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I’ve been reading again . . . Sometimes it takes someone else explaining something before the light comes on and you say, “yes, that’s exactly right!” This time it’s an interesting post which addresses the question, “what does a house really need to function and how much does a person need to live well.” It explains why I have been resisting square houses and inflexible design.

Quite a number of years ago I purchased a magazine of house plans. In this particular issue most of the houses have rooflines of multiple angle changes and bits that stick out here and there. Since I purchased this magazine my tastes have obviously changed. The elevations are really unappealing to me. It took me a while to figure out why. It’s the waste of material, manpower and money, the aesthetic clutter. In the entire magazine there’s one floor plan I find appealing, though the house is very small and the outside of the house has an overly steep roof and way too much gingerbread. (Hansel and Gretel revisited.) The floor plan is appealing because the inside isn’t divided up into unimaginative single-use boxes. A two story two bath on this footprint would be very nice.

I know it’s possible to have an elegant and functional house without the waste.

I like seeing what the straw bale folks do. They seem to be able to come up with functional homes that are attractive and functional while still being low cost. While I don’t want a straw bale home, I do appreciate them and admire those who build and live in them. I also like earth sheltered passive solar homes. I love plants and the thought of having all my lovely plants growing across the front of my home is a delightful vision.

My next project is a scale model of my plan. It should be fun!

I’m researching tiltwall stuff again. I’ve learned some neat stuff, but obviously have more to learn. What I learn I will have to adapt to my application.

Tiltwalls are generally made with the structural layer on the inside and are quite thick. For example, a fresh fruit processing plant in Florida has a 6″ structural layer (inside the building), then insulation, then a 3″ external wythe. The outer layer was formed first, then the insulation was added and then rebar and the final layer of concrete. My inner layer will indeed be 6″ and will be laid first, but it will be papercrete and non-structural. Then one inch of foam and the 1″ ferrocement structural layer.

This link has a good image of a residential tiltwall being lifted into place.

I found a company who does residential tiltwall construction. They don’t do the standard sandwich; structual wythe/foam/fascia wythe. Instead, they lay foam, insert windows and doors, add reinforcing and pour the structural wythe. Once the wall is in place they wire and plumb, then add sheetrock. None of that is what I found interesting. They do something I had planned on and it’s neat to see my idea in action. (Don’t get me wrong, I’ve very sure they or someone else thought of it first.) They set the wall on pier blocks and pour the foundation beneath it. Very cool! I also notice the blocks aren’t in the corners, which is interesting. They aren’t even uniformly set.

So far I’ve come up with a number of ways to connect together the layers of my wall. As I mentioned before, Owens Corning has a push through connector that comes in various lengths. This product is sold in conjunction with their PinkCore XPS foam. Composite Technologies has a system of connectors which require predrilled holes which is designed to be used with Dow rigid insulation. Composite Tech hasn’t answered my queries regarding their product. I’m suspecting they only deal with builders, as does Owens Corning. I would have to get the product from one of their distributors.

But, I’ve come up with a really nifty third connector, a low tech, low cost approach that will work for me. Drum roll please! Threaded nylon rod. I’ve found at least two companies that offer this product. One obviously manufactures the product because they can offer it in any length for all the thicknesses they produce. The other has various thicknesses in 12″ lengths, so it’s a product they order from a manufacturer, not a product they produce themselves.

I’m viewing threaded acetal rod as a good connector for my app because my connectors don’t have to be very structural, they just have to hold everything together while the wall is being moved into place.

For my app (tiltwall of 6″ papercrete, 1″ foam, 1″ ferrocement) it will work. It can be cut to length or ordered in a certain length. If I need a stop I can thread one on. If I need more holding power (around windows, doors and edges) I can spin on a nut. And it should have enough flexibility to allow the layers to expand or contract without causing cracking of the ferrocement layer.

