Category Archives: Roofs

Correx: cheap, light, useful. Choose any three

Synopsis : From quick fixes to permanent solutions, Correx – extruded, twinwall, fluted polypropylene – has multiple uses in beekeeping. If you learn how to fold, stick and shape it you can save time, money and space. Here are just a few of the things I use it for.

Introduction

The Spring honey is almost ready to harvest. Supers went from ”filling nicely” to ”Woah! Damn that’s heavy” in the space of a week. They’re now fast approaching ”No more than two at a time” territory which means; a) they’re full, and/or b) I’m less strong than I used to be 1.

The corpulent supers prompted me to rummage through a teetering stack of equipment to try and find sufficient clearer boards to use before removing the honey supers for extracting.

Clearer boards are effectively one-way ‘valves’ that funnel the bees down into the brood box 2.

Quick fix clearer board – hive side

These are two and bit times a season pieces of kit … the Spring and Summer honey harvests and irregular usage to empty the odd brood box when compressing colonies prior to the winter. The rest of the time they sit, unused, unwanted and – not infrequently – in the way.

And, for convenience, you need more than one.

I like to have one for every hive in the apiary, particularly when taking the summer honey off. That way you can strip all the hives simultaneously, so avoiding problems with robbing. None of my apiaries are particularly big, but it still means I’ve needed up to a dozen clearer boards at a time.

That’s a lot of wood and limited-use kit to sit around unused. I therefore build lots of them from Correx.

Clearer boards – one wood and six made from ekes and Correx

This post isn’t about clearer boards. I’ve described those before.

Instead it’s about Correx and the myriad of uses that it can be put to.

If you don’t use it you’re probably missing out.

If you do, you probably have some additional uses to add to the list below.

Correx

Correx is a registered trademark owned by DS Smith. Other trademarks (by other companies) include Cartonplast, Polyflute, Coroplast, FlutePlast, IntePro, Proplex, Twinplast, Corriflute or Corflute … and there are probably some I’ve missed.

It’s all very similar stuff, variously described as corrugated plastic or corriboard, and perhaps more accurately described as an extruded, twinwall, fluted polypropylene.

If you don’t know what I’m talking about then you’re probably familiar with the material they make For Sale signs from … that’s Correx 3.

Under offer ...

For sale …

Correx is lightweight, impervious to most oils, solvents and water, relatively UV resistant and recyclable. These characteristics make Correx ideal for a range of beekeeping applications.

It is easy to cut and can be folded, with or across the ‘grain’ if you know the tricks of the trade.

Correx is available in a range of thicknesses – typically 1-8 mm. Two millimetre Correx is often used as a protective floor covering in new buildings. However, it’s rather thin and flimsy.

Almost everything I use is 4 mm and so, unless I state otherwise, assume that’s what I’m referring to in the text below.

Almost certainly the stuff I use is not Correx, but I’ll call it Correx for convenience 4.

Before discussing 5 applications I’ll make a few comments on sourcing Correx and cutting, gluing and folding it.

Free Correx

For Sale signs belong to the estate agent selling the house. However, they’re often not collected after the house sale completes and are dumped in a nearby ditch, stuffed down the side of the garage or otherwise discarded. Many still have the 2.4 m wooden post attached.

If they really are unwanted it’s often a case of ’ask and ye shall receive’ … and, if the sign is in a ditch, you don’t probably even need to ask.

When I lived in a semi-urban area I used to carry a handsaw in the car to help my repurposing of these sorts of signs.

Elections are another good source, particularly if the candidate in your ward a) loses ignominiously, and b) immediately retires. It’s unlikely the political party will find another Archibald Tristan Cholmondeley-Warner to stand for them, so the electioneering signs are – like the politician – surplus to requirements.

As always, never walk past a part-filled skip without having a good look at the contents 😉

Never!

Buying Correx

Correx is relatively inexpensive when bought in multiples of 2.4 x 1.2 metre sheets 6. I’ve paid about £10 a sheet delivered for 5 or more, purchased from eBay, but can’t find anything quite that price when I had a quick look this week.

You might not think you need 14 square metres of Correx but you’d be surprised at the things it can be used for. It’s also easy to store behind a bookcase or in the shed.

Correx sheet

Correx sheet …

It’s also worth asking at local plastics and printing companies that may have offcuts or failed print runs. It doesn’t matter what’s printed on the Correx 7. There’s a beekeeper in Northern Ireland that crafted a nuc box out of election propaganda bearing a photo of the candidate. The nuc entrance was arranged to be the politicians mouth.

