Introduction: I Love Papercrete

Picture of I Love Papercrete

Papercrete??  What’s that?? 

That’s the response I always get when I’m describing my favorite building material.  Not surprising since it occupies a spot in that backwater known as ‘alternative building materials’.  Papercrete is just what it sounds like actually.  It’s concrete made with paper.  I tell people to think of it as industrial paper mache.  It’s inexpensive to make, amazingly sturdy, lightweight and insulating.  

I didn't invent it but I have played with it quite a bit over the past several years. In this Instructable I'm going to go over a little of the history behind it, exactly what it is and how to make and use it.  By the time we're done you'll love it too!  

Step 1: A Brief History of Papercrete

Picture of A Brief History of Papercrete

Papercrete was originally patented in the 20's.  The patent lapsed because it was too easy to make on your own and the patent holder wasn't able to make any money off it.  It really came into it's own as a building material in the 80's.  Eric Patterson and Mike McCain are widely credited with independently inventing (rediscovering) it and actively developing techniques and machinery for working with it.   

I discovered papercrete in the late nineties.  I used to own a magazine distribution company that specialized in small press and unusual magazines.  One of the titles we carried had an article about people who were recycling newspapers and building with papercrete down in southern New Mexico.  It was a total off the grid hippie dome sort of scene.  The domes weren't my thing but I was captivated by the material and the process of making it.  I saved a copy of that magazine and told everyone I knew about it. 

It was especially appealing to me because of all the waste involved in magazine distribution.  All the unsold magazines would be returned to me and I would have to pay to have them hauled away for recycling.  Turning them into building blocks would have been a perfect solution.  Unfortunately at the time I didn't have a place to experiment with building projects so eventually the papercrete article went into storage and the idea went on the back burner.  

My biggest obstacle was the mixer.  To make papercrete you have to be able to grind up paper… lots of paper.  In order to do so you need a mixer capable of shredding paper.  A regular cement mixer won’t shred the paper it will just stir it around.  Luckily for me, Mike McCain had already invented an ingenious papercrete mixer that you tow behind a truck.  You just throw everything in and drive slowly for about a mile.  When you’re done you have papercrete slurry ready to be cast into something.  

Step 2: So....What Is This Stuff Anyways???

Picture of So....What Is This Stuff Anyways???

Well, like I said in the intro papercrete is basically concrete made with paper.  The process consists of adding a certain ratio of paper and / or cardboard to water and then adding portland cement.  The mixture is then stirred with a blade to re-pulp the paper and mix everything together.  When it is properly mixed it becomes a slurry that has the consistency of lumpy oatmeal.  This slurry can be poured into forms and cast into shapes such as blocks or beams or dome sections.  You use the same stuff as a mortar to glue the blocks together.  It can also be used as a plaster to make a smooth finish coat on the inside and outside of a structure.  

Papercrete has an R value of 2 per inch so a 12" wall has an R value of 24.  Not bad..  

It’s sturdy but lightweight- A block only weighs a few pounds but can hold up a car! 

It’s weatherproof-  I’ve had blocks out in the elements for 4 years and they haven’t changed at all.  It does absorb water like a sponge so if they are going to be used for walls they need to be protected from moisture.  Similar to wood they will decompose if buried underground so they need to be up on a raised foundation.

It’s a really easy material to make- As long as you stick to the rough proportions of water, paper and cement you’ll end up with a usable product.  I can make 45 blocks by myself in two hours.

It's easy to work with- You can use regular woodworking tools to cut or drill holes in papercrete blocks.

It’s green- Totally overused term these days, I know, but I use all of our paper trash for the year and then quite a bit more.  It’s fun to go to the recycling center and see their faces when I ask for paper rather than dropping it off.  Now we even grind up all of our plastic trash in a paper shredder and mix it right in!  Making papercrete turns nearly all of our household trash into building materials.