My concern is not how the connectors will hold in the ferrocement wythe. How will they hold in the papercrete layer? Will the papercrete back away from the nylon as it dries? How far into the papercrete do I need to sink the connectors to get really good grip? I have a six inch layer to work with, but don’t want to waste material or have the rods interfer with placement of boxes and conduit.

The papercrete layer cannot be constructed at the same time as the ferrocement layer because the papercrete must be able to breath on all six sides until it’s dry to maintain uniformity. The foam layer cannot be laid immediately on the papercrete layer because it will prevent drying. If I were doing cement/foam/cement (or ferrocement as the case may be), I could lay my first wythe, lay on the foam, apply the connectors, lay my last wythe and walk away until it’s set. Using papercrete, I can’t do that. The papercrete layer has to dry, then the foam and connectors are applied, then the ferrocement wythe is laid. I have to have a method by which I can get the connectors, foam and papercrete married without a lot of extra work or hassle.

There’s a couple different ways I can approach putting the connectors in place.

If I have a jig I can lay on the papercrete layer to produce the holes in the papercrete, once the papercrete layer is dry I can glue the nylon rod in with white glue. With this method I have to figure out how to thread the rod through the foam. Drill holes? Trying to lay foam on a bed of protruding nylon rods could really be a bugger. Lay the foam first? Trying to drill the foam to match the holes in the papercrete could also be a bugger. I don’t think I want to try and drill holes into the papercrete, though I’m sure that could be done. Not easily, as my papercrete will have sand in the mix. As you can see, I’m still pondering this step.

I found an interesting link with instructions for making a ferrocement composter. The instructions show how the mold is made and instructions for making either a tie together unit or panels that can be ferrocemented together once the panels are complete. The design is a tidy little composter that will last forever.

This is very much the same technique I want to use in building the walls of my house. The technique as described doesn’t use as many layers of reinforcing, but the idea is the same.

I’m a bit of a “want to know it all” and am constantly reading to expand my pool of knowledge. I ran into a great technical paper on ferrocement. Then I ran into something really charming, the architecture of Roger Dean. How very cool! But the outside is relatively grotesque. It would be okay if it were completely earth sheltered so the lack of harmony of the exterior could be hidden.

Here’s a link to another architect whose buildings are quite fanciful. And this guy does really nice stuff.

This is very cool! A panel built cantilevered veranda roof in India! I wish there were more photos so I could see what the barrel parts of the mold was used for. At a guess I’d say it’s for water collection/storage.

Here’s a paper presented at the Structural Faults and Repair conference in Edinburgh Scotland in 2006. Really fascinating reading.

This is a bit of a side trip, but remember the reciprocal roof thing? Here’s da Vinci’s take on it. VERY interesting. Click through and read the whole article. I kept saying “Wow” as I worked my way through.

Every once in a while I run across what I call “painful architecture”, or architecture so ugly only its designer/builder could love it. With little more effort or expense it could be cute, though it would probably never be elegant, classy or on the cover of Architectural Digest.

This page has a strawbale house at the bottom that has a lot of aesthetic appeal. There’s a balance to the structure that’s very attractive. It’s not square, it’s elegant, it has a sense of chic. Very nice. Look at the next to last image on this page. It’s lovely! A little extra effort really makes a difference.

This is really cute! They’re domes, but they’re dressed up and look really cute! I’d love to see this roof and dormer treatment done on a concrete dome. The break in the roofline makes all the difference, and the shape of the dormers is far superior to anything I’ve seen on a hard shelled dome.

As this post is a conglomerate of things, I want to include a link for the skylight/suntubes I like.

This link’s got some great architectural examples. Some I positively drooled over. This guy really knows his stuff. Too bad he’s in New Zealand.

I’ve been perusing the net reading up on papercrete; what people have done and what they think. I ran across a bit from someone who asked why anyone would want to pour a whole wall at once. They stated it would be heavy but it could probably be done with sufficient rebar to keep the wall structural intact while being lifted into place. Rebar? Okay, I can see where that could be a good thing if you didn’t already have a support scheme in mind for the wall or you expected the papercrete portion of the wall to be structural.

