Introduction: Cardboard Lumber

Picture of Cardboard Lumber

How would you like an incredibly strong, cool, and cheap building material for making lightweight tables, chairs, shelves, or anything else you can think of. Reusing cardboard to make furniture has always been a good idea, but the results I've seem have been either incredibly complex, or shoddy looking.

By laminating sheets of cardboard together into a large block and cutting this up with a table, or circular saw, you can create cardboard lumber of any dimensions you want: 2x4s, 2x8s, 4x4s. If you alternate the grain of the corrugations you can create plywood. If you glue your lumber together end-to-end you can create strong honeycomb-like boards.

You will only need three things to create cardboard lumber:
1) A Saw
2) Lots of cardboard
3) Glue... lots of glue

Step 1: Types of Saws

Picture of Types of Saws

Table Saw: The best saw you could possibly use to do this is a table saw. You can adjust a table saw's fence to help you cut perfectly uniform lumber out of your cardboard block. This allows you to easily mass-produce cardboard lumber. Because of a table saws fence, you should be able to cut lumber twice as thick as the max height of your blade by cutting once, and then flipping your cardboard block over and cutting through entirely.

Circular Saw: If you're really good at cutting straight lines and have no other option then I guess you could give it a try.

Hand Saw: Possible, but too labor intensive for me.

Band Saw: If your band saw is as powerful as a circular saw than go for it, this could open interesting options.

Chain Saw: Messy...

No Saw: Unfortunately for people without access to saws, this instructable is not for you. I know it looks cool and all, but it's just not gonna work out.

Step 2: How to Get Cardboard

Picture of How to Get Cardboard

Super Moral and Totally legal free cardboard:
Save up cardboard from boxes your family uses. You'll be surprised how fast it adds up.
Go around town and ask any businesses if they have any cardboard you could take. It will likely be already broken down for you.

Super moral and Mostly legal free cardboard:
If you're in a hurry, or just lazy, you can drive around the back of stores and look through their recycling dumpsters for cardboard. Be warned though that dumpster diving is a crime, but most people will be fine with you hauling away some of their trash.

Maybe legal and moral free plastic cardboard:
Those corrugated plastic advertising and campaign signs scattered around your neighborhood are considered litter/unclaimed property in *some* areas. Snatch a bunch of them up fast and you'll have an awesome start to rock solid, corrugated plastic lumber (Be sure to use glue designed for plastic though. Wheatpaste won't work.)

Most of my cardboard came from my school cafeteria and my family's recycle.

Step 3: Prepare the Cardboard

Picture of Prepare the Cardboard

I will be making a large solid block of cardboard with all the corrugations pointed the same way. If you want to make classic plywood, alternate the corrugations throughout the block. The second way could be stronger, but I'm going to make it this way because it looks nicer.

You have to cut your cardboard so that each single layer lays flat, and is completely filled with cardboard. The look and strength of your lumber will all depend on how well you cut your cardboard layers up. It would be best to have all cardboard meet at hard, squared off corners.

To prepare your raw cardboard boxes, you have to cut all of them into flat rectangles, removing all tape and anything you can to make them just cardboard rectangles.

Step 4: Stack the Cardboard

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Before you glue everything together, stack the cardboard in a neat pile. It's okay if there's a couple little gaps, we're just making sure we have enough. I wanted to make a 4'x4' square of cardboard the thickness of how deep my saw could cut.

Now is a good time to estimate the sq. ft. of cardboard and see how much you can build.

Step 5: Get Some Glue

Picture of Get Some Glue

You have a couple options here, and by a couple I mean exactly two:

Wheatpaste: At less than a buck a gallon, this is what I will be using. You can view my wheatpaste instructable here, or basically heat 1:4 part flour/water until it get's thick. Wheatpaste, when made properly and applied correctly will be pretty much as strong as the glue that holds the corrugations of the cardboard together (they use a starch glue, white flour is starch...). It's used by paper machers and also graffiti artists to post paper pictures to concrete walls and create a rock hard irremovable poster. I would recommend adding any bacteria deterrents you have (see instructable).

