Category Archives: Wall Systems

Cordwood Construction: Best Practices 2012

The book Cordwood Construction: Best Practices is hot off the presses. It is written by long time cordwood builder Richard Flatau and is reported to be the most up-to-date tome on cordwood building.
Here are a few of the details.

Cordwood Construction: Best Practices

A log home building method using renewable resources
and time honored techniques (2012)

Authored by Richard Flatau

List Price: $25.00
8.5″ x 11″ (21.59 x 27.94 cm)
Full Color on White paper
196 pages
Cordwood Construction Resources
ISBN-13: 978-0615592701 (Custom Universal)
ISBN-10: 0615592708
BISAC: House & Home / Do-It-Yourself / General

259 color photos, diagrams and formulas will take the novice or experienced builder from house plans to cordwood home occupancy. Sections include: mortar mixes, R-values, code compliance, types of wood, drying wood, shrinkage tables, foundations, how we became mortgage-free, post & beam framing, formulas for estimating materials, homeowners insurance, Cordwood Conferences 2005 & 2011 summary, Best Practices with cordwood construction, lime putty mortar, cob, paper enhanced mortars, Permachinking walls, building codes, color photo album, making stained glass bottle ends, how-to “mortar-up” a cordwood wall, tuck pointing, FAQ’s, maintenance, weight of a cordwood wall, cost analysis, Cordwood Education Center, White Earth Reservation cordwood home, a condensed version of Cordwood Cabin is included (which is architecturally drawn and state code approved and now serves as a classroom for the local public school), 196 pages, and much, much more…

Here are two reviews of the book, one by Richard Freudenberger, editor of Backhome Magazine and the other by Rob Roy, Director of Earthwood Building School.

Excellent Up-to-Date Cordwood Reference May 8, 2012
By R. Freudenberger

This book by veteran cordwood builder and instructor Richard Flatau turns out to be one of the most comprehensive references available on cordwood construction. Flatau has put a lot of effort into the “Best Practices” studies, and as a result we all have the benefit of other builders’ experiences, much gleaned from his involement in organizing some of the large Cordwood Conferences held in the U.S. and Canada. All the basics are here as well for novice builders–foundations, framing, wood choices, mortar mixes, special effects, utility interfaces, and increasingly important code compliance. The book is full of illustrations, tables, a few floor plans, and lots and lots of good color photos. The bottom line is that cordwood masonry is cost-effective, energy-efficient, fire-resistant, and very sustainable…and it’s a perfect do-it-yourself endeavor for the owner-builder.
Book Review by Richard Freudenberger Editor of Backhome Magazine

Cordwood Construction: Best Practices … Richard Flatau CoCoCo/05 organizer (and long-time cordwood writer and builder) Richard Flatau has just published this new compendium, his best yet. True to its title, the author details “best practices” methods about cordwood masonry and its relationship to foundations, electrical considerations, energy codes and so much more. By themselves, two recent case studies (the Cordwood Education Center in Wisconsin and the Whole Earth Reservation Cordwood Home in Minnesota) are worth the price of this beautifully illustrated and meticulously documented work. 196 large 8.5″ by 11″ pages, including 259 color pictures and diagrams.
Book Review by Rob Roy Director of Earthwood Building School

Cordwood in Kenai, Alaska

This is Mark & Chelsea in front of their cordwood home in Kenai, Alaska.  The walls are 14″ spruce with foam insulation in the center cavity between the two 3″ mortar beads.

Here are more photos of their two story home.  They used a log wizard to craft the beams, posts and rafter.

Alaska provides ample solar time to work during the summer, but in the winter it can be a challenge.

Interior cordwood

Riding the wheelbarrow up to the second floor.

A final picture.   Nice job Chelsea and Mark.

Inspiration for future cold weather cordwooders.

Happy Trails,

Richard Flatau

Cordwood Construction Resources

Flato@aol.com

http://www.daycreek.com/flatau

http://www.daycreek.com/dc/html/dcrflatau3.htm

Cordwood Hobbit Style House with round door and living roof in Wisconsin

Dan and Jessi P. built every hairy footed hobbit-fanciers dream home.  A 16 sided cordwood home (in Wisconsin,) complete with post and beam framework, living roof, masonry stove/heater/bake oven, stained concrete floor and a round, green hobbit door.

