Polytunnel or Polycarb greenhouse on windy plot...?

[Lost_the_plot]

Hi,

I figured I'd ask the experts as I'm a newbie... I've taken on a small plot in Brighton on a windy, hilly, fairly exposed site. Nothing like a challenge eh?

I was previously a co-worker so know what the weather can be like up there. I'd like to have either a polytunnel or polycarb greenhouse in order to extend the growing season and to grow the crops that cost a fortune in the shops! My two sticking points are:

1. Cost
2. Wind. I don't want the bugger blowing away in our usual force 6 winds at this time of year.

Does anyone have any advice as to which out of a polytunnel or polycarb greenhouse would be my best option please? Floundering a little when my partner has costed them up to be around the £300 mark even if we do it ourselves??!! ( I personally think he's planned a flippin' en suite and movie room in at those prices!!)

Any help would be appreciated!

Jo

p.s. The 'tunnel/house' will be around 2m x 5m

[bearded bloke]

Hello & welcome If you put an approximate location in your profile it will appear at top right of your posts & should help with advice given

Ahhhh,just re-read & I see on a hill in Brighton,yep it can get a tad windy in the 'Dene's,what are other plot-holders using ? that will give a clue,if it really is bad then maybe some old fashioned cold frames might be a good idea to get things started in a little earlier than direct sowing.

[Bill HH]

I have one of each, both have to be securely fixed to the ground, I have also used silicone sealant on the polycarbonate panels. However the wind still blew out two panels last night. I would think the poly tunnel may be the better option. If you dig the edges of the plastic into the ground and secure timbers to the plastic and the ground with some strurdy stakes it should be ok.

Oh and if it helps the poly tunnel is much easier to build than a polcarb in my opinion and you will get a bigger one for your money. Avoid the ones with zip up door they are horrible.

[lottie dolly]

Hi there and welcome,firstly,poly carb structures do not have a very good reputation,a puff of wind blows the pannels out,1 on our site is a mess,there are some threads on hear somewhere with peeps personal experiences,i do believe some have fixed then in with sealent,regards a green blow away,you will need to hold it down well,slabs or soil ext,a body on our site has removed the cover for the winter,having learned the hard way,good advice from BB too

[chilli_grower]

I live in Cardiff, and have a polycarbonate greenhouse, mainly because I have a young daughter.

I laid a concrete base myself and bolted it down securely.

I used twice as many glazing clips that came with the greenhouse, and I used around 6 tubes of clear silicone.

The window did blow out once (whilst it was closed), during approx 35mph gusts.

I since put some 'bulldog style' clips on the window handle inside the greenhouse, and no problems at all since.

Although - I am not in a particularly exposed area.

I would guess a polytunnel is the way to go.

But polycarb greenhouses are good in the correct environment.

Especially as mine was only £150

[plotman]

All the professional growers use polytunnels. Guess they must have costed out the options. I have a small polytunnel, I bought the hoops second hand on ebay and spent out on quality plastic also on ebay. One thing i did do was use sponge lagging on the steel hoops to protect the plastic. A polytunnel is more aerodynamic than a greenhouse so should withstand wind better

[Brom]

From my own experience, a polytunnel is extremely good in strong winds. We live in the north east of Scotland and suffer from winter gales where gusts of 60 - 70mph and more are not uncommon during winter storms. The year our tunnel was built the wind turbines next door to us registered gusts of 115mph during one freak storm. It's withstood all that nature could throw at it over the past 2 1/2 years, as well as producing lots of lovely veg for us.

If you should go down the polytunnel route, the best advice I could give would be to pick a calm, warm day to assemble it, anchor it well to the ground (we used base plates on each support, sunk 30cm into the ground), and make sure the cover is tight with no bits that could flap in the wind. Ours is a commercially produced product that was delivered as a kit, however, I would suggest that this advice holds good for a home produced product as well.

Afraid I can't advise on polycarb greenhouses as I have had no dealings with them. Reading posts from others on the forum it would seem they have problems in strong winds.

Whatever you decide I'm sure you wont regret it.



Our tunnel during construction.

[Lost_the_plot]

Wow, thanks for such prompt and detailed replies! Much appreciated.

From what you've all said it seems that there are ways to secure in the polycarb windows, but if they do pop out then they'll likely be in a completely different site! And that a polytunnel is more aerodynamic so potentially could hold out on those crazy windy days and be cheaper to set up! Which answers my original dilemmas!

Will be off to youtube shortly to see how to build the thing and begin scouting around for materials. Seems Brighton Freecycle moves at a rate of knots!! Thanks again everyone

[The Nichols']

I have a polytunnel on the allotment and never had a problem with it. In truth, the only thing that worries me is other people's stuff flying into it and ripping the polythene.

When I bought it (Polytunnels For Sale, Garden Poly Tunnels - Free UK Delivery) I bought the base plate kit. Basically, 30cm Sq metal plates that fix onto the 4 corner hoops and make it even more secure in the ground. There's no wind that can lift that.

[polc1410]

I'm hoping to prove everyone wrong with my polycarbonate greenshed, I'm on a pretty open windy site. There are a number of polytunnels a mix of home built (gas/water pipe jobs) and green square blow aways most of which have had some form of 'beefing up'. Some of those are starting to look rather tired.

There are a few glass greenhouses. The owners of them say the wind distorts the frames enough in a real blow that the glass can crack. So they think I've done the right thing in trying a polycarbonate. I grabbed it as an absolute bargain from fleabay.

I built it last week. 2 days from start to finish. Its sat on a 6x2 wooden base that is staked into the ground.

On the first night it was glazed and siliconed the temp was probably <5C (silicone usually says use >5C) and then it lashed down and the wind picked up. By the next day at 6pm all but 3 panels had gone and the silicone was still not set. I'd lost a few spring clips for the 'glass' during fitting so I knew I was pushing my luck.

Yesterday I glued (a silicone adhesive rather than sealant) with a glue that works* even on wet surfaces (it was lashing down) and clipped in the panes with at least 2 extra clips per pane so a 4 x 2 panel which is supposed to have 3 clips down each side now has at least 8 on the panel and some have 10. I taped some sections but struggled to get grip once the rain really opened up.

I've then added 4 Gravity Grilles like you get for a extractor fan. The close themselves if no air flowing but if air is inside the house and trying to get out it provides a route out. There is also a suction effect as wind flows past the house and it will open the flaps rather than bend the 'glass'. One on each side. Screwfix sell em for about £2. Homebase for £12!!

I've secured it to its base using 4" nails hammered through 1 1/2" x 3/4" exterior pine and through the aluminium base (a good whack with the hammer is all it took!) the pin acts as a lip to hold the 'glass' in place...

Completely lost 3 panes to the wind. So waiting for replacements. Has been windy but not as windy as last week so hard to compare. At the moment wind can get in the holes though and hasn't blow anything through.

Will be further silicone added when dry and some clear tape / clear duct tape added to difficult spots and I have another 100 clips on their way.

Only time will tell. Basically I'm hoping over engineering will help which is what I was going to have to do to a polytunnel anyway.

*claims to be the strongest glue you can buy. Used it before for other things and it is strong. It doesn't like pound shop caulking guns as its very stiff.

[Bill HH]

I'm hoping to prove everyone wrong with my polycarbonate greenshed, .

Seems to me you are proving everyone right. There is no doubt you can stop the panes blowing out but you shouldn't have to. The amount of work you are putting in makes a poly tunnel look even more attractive. My rather cheap poly carb doesn't have clips just plastic channels that the sheets slide into. Silicone seems to be holding them but where I didnt use silicone they have blown out again. At the moment I have a few pallets leant against the iffy panels until its dry enough to fix.
The only saving grace I can find for the polcarb is that it looks like a greenhouse, the poly tunnel looks like a gypsy camp.

[Lost_the_plot]

Ooohh even more food for thought!

The Nichols - I reckon i'll buy the anchor plate & foundation post from that first tunnels company you recommended & also trench the polytunnel cover. Better safe than sorry!

Polc1410 - good to hear that a polycarb is working out for you. I went to the plot today to discover several sheds blown over and greenhouse frames bent all out of whack. The structures still standing on the site after our recent bout of weather were the community storage container, sheds that look older than the ark & polytunnels. I think the blue water pipe allows the polytunnel to flex in the wind whereas a polycarb greenhouse won't. Our site has wind directly off the sea....

You guys are just awesome. I'm amazed by how much experience there is on one forum! Thanks again for taking the time to reply

[polc1410]

Seems to me you are proving everyone right. There is no doubt you can stop the panes blowing out but you shouldn't have to. The amount of work you are putting in makes a poly tunnel look even more attractive.

The guy who had my plot before me had a home made polytunnel using 2inch water pipe with a blow away green mesh re-inforced cover. It was up 2 years and then we had an absolute lashing rain fall (the stuff that hurts when it hits your skin) and the little clear squares started to pop through leaving just the green mesh.

It had a 2 x 4" roof support running its length. With 1ft of snow on top it snapped. Snapped along the 2" direction.

What I'm seeing is people re-inforcing their polytunnels which is no different to what I'm doing and speaking to people the green blow aways need a new cover every 2 years and the clear ones every 4 years.

My 6 x 8 polycarb cost £120 of fleabay. If it'll last me more than 2 years I beat the value of a polytunnel. I might have to replace a panel or two but not all the panels at once (I hope!).

[plotman]

The guy who had my plot before me had a home made polytunnel using 2inch water pipe with a blow away green mesh re-inforced cover. It was up 2 years and then we had an absolute lashing rain fall (the stuff that hurts when it hits your skin) and the little clear squares started to pop through leaving just the green mesh.

It had a 2 x 4" roof support running its length. With 1ft of snow on top it snapped. Snapped along the 2" direction.

What I'm seeing is people re-inforcing their polytunnels which is no different to what I'm doing and speaking to people the green blow aways need a new cover every 2 years and the clear ones every 4 years.

My 6 x 8 polycarb cost £120 of fleabay. If it'll last me more than 2 years I beat the value of a polytunnel. I might have to replace a panel or two but not all the panels at once (I hope!).

Well the first thing is not to confuse a little cheap green mesh so called polytunnel with real thing. These cheap little plastic reinforced wendy houses are waste of money. If you use proper commercial ultaviolet protected sheeting available and cut to length from many suppliers on ebay, then its relatively inexpensive and good for 6 to 8 yrs. I recovered mine (11 ft x 6-6" )last year after 7 yrs use. It cost me £46-00 and 3 hrs work. For that i have a perfect growing enviroment with anti uv protected screening for young plants ). Works out £7-00 a year. Cost of two bags compost

[Lost_the_plot]

Ohh, good point though polc. I hadn't considered that those reinforcing beams would take a fair degree of weight with snow & the thrashing of the rain. I guess if i made them from thicker wood then they could double up to hold any training wires for fruit in the tunnel? Provided the fruit isn't too heavy, as then i'd still have the same prob.

Plotman, It's good to know how long the tunnel covering can last when looked after. Could i ask where you got your covering from?


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