It’s cheap- It costs about a quarter to make a 8″ x 12″ x 5″ high block.

Are you sold?  Itching to start making blocks?  First, we have to make that mixer...

Step 3: Papercrete Mixer

Picture of Papercrete Mixer

The McCain mixer is sheer genius in its backyard engineering brilliance and simplicity. It consists of a trailer made from a truck rear axle with a stock tank mounted on it. The axle is rotated up 90 degrees so that the end where the drive-shaft would normally attach is sticking up through the bottom of the tank. A lawn mower blade is mounted on the differential stub so that as the trailer is towed it turns the lawnmower blade creating a giant blender.

I built my own McCain mixer a few years ago and it’s worked really well for me. I’m going to go over my build here knowing full well that it would take an intrepid soul to actually go ahead and build one of these but hey, maybe you'll get inspired. (I lost my !@%$&# photos from building my mixer so we’re going freehand from here people!)  

First I gathered up my materials which included:

A four foot diameter metal stock tank
A full sheet of 3/4″ plywood
Metal beams
The rear end from a Land Rover (I think I have the classiest trailer in town)
A trailer hitch
The rubber inner tube from a large truck tire
A couple hinges
A lawnmower blade
A small can of bondo
A tube of silicone and liquid nails
Assorted nuts and bolts and some wood screws

The first step was to assemble the trailer. I needed a contraption that could securely carry several hundred gallons of water. I used galvanized I-beams that were way heavier duty than I needed to build the trailer with, but hey, they were pretty cheap at the scrap yard and about the length I needed already. I welded them together along with the rear end from a Land Rover to create the framework. Once I welded on a trailer hitch from Pep Boys I had a trailer.  You can get the idea from the first illustration.

Next, I cut the plywood sheet in half and glued and screwed the two halves together to make an inch and a half thick platform to hold the stock tank. I cut a hole in it where the end of the differential would stick through. I cut the plywood to fit snugly around the differential so that it would be relatively easy to seal later. After that, I cut a hole in the stock tank as well so that it sat on top of the platform and fit over the  differential too.  Once everything was aligned I drilled through the tank, plywood and trailer rails and bolted everything together.  

In order to get the papercrete out of the mixer I needed a drain.  I took the tank off and cut a hole that was the circumference of the truck inner tube.  I cut a third of the inner tube off and slid it through the hole in the plywood and secured it with a couple screws.   It looks like an elephant’s trunk sticking out of the bottom! I cut a matching hole in the stock tank but made the hole an inch smaller so that I could cut tabs and bend them down to secure the tank over the drain. I bolted everything together and sealed the joint between the differential and the tank with bondo. I also made a flap under the trailer to hold the drain shut.  All that remained was to attach the lawnmower blade to the differential and I had a mixer.

How long did it take?
I took my time acquiring parts over a few months and then once I got started building it took me the better part of a couple of weekends to construct it.

How much did it cost?
I scrounged as much as I could.  I got the rear end from a mechanic that I knew.  I bought the metal for the trailer from the scrap yard so it only cost about $35. The trailer hitch was another $20 and the stock tank was about $175.  Maybe another $20 for bondo, bolts, glue and silicone.  So a total of about $250.

What you do different next time?
I would re-design the drain so it was easier to use and make it larger to let the mix out better. I also need to put a couple of chains on by the hitch in case something bad ever happens and the trailer comes off.

OK , that's cool and all but I want to try making a few blocks before I commit to making a contraption like that.
No problem. just use a plaster mixer on a heavy duty(1/2") drill in a 5 gallon bucket for a test run.

Next up we’ll go over actually making a batch of papercrete and casting it into blocks.

Step 4: Making Papercrete Blocks

Picture of Making Papercrete Blocks

Making blocks is super easy.  After mixing up a batch you just cast it into forms.  

