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Smashing Greenhouse!

Discussion in 'Greenhouse Growing' started by dave1510, Feb 6, 2011.

  1. dave1510

    dave1510 Apprentice Gardener

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    HI,

    Can anybody give me some advice please.

    I have been in my current house for 2 summers now.

    I have a small six foot by six foot greenhouse, from B&Q. It's on a slab base with a proper steel base.

    In the Autumn, I lost 2 panes of glass (24" x 24" Hortic glass as supplied with the greenhouse) and replaced them with a piece of pespex 24 x 48.

    Next Gales, this blew out together with about 6 or 7 more panes.

    2 days ago I lost a few more, and have now removed all the rest of the glass.

    The little clips seem not suitable to hold the glass.



    What can I replace the glass with?

    I'd rather use perspex, as cleaning up glass is hoerrendous.

    I think acrylic is too expensive (£40 per 24 x 24 pane!!!!)

    and the plastic sheets which are 2 layers with sections won't fit this greenhouse as this is designed for glass.

    Is there a better clip around?

    Anybody had this problem, and if so how did you get round it?

    Thanks - Dave :)
     
  2. Steve R

    Steve R Soil Furtler

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    Trouble is perspex is flexible so would blow out easily in high winds...once the wind can get in it will blow other panes out too. If it was my GH I would put all glass back in and replace the original two that broke with glass. But see what others have to say about it first.

    Steve...:)
     
  3. lukenotts

    lukenotts Gardener

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    Hi Dave,

    I recently purchased a greenhouse (very similar to the b and q one) and have had a few problems with the current weather.

    I have Twin-wall polycarbonate panels in mine held in with the supplied 'w' clips. I have made sure that more clips are in place towards the exposed sides (not sure what aspect your greenhouse is in?) and this has helped a little.

    I have read before about people using silicone to set them in place, but as it requires 5 celcius for it to set, i have yet to give that a go (no use while wind is so bad either)

    The other problem I have at the moment is that the door has blown off. My solution was to use net curtain wires (the elastic white cords used to hang curtains up, with hooks at either end) stretched across the whole of the front of the greenhouse, from one side of the frame to the other.

    I have also tried this on the other sides and thus far have yet to lose a panel, and the door seems pretty solid too. Sadly though, I fear this wont help you out with glass, as it will just fall straight out.

    I would try the silicone idea though along with additional 'w' clips. might be worth a shot?

    I agree with steve about using glass where you can. I would use glass myself, but with children, decided to go down the safer route with polycarb.

    - Luke -
     
  4. pete

    pete Growing a bit of this and a bit of that....

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    To blow out the glass, the wind must be getting inside the greenhouse.
    The clips are not designed to stop the glass blowing outwards.
    They just hold it in place, if the door is kept shut in windy conditions the glass gets blown inwards, against the glazing rebates.

    If you should use silicone on polycarbonate make sure you use the low modulus neutral cure one, not the acetic cure that is more commonly available.
     
  5. davygfuchsia

    davygfuchsia Gardener

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    Hi Dave

    I'd personally replace all missing panes with new glass and make sure correct amount of clips used .. and as Pete said make sure wind is not getting inside .. Once a pane is out the wind is in ..

    Dave
     
  6. Sheal

    Sheal Total Gardener

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    Hi Dave,

    I live in a windy area. I bought my greenhouse three years ago and upgraded to toughened glass at the time of buying which is heavier. It went through a force ten gale last year with not a murmur! So perhaps it's not the clips but the weight of the panes that is the problem.
     
  7. ARMANDII

    ARMANDII Low Flying Administrator Staff Member

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    I built a new greenhouse this year with the same sort of base as you. I've put silicon on all of the clips where the clips rest on the glass and where the legs sit on the frame. So far I have had no problems with blow-outs although Cheshire has had it's fair share of high blustery winds in the past weeks. I think [hope] that I'm only vulnerable from the South and West where the garden is more exposed. The East and North sides are protected by my house and garage. The Greenhouse door faces West. I don't think swapping to plastic glazing will stop the blow-outs. I went through the pain of digging out and preparing a base and then the mind bending experience of assembling the Greenhouse with inadequate plans, like a lot of others, but I've got to ask and I know you thought about it a lot, but is the Greenhouse in the right place? Being convenient in locality to the house is a nice option but not if it's not sheltered.
     