As to the weight, 60 pounds of paper, 65 pounds of sand, 94 pounds of concrete and 1334 pounds of water makes a pretty hefty wall (1500+ pounds). But a bunch of that water is going to drain away when the slurry is poured into the mold, then a bunch more is going to evaporate as the wall cures and dries. So say you’re left with 10% (actual dried wall content should be closer to 2% - 27 pounds) of the water still in the wall. That’s only 150 pounds! That would give you a total papercrete wall weight of 369 pounds per mixer load of water. So if a wall takes two mixer loads, you’d have a finished papercrete wall weight (12′x8′x6″) of around 700 pounds. Not too shabby! I’m asking Nolan what he thinks a ferrocement wall would weigh.

I’ve seen mention of people making papercrete logs (actually, really long bricks) that break in two when lifted, so I can see tensile strength is an issue. Being able to use the layup table to tilt the wall to an upright and pickable (a lift is called a “pick”) position is going to save me from adding structural steel to the papercrete layer. I may cheat and add one layer of chicken wire between the two batches of slurry as insurance, though having the papercrete layer tied to the ferrocement layer should be all the stabilization the wall would ever need.

Nolan says a square foot of cement weighs 130 pounds. If I assume my ferrocement layer is going to be 1″ thick, that gives me a square foot weight of 10.33 pounds. That puts the ferrocement layer for my sandwich wall at approximately 800 pounds. I’ll bump that to 850 pounds to give myself some wiggle room. I’m not calculating the full 12′ x 8′ because I have to have the reinforcing exposed around the edges for connecting to foundation, bond beam and reinforcing of the adjacent walls. Leaving 6″ exposed all the way around may be too much, but for testing I’d rather have too much exposed than not enough to work with. I can add concrete, I can’t necessarily take it away.

I did a little gross calculating and have determined it will take two mixer loads to build each papercrete wall panel. The mix of choice is:

160 gallons of water
60 lbs paper (newsprint)
65 lbs sand
94 lbs (1 bag) portland cement

Two batches should give me a panel that’s a little over 6″ thick. I will have to find something to do with any leftover mix. I will also have to figure out how to make sure all the panels are the same thickness. The panels all have different window and door configurations, so this could get interesting.

Because I am using only 16 bags of portland cement for the papercrete (2 per wall), I may want to use white portland for the first layer of each wall (the portion of the wall that is inside the building) and regular portland for the subsequent mix layer. That would give me lighter brighter walls inside allowing me to use a latex wash on the walls instead of actually applying layers of paint. The inside colors would then be brighter and clearer without the gray cast of the portland cement.

Using papercrete does cause a problem. Because I need an expansion layer between the papercrete and the ferrocement layer, and because I can’t cover the papercrete until it’s dry, push through connectors aren’t going to work. I can’t lay the EPS over the wet papercrete or drying will be inhibited.

In searching the net for nylon screws I hit on a neat thing! Threaded nylon rod, a 12″ length for $1.50! With 1″ EPS, I can take a 12″ rod, cut it into 3 pieces and push the nylon into the wet papercrete so it protrudes enough to go through the EPS and lock into the ferrocement layer. Poof, instant push through connectors. I can even spin nuts onto the end if I think I need a little more grip, around the outside edges or on the corners, for example. 16″ centers is probably too close for my app. 16″ on center is structural, and I don’t need structural. I just need everything to be held together until I can get the walls up and fastened together. 30 connectors per wall should be adequate. That’s 10 nylon rods, $15 per wall for connectors. Wow! I bet I can’t get any fancy connector for anything close to that price.

Now I just need to figure out how to keep the connectors upright and in place as the papercrete dries. I’d like to be able to put a *weight* on the form to add some compression while it’s drying. Not anything heavy, just something to help with the initial leveling to give me a more uniform layer. I’ll have to think on this some more.

To use papercrete I must build a mold that will allow water to drain away from the papercrete. As my walls are 12′x8′ (yeah, I know, the height keeps changing), with the two *tall* walls being 30″ taller at one end, I need a 12′x11′ layup table.

The frame can be 2″x6″, over which I’ll fasten an expanded rolled metal layer (I’ve got a couple sheets I can cut and weld together to make the face of the mold), over which I’ll spread shade cloth. I can get a sheet of shade cloth for ~$100.

Building the walls for the pump house will tell me whether I need an additional stiffening layer between the shade cloth and the steel layer to keep the facia wythe from mirroring the topography of the rolled expanded steel.

I’ve looked at a lot of papercrete blocks on the internet, and walls slipformed out of papercrete. I like the way the slipformed walls look. Very reminiscent of rammed earth. Looking at the blocks sparked a thought. Ferrocement is vibrated into place to evenly and thoroughly distribute the concrete into the layers of reinforcing. Shouldn’t papercrete be vibrated as well to evenly distribute the fibers throughout the slurry to produce a panel with uniform shrinkage, strength and insulative value? Makes perfect sense to me. I’ll have to try and see what I get.

The side edges of the papercrete panels will have to be slanted to accommodate the joining of the walls. For the pump house the panel edge angle will be 45°. Because the house pods are 8 sided, the panel edge angle will be 22½°. I’ll rip a couple boards to stick under the edge of the shade cloth to get the angle I need. I can screw the slanted boards in place through the expanded metal. When the walls are stood in place I’ll glue the joint and apply additional papercrete to smooth out the joint. Because the papercrete is not my structural layer I am less concerned with the possibility of a poorly glued joint.

I’m hearing from people on the list that concrete won’t stick to extruded polystyrene (XPS), but will to expanded polystyrene (EPS), a good tidbit to know. I don’t know how crucial that is when using push through connectors.

I found the other connectors for making insulated cement sandwiches. They’re made by Composite Technologies Corporation. I’ve put in a request for additional information. We’ll see what I get back.

I had an epiphany two days ago, but with all the weather and server issues I haven’t had a chance to sit down and talk through the process.

Rather than try and put the electrical boxes and conduit in place in the mold and pour around them I’ll add block outs to the mold, leaving channels and box shaped holes in the papercrete layer once the wall is pulled off the mold. When the walls are tilted into place I can easily install the boxes and run the conduit, filling the channels with papercrete once the wiring’s inspected and okayed. If I block in the power runs before adding the papercrete to the mold I don’t have to worry about cutting the runs and holes in after the wall has been set in place.

For the walls of our house I am leaning toward 6″ of papercrete on the inside (out of the weather), an expansion layer then my structural ferrocement layer. That all sounds pretty simple, and it is . . . until I start working on the formula for the papercrete layer.

If I mix the papercrete without sand, I’m going to have significant shrinkage issues, reduced thermal mass and a product that will smolder if exposed to open flame. But the layer will have better insulative values.

If I add sand to the mix I’m decreasing the shrinkage and flammability and increasing the thermal mass (good), but am reducing the insulative properties (bad) and making it more difficult to do alterations later. There’s a papercrete technical bulletin on mixes and testing results (strength and thermal properties) I’ll need before I can make a final decision.

Because the ferrocement layer will expand and contract at a different rate than the papercrete layer, it will be necessary to have a buffer between the layers, a 1″ layer of EPS. EPS has an R-value of 4 per inch. If I conservatively rate the papercrete layer at an R-value of 2 per inch, and I’m working with a 6″ layer, I’ll have a R-value of 16 with the EPS and a complete thermal break.

I’ll be up front about my reasons for using ferrocement. I want to be warm and dry on a budget. I want something that is functional and looks nice when I’m done. I want low/no maintenance. I have to like looking at it AND living in it and it’s got to suit the site. Being a woman, I want it all.