The work is artistic, attractive and very nicely done.  The bottle end  and cordwood walls are artistic, attractive and very well done.   The nasturiums on the floor add a touch of whimsy.

Here is a quote from Jessi’s blog.

“We’re proceeding apace with the walls, which look so lovely when they’re done – from a distance they look like stone. Labor intensive and messy, but beautiful. We also have the framework for the round green door done. So we’re looking hobbity!”

Jessi ends her emails with the following quote:

Not all who wander are lost.   J.R.R.Tolkien

Here is another quote from Jessi.

Subject: Cordwood House

Hi Richard – glad you like the looks of our place! All told, if you count the tree cutting/peeling summer, it took us about 5 years, but the actual cordwood stuff we squeezed into about two and half months – we started in October and laid up the last bit of wall the second week in December two years ago with the aid of much tarping and space heaters . It’s sixteen sided on a floating slab. The logs are 18 inches with loose fill insulation in the cavity. They are a mix of hemlock, spruce, and red pine which we took for the most part off the property. Our masonry heater was done by Gimme Shelter Construction over by you and then faced by a local mason, Wayne Kostka. Don was partially right in his comment – even on the coldest days this winter we were comfy with two fires a day, and it has stayed cool enough this summer that we haven’t bothered to move the window air con over from our old house. The roof is 6-8 inches of dirt over an Enkadrain drainage layer. Sedum we put in last fall has spread nicely and we put in another couple pounds of cuttings this summer, so in a few years when we’ve worn out the weeds it should be a nice low maintenance roof. All the rain we’ve had this year has given it a good test

To Jessi & Dan:

Kudos, congrats and thank you for sharing your wonderful cordwood home.

Richard Flatau

Cordwood Construction Building School

flato@aol.com

715-212-2870                715-536-3195

http://www.daycreek.com/dc/html/dcrflatau3.htm

Nauhaus Prototype Gets Plastered

Exterior and interior plastering is underway on the carbon neutral Nauhaus prototype.

The interior surface of the hempcrete walls has a base coat of earthen plaster consisting of sub-soil harvested from the construction site and mixed with sand and water. The mix was chosen after testing sixteen different compositions, a process spearheaded by intern Shannon Levenson. Earth plaster serves the Nauhaus prototype mission because it requires almost no energy to make or transport, and therefore has very little carbon emissions associated with it. In addition, earth plastering is fairly easy to learn, requires few tools, and is instantly gratifying, both because it’s beautiful at any skill level and very similar to playing with mud pies, a therapeutic experience that many adults realize they have been neglecting for too long. Whatever the reason, the earth plastering process attracted volunteers and interns like flies to…well, compost.

The exterior wall surface has been covered with a base coat of lime-based plaster supplied by Lime Technology as part of the hempcrete wall system. Both interior and exterior plasters were applied directly to the hempcrete which proved to be an excellent plaster substrate. Fiberglass mesh, similar to mesh drywall tape, were embedded in plaster over any joints or cracks in the hempcrete. Together these plasters over hempcrete create a vapor permeable wall system, sometimes called a “breathable wall”. The idea is to create a wall that is open to taking on and giving off water vapor in response to humidity levels in the air inside or outside the building.

We believe vapor permeable walls will last much longer and help create better indoor air quality than cavity wall systems that dominate US residential construction. As any builder will tell you, it’s pretty much impossible to keep water out of walls. Permeable walls are designed with the idea that it’s okay if some water gets in as long as it can get out just as easily and won’t cause any damage in the process.

We've Got Windows

A quadruple pane window from Serious installed in a hempcrete wall in the Nauhaus Prototype
A quadruple pane window from Serious installed in a hempcrete wall in the Nauhaus Prototype

Well, we finally got the windows and doors installed. Okay, let me vent for a sec: prototypes are a bitch. We had to do a lot of head scratching and trial and error to figure out the best way to insure airtightness in our installation. The hempcrete is awesome, but it create its own set of challenges, especially since our truly wonderful Serious windows aren’t really designed to be installed in the middle of thick walls. (Serious is a partner with us on this project and we’re working with them to make things easier when you decide to replicate what we’re doing.)

