Greenhouse expert advice needed / polycarbonate greenhouses

[emarisa28]

Hi peeps
Advice on 2 things needed please regarding greenhouses...
Polycarbonate ones - does anyone here own one and what are their thoughts? I have read that they are a lot better these days and they are also warmer in winter etc and don't discolour anymore. Although i think you need to make sure of the type of polycarbonate needed and could people let me know what i need to look out for (ie thickness of polycarb, standard of it etc)

The second thing is (and please don't laugh) why do you need a foundation for a greenhouse (both glass and polycarb) is it to stop getting it blown away? I would have thought that the glass would make it heavy enough. You are not allowed to lay concrete in the soil at my allotment anymore and as all the ones there are pre this rule no one is certain what to do instead. So would you have any suggestions please? Could i lay proper paving slabs in each corner and then secure the base to them? Or should i have the slabs going right round the whole edge as corners aren't enough. And do i need to do this with both glass and polycarb greenhouses

THANK YOU THANK YOU THANK YOU

[Jay-ell]

Glass greenhouses will still shift in a strong wind and polycarbonate is a lot lighter than glass.

Some people have bolted them to paving slabs - sometimes just laid on the perimeter where the base overlaps to give a path outside and sometimes laid inside paving the entire greenhouse for growing in pots.

Does the ban prohibit all concrete or just the large cast concrete a regular base would use? Can plotholders use postcrete to secure fence posts? If yes then you can use anchor posts fixed to the base and postcrete them.

Sleepers/stout timbers are another way to build your base and something solid to hold it down. What about bricks/cement blocks - are they allowed?

[emarisa28]

I've no idea....and i really don't understand any of what you are saying - where would you put the blocks, in the soil? In each corner? do you still need to bolt the base to the slabs?This is all totally beyond me, even after watching Youtube videos!, i am a total novice with this. What do you think of polycarb greenhouses, are they decent?

[veggiechicken]

Let me translate into chickenspeak

Glass or polycarb GHs need bases or they'll move in the wind.
Polycarb is lighter so may move more. Its also safer to handle IMO. If your site is prone to vandalism, you don't want broken glass on your plot.
You need to be sure that the base is level and square before you attach your GH. If its not, you won't be able to glaze the GH as the panes won't fit.
Its easier to level a base if its a complete square, not just blocks in a corner.

I'm sure there's more...................

[emarisa28]

yes but the bases sold with the greenhouses are just narrow metal strips, or 4x2 wood, which is not strong enough to stop it from blowing away is it? what can i do if you are not allowed to put concrete in the soil?

[Jay-ell]

The blocks would be used to build a solid rectangular base around the perimeter of the greenhouse where the greenhouse base.

The bases you get with greenhouses really need to be fixed to the ground in some way. Anchor spikes are a way you can go if the concrete, blocks, railway sleepers aren't available to you.

Google "greenhouse ground anchors" and you'll see there are several different types, some which need to be concreted in and some that are supposed to be hammered or screwed into the ground.

At work there was an 8x10 glass greenhouse that was just sitting on the cast concrete platform. One day there was an 8x10 greenhouse frame lying upside down in a flower bed and lots of glass shards.

It had the metal base designed for it which had holes on the bottom to bold it to the concrete platform, however the council workers who installed it never finished the job.

Polycarbonate is lighter and has a tendency for the panels to blow out (I've stuck a brick on each roof panel which has helped) but doesn't shatter and throw glass all over the place. The front of my plot has so much glass in the soil from previous greenhouses that it was pointless trying annual beds and I put my fruit there.

[Muddy_Boots]

Storm Doris recently managed to blow over one of the greenhouses in our lotties which was on a slab base but not anchored to it, the frame is now all twisted and has one surviving pane of glass in it. Next to it is a a pile of glass shards which he's fortunately managed to collect so its not scattered over a wide area. That proves you MUST anchor a greenhouse down somehow else during one winter it will all end in tears and be a large expense to replace the glass panels.

The metal greenhouse base is only to attach the greenhouse to it, make the greenhouse itself stable and give it extra height you then need to anchor it to the ground somehow. Mine was supplied with hooks to hammer into a soil base and hold it down but as I was resting it on a slab base I drilled 2 holes into the metal base on each side and corresponding holes in the slabs. I then put in Rawle plugs and using brass screws screwed the greenhouse base to the slabs so it would never move.