Papercrete mixer

Block molds- mine are made from 2x6's and scrap siding

Bathroom scale- for measuring out the paper



Paper (used of course)

Shredded plastic (if you want)

95 lb bag of cement (cement not concrete- no rocks or sand in the mix)


1.  Set out your molds.  You will need enough flat space to drive over them and pull your truck and the mixer in all the way in front of the molds.

2.  Fill the mixer 3/4 full with water.   I just eyeball it.

3. Put in the paper/plastic.  I use about 75 lbs. 

4.  Add the bag of cement.  You don’t need to open it,  just toss it in.

5.  Cover the mixer securely.  This is very important.  Just think of what happens when you have a blender top malfunction and multiply it by 100…  I use a canvas tarp with a cargo strap.

6.  Drive slowly- 5-10 mph for one mile.  The mixer will chop up the paper into a pulp and mix it with the water and cement.

7.  Empty the slurry into the molds.  If you got the mix right you should be able to open the drain, fill some blocks, close it, pull forwards a bit, repeat.  If the papercrete is too thick you've got some shoveling to do.  The type of material you are using can make a difference too. Cardboard makes for a thicker, chunkier mix where newspaper is finer and smoother. Sometimes I use a plunger to force it through too.  A lot of poop jokes get made here. Let your imagination run wild. I get about 45 blocks per batch.

8.  Remove the molds.  I do this right away.  I want as much air flow around the blocks as possible to help them dry.

9.  Wait a few days for the blocks to dry.

10.  Stack the blocks under cover to dry further.  I like to wait a couple weeks before using them.

11.  Do it again and again until you have several pallets stacked with bricks and your year’s supply of paper trash is gone.  That’s 10-15 batches for me. 

Once you have a big stack of blocks It's time to build something.  I've been putting up little buildings all around our place.  Let's take a look at a yurt I built out of papercrete blocks.

Step 5: Building Time!

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Finally!!  You built the mixer, saved the paper and made the blocks. Now it's the fun time- putting them together to actually make something.  My first papercrete project was a permanent yurt.  We had purchased a yurt years before and after going through three outer covers in five years it was clear that our climate was just too harsh for a ‘permanent tent’.  At the same time, the yurt was so cool that we really didn't want to give it up.  What we needed was a weatherproof exterior that would not need to be replaced….ever.  The only way to do that (in my twisted mind) was to build a real building and put the yurt inside of it.  Then we would have something that would last with all the yurt goodness inside of it.  What better material to build a backyard folly with than papercrete?

The first step was digging a trench and casting a foundation for the building.   I used a metal stake and a piece of string as a giant compass to scribe a building sized circle in the dirt.  After shortening the string to match the inside of the building I drew a second circle.   Now I knew exactly where I needed to dig.  The foundation was one foot wide and six inches deep.  It was filled with (real) concrete and had rebar reinforcing inside of it.  I also cast a small front entry stoop at the same time.  The foundation didn't need to be too heavy duty since the papercrete is so lightweight.

The door frame from the yurt was attached to the stoop and a ring of cinderblocks were put down as the first course on top of the foundation.  The exterior of this initial ring was coated in roofing tar to waterproof it.  It will act as a water barrier and keep moisture from wicking up into the papercrete blocks.

Next it was just a matter of stacking and mortaring the blocks together.  It was a lot of labor but went pretty fast.  I was able to complete the wall ring by myself in just a couple days.  I also used the papercrete to start to plaster the inside of the walls.  After the walls were up I made a double layered ring of plywood that went all the way around the top. This ring is called a bond beam and it ties all the blocks together at the top so that the weight and pressure of the roof doesn't spread the walls apart. It's screwed into the walls with 6" long screws.

Life intervened and it was two more years before I got back to working on the yurt.  It would have been longer but my sister, sick of sleeping on the couch when she visited, started instigating for more yurt progress.  I told her “Fine, we’ll work on it next time you’re here.”  thinking that would be the end of that.  Well, she promptly came out and it was yurt building time again.

Part of the reason I had been procrastinating on the project was that I wasn’t really sure how to build the roof.  It needed to be self supporting and not have any columns holding it up because the original yurt structure needs to fit inside of it..  It also needed to be very sturdy.  We've gotten three feet of snow in a single storm and the roof needs to be able to handle that as well as our 50-60 mph spring winds.

We started by making a central ring out of a couple layers of plywood that all the rafters would connect to.  The ring was about 5 feet in diameter with a large hole in the center for a skylight.  Next, we needed some way to hold this ring in the right place to attach the rafters to it.  We erected some scaffolding and spent quite a bit of time getting the placement of the ring correct.  It needed to be at just the right height and exactly in the center of the building.  Oh, and level too.  Eventually things got worked out and the yurt is finally weatherproof.  It still needs to be finished out but it's coming along.

Step 6: Wrap Up

Picture of Wrap Up

So there you have it.  All the joy and wonder that is papercrete.  While it's probably not going to ever make it as a mainstream product, it's perfect as an inexpensive alternative for someone who has more time than money to spend on smaller projects.  

It really lends itself to piecemeal progress.  Save all your paper trash throughout the year.  In the summer make some batches of blocks in the evening after work and soon you have enough inventory to build something.  Start a building.  Add another room next year.  So on and so forth.

Don't limit yourself to buildings either.  I use it all the time for raised garden beds. Papercrete can be cast into any form you can imagine too.  You could use it to make planters, outdoor benches, sculpture or anything else.  Just get your hands dirty with it and I guarantee, a love affair will be born.


CigarSmoker2 (author)2017-12-25

The mixer design is absolutely genius! Any idea how fireproof papercrete is? I think of paper as burning easily, but have no idea of papercrete.

shaddoty (author)2013-06-10

Green is overused, I was reading an advertisement by a high end audio company and their products were "Green"

spike3579 (author)shaddoty2013-06-10

I agree. Papercrete is grey anyhow but that's not very sexy.

pfred2 (author)spike35792013-06-10

You could probably dye the mix. I'm wondering if bugs chew into this stuff.

spike3579 (author)pfred22013-06-11

I haven't had any problems with bugs. I've heard it's fairly termite resistant.

sgriffith62 (author)spike35792017-05-29

I know Mike McCain, and worked with him in 1998 in Arizona at a papercrete workshop. we built a couple of small Casitas using papercrete. If you can, contact companies who do shredding for corporations. In that respect, you can use a cement mixer. Mike had published a book on papercrete, not sure if it's still available.

l8nite (author)pfred22013-06-11

I'm sure you could add borax into the mix to make it more bug resistant

spike3579 (author)l8nite2013-06-16

Borax will help with bugs and fire resistance. I've read that adding 5 lbs to a batch is a good ratio.

_Radium_ (author)2017-01-01

What did you mean by "stack the blocks under cover to dry further"?

What cover?
And why cover!?!? Aren't we drying them?

Can't we just put them in sun to dry fast after they cure?

spike3579 (author)_Radium_2017-01-02

Any cover you like. I put corrugated sheet metal over them as a little roof to keep the rain off. If you live somewhere it doesn't rain then don't bother.

PlaidPete (author)2016-03-13

What is stronger paper Crete or aircrete?

Hargreaves (author)2016-02-13

We need to replace our tile shower. I was thinking of doing a wattle-&-daub with the papercrete. Would that work if it was sealed properly? I saw a sink made out of papercrete.

spike3579 (author)Hargreaves2016-02-15

I personally would not put papercrete in a wet environment like a shower. While It should hold up if it is waterproofed sufficiently It would be a drag to have to rebuild it.

My experience is that papercrete blocks that are left out in the elements hold up fine but those in a constantly damp situation, such as buried in the ground or as a raised bed border, do break down over time.

If you do decide to do It l'd love to see a picture and hear what your experiences are so that others could learn about pushing the material into a new direction.

