super-heavy-duty vise) but that is an option too. You do actually have a quarter-inch (maybe even a half) or so to work with in re: turning those short pipes into the galvanized fittings--you can turn them just until they "catch" in the threads, or you can keep turning until they are all the way into the fitting. Turn a little, rotate the pipe down into position and see how it mates with the stud, turn some more in-or-out until it's a good fit.

Good luck--I hope your GH survived the storm and expect that it would simply with the screws you used.

>I'm wondering how you attached it to the frame.

Just realized maybe I didn't answer your question. For all of the 10' EMT conduits that I ran from side to side (2 as top-wall beams and 3 as shelf supports) I flattened the ends, bent-and-drilled them, then secured them into a side wall stud.

For the top beams I used the existing top bolt in the side wall studs. For the shelving (3) I added T-bolts at approximately the 36, 54, and 72-inch levels in the last wall studs.

IIRC even the short bolts worked for this--I ended-up using all the HF bolts that were included in the kit, and didn't need to buy any more or otherwise jury-rig anything, though I decided that for the back wall it was easier to grind-down T-bolts and insert/twist them rather than partially dissassembling that back wall.

mary_pacifica
If you need a quick fix drive some stakes in the ground use a nylon cord tie it under a couple of the screws on the back that you have holding on the panels and then tie to the stakes. If you don't already have a screw in the center put one their. This would be a fast fix and would hold the wall from flexing.
When I attached tubing in mine I used heavy L bracket and screwed them to the corners cut the tube to length flatten a couple inches on each end and held it in place with vise grips till I could get some screw into them.
Several ways that you can do it I prefer to bolt it together as to flatten and bending on the ends because where you bend it will not be as strong.

The greenhouse is fine so far and as yet I haven't done anything. The weather has been mild since the storm. I've been working on a plan adapted mostly from Lazerfan's pipe structure. Gardenwantobe thanks for mentioning the simple way to stabilize the back using a cord. This weekend we'll get something done.

Mary