Per square foot house construction costs vary greatly. There’s a log home construction business on the freeway going north that was advertising homes starting at $25 a square foot. I’m pretty sure that’s only for the structure, no site prep, etc. Some papercrete people say the cost to build a papercrete home is around $1 a square foot, others say it’s more realistic to estimate the cost at $10/sf. The first probably doesn’t include the cost of windows, wiring, plumbing, foundation. The $10/sf figure might take those costs into consideration. So when it comes to figuring out what a home is actually going to cost, it’s necessary to know what is being included in the figure being quoted. For the sake of discussion, let’s assume we’re only speaking of structural materials expense. No labor, permits or professional consulting (ie: engineering), no toilets, tubs or chandeliers.

Certain costs are going to be the same per square foot regardless of the method of construction. For identical floor plans on the same site, the wiring, plumbing and foundation(+/-) should be comparable. The difference in structure cost appears when you start considering different structural materials and methods. As an example, there’s a fairly brisk span between the structural costs of log and papercrete homes.

Even in buildings with the same basic components, the method of application is going to effect cost. Papercrete and ferrocement both use concrete for construction. Ferrocement has significantly more reinforcing. Papercrete may actually use more cement.

Papercrete has a lot to offer as a building medium. The volume of paper that can be obtained at a truly minimal cost is impressive. But without established building code and accepted building practices, getting plans for a papercrete house permitted in our County could be decidedly problematic. If I were adamant to have a papercrete home I might want to push it. We’ve got domes and earthships already, so why not papercrete.

I am considered two different ways to marry ferrocement and papercrete. Neither method exposes the papercrete to our weather nor asks it to play a structural role.

The first is to use papercrete as the fascia layer. Papercrete out-performs concrete in echo suppression and insulative values, but underperforms it in thermal mass/inch of thickness. My primary concerns with papercrete are shrinkage when curing/drying and water absorption after construction is complete. What changes can I make to the papercrete making process to make it perform closer to what I want as a fascia layer?

In the process of mixing papercrete, the cement bonds with the paper and the pulping water drains away clear. Can the same be said for water proofing additives? Would the additive stay bound in the papercrete or run away with the water? If adding a water proofing agent to the pulping process isn’t an option, is it possible to add the admixture after the papercrete has drained? Can the resulting mortar be mixed with waterproofing before being applied? I haven’t heard of anyone doing this, so don’t know if it’s a viable option. Would subsequent mixing of the papercrete mortar negatively effect the good qualities of the papercrete? Inquiring minds . . .

Can papercrete water be recycled back into the process? If it can and a waterproofing agent was part of the initial papercrete making process, how would subsequent admixture amounts be determined?

Someone’s bound to say “waterproof it after it’s dried”, but I don’t see that as being an ideal option because it leaves far too much of the bulk of the papercrete free to absorb water.

Beyond its possible use as a fascia layer, papercrete has a reported R-value of 2.5 per inch. I don’t know how accurate this figure is, nor have I seen any certified test results. For the sake of projection, let’s say papercrete really is that insulative. A single 6″ layer could serve as both fascia and insulation performing multiple. (I’m ignoring the shrinkage and water retention issues for now.) So, I could spend thousands on XPS or EPS insulation and non-thermally conductive connectors to make my tiltwall sandwich, or I could use a 6″ layer (R-15) of much less expensive, but more labor intensive papercrete. If I could waterproof papercrete at the particle level and minimize shrinkage without compromising the insulative value, this would be a hugely attractive option. More research here is definately needed.

Sand reduces shrinkage but also reduces insulative values. Would replacing the sand with EPS beads minimize shrinkage while upping the insulative value? This is, of course, assuming the mortar could be mixed after the water is drained away without the subsequent mixing compromising the paper fibers. Wet the EPS beads down with dish soapy water and fold them into the papercrete mortar once it’s drained. I can see I need to talk to one of the papercrete fathers of design.

How does centrifugal water removal and compressive molding effect papercrete’s properties, separately or together? Again, inquiring minds . . .