Hargreaves (author)Hargreaves2016-02-13

The measurments are (roughly) 35"/36"/82". How much paper would you think that would take?

kanemaui (author)2013-07-13

One small suggestion: 'Cement', at least the 'Portland' kind, is composed of the following materials:

Lime or calcium oxide, CaO: from limestone, chalk, shells, shale or calcareous rock
Silica, SiO2: from sand, old bottles, clay or argillaceous rock
Alumina, Al2O3: from bauxite, recycled aluminum, clay
Iron, Fe2O3: from from clay, iron ore, scrap iron and fly ash
Gypsum, CaSO4.2H20: found together with limestone

When it comes into contact with water it begins to form a crystalline structure which gives it its inherent 'hardness' and building qualities. Spike mentions he removes the molds for the bricks IMMEDIATELY allowing more 'air to circulate' for, I assume, the quicker availability for the bricks to be used in the project.

BIG PROBLEM HERE: Quickly drying cement does NOT allow for adequate crystal formation in the cement therefore a weaker brick SOMETIMES not curing at all which subsequently will cause it to crumble.

SUGGESTION: AFTER stripping the molds from the bricks, cover the bricks with gunny sacks OR ANYTHING that can hold moisture, ie, rags, towels, sheets, etc. There's even a product you can buy just for this purpose, but since economy is a driving factor here, the cloth-type coverings work just fine. The trick here is to NOT LET the CLOTH dry out, EVER! Afterwhich, over the next few days, better if it's weeks, maintain the moisture on the gunny sacks which will allow the crystalline structures to form which will result in a brick harder and stronger than the Hinges of Hades and MORE moisture resistant to boot. IF POSSIBLE, allow the bricks to 'cure' for a month and you'll find your bricks harder and stronger than even Thor could destroy.

I once did a concrete job in La Costa/Carlsbad California where we were able to actually bury a house slab UNDER WATER for 30 days. When we uncovered the slab and had to make saw-cuts for some revised plumbing, our Demolition Contractor said he'd NEVER seen concrete that hard and had to blow through more diamond bladed saws than he originally bid the project for. We were glad to compensate him for the additional costs because he did a GREAT job ~ ~ ~ The slab didn't even crack and the FIRST RULE of CONCRETE work is: "Concrete is GUARANTEED to crack! EVERY TIME" ~ ~ ~

mountainberry (author)kanemaui2015-12-27

Really appreciated this extra information Kane. Solves a lot of problems for me making some garden pots. Wanted to add that I once made self drying modelling clay using dry power clay from under my house & mixing it with polyvinyl glue (Aquadhere). I made several large pieces of fruit & left them in the garden for decorations. 15 years later they are still there, have not cracked or weathered in spite of intense heat or weeks of rain. This surprised me as PVA is a water based glue. Was thinking of adding some to the cement mix but after your advice on the proper curing method the PVA does not seem necessary.

spike3579 (author)kanemaui2013-07-14

Great comment thanks!
Lots of good info.

mountainberry (author)2015-12-27

I love this, can't wait to start making something from this material. Love the idea of finally being able to use all the waste paper in something constructive. Definitely my new project for 2016, think I'll start with some garden pots.

Green_Primus (author)2015-08-08

I read in cellulose fill howto that adding borate will make not only fireproof your paper/cardboard mix, but also mildew and rodent proof it! Now I found that the major ingredient in Borax is sodium borate?! Is there any way, by adding borax to your mix, make the papercrate even better?!

spike3579 (author)Green_Primus2015-08-10

It is entirely possible that adding borax would be a benefit. I haven't seen any studies that methodically tested it. I know that in my experience I haven't had any issues with insects. I've tried burning papercrete blocks and it takes quite a bit to get and keep them going because they are relatively dense compared to paper. For me, the cost of an additive outweighs the benefits. I would be interested to know if anyone had tried adding borax and done side by side testing.