Be creative.

Finally, Correx is often used to make guinea pig cages or runs, so befriend a cavie-keeper and you might locate the mother lode 8 😉

Correx engineering

Thin Correx (4 mm) is easy to work with. It can be cut with a Stanley knife. All you need is a good straightedge, a steady hand 9 and a sharp blade. Marking up the sheets is easiest in pencil as many pens don’t work on the smooth impervious surface 10. Pencil works equally well on black or white sheets.

I’d recommend you don’t use scissors as they tend to crush the sheet. It’s also difficult to cut large sheets with a small pair of scissors.

Folding Correx

Correx has a ‘grain’ created by the vertical internal ribs that connect the upper and lower faces of the sheet. If you need to fold the sheet you’re working with, the method used depends whether you are folding across or with the grain.

To fold across the grain you need to crush the ribs without cutting through the upper face of the sheet. To achieve this use a pizza cutter and a straightedge. A pizza cutter is usually sufficiently blunt that the sheet isn’t cut. The crushed side of the sheet becomes the inner angle of the fold.

Pizza cutter

Pizza cutter … take care scoring the Correx

Making folded corners requires a little ingenuity but is obvious once you realise how the sheet folds 11.

Corner detail

Corner detail …

To fold with the grain requires a small amount of surgery. First cut on either side of a rib, then fold the sides back leaving a T-shaped piece – formed by the rib and a small piece of the upper face of the sheet – protruding. Then, with a steady hand and a sharp knife, cut the leg of the T away.

Folding Correx with the grain – cut one of the ribs away

The sheet then folds easily with the uncut face forming the outer angle of the corner.

Gluing Correx

This is tricky. I’ve tried every glue in my workshop and none of them work. The surface of Correx has some sort of treatment that means that glues do not adhere. There are tricks that involve flaming the surface to remove the treatment, but – at least in my experience – they are hit and miss.

Usually miss 🙁

There are commercial hotmelt adhesives 12 that can be used – like the ones the estate agents use to stick two signs back-to-back – but they are quite expensive.

Whatever the surface treatment is, it also prevents many sticky tapes adhering properly or permanently.

But there’s one exception … Unibond Power Tape Plus. It’s available in silver and black. Critically for beekeeping it’s both waterproof and temperature resistant. This tape is about a fiver a roll and this represents excellent value for money.

Sticky stuff ...

Sticky stuff …

I’ve got some Correx hive roofs held together with Unibond Power Tape that have been in constant use since 2014, outdoors (obviously) in temperatures ranging from sub-zero to 30°C or more 13.

Highly recommended.

To help the tape stick even better it’s worth gently abrading the surfaces to be taped together using wet and dry sandpaper and then cleaning with a solvent like acetone. Press the tape down firmly and check it in about a decade or so.

Uses

I’m going to concentrate on the uses I make of Correx, because those are the things I have experience of.

There are lots of other things you could use it for … for example, I’ve not built nuc boxes from Correx, but I know you can. They are increasingly used by the bulk commercial nuc suppliers. If you don’t want to build your own you can purchase these boxes for £9 to £12 each 14, flat-packed, in National or Langstroth formats. These boxes tend to use interlocking tabs to hold them together, rather than tape or glue. They might be suitable for short term, summer usage, but not for overwintering a nuc colony.

Roofs

I’ve made lots of Correx roofs and they are still in everyday use, either on hives or on stacks of spare boxes. I’ve described how to build them in detail, together with their pros and cons.

Correx in the frost ...

Correx in the frost …

Everything I wrote 7 years ago is still valid, so I won’t repeat it here.

A single 2.4 x 1.2 sheet of Correx is big enough to produce 8 roofs. Even if you can’t find Correx cheaper than £13 a sheet that’s still less than £1.75 a roof including the cost of the tape holding it together 15.

I routinely successfully overwinter colonies with Correx roofs covering a 50 mm thick block of Kingspan insulation.

Semi-permanent division boards e.g for vertical splits

In my experience these are one of the few things 16 that cannot be satisfactorily made from 4 mm Correx.

These types of boards might be separating brood boxes for a month or more while one half of a vertical split requeens. During this time the board tends to warp. The bee space increases on one side and is destroyed on the other. Consequently the bees build unwanted brace comb above and below the frames.

Split board ...

