# The wisdom of using MDF/plywood for beekeeping frames



## ugcheleuce (Mar 4, 2016)

Hello everyone

I'm a hobby beekeeper and I'm always trying to find cheaper ways of doing my hobby. A large, regular expense is frames. I'm wondering whether one can use MDF or cheap plywood (or even OSB) to make frames for beehives.

All beekeepers know (or: have been taught) that MDF and ordinary plywood is bad, because of the way it reacts when it gets wet. It is known (or taught) that bee hives from MDF won't last more than two or three years, and the same would apply to plywood, even if painted annually. And anyone who even thinks of making frames from either of these are considered an idiot.

My question is whether this is just superstition. Can one make frames from MDF and/or the cheapest plywood (e.g. 9 mm poplar)?

I have very little woodworking equipment (the cheapest table saw and the cheapest mitre saw, and a hand-held figure saw), so I'm rather limited in the type of wood that I can use to make my own frames. If I had a planer and a slightly more advanced table saw, I would have been able to make frames from scrap wood.

With shop-bought frames, the wood is 1 cm thick and 2.2 cm wide, but frames made of wood of up to 1.2 cm thick and up to 1.8 cm wide would still fit in the hive.

The advantage of MDF or plywood for me would be that it is dead flat and doesn't warp during working with it. It is also cheaper than any non-warp wood that I can find in the appropriate thickness. I would prefer to use a light material (anything that reduce weight in a bee hive is a good thing).

A little more background information:

A beehive is basically a stack of bottomless crates, with some rails inside. The wooden "frames" have lugs on both sides, and hang from the rails by those lugs. The bees then build comb in the frame, and fill the comb with baby bees, pollen or honey.

Most bee hives stand outside, in the sun, and rain, and wind, and snow, etc. Bee hives often have metal sheet roofs and they don't stand directly on the ground. Hives are painted on the outside, but not in the inside, and the frames are not painted either.

In my region, we use non-self-spacing frames, which means that if the wood of the frames should expand slightly in thickness, it would not be a bother. The important thing is that the frames should not fall apart when handling them, and that the top-bar should be able to carry some weight (max 1.5 kg per frame) without bending more than 2-3 mm in the centre. The frame's top bar is 35 cm long, from rail to rail. Most of the weight hangs off the top bar, but not all, since the comb is also attached to the side bars of the frame.

The bees regulate the temperature and moisture in the hive. During spring, summer and autumn, the humidity inside the hive is 50%-60%, regardless of outside humidity. In winter, the humidity rises, but condensation only occurs along the very top inside edge of the hive, so only the frames in the uppermost crate get some water on it. At times (when the beekeeper blunders about), honey may be spilled onto the frames, but the bees will lick it up within an hour or two. Honey is 80% sugar, 20% water.

It is my layman's understanding, from documents such as http://www.ewp.asn.au/library/downloads/ewpaa_facts_about_pb_and_mdf.pdf, that MDF or plywood could be suitable for frames, since it is dry inside the hive (apart from the humidity and winter condensation).

Your expert thoughts?

Thanks
Samuel


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## CB_Cohick (Dec 22, 2014)

I think the "hive" mind is correct on this one. Painted plywood may last a year or two. I would expect MDF to fall apart shortly following being placed outdoors.


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## ChrisK (Dec 18, 2009)

Take a piece of MDF and get it wet. Lay it out for an hour and see what happens.

MDF is fine for indoor stuff that does not get wet. It will double in size if you give it enough water.

Most plywood is made with glue that will resist water. The wood will rot if left wet. If you can paint the plywood with good paint it will last a few years.

Plywood frames might not be stiff enough. Thin pieces will bend a lot, they may not break but they will bend under kind of load.


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## isotope (Dec 14, 2013)

I would no use MDF, as it does not handle moisture well, nor is it particularly strong. It's not that cheap either. Plywood would better. But, as mentioned I'm not sure it'll be strong enough, since 1/2 of the layers will have the wood grain running in the "wrong" direction. You'd have to try and see if it works.
If you really want to save money, there are lots of opportunities to recycle/upcycle wood. Craigslist-free is your friend. Around here, there are many people giving away wooden tables, wooden dressers and shelves. Look for the ones that are made out of solid wood, not particle boards. Since you are looking to make small pieces, these can be easily dissambled and cut into the sizes you need. 
If you are looking for recycling inspiration, check out videos by woodgears.ca. He makes a ton of stuff from discarded furniture.


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## wapakfred (Jul 29, 2011)

MDF would be a bad choice, but plywood may be as well. Would the adhesives and whatnot in the plywood be a problem (I'm sure the MDF would) for the bees?


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## JBrow (Nov 18, 2015)

ugcheleuce,

Since this is an economic question, a cost comparison is required to determine if sheet goods suitable for outdoor use are less expensive than the alternatives. Regarding sheet good choices:

1. MDF is designed for indoor use and is a poor choice for the outdoors.

2. Even though typical plywood is made from water resistant glues, in my experience it will fail when exposed to the elements.