Green_Primus (author)spike35792015-08-10

I had planned to build a test tiny house out of pallets and use a form of papercrete as insulation ( inbetween pallet top & bottem) wasnt considering using concrete thou.. just cellulose "panels".. but the 'crete might the ingrediant I need.. maybe half the crte in favor of the borax and press out the remaining water? Hmmm this will take some thinking..

cbyrd8 (author)2015-07-16

I'm obsessed with your instructibles and your website these past few months! I have space constraints in my yard, so a tow mixer isn't practical. My dad and I are discussing a stationary mixer powered by a giant, powerful, industrial drill he already has (he's a heavy machinery mechanic and welder). I'll share if this idea pans out. Meanwhile, I'm experimenting with smaller batches using cross-cut, pre-shredded paper and a bucket. I've started testing recipes by hand-sculpting big faux rocks for my garden. I wanted big, natural stones, but I can't manage the weight of real rocks by myself, and the cost of the lovely stones I liked would have allowed me to buy maybe one, haha. Now I can make as many as I want. For bigger rocks, I hide nonrecyclable trash (mostly styrofoam packing material) in the middle, inspired by the really cool "trash rocks" ible. I paint them using flat-finish paints in natural colors. So far, they look great and are easy for me to move around and rearrange to my heart's content. We'll see how they hold up, but I plan to try to use my fake rock technique to build a small "stone" privacy wall to hide my trash cans. Then maybe a garden shed...and then maybe.... Thank you for all the inspiration!

spike3579 (author)cbyrd82015-07-28

I think there is a lot of potential in casting papercrete into all sorts of shapes. I'm looking forwards to seeing some pictures of your rocks. The one thing I would say is to make some sort of foundation for the "rock" wall. While there is no need from a weight perspective, it is important to have a barrier between the PC and the earth. I've found that the blocks I used to make raised beds with are slowly decomposing from their exposure to moisture. You might try metal flashing underneath the wall.
Good luck on your projects!

JerryHamilton (author)2015-02-24

This looks like it would be a excellent material to build this

allan.sivell (author)2015-01-18

Quick question. It may have been ask already, but what do you do to water seal papercretw? You mentioned it can not be buried because it will break down. You also said it soaks water like a sponge. What do you do for out door use. Can you use thompsons water seal or some other concrete water sealer.


gary.j.mcneish (author)2014-10-14

I am working on a building material that is far more versatile and costs from. £0.00. Yes thats right you can get the material for nothing. Some places charge I am going to use it for pre casting wall/door/window panels. Anyone interested email:

HelenaTroy (author)2014-08-24

I first found out about papercrete while searching for an alternative to hypertufa (I'm visually impaired and didn't fancy the chance of inhaling any of the fine cement dust because I'd need to be close), but your Instructable really explains it, thank you. Not that I want to make a house! I've been wanting to do craft casting, small items, and this encourages me to have a go.

ledshed (author)2013-10-19

Brilliant, but I think the amount of rain we get in the UK would make it impractical.

astral_mage (author)ledshed2014-04-07

not really just use a water based breathable spray on coating.

al_packer (author)ledshed2013-12-07

Here in western Washington state we get lots and lots of rain. The best siding material for our houses is Hardi-Plank, which is a paper fiber/Portland cement composite. It's all a matter of how good a job you do of shredding the paper and mixing its fibers into the cement matrix. Done properly, the stuff will last for a geoduck's lifetime.

cbochman anderson (author)2014-01-24

I live where wind chills of -40°F are normal. Some years we have 10 or more feet of snow. I have two questions. 1 - if filled full of dirt to begin with will raised garden beds withstand that kind of weight? 2 - I will only be able to make a few pieces at a time. How warm does the outside temps have to be for these things to cure?

abut the same 4 a normal concrete block.

I tie the back of the papercrete blocks together with a strip of galvanized steel which is screwed to the blocks. This helps keep the dirt from pushing the blocks over. As far as snow I think that all the snow around the bed would provide some sort of support. I've had three feet of snow with no I'll effects.

As far as temp. I'm in New Mexico where it is quite warm and dry in the Summer. I usually cast blocks in June-August with temps in the 80's - 90's. The blocks dry in a week or so. They will cure at any temp above freezing but may take a long time to fully dry. One thing to do is make blocks one season and stack them to dry with some sort of cover and come back the next year to build with them. I've done that with larger projects where it takes a while to get enough bricks to build a building.

davhi8 (author)2014-02-14

I am using a different size tank for my mixer. Can you give me an estimated amount of water you use? Also, can I add wood shavings from a planer to the mix?

Thanks in advance!


spike3579 (author)davhi82014-02-14

I'm using about 150 gallons of water to one bag of cement to 75 lbs paper. I think it would be perfectly fine to add wood shavings though you may need to add more water if the mix is too thick. Don't skimp on the paper since that's what's holding it all together. A little experimenting will dial in the perfect mix.

davhi8 (author)spike35792014-02-14

Thanks a million Spike! I will post photos when I finish my mixer and any tech notes I may come up with.

spike3579 (author)davhi82014-02-14

Awesome! Looking forward to it.

ChinaMike (author)2013-10-12

I really enjoyed your project. I found it first on Mother Earth, then came here via a link. The only thing I would criticize is calling this a yurt. Just because it is a round dwelling with a self supporting roof does not a yurt make. The true definition of a yurt is a completely modular dwelling that can be taken down and reassembled. You could rename it a yurt-like building, but this is like calling an A-Frame house a giant pup tent!
The mixer thing is brilliant. I plan to move to Austin soon (I am currently in Hawaii) and will be purchasing some lake land property and am looking at all kinds of simple yet structurally sound building ideas. Yours is definitely at the top of the list!

georgelstuart (author)2013-09-25

Spike, I apologize if you covered it somewhere but I couldn't find it - did you mortar between the blocks? It looks like you did... what did you use? If it is traditional cement mortar, how well does it bond to the blocks, especially over time? Some of the comments about the papercrete absorbing moisture and expanding/contracting similar to what wood does as humidity levels vary makes me think that traditional mortar would eventually separate from the papercrete.

spike3579 (author)georgelstuart2013-09-25

I used papercrete to mortar the blocks together. You can also use it as a plaster as well. It adheres really well to the blocks. Cement mortar doesn't stick well at all.

jack8559 (author)2013-09-22

Do you need to spray poly or something else over this after it dries to make it more waterproof or does it not swell at all when it gets wet, or will poly or other product hold moisture in and make it deteriorate faster? How about anchoring it to the foundation, is it necessary, and if so, what would be the best method- threaded rods through the wall down to the foundation? How deep and wide does the foundation need to be, 6 inches wider than the blocks and a foot or more thick? This looks like a really good product you are making, I just want to know more about it so I can build stuff with it and know how well it will withstand the elements in central North Carolina- high humidity all year long, some snow in winter and 100 degree days in the summer. Sometimes it will rain for days in the winter as well. Any input there for me?

spike3579 (author)jack85592013-09-23

Putting an outer coating on the papercrete is probably a good idea for where you live. There are bunch of ideas/suggestions in the comments. I'm opting for large overhangs on the roof and maybe stucco someday. My foundation is only 1' wide and 6" deep w/ two rings of rebar inside. I didn't tie the building the foundation but threaded rod or J hooks would be the way I would go. If it were me I would make a small shed or other starter building first to see how it holds up in the NC climate before I invested a bunch of time in a major building project.

shuja.shaher (author)2013-09-16

One of the best - I love this instructable
can you actually give the proportions the way it is mentioned in cement mortar
like 1:2; 1:4 etc?