Correx split board …

I now only use my 4 mm Correx split boards in extremis. I know that some of the commercial beekeepers use 6 mm or 8 mm Correx split boards. The additional rigidity of the thicker Correx presumably withstands warping sufficiently.

If When I run out of equipment I’ve been known to use split boards as crownboards. For the same reasons – warping – I try and avoid using horizontal sheets of Correx in the hive for extended periods.

Temporary division boards e.g. Cloake and clearer boards

In contrast, Correx is ideal when used for limited periods in the hive. One obvious application is the removable slide in a Cloake board for queen rearing.

Cloake board ...

Cloake board …

Mine was built from a For Sale sign rescued from a skip in Newcastle. It’s one of the thicker pieces of Correx I’ve used (6 or 8 mm) and is significantly more rigid than the standard 4 mm sheets. However, I’m sure that 4 mm would do as the slide is only in place for about 24 hours to induce the emergency response and initiate queen cell production.

As I wrote in the introduction, the majority of my clearer boards are built from Correx. I now zip tie the escapes to the underside of the board 17 and then pair them with a simple eke when I need to use them for clearing supers.

Zip tied escape on a Correx clearer board

These work fast and efficiently, they don’t warp and they can be separated from the eke and stored separately (where they take up little space) if/when the eke is being used for something else (like a spacer to provide an upper entrance, or whilst vaporising from above the brood box).

Floors

The only floors I’ve built with Correx are those for bait hives when paired with two stacked supers. These work really well.

Inside ...

Bait hive floor

Bait hives should have solid floors, so if I want to use an open mesh floor on a bait hive I simply lay a small sheet of Correx on the mesh and remove it once the hive is occupied.

Varroa trays

Most, or at least many, commercial Varroa trays are made of Correx 18. To make counting mites easier it helps to draw a grid on the tray.

Varroa tray gridded to make counting mite drop easier

Of course, to make counting mites really easy it helps if there are few of them. Use miticides properly and at the right time. In that way your Varroa levels will never get too high and you’ll never run out of fingers when counting the mite drop 😉

OK, perhaps a slight exaggeration, but it’s certainly easier to count low numbers of mites rather than thousands. I’ve seen post-treatment mite drops so heavy you could trace patterns through the mite corpses with your finger, and the easiest way to count them was with a digital lab balance.

Ewww!

Landing boards

Almost all of my hives have Correx landing boards. Some are integral to the kewl floors I use …

Correx kewl floor landing board

… while others are attached to the outside of my bee shed.

Laden foragers returning ...

Laden foragers returning …

You can paint Correx with a variety of different types of paint. Radiator enamel or car spray paint works well. Using different colours and/or decorating the landing board with distinctive shapes helps bees orientate to the hive entrance and reduces drifting.

For vertical surfaces, try sprinkling sand onto the semi-dry paint before over-spraying to provide laden foragers better grip when entering the hive.

My white Correx landing boards are starting to exhibit UV damage after 4-5 years of use. Either avoid white, paint them or put up with having to infrequently (and inexpensively) replace them.

Miscellaneous

Most of my nucs are red 19 or blue. When I’m making up lots of nucs for queen mating I pin Correx shapes above the entrance to help the bees – and particularly the queens – distinguish between the hives. Again this reduces problems with drifting.

Correx signage on poly nucs

Almost all my nuc boxes are Thorne’s Everynucs. These are well designed except for the cavernous entrance. Again, Correx can be used to fix the situation; I use it to block the entrance entirely for travel, or to provide a much reduced entrance that is easier for the small colony to defend.

Correx, the beekeepers friend ...

Correx, the beekeepers friend …

I’m currently busy rearing my first queens of the season. The method I’m using involves sealing the standard hive entrance and redirecting the bees to an upper entrance 20. This process is really speeded up by leaning a sheet of Correx against the front of the hive, directing the returning foragers to the upper entrance.

Correx sheet redirecting returning foragers

Doing this stops the bees milling around the original entrance and is particularly helpful in borderline weather conditions e.g. low temperatures and intermittent showers 21, when it prevents bees getting chilled.

Correx and tape were used to build these ‘fat dummies’

Fat dummies for queen rearing? Correx to the rescue.

I could go on … but I won’t.

You’ve got the general idea by now.

If you’ve found additional uses for Correx then please add a comment below.


 

Quick fixes

Honey bees are remarkably resilient creatures.

As beekeepers we blunder around the hive on a weekly basis trying to ensure they don’t leave us for pastures new.

The custodians of the environment fill it with chemicals and replace those pastures with acres of distinctly bee-unfriendly monoculture.

Rather too much arable …

And, to add insult to injury, we crowd hives together and move bees with little consideration of the gallimaufry of pests and diseases we are helping to transmit.

Yet, despite this, colony numbers worldwide are increasing 1. This reflects the popularity of beekeeping, the value of honey as a commodity and the important use of honey bees to provide ‘ecosystem services’ (largely pollination) for agriculture.

Home is where the hive is

So, considering all the problems bees face when they’re out and about gathering nectar and pollen, the least we can do is provide them with well-built, watertight, secure and draught-free accommodation.

And, most of the time we do.

The quality of most commercial 2 hives these days is generally excellent. Independent manufacturers and the big national suppliers all sell very good beehives.

Even the flat-packed, second or third quality stuff you fill your car boot with on the annual ‘sale days’ is more than adequate.

You build it, you fill it with bees and they thrive.

They overwinter well, they build up strongly in the spring, you make some early splits to increase stocks and avert swarming.

They continue to thrive. It’s turning into a bumper season. You run out of supers during the strong spring nectar flows.

And then the swarming begins … and you run out of brood boxes (you’ve already run out of supers), crown boards, roofs etc.

This is when you discover all sorts of quick fixes that the bees cope just fine with. These allow you to continue beekeeping through periods with too many bees and too little equipment.

I’m going to use mostly pictures rather than lots of words. This is not an exhaustive list and it’s not restricted to the May and June swarming frenzy.

I’m sure many readers have their own solutions to short-term (or long-term) beekeeping problems. Feel free to post them in the comments section.

Hive stands

Abelo hives on pallet. Note entrances face in opposite directions.

Wooden pallets work fine as hive stands, as do stacked car tyres, or even simply stacking one hive on top of another (which saves a roof). If doing the latter it can help (the bees, but not necessarily the beekeeper) to have the entrances pointing in opposite directions.

Floors

You don’t need a fancy open mesh floor with an adjustable entrance. A sheet of Correx and some strips of softwood can be perfectly adequate.

Inside ...

Cheapy, cheapy floor … when you’ve run out of everything else.

And if you’re really running short of kit drill a hole through the sidewall of an eke and place it on the roof of another hive i.e. no floor at all.

It’s critical the hole is about the diameter of the cork from a good bottle of red wine. This is essential. For obvious reasons … you do want to use it as an eke again sometime in the future 😉

Boxes

Two stacked supers are a bit deeper than a single brood box (National hive). If you haven’t run out of supers (yet … you will) they make a perfectly adequate substitute.

Under offer ...

Two stacked supers, in this case set up as a bait hive. Note also the hive stand. And the roof.

Half of my bait hives are built from two supers.

As an aside, if you want to unite bees from these Paradise/Modern Beekeeping poly hives (see photo above) over the top of a standard National brood box, you’ll need a thin, wide shim to avoid bee-sized holes at the junction.

Shim

Shim …

This shim wrecks the ‘bee space’ but it’s only in use for a few days so it isn’t a problem 3.

Which, in a way, is the definition of the sort of quick fix I’m describing here … something that’s pressed into service for a relatively short period of time and that works satisfactorily, though perhaps not perfectly.

And is often still in use years later 😉

Crownboards

That’ll be 25p please

Poly crownboard ...

Poly crownboard …

… though a (well washed) fertiliser sack works just as well and is even cheaper.

Roofs

Might not be necessary at all if you stack another hive on top (see above).

However, if they are then Correx roofs take some beating.

Correx in the frost ...

Correx in the frost …

Literally.

These cost about £1.50 each to make, take minutes to build and are fully weathertight 4. I’ve got several that are over 5 years old and still going strong.

Not a quick enough fix for you?

Planting tray roof …

My bait hives were popular this year and I caught two swarms on successive days to a hive in the same location. I used an upturned planting tray for the roof of one of the bait hives and the bees didn’t seem to mind at all.

Incoming! from The Apiarist on Vimeo.

Clearer boards

Having planned to reduce my colony numbers this year I singularly failed to do anything of the sort.

I therefore ran out of clearer boards when I came to harvest the summer honey 5. I could have made multiple trips to the apiary but solved it with a quick fix.

Undaunted, a combination of some 4 cm ekes, a sheet or two of Correx (of course), a bit of gaffer tape (what else), a ‘lozenge’ escape or two, a Stanley knife and the inevitable half a dozen Band-Aids … and voila!