1:1 Wood Glue: You might be able to find a gallon of wood glue at your local hardware store for about $10 if you're lucky. This should be diluted with water 1:1 because we're covering such a large area, and only want a thin coat, and also to help the glue soak into the cardboard. This comes out to $5 per gallon. The advantages of this is it's much stronger, the corrugations will always rip before the wood glue seams, and is easier to make and apply (but not much). After doing this with wheatpaste, I would recommend this way, simply because the wheatpaste is not as sticky as it needs to be.

Note: You could also use Wallpaper paste I guess; it comes in a powder at the hardware store.

You will need a minimum 2 gallons of either to properly glue the amount of cardboard I am doing.

Step 6: Glue!

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Lay our your cardboard on a flat surface and get your first layer ready. Apply a VERY large amount of glue to one section by POURING it on the surface and spreading it evenly. If you think you used too much, then you almost have enough glue on. Now apply glue to the piece to be put on for the second layer. Don't think of this as glueing cardboard together! Think of it as paper mache WITH cardboard! Lots of glue! Continue fitting cardboard together neatly and gluing it until you reached your last layer and you're out of cardboard.

My 4x8ish block was a little thin, so I cut it down the middle and doubled it up.

Step 7: Wait...

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Clamp down your pile, or stack a bunch of things on top. I would wait at least a couple hours in the sun. Overnight if it's indoors.

Step 8: Cut!

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I used a circular saw and a T-square to cut three even sides. I was pretty surprised with the firecracker-like sounds the cardboard made when i cut it.

Then I used a table saw to cut everything into 1.5" strips. I would highly recommend a partner to help you cut up the block. It's heavy and unwieldy.

Step 9: Honeycomb Plywood

Picture of Honeycomb Plywood

Once you have your lumber, you can either use these individual pieces, or you can glue them, edge-to-edge and create a very, very strong block of cardboard suitable as a tabletop or seat. Because the corrugations are all vertical (as a tabletop) and not horizontal, it has much greater strength.

Step 10: Build!!!

Picture of Build!!!

Use your imagination! This is an entire new building material that you have to figure out how to use.
To further strengthen your projects, you can seal the whole thing in wheatpaste like i did in the previous step.

Ideas for using this stuff, suggest anything you want to add:
Scapile (my original inspiration for all of this)
A cardboard playhouse made by Piersg
a MASSIVE amount of completed woodwork projects (search with the "view more tags" link)
lots of lumber plan blueprints
Andy Lee coffee table
nice table design
cool sitting bench
another bench
and another
snap together table from instructables
Pano Chair

Please rate and comment...
But Note:
Can we stop talking about the environment guys? I wasen't really trying to make any point that this would help the environment anywhere in my instructable. If you have easy access to cardboard, flour and power tools, then you might be interested in making this. Go ahead, try it and tell us what happened. If you don't like this idea, then please suggest better alternatives. Please calm down the comments on your assumptions about how cardboard and wheatpaste effect the environment.


nikol8 made it! (author)2017-10-13

Great! We also invented this a few years ago. We wanted to build a raised floor for storage but wood is too expensive! So we made 21cm wide beams from cardboard lumber (or cardboardium alloy). 5 years later they are still going strong! They've aged very well. We varnished them with boiled linseed oil. It's an amazing resource!

ShilpaAtwaal (author)2016-05-27

wow… its awesome

AtOurOwnPace (author)2012-05-18

I think this is the coolest 'able. A great resource for a good cardboard supply is your local bicycle shop. Bike boxes are big, thick and most shops have a lot of boxes laying around. They'll be very excited to give you the boxes if you volunteer to break down the boxes for them!

imcp1024 (author)AtOurOwnPace2016-04-30

many furniture, and appliance stores too.

Jagr816 (author)2015-11-08

Amazing idea, I look forward to using this concept in future projects.

AlinesCardboard (author)2015-05-11

Looks great!

Rich_Limburger (author)2015-04-11

a long, long time ago, somewhere about, when i just joined instructables i came across this one. I love the idea of this green project and you making a table out of cardboard. great instructable.

Derek Scott Customs (author)2013-11-19

I love this. I'm planning on turning a cargo van into a camper and was dreading the cost of all the lumber, not to mention the weight. With this it will be almost free and light! All I would have to have is lumber for main structural supports. How does it hold up over time?