spike3579 (author)shuja.shaher2013-09-19

I get 13:1:0.75 water,cement,paper by weight. Your results may vary but it's a starting point.

rgagne2 (author)2013-08-25

i am prototyping natural fiber reinforced garden and patio-ware in limecrete. burlap, weldbond, perlite, portland, builders lime, foam and hemp hurd are in the mix. papercrete and hempcrete are not recommended to be in direct contact contact with earth yet you are making raised beds and planters..for precast pots and such my mix needs to be pourable so i treat the burlap and hemp hurd with acrylic cement binder, (weldbond) . this makes the fibers not soak up water and the mix retains good workability. your planters show some breakdown on soil side after three years... in desert climate. i have no idea how long my pots will last, but 3 years seems a bit short for commercial product...any thoughts?

spike3579 (author)rgagne22013-08-27

I have the biggest breakdown issues where the PC is buried underground. Treating the earth facing side I imagine will address most breakdown issues for a planter. Really you would just have to test it to see. PC is great as a castable material. It molds really nicely.

NightHawkInLight (author)2013-08-13

The best part about this article is the mixer. Genius.

mknoop18 (author)2013-08-13

I love you, thank you

Replicator (author)2013-08-07

Papercrete similar to timbercrete IS a brilliant building material. Having worked at timbercrete for 2 years and personally comparing different materials against it..... i would never build with anything else.

kanemaui (author)2013-07-14

Well, actually Spike, THANK YOU!! GREAT stuff here. I live between Maui and Southern Oregon and have wanted to build some simple out buildings on both properties for some time now. Though CMU is DEF a possibility, I LOVE the similarities and flexibility with the Papercrete approach because I'm NOT limited to the dimensions (AND cost) of traditional CMU's. Though you mention the R-values of PaperCrete Units (PCU's), let me ask: How are the thermal qualities in WARM weather. I'm pretty much assuming they are similar in the 'reverse', keeping the interior cooler when it's hot outside ~ ~ ~

Also, can you provide a more specific 'recipe', ie, %concrete to %paper to %plastic. You mentioned about 75lbs of paper to 95lbs of cement, which is about 45% paper and 55% cement. I guess I'm asking this: What would you consider to be the upper range of % of paper content? Could the ratio be 50/50 by chance. Here's another assumption I'm making: The 'paper' one adds to the mixture could be pre-shredded if one were to acquire a source of that nature. Since you mention you get 45 blocks with a dimension of 8″ x 12″ x 5″ per block per 'hopper', with a mortar bed that's roughly 2 blocks per square foot and 22 square feet per hopper. NICE!!!

To address a comment about 'bottles' and 'stack wood': IF you were to incorporate these 2 different design features into a Papercrete building you would need to assure that the 'joint' between the 2 different building types adequately addresses the load differentials that would be an inherent part of the structure. For bottles, it would be BEST if you build a lintel 'header' over the are you anticipate installing a bottle section. Glass bottles are NOT inherently strong NOR are they 'structural' IN ANY WAY. They are WAY too brittle, and just imagine what a PIA (Pain in the A**) it would be to replace one that broke from a poorly planned installation. If you build a lintel over the area where you intend to install a bottle section, that lintel will carry the weight of the Papercrete blocks above and therefore (HOPEFULLY) prevent pressure cracks/breakage on your bottle section.

With 'stack wood', there is another set of issues related to a combined style of building in that 'stack wood', unless TOTALLY dry with optimum moisture content (roughly 3%) and dimensionally stable, will shrink, warp, crack, and check. It is IMPERATIVE that you structurally segregate (expansion joint material) the stack wood from the Papercrete so that any of the wood's dimensional instability can be isolated from the rest of the Papercrete blocks OTHERWISE you'll lose structural integrity in the Papercrete blocks as well as the stacked wood ~ ~ ~

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Bio: I have a compulsion to make stuff, all kinds of stuff. I'm glad to be here...
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