Quick fix clearer board – super side

Quick fix clearer board – hive side

These worked just fine and can be disassembled in minutes should I need the ekes again.

I’d bet good money they are used again next year …

etc.

To me, one of the great attractions of beekeeping is that it is an inherently practical occupation. In addition to the pleasure of working with the bees to produce a delicious, high quality and valuable product, you often need to use practical skill and ingenuity – coupled with Correx and gaffer tape – to solve day-to-day problems on the way.

For example, if you’re moving hives any distance it’s important they are well ventilated and that the frames don’t slide about with the consequent risk of crushing bees 6.

Travel screen mesh and eke

Travel screen mesh and eke …

Fibreglass net insect screening makes an ideal travel screen and is easily held in place with staples (in most poly hives) or an eke and a couple of stout straps.

And to stop the frames from sliding about a block or two of closed cell foam wedged between the hive wall and the dummy board is ideal.

Foam block ...

Foam block …

This type of closed cell foam is regularly supplied in packing material and is well worth saving if you find any. It’s the perfect example of a ‘quick fix’ that solves a problem at little or no cost.

Of course , you can never have too much gaffer tape. A quick fix to wasp problems until you find the errant entrance block.

Gaffer tape … remember to cover the sticky bit on the reverse to protect the bees.

And finally … you can never have too many straps to hold hives together or hold roofs down.

But you can often have too few.

Batten down the hatches … too few straps and fondant to the rescue

This photo was taken on the 14th of June, 2018. It looks balmy, but the windspeed was approaching 50 mph. I’d arrived to find some roofs already off 7 and too few straps to hold everything down.

There are two quick fixes in the picture. On the left a wooden plank holds the middle hive down with straps holding it (and the roofs on the flanking hives) in place. On the right, 25kg of fondant was press-ganged into service.


 

Building Correx hive roofs

Smoker on roof

Smoker on roof

What does the hive roof do?

  1. it provides protection from rain and snow
  2. as a consequence of its weight it may help keep the hive together in high winds
  3. (on an adjacent hive) it is a stand for your smoker, hive tool, notebook, flask of tea etc. during inspections
  4. it is used – inverted – as a stand for supers during inspections

A standard hive roof has cedar or ply sides around an internal frame attached to a board, perhaps of ply or OSB, with the entire thing capped with some sort of weatherproof cover. Commercially made roofs usually have a galvanised metal cover, homemade ones might use roofing felt, damp proof membrane or empty compost or fertiliser sacks. All of which makes them rather heavy and potentially quite expensive (an eye-watering £57 for an assembled cedar roof from Thorne’s … )

The Correx alternative

Correx in the frost ...

Correx in the frost …

I’ve built a number of roofs from Correx (the sort of twinwall, extruded, fluted polypropylene used to make estate agent signs) which work pretty well. They are very lightweight, totally weatherproof, easy to build and incredibly inexpensive. Their weight means they either need a brick added on top, or – better – a strap around the hive and stand. They’re not structurally robust, so you can’t stack supers on top of them. However, there are ways around this – use a spare hive stand or a standard roof from an adjacent hive in the same apiary. Correx roofs provide no insulation, but a standard roof doesn’t really either. In the summer this shouldn’t be an issue. However, I use insulated crownboards containing a 50mm thick block of Kingspan. These are used all year round and ensure little heat loss during even the coldest weather.

Building Correx hive roofs

Correx (which is a trade name and used generically … any equivalent twinwall, fluted, extruded polypropylene will do) is available online or can be scavenged from election posters or estate agents signs. Five 2.4 x 1.2m sheets of 4mm Correx should cost less than £50 (delivered … try thealuminiumshop on eBay for example), with each sheet being big enough to make 8 roofs. That’s about £1.50 a roof … what a bargain.

Correx cutting ...

Correx cutting …

National roofs are square. A 60 cm2 piece of 4mm Correx makes a National roof with an ‘edge’ about 6cm deep. If you want a deeper ‘edge’ you’ll need a larger sheet, which means you can’t cut two width-wise from a 1.2m wide sheet of Correx. If you use Langstroth or some other hive type you’re on your own as far as measurements are concerned. For a National roof the relevant measurement is ~63mm from the edge for the fold. You need to crease the Correx so you can fold it along the crease, and then make four cuts, one at each corner, to allow the corner to be folded over and stuck on place. When cutting the Correx remove a 4-5mm sliver as shown in the ‘Corner detail’ image below. This makes the corner fold more neatly. To ‘crease’ the Correx and make it easier to fold you need to use a pizza cutter. When using it with the grain don’t press too hard or you’ll cut right through the Correx. When going across the grain (as shown in the ‘Pizza cutter’ image below) you’ll need to use quite a bit more force to compress the ribs and allow the Correx to fold easily along the crease. Once creased, simply fold along the crease … this is made easier if you line the crease up with a right-angled edge and fold along it. It’s more easily done than described, so practice on offcuts.