IanTrek (author)2013-06-26

Would a large piece of this, about the size of a parking slot, be able to support people and several other things?

pastdue (author)2013-05-11

I saw kitty blocks at $35-$50...I would like to make my own and I think I can do it after reading your ible! I have access to ALOT of cardboard and am thinking of just making a template and gluing the pieces together with some kitty safe glue that won't attract roaches (ewwww...Las Vegas is full of them). I could do it your way if I only had the might go faster. Thanks!

threecardmonty (author)2009-07-30

How is this on weight versus wood?

theRIAA (author)threecardmonty2009-07-30

I would say half the weight of wood, volume-wise, and 1/4 the strength of wood weight-wise. aka, i think you could make something stronger and lighter with wood.

armored bore (author)theRIAA2013-05-01

Yeah, that's the feeling I've gotten so far. It seems to have a surprising amount of compressive strength (I've stood on a sample without any alarming damage), but not so much laterally between layers. That might be solved with just a bit of wooden reinforcement.

mhyden1 (author)2012-08-27

If you have no saw available, why not pre-cut the cardboard before gluing it together with a knife or scissors etc. more time, but it should work if you're bent on doing it without better tools.

armored bore (author)mhyden12013-05-01

You could do that in theory, but you'd have to be very accurate and painstaking in your cuts. Any lapse would result in a kind of wonky edge.

I could see it being done with a jig or fixture of some kind, but you'd probably already have some kind of woodworking saw to even make one of those.

theRIAA (author)2009-07-27

yea.. just like you cant go into safeway and walk behind the register to look through the drawers for things you want, you cant go in back and look through the cardboard.

ipisors (author)theRIAA2009-09-12

You don't go in "the back", you just go in the main store while they are unpacking and take them. Almost any store in the US will let you take empty boxes from them, every day. it's trash. yes, they get maybe a penny a box for recycling them, but it's about equal to the work you're saving them from baling and processing it.

jarikcbol (author)ipisors2013-01-24

I work in a grocery store in the US, and we have a baler on site, and bale all our cardboard boxes (and bag all our plastic). we get 200$ per bale, and we make about 6-7 bales a week. (and this is a pretty small store). We do however let people take boxes/cardboard if they need them/show up before they get crushed.

foobear (author)2012-08-22

Any updates on how it has held up over time? It's been three years now, how did the bench do over that period? Thank you

PitStoP (author)2012-07-04

Great info here..
When I usto rent in the past and I needed cardboard to work under my car to avoid sand/dirt from getting on my clothes and tools when greasy I used to go to the furniture stores near by and get really large carboards boxes (from headboards) that they dumped. They were really long and wide and they covered the whole bottom of the car. They will be great for making longer pieces. I just started looking into this and my question is.. Can these cardboard lumber be used for outdoors and can it be sealed and protected like wood maybe using an oil base polyurethane or other? Just wondering if anyone have try this and how did it hold up? Thanks for the instructable btw!

kkuo47803 (author)2012-05-27

This looks great!
How cleanly does a jigsaw cut through the cardboard plywood? I'm thinking of making some cardboard furniture like Gehry's "Easy Edges" and was thinking that it might be faster to first create some cardboard lumber and cutting out a pattern from those rather than cutting out individual layers with a craft knife.

skatattookid (author)2012-02-26

interesting link on this topic..

Mr.Miz (author)2009-06-11

Lumber in Colorado is expensive. Good hardwood is hard to find. I've read all the comments so far and I'm probably too far down the line for my comment to even get read, but I think the real value here is for making models. I'm a pretty below average wood worker. I can't tell you how much expesive lumber I've messed up learning. If I start using cardboard instead of lumber I will save myself TONs of money and it gives me a VERY abundant material to work with. THANK YOU this is VERY helpful and a wonderful idea.

paulzef (author)Mr.Miz2011-12-20

I agree with you. I live in Aus and I'm only a first year uni student, I can't exactly afford to go out and buy hardwood or lumber, so why not reuse the 3000 cardboard boxes that my neighbours throw out everyweek; not to mention I work in a supermarket and everynight there are 3 large (2 meter cube) bales of cardboard that just gets sent off for recycling without any monetary gain, I doubt my work would care.