3. Marine grade plywood should hold up to the elements, but confirming this at the lumber yard would be a good idea.

4. I believe (but not sure) that outdoor signs are made from Medium Density Overlay (MDO). Therefore it should hold up to the weather. However, since I have not used the material, I do not know how well it holds screws. Again I would check with your lumber dealer before committing to this choice.

5. Pressure treated plywood is design for outdoor use. However, since it is treated with toxins, it is probably a bad choice. The poisons that keep the plywood from rotting can be hazardous to the bees and the humans who eat their honey. I keep pressure treated wood materials out of my garden.

One problem that can occur with plywood and perhaps MDO is that it may not remain flat. Installing aluminum U channel on at least one vertical and horizontal surface can help keep it flat. But the channel can be expensive. 2" x 2" lumber screwed to the outside of the box will also keep the sheet good flat. Applying 2" x 2" strips vertically on the outside corners provides solid material to which the side panels can be attached. This means thinner sheet goods can be used in building the outer box.

The other consideration in using sheet goods is whether off-gassing from the glues would have an undesirable effect on the bees. You probably know better about this question than I.


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## knotscott (Feb 27, 2009)

If you enjoy building them, use MDF or cheap ply. You'll be doing it often.


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## ugcheleuce (Mar 4, 2016)

Thank you, everyone, for your replies so far.



> CB_Cohick wrote:
> I would expect MDF to fall apart shortly following being placed outdoors.


I think most people "expect" MDF to do something particular outdoors.

A few years ago I made a rabbit hutch of MDF. I gave it two layers of glossy paint. It lasted two years (unfortunately longer than the rabbit). I also used left-over boards of MDF (painted with indoor paint, since they used to be cupboards) to make a temporary compost container (also outside) for a year long, and the boards are still in my shed because they still look salvageable for a future throw-away job (a little thicker than they were, though). In fact, I used some of those boards again to make a birthing cage for my other rabbit, and it was perfectly useable (although very heavy), and even now it stands unused outside in the rain, and still appears pretty solid.

Yes, MDF soaks up water, and eventually it behaves like wet cardboard. But I'm surprised at how long some of it lasts.



> ChrisK wrote:
> Take a piece of MDF and get it wet. Lay it out for an hour and see what happens.
> Most plywood is made with glue that will resist water. The wood will rot if left wet.


Yes, but read my post-the frames will not be used in a wet environment. It is a dry environment, with high humidity, but if I don't use MDF in the uppermost crate, no water will contact the MDF.



> isotope wrote:
> MDF … is not that cheap either. Plywood would better.


MDF in my area is half the price of plywood, and plywood is slightly cheaper than the cheapest knotty pine/spruce. The cheapest "ideal" wood to make frames from would be white poplar, but that's twice the price of plywood, and not counting the costs to have it planed.



> isotope wrote:
> If you really want to save money, there are lots of opportunities to recycle/upcycle wood. ... Around here, there are many people giving away wooden tables, wooden dressers and shelves. Look for the ones that are made out of solid wood, not particle boards.


I have actually done that. I made some hives from very expensive (but unwanted) furniture-I have a crate here made from Brazilian walnut (used to be a couch). It's heavy but I don't use it on a hive that needs to travel.

The big problem is that it is extremely difficult to distinguish laminated particle board from real wood, even if you look at it and not just in a photograph. My current rabbit hutch (which must be replaced since it's falling apart) was made from a "solid wood" television cabinet, but after six months it turned out to be just solidly made particle board. If I had cut the wood, I would have noticed that it's not real wood, but I used the cabinet as-is (and added some doors and screens).

A problem with making frames from furniture is that most of the wood is not the right thickness, and I don't have a planer.



> Fred Hargis wrote:
> Would the adhesives and whatnot in the plywood be a problem (I m sure the MDF would) for the bees?


No, the bees are more resilient than most people expect, and the honey ends up with only trace quantities of chemicals. I think it would even be safe to build hives using green treated gardening planks (not sure about those old chromated copper ones, though). In fact, we treat bees for diseases using chemicals, including e.g. oxalic acid (wood bleach).

And the chemicals won't make it into the honey in any quantities that matter, unless the air has a very high concentration of it, or if the flowers have been sprayed with such chemicals recently.



> knotscott wrote:
> If you enjoy building them, use MDF or cheap ply. You'll be doing it often.


Although beekeepers with larger establishments have equipment to clean old frames and re-use them for decades, hobbyists can't really afford to re-use frames for more than 3-5 years. The effort of cleaning the frames is so much that it's better to just buy new ones, and use the old frames as fire lighters. If MDF or plywood frames can be made to last 3 years, I'll be satisfied with the cost/effort ratio.

You'll hear stories about old beekeepers who had used the same frames (even the same comb) for decades, without sterilising them, but many modern beekeepers either renew or sanitise their frames at least every 2-3 years. Blame the varroa mite, having spread worldwide since about 1980. Mites cause injuries to bees, making them more susceptible to diseases left over in old frames.


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## Mahdeew (Jul 24, 2013)

I've made several supers with 3/4" plywood and framed them with 6 finger joint like joints on each side and secured them with waterproof construction adhesive and painted them with high gloss paint. I made the foundation out of pine- same treatment. After 2 years, the foundation failed but the supers held up well until the bears came.


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## WillliamMSP (Jan 3, 2014)

You seem to be dismissing the consensus opinion, so why even ask? Just go do what you want to do and learn from the mistakes or triumphs.


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## ChrisK (Dec 18, 2009)

I agree with Bill. Just make some, paint them, and try it.

For me the time and cost of painting MDF to survive in a high moisture area is not worth it.


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## ugcheleuce (Mar 4, 2016)

> WillliamMSP wrote:
> You seem to be dismissing the consensus opinion, so why even ask?


The fact that I'm replying to replies (e.g. by clarifying a point) should not be seen as me dismissing any opinions.


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## Pezking7p (Nov 17, 2013)

Plywood will be fine. Keep it painted with good outdoor paint. Bees will coat the inside anyway so don't worry about the inside.


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## ugcheleuce (Mar 4, 2016)

> Pezking7p wrote:
> Plywood will be fine. Keep it painted with good outdoor paint. Bees will coat the inside anyway so don't worry about the inside.


Thanks, but my question was not about hives, but about frames. For hives, I'll definitely consider plywood (though at this time I'm experimenting with various pine designs for the hive bodies).



> JBrow wrote:
> 3. Marine grade plywood should hold up to the elements, but confirming this at the lumber yard would be a good idea.
> 
> 4. I believe (but not sure) that outdoor signs are made from Medium Density Overlay (MDO). Therefore it should hold up to the weather.


Thanks, I've heard about "marine plywood" on several forums, but I've yet to figure out what it's called locally.

As for MDO, in the Netherlands it's called "betonplex" (which means "concrete plywood", probably since it is used to hold back poured concrete). Only the flat surface of MDO is watertight, and since frames are made from strips (not sheets), the fact that two of the six sides of it are watertight won't really make a difference.


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## bondogaposis (Dec 18, 2011)

My question is whether this is just superstition.

No, it's not, MDF sucks in outdoor applications. Exterior grade plywood should work fine, OSB does not weather well either but would last longer than MDF.


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## thirdrail (Feb 8, 2011)

Do what ever you want, but I'll tell you one thing, I wouldn't buy your honey, nor would most other people if they knew.


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## JBrow (Nov 18, 2015)

ugcheleuce,

If you are replacing the hives every two or three years and MDF is the cheapest way to go and it works for you that long, then that is what I would use.

I pretty sure marine plywood will be a more expensive alternative than MDF. But if you want to check it out then there is a Dutch company that seems to make marine plywood. Perhaps this web site can get you started:

http://www.dutchmarinepanels.com/about-us/

Another option not yet mentioned is cellular PVC planks. It is plastic and machines like wood. Perhaps you can find the right dimensions so that cutting is minimized. Cellular PVC is expensive but it will last forever - it is impervious to insects and rot. Because it is PVC, you may be able to chemically (not by heat) sanitize it and thus avoid rebuilding the hives every 2-3 years. That could make it cost effective. If you went this way, any PVC exposed to sunlight should probably be coated with paint that will hold up on PVC. Not all paints will. I am just not sure what sunlight would do to the PVC.

While I am at it and if you need solid sheets, you might check out Ultra High Molecular Weight (UHMW) Plastic sheets. I do not know much about them, but I would want to know how sunlight affects them and whether these accept paint for sunlight protection. If you can sanitize the hives and continue using the material, it too could be cost effective.

If you go the plastic route, using stainless steel nuts and bolts as fasteners would keep thing together better than screws. The stainless steel would also last a long time.


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## ArtMann (Mar 1, 2016)

I was a commercial beekeeper for several years and I used to build all my frames and supers. I also sold some to other people. Frames get pretty rough treatment and neither plywood nor MDF is strong enough to withstand a prying hive tool. In addition, I would be concerned about outgassing of chemicals from these materials. I built supers and brood chambers out of premium grade Southern Yellow Pine.


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## rwe2156 (May 7, 2014)

> =I would be concerned about outgassing of chemicals from these materials. I built supers and brood chambers out of premium grade Southern Yellow Pine.
> 
> - ArtMann


Excellent point!!

So what's that? 16 Against, 1 For?


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## MadMark (Jun 3, 2014)

Do it and see what happens. Let us know how it works. We need your results since no-one in the history of the world has done it your way.

Inquiring minds want to know …

M


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## ugcheleuce (Mar 4, 2016)

> rwe2156 wrote:
> So what s that? 16 Against, 1 For?


By my count, it's:

For ply: 3
Against ply: 3
For MDF: 0
Against MDF: 6
Other: 5

Thank you everyone for your replies. I believe you all.

Please take a quick look at the PDF file I mentioned in my first post:
http://www.ewp.asn.au/library/downloads/ewpaa_facts_about_pb_and_mdf.pdf
What does this mean:


> When Standard MDF is exposed to changes in relative humidity, it changes in length about 0.03 - 0.06% for every 1% change in moisture content. In thickness, the panel will change by 0.3 - 0.5% for each change in moisture content. These values relate to a linear hygro expansion of 0.3% from 30% to 90% relative humidity and a thickness expansion of 6% from 30% to 90% relative humidity.


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