  8. ARMANDII

    ARMANDII Low Flying Administrator Staff Member

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    I think the Gods are having a laugh at my expense. After posting comments regarding Dave's Green House last night we in Cheshire had a really blustery windy night. I'd talked about being vulnerable to winds from the West and the South, what I should have included was garden furniture being a danger! This morning I went to inspect the garden for any wind damage and found that the wind had picked up my next door but one neighbour's white plastic garden chair, flew it over four fences and over 150' in distance into my garden. It hit my Green house door smashing the top 600mm x 600mm pane!! I guess it could have been a lot worse and I could have lost the adjacent tall front panels and the other door panels- so I'll count my blessings. I've returned the garden chair to my neighbour who was wondering where it had gone to and inferred that he thought it was his fault and offered to pay for the damage. I didn't think it was his fault and refused the offer but it's nice to know I have good neighbours [which I've always known]. Anyway, I've ordered the new pane
    from the Greenhouse manufacturers and I'll be picking it up tomorrow after a 60 miles round trip!!
     
  9. Marley Farley

    Marley Farley Affable Admin! Staff Member

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    :thumbsup: Hi Dave..
    Good advice has been given I think & I would go with replacing all the glass & do not use perspex, also get yourself a new pack of "W" clips so you have extra of those holding the glass in...... :WINK1: :thumbsup:
     
  10. ARMANDII

    ARMANDII Low Flying Administrator Staff Member

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    I second Marley Farley's advice, Dave.
     
  11. dave1510

    dave1510 Apprentice Gardener

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    Well - I am truly impressed with the level and quality of the responses I have had to my problem.

    I have dug out photos I took when I built the greenhouse

    [​IMG]

    It is vulnerable to the South and slightly East.

    I am going to replace the glass as you have all suggested - but not until I have devised a sort of method to help hold in the clips.

    I did have a piece of wood accross the middle where the 2 600mm panes join, and this was jammed between the uprights. This pair of panes stayed put.

    I think it's back to B&Q to buy some more glass, and some wood to make a lot more "reinforcing bars"

    I will probably put twice as many clips in to hold the glass as it originally had (2/pane/side)

    I did think of surrounding it all with trellis as well. (The curtain wire was also a possibility)

    Thanks

    Dave :)
     
  12. ARMANDII

    ARMANDII Low Flying Administrator Staff Member

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    I noticed from the photo,Dave, the Greenhouse is in between a shed, a building and to it's front and West side by a rise in the ground. If the wind which did the damage was coming from the Southwest it would have been hitting the front and west side and might have be funneled by the surrounding structure and ground with the fence and side passage of the East causing a up-lift and side draft, all being accentuated by the blustery nature of the wind. I have a area on my drive by the side of the house where I can actually get a swirling effect just like a whirlwind in the wind's in the right direction. If my Greenhouse was in that position I'd have lost all my glass!!
     
  13. pete

    pete Growing a bit of this and a bit of that....

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    I still fail to see how glass can be blown outwards if the house is closed down during strong winds.:scratch:

    The clips on most commonly available ali greenhouses are designed to just hold the glass in place, all the pressure should come from the outside during a gale, thus forcing the glass in place against the glazing tape or rubber seal.

    If its blowing outwards the wind must have got inside the greenhouse and that's a disaster, waiting to happen.
     
  14. ARMANDII

    ARMANDII Low Flying Administrator Staff Member

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    I agree, Pete, but a Greenhouse isn't airtight especially around the door area!! You'll have to look it up on how air pressure rises with an increase in wind speed as while I did know the formula in the distant past ,when I was in the RAF, I can't bring it to mind now. A simple example of what happens in any structure when the pressure rises is say, blowing up a balloon or tyre. The rising pressure inside pushes outwards. Wind is a force that can increase pressure dramatically and when you get the wind blasting through the imperfect seals of a Greenhouse that's exactly what happens. The dramatic rising and falling of pressure inside a Greenhouse will push outwards thereby forcing the glass outwards - in the direction that the retaining clips weren't designed for. The situation is made worse if there's any structures nearby disturbing, and increasing the air flow. Another strange thing in aerodynamics is if a Greenhouse is too close to a wall or high fence, and the wind is blowing in the direction of the wall or fence, is that it can create a low pressure area between the Greenhouse and the fence or wall. When that happens the increased pressure inside the Greenhouse and the low pressure on the fence/wall side results in only one thing - a blow-out.
     
  15. dave1510

    dave1510 Apprentice Gardener

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    I agree with the funneling effect. The first panes to go where nearest the house (white bucket).

    I can not GUARANTEE that the door was completely closed initially, as it had no catch. (It has now!)

    I am wondering if I should block off the area between the shed and greenhouse with a panel especially in the winter, to help stop the wind funneling.

    Thanks - Dave :)
     
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