I will take some pics of the base of my greenhouse tonight to show what I mean as 'a picture is worth a thousand words' as they say.

[emarisa28]

@ Muddy Boots please do!! When you say slab base do you mean paving slabs? I would like not to have slabs across the inside if possible. But definitely post a few photos.On another note......isn't it cold today!!!!

[Potstubsdustbins]

I have had a 8 x 6 polycarbonate for 6 years have yet to lose any glazing (now I am tempting fate) but I spend a good few days doing the job properly.

If you go polycarbonate it must be well secured or in most any kind of wind it becomes a kite and I am not joking. I could easily pick up my assembled/glazed 8 x 6 on my own. A minimum requirement would be 2ft x 2ft concrete paving slabs around the complete perimeter and the base supplied by the manufacturer well screwed down to every one, you could of course form a base from something like railway sleepers.

Do not purchase a single glazed one like some of the discount stores sell. Get one glazed with 4mm twin wall polycarbonate, this is much stronger and warmer even than glass. If you can find one where the glazing panels slide into grooves instead of laying into the openings so much the better.

Finally secure the glazing panels with the correct grade of silicone, one of the best is Evo-Stick 'Sticks Like Sh*t' which will bond to plastic and metal and is unaffected by weather and extreme temperatures.

And as VC pointed out make sure your base is level in all directions.

[Jay-ell]

Yes slabs are paving slabs. You can lay your slabs so that they form a rectangle with a dirt hole in the middle

This hole is slightly smaller than the base so that the base can then sit on the edge of the slabs, but the floor is left clear if you want to build beds and grow into the soil, or covered with membrane to allow drainage. The majority of the paving slab would be on the outside of the greenhouse forming a path with only a couple of inches under the base. It's best to secure the greenhouse at it's corners and along the sides if possible.

Some people, not all, like to pave over the entire floor of the greenhouse because they grow in pots and this gives a stable hardwearing surface.

[maverick451]

Have you looked at a 2nd hand greenhouse? I got mine on ebay for £35 dismantled.

An easy way to make a base is to use thick fence posts, lay 4 in a rectangle and then screw the frame on the greenhouse onto the timber

Personally I would get glass

the greenhouse needs to be on a really level surface, hence the base, if it isnt level then the frame will twist and the door and glass wont fit properly, dont ask me how I know this!

[Elfeda]

I am planning to put up polycorb greenhouse frames at allotment. but I do not have paving slabs or railway sleepers. and I guess they are expensive to buy. so may be I can buy sleepers for a some up to 6x10 size maximum.

Since I have some extra frames collected during recent clearence of b and q. can I convert them as cloches of 4 feet height with twinwall polycorb and any possible protection around for wind protection?

also,if I erect the excess frames without glazing (bean frame) and base secured to ground with the available kit with frame , will the stand against winds?

[Jay-ell]

6x10 posts should be ok I think, but not sure.

Can't comment on the second bit as I have no idea about your DIY skills You can treat it as a big box of mechano if you want - you may have to cut, file, drill and hammer struts to the right length (I'm assuming that the vertical struts would need to be cut down) You'd have to work out how to get at your plants inside - unless you are going to crawl through the shortened door opening on yer belly.

For 3 you might want to pop a couple of stakes in the corners just to secure it a bit. As it won't have the full sail effect of a sheet of glass/polycarb it should be OK but when covered with beans they can't half catch the wind and act like a sail (although their stems and roots may help a bit you don't want them to be uprooted)

[Muddy_Boots]

@ Muddy Boots please do!! When you say slab base do you mean paving slabs? I would like not to have slabs across the inside if possible. But definitely post a few photos.On another note......isn't it cold today!!!!

Slab base means paving slabs some do just place them where the edges of the greenhouse go to anchor it to and leave the inside as soil and the plants go direct into the soil + fertiliser. Its all a matter of preference and/or cost in the way you put your greenhouse up. My mum just had paving slabs under the metal base edge and the inside was just soil and she did her planting into the soil so its up to you. I'm in work atm but when I get home I will take pics of mine thats on a complete paving slab base so you can see how its secured.

[emarisa28]

THanks. I just came across this, pretty much what i had in mind BlogPM: Moving a greenhouse from there to here ...

Would you all agree with this method?