extrordinary1 (author)Mr.Miz2009-06-11

In the movie Lord of the Rings, the entire Shire Village was constructed from cardboard. All the homes were built with carboard. I think it was in New Zealand where they constructed all of it. Now i am provoked to build a cardboard electric tri-hull pontoon boat for fishing and recreation! Conv. stores get a lot of cardboard too. Every week they throw away a lot of card board. I worked at a chain that has over 50 stores now. 9 years ago, there were only 7 stores. Wonder if I can design a trailer too from cardboard. I think I'll use the expoxy for extra strength. I've tried cardboard stuff in the past, but my results were poor. Thanks for this instructable!

theRIAA (author)Mr.Miz2009-06-11

You're welcome, it sounds like you're on the right track to becoming a great woodworker. and don't worry, new comments automatically go to the top.

micraman (author)2011-10-19

Great ible! Love laminated cardboard. But I am a little skeptic about the strength of the wheatpaste... I made a tiny bottlecap full and it seemed pretty sticky but doesn't feel as hard as glass like you say. Is it waterproof?

sonipitts (author)2009-07-26

Actually, dumpster diving is NOT a crime in most areas, as long as the dumpster is not on private property, locked or fenced up. YMMV, depending on where you live, but the law generally considers trash to be abandoned by the owner and therefore free game. OTOH, most cardboard storage dumpsters are going to be on store property. So ask first, and leave the place at least as clean as you found it, if not more so.

flamekiller (author)sonipitts2011-10-08

This. For example, LE can look through your trash without a warrant once you put it on the curb. By the same token, if the cardboard bin isn't in an area that's off limits to the general public, you're more than likely good to go.

That said, to avoid any problems, just ask the store.

hardlec (author)2009-08-08

There is a product called PC Petrifier that is designed to restore dry rot. When applied over paper or cardboard, it makes the cardboard much sturdier. In the Victorian era, Boiled Linseed oil was used to reinforce paper machie. I'd like to know more about either, but I really like the idea of using cardboard. What is the cost ratio to wood when all the glue is taken into account?

Sequimania (author)hardlec2010-12-16

I've used a product called Wood Hardener on all kinds of weakened/open-grained wood that was either too valuable or difficult to replace. Love it but I think cardboard might soak up an awful lot of this stuff and it isn't cheap.

Boiled linseed oil used to be used as a finish for antiques but I've heard that it isn't recommended any longer. It does have a strong smell that lingers, sometimes for years.

A neuron just fired - Is there a new type of boiled linseed oil on the market that dries faster and has anyone used it?

Avatar_I_Am (author)Sequimania2011-09-12

Try going to your local hardware store and look for "HOMER FORMBYS FURNITURE FINISH".
I have been using Formbys for about 30 years in place of boiled linseed oil on anything I do with wood, if I want to have a durable finish.
There is nothing wrong with B.L.O., but Formbys gives you a hard waterproof finish that brings out the grain/colour of the wood, like B.L.O., with a matte varnish-like finish.

Sequimania (author)Avatar_I_Am2011-09-15

I've seen this in stores. I usually use a mixture of 1:1:1 mineral spirits, BLO, and denatured alcohol to restore a wood finish. After that any top coat can be used.

I restore antique sewing machines. In the interest of historical authenticity it is generally preferred that BLO is the final finish on the box-case-treadle stand. Unless they are for my own use and then, depending on how accessible they'll be to company, I choose btwn BLO and a satin poly. I've been wiping the poly on with a clean rag and it gives a nice finish.

Thanks for the tip.

theRIAA (author)hardlec2009-08-08

I guess I paid $8 for flour, but I wasted a lot. I think they have a different starch glue that they use that is much cheaper though. A much sturdier stool could be made from $3 worth of 2x4s.

precipice (author)2011-08-23

harika tebrikler..

quark43 (author)2009-06-11

if you painted it with Kilz or regular paint would that waterproof it. Im thinking of building a shed with this. thanks for the ideas

smutjeuk (author)quark432009-06-13

Just use marine ply (thin sheets will do) for the ouside and you got yourself a shed that IS waterproof. I raised my 'cardboard shed' with treated 4x4 garden poles (The shed walls are 4" thick as well and are sitting fine on it) on the ground to protect against standing water but just used thin sheets of marine ply (got offcuts from a local boat builder and had them overlapping, Just used 8x4's for the roof together with 'roofing tar sheets'. Total Waterproof and better insulated then my house in the winter. You just have to be careful with open fames or high heat as you are having a building made from flammable material. Maybe someone could come up with some cheap, home-made flame-proof material that could be painted on? Also I used water resistant wallpaper paste, it works really well and I have got no problems with rot or damp/moisture (and my shed is coming in to its 4th year by now. If you can not get marine ply you could use one layer of Fiber glass, it would do the trick as well but would be more expensive and would not look that well. All in all I paid no more than £100 for everything bit for that I got a 16x20 shed/workshop That looks the job and is better from what you can get in any Garden Centre, let alone the savings compared to a garden shed/house you would pay in any of them or DIY stores. Hope that helps.

xenor (author)smutjeuk2009-06-17

I'm thinking that the only way to safely fireproof this stuff would be to mix some sort of fire retardant in with the glue. That way it's all the way through the material, rather than just a coating. Does anyone know what they treat cellulose fiber insulation with to make it fire resistant?

johnny3h (author)xenor2011-07-24

I "think" I was told that most wood and fabric fire retardants were "salts" of Borax.

Someone else told me that just making a water solution of Borax laundry detergent [I understand that it's just pure Borax with no additives] and thoroughly soaking the item to be made fire resistant in it will do the job.

I've never tried it on cardboard [but we successfuly used it on home-made drapes] but soaking cardboard with water doesn't sound like a good idea to me.

Another excellent method of making something fire resistant is to use an INTUMESCENT PAINT [found at COMMERCIAL paint supply stores for professional painters (Like the Sherwin-Williams chain)]. 

It's VERY expensive, BUT... will protect a piece of cardboard so well that a several minutes long applicaton of the blue-white tip of a Propane torch flame will not even discolor the cardboard beneath the paint.

Intumescent paint, when exposed to the high heat of a fire, SWELLS up creating a FOAM, which then chars from the heat of the fire, and the charred foam acts as an incredible INSULATOR against high heat..

I've never used this paint because of the cost, but from demonstrations I've observed, and online research, I'm convinced it's an excellent product.

Although I've heard there are now several brand named intumescent paints available, the only one I recall is the frist such products which were made by an outfit called "Oceans" back in the 70s.

a4great (author)xenor2009-12-22

you could add something fireproof inbetween or in the cardboard.

shantinath1000 (author)xenor2009-08-29

Actually this is fairly fire proof as it is- and that is for the same reason hay bale houses are fairly fireproof. the material is so densely packed that it is difficult for combustion to take place. don't forget that the combustion triangle is fuel, oxy, and heat. this method packs the insides so tightly that Oxyis the limiting factor.

Speedmite (author)xenor2009-06-20

Good idea.

Amon-100 (author)smutjeuk2009-09-03

A cardboard shed sounds like a cool idea. I just have a few questions: 1. What did you use to water proof the cardboard? 2. What sort of adhesive did you use to glue that cardboard together and 3. Would it be possible to get a picture of the shed.

quark43 (author)smutjeuk2009-06-16

It does help i like your ideas though im not sure i can get marine plywood but im going to look. My shed wont be that big only about 8x8.

rrrmanion (author)quark432010-11-13

i would put layers of plastic in somewhere, or put wayyy too much glue on the outside layer(s)

glorybe (author)quark432010-11-13

Paint and other surface finishes do little to stop water intrusion. There are leak sealers that might work. Fiberglass and resin are known to work well as is sheet metal.

theRIAA (author)quark432009-06-12

nope, not waterproof. I would only keep this inside.

Silence (author)theRIAA2009-06-13

Not being waterproof can be fixed... you could glue a flat sheet to al the exposed corrugation and then paint the whole thing with a waterproof coating. paint or varnish. would add extra strength too.

lukeyj15 (author)Silence2010-03-21

Just find something similar to clear nail polish

rrrmanion (author)2010-11-13

hard as glass? technically, glass isn't hard, because in fact, glass is a liquid... though this may just be an expression, but i've never heard it.

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