Most glue doesn’t work on Correx. The stuff is coated with some sort of chemical which makes water – and therefore most liquid glue – bead and stick poorly. There are ways of flaming the surface with a blowtorch to allow some glues to work – more details, including a range of glues that might work, are available online. My advice is don’t bother – none of the glues I tested (Gorilla, EvoStick or cheapo stuff from a glue gun) worked for more than a day or two. Instead use Unibond waterproof POWER tape. This is readily available, relatively inexpensive and works. Two small pieces across each corner are sufficient. Look at the ‘No overhang’ image below to see how to use them. To make them stick even better to the Correx slightly roughen the surface using fine grade sandpaper.

I’ve been using these roofs all winter, both on hives and stacks of stored supers. All look as good now as they did when they were built (or as bad … depending on your viewpoint). Water still beads on them and the bees have done just fine. All the taped corners have held securely. I also secured some with zip ties at the corners and these have fared less well. Just use tape. They’ve yet to be subjected to hot weather or prolonged periods of sunshine (which might soften or degrade the tape) but appear unaffected by long periods of heavy rain or repeated freezing/thawing.

Other advantages

  • You can get Correx in a range of colours so could even choose something inconspicuous and make the hives invisible from the air.
  • Queen marking pens work well on them if you’re the type of beekeeper who writes notes on the hive roof.
  • Used upside-down these should also make a perfect ‘tray’ to stack supers in when transporting them, or during extraction, preventing propolis and honey getting on the car or carpet. Correx does compress, but is regularly used as a floor covering during building construction, so should be able to take a fair amount of wear and tear. Unlike an upturned metal roof they won’t scratch the floor or rip the car upholstery.

And the disadvantages …

  • As already mentioned you need to use a hive strap or brick to hold the roof in place.
  • During inspections on a breezy day they tend to blow about a bit if you’re not careful
  • You can’t stack supers on an upturned Correx roof … at least, not without trashing them.
  • I’ve not yet melted one with a smoker – I usually try and stand the smoker on a spare dummy board – but fully expect to sometime 🙁

But for £1.50 … you can’t expect everything 😉

Correx roofs

I’ve got a variety of roofs on my hives. Some are homemade, covered with roofing felt or damp proof membrane. I have a number of disappointingly flimsy ‘seconds’ from Thorne’s purchased at about £18 each from trade stands at the National Honey Show or Spring Convention. Finally, I have a few beautifully made ones from Peter Little of Exmoor bees and beehives (highly recommended if you don’t want to make your own equipment). My DIY roofs and the cedar ones from Peter are strong, but they’re also quite heavy. It’s not as if there isn’t already enough heavy lifting to do when beekeeping …

A collection of roofs ...

A collection of roofs …

I use fluted polypropylene such as Correx or Corroplast for a variety of purposes – landing boards on Kewl floorsVarroa trays, fat dummies, temporary crownboards and – I fear in the future – as SHB traps. I usually scrounge abandoned ‘For Sale’ signs, advertising boards or political posters, but these are rarely larger that A2 in size. I recently bought (from eBay) five sheets of 1.2 x 2.4m 4mm Coroplast for about £12/sheet (delivered) for another project and built some roofs from a spare sheet. I can get 8 National roofs from a single sheet i.e. each folded from a 60x60cm square, making each cost about £1.50 (plus a few pence for tape or glue).

Correx sheet

Correx sheet …

If these withstand the rigours of the 2014/15 winter I’ll post some simple construction details in due course (it turns out there are  tricks to folding and gluing Correx … you’ll need a pizza cutter). Correx roofs aren’t an original idea … Jon from the NIHBS, the acknowledged Correxmeister on the SBAi forums, has previously posted details of both roofs and nuc boxes built from election posters and yards of gaffer tape.

Correx roof

Correx roof

At the very least these lightweight roofs are likely to be very useful on bait hives which are both temporary and usually moved soon after being occupied.