First, let’s sing the praises of these windows. Though a number of German companies make windows in this category, Serious Materials is the only US company that can meet the required specs for a Passive House. All window and door units on the project have fiberglass frames and quadruple pane glazing. Southern glazing has a center of glass insulation value of R-7 with an impressive solar heat gain coefficient (the percentage of solar heat that passes through the glass, 1.0 would be 100%) of about 0.7. This allows for heat gain from the low southern winter sun, a strategy integral to the Passive House integrated design system.

North, east, and west glazings weigh in at an amazing center of glass rating of R-11, a rating equal to the fiberglass insulation in some conventional stick frame walls! This is compared to R-2 for a typical double pane window found on most US projects. Unlike the heavier European windows, Serious reaches this performance level with two pieces of glass and two pieces of plastic allowing for a thinner profile more like conventional windows typically available in the US.

Why all the fuss? Well, I’ll tell you. In a Passive House in our climate region, walls need to be about R-40.  Sticking an R-2 hole in an R-40 wall just doesn’t make sense.  In a Passive House, the idea is to spend money on passive elements, extra insulation and really good windows for example, that don’t require energy inputs to do their job once installed, unlike heating, cooling, and ventilation equipment. In the right configuration, these passive elements combine to allow for a much simpler and less expensive mechanical system, thus saving money in construction and afterwards with much lower energy bills.

Anyway, we’ve got video footage that we’ll eventually compile into a bunch of great educational how-to videos on the ins and outs of all this nifty construction detailing. If anyone out there is getting antsy for the goods, getting us a grant to fund collation of the documentation footage would really speed things up. Until then, wet your chops on these few photos:

Here you see our custom plastic lumber sill piece with groove for backer rod and space for spray foam, the edge of the bituthane sill pan (green stuff), and the poured in place concrete exterior sill
Here you see our custom plastic lumber sill piece with groove for backer rod and space for spray foam, the edge of the bituthane sill pan (green stuff), and the poured in place concrete exterior sill.
All windows had to be pre-drilled through the fiberglass frames...
All windows had to be pre-drilled through the fiberglass frames...
...then screwed to the stud framing in the middle of the hempcrete wall.
...then screwed to the stud framing in the middle of the hempcrete wall.
Jeff installs backer rod as part of a multi-step installation process to insure maximum airtightness
Jeff puts his engineering degree to work installing a backer rod as part of a multi-step installation process to insure maximum airtightness
The plastic lumber sills were filled with foam after installation through a series of pre-drilled holes...ingenious!
The plastic lumber sills were filled with foam after installation through a series of pre-drilled holes...ingenious!
Southwest view showing all the windows installed. Doesn't look like any big deal, does it?
Southwest view showing windows installed. Doesn't look like any big deal, does it?
Installing the doors was a whole different story...don't get me started!
Master carpenter and benevolent genius Tim working on a door. Installing the doors was a whole different story...don't get me started!

Legalize Industrial Hemp Nau

Well, it’s Hemp History Week.  Here’s the short version of the industrial hemp rant:

If you think the US is a capitalist country, think again. We can buy all the industrial hemp products we want, but we can’t grow the raw material to make the products ourselves. Can you say, “trade imbalance”? To learn a bit more, watch these two short videos we were involved in that discuss industrial hemp generally and then specifically as it applies to our Nauhaus prototype:

Firewood: Don’t Burn It, Build With It

This article by Clarke Snell was originally published in the New Life Journal.

Western North Carolina is becoming an incubator for green and natural building. As far as green building goes, homes built to Healthy Built Home standards have skyrocketed. We’re also well stocked with the latest cutting edge technologies and building concepts. For example though they were rare only five or ten years ago, you pretty much can’t shake a stick without hitting a hydronic in-floor heating system these days. Solar hot water is WAY back in, too, I’m happy to say. On the natural building side, it’s a real smorgasbord around here. We’ve got a number of code approved straw bale houses in several area counties. I know of two Earthships (a housing system that uses old tires packed with dirt as the wall system) in good old Madison County for god’s sake. We’ve got some cob, adobe, clay-slip straw, and the other earth/straw permutations around, too, though they seem to be more often built below the code radar than not. Conspicuously absent from our collection has been cordwood construction….until now. Toby Crawley and Maria Muscarella are nearing completion on a code approved cordwood house in Leicester. Let’s check it out.

What is Cordwood Construction?

Cordwood is firewood: air-dried, unmilled wood cut to length. Cordwood construction (often called “cordwood masonry”) is a technique for building walls with firewood. In the most basic approach, sticks of wood are placed in two beds of mortar separated by a space, usually several inches wide, which is then filled with some kind of loose insulation such as sawdust or vermiculite. (PHOTO). There are many possible mortar mixes. One popular mix contains sand, wet sawdust, lime, and Portland cement. Another uses lime and sand. Another paper pulp. Yet another simply clay, sand, and straw (cob). Cordwood walls can be designed to carry roof loads or they can be installed in combination with some form of post and beam structure. Since wood can shrink or swell, species and drying time are variables that are often debated by cordwood enthusiasts.

Cordwood Pros, Cons, and Performance

Pros: If you live in the forest, then the main advantage of cordwood is obvious: it’s an abundant, locally available, affordable building material. If you choose to go with a cob mortar and sawdust insulation, you could collect almost all of your wall volume from your building site. That’s saying something these days! In addition, laying cordwood requires only basic tools and simple skills. Once laid, cordwood walls require no additional finish such as drywall or wallpaper with sea shells on it. (Note: I’m only talking about the cordwood portion of the construction here. You still need a foundation, window and door framing, a roof system, heating and cooling strategies and systems, and all the other things that make a house a complex animal.)

Cons: Laying cordwood is a lot of hard, physical work. It also takes a lot of forethought in terms of cutting and drying the wood. (It’s a good idea to let cut and split wood air-dry under cover for at least a year before using in a wall.) In addition, the exposed end-grain of each piece of wood facing toward the exterior is susceptible to water infiltration and therefore mold, insects, and other damaging forces. Good design such as a proper foundation and good roof overhangs can go a long way to solving this issue. For me, perhaps the main functional cordwood con is wood shrinkage which can cause gaps and cracks that lead to air infiltration and even separation of cordwood from the mortar.

Performance: Comparing cordwood’s thermal performance to a more conventional wall system is difficult to generalize and beyond the scope of this column. However, I will say that since cordwood is made on site, it’s thermal performance can be adjusted to suit the specifics of the house project it is serving. The thicker the wall, the better it will resist the flow of heat, so you can theoretically generate the performance you need by adjusting wall thickness. In colder climates, an option for increasing thermal performance is double wall cordwood masonry, a system employing two cordwood walls separated by a space filled with insulation. Wood is both a decent insulator and a good thermal mass, so it is competent at both resisting heat flow and holding heat. Another potential performance plus for cordwood is it’s hygroscopic nature…it’s ability to take on and give off water vapor in response to changes in humidity levels. This trait theoretically helps wood to balance indoor humidity levels and therefore potentially improve indoor air quality.

Toby and Maria’s House

As someone who has been hangin’ around the natural building water cooler for a number of years, I have to say that I’m always skeptical when I hear about the next wave of novice owner builders taking a shot at home construction. Sometimes it works out great and sometimes…well it’s a disaster. I’m happy to report that Toby and Maria are doing a good job and look like they are going to make it through intact. In my opinion, their secret to success has been (1) an initially somewhat realistic budget and (2) the financial flexibility to go well over their initially somewhat realistic budget.

After doing their research and checking out a variety of options, Toby and Maria chose cordwood over other “natural” building options because they thought they could muster the skills and reasoned that cordwood could pass code in the area. This turned out to be true probably mainly because they chose a post and beam structure with cordwood infill. The post and beam construction was stamped by a structural engineer leaving the cordwood infill with no official structural role. They cut cordwood from poplar harvested on their property and bought most of the rest of the framing lumber from a local mill. They salvaged hardwood floor from a dumpster (it looks great!) and bought most of their doors and windows from Habitat for Humanity.

The approximately 1,400 square foot building is 16-sided and roughly circular. It will have a living roof planted with sedums. The north section of the first floor and the small second floor are wood framed and insulated with Icynene spray foam leaving roughly the east, south, and west areas of the first floor in cordwood. Though they are hooked up to and existing well and septic system and have a flush toilet, Toby, Maria and family plan to continue using their sawdust toilet and composting their humanure for use in the garden. (Yeah, baby! See my rant against flush toilets in other of my writings or just stop me on the street to get an earful.) They have hydronic in-floor heating fed only by solar collectors, i.e. there is no boiler back-up and therefore no petroleum based fuel input. The back-up heat source is a high efficiency wood stove. Last, but not least, they are using Earthpaint finishes throughout the building. (If you don’t know about local paint and finish manufacturer, Earthpaint, get with it already!)

If you want more information, Toby and Maria have graciously agreed to supply a contact email address (tcrawley@gmail.com). They still have some cordwood to lay, so get in on the next cordwood party! As for me, I’m always looking to deepen my knowledge of the local natural and extreme green building scene, so don’t hesitate to send me leads and contact info for interesting projects at clarke@thinkgreenbuilding.com. Until next month, keep it green.

Cordwood Education Center on the cover of Backhome Magazine Jan/Feb 2010

There is a fine photo of a team of Percheron’s pulling a sleigh on February 14, 2009 in northern Wisconsin on the cover of Backhome Magazine (which is published in Hendersonville, NC.)
www.backhomemagazine.com

The Cordwood Education Center in Merrill, WI
The Cordwood Education Center in Merrill, WI

There is a 3 page article entitled Community Constructed Cordwood which details the volunteer labor used to build and then donate this 850 sq. ft. building to the local school system. The cordwood building is constructed using Best Practices and Energy Star Guidelines.  There is more information at

http://www.daycreek.com/dc/html/cordwood_education_center.html

To read the complete article go to:     http://www.daycreek.com/dc/pdf/Backhome_104.pdf

A recycled bottle end (stained glass) wall at the Cordwood Center.
A recycled bottle end (stained glass) wall at the Cordwood Center.

Richard Flatau

Cordwood Construction Resources

Merrill, WI

flato@aol.com

www.daycreek.com/flatau

Cordwood Bookstore link
http://www.daycreek.com/dc/html/dcrflatau3.htm

The Latest in Prototype News

For the last couple weeks, Matt and his crew, plus volunteers, have been continuing the second floor Hemcrete installation.

If you’re interested in volunteering for the Nauhaus Prototype Project, please contact Billy.

Click here to view the entire Nauhaus Prototype Construction Chronology.

Current View of Southeast
Current View of Southeast
Current View of Southwest
Current View of Southwest
Hemp Stacked and Waiting
Hemp Stacked and Waiting
The Trusty Mixer
The Trusty Mixer

Ben is the fastest Hemcrete installer in the West!
Adam is the fastest Hemcrete installer in the West!
Support for the upper forms on the North side.  The black landscape fabric covers the CMU blocks, which will be beneath grade.
Support for Upper Forms over CMU Wall
Closeup of Form Attachment
Closeup of Form Attachment
Scaffolding
Scaffolding
The forms are built up almost ot the overhangs, and are stuffed by hand.
The forms are built up almost ot the overhangs, and are stuffed by hand.

Completed Window Opening
Completed Window Opening

Thermally broken mounting bracket for roof supports.  The pink is foam insulation.
Thermally broken mounting bracket for roof supports. The pink is foam insulation.

Closeup of Hemcrete in Form
Closeup of Hemcrete in Form

A combination of custom and pre-made forms is used on the 2nd floor.
A combination of custom and pre-made forms is used on the 2nd floor.

This Week in Prototype News

The big blizzard of ’09 temporarily put the kibosh on construction, but we’re back up and running.  The Hemcrete forms have come off of the first floor, Serious Materials windows have arrived, and the roof is moving forward, with horse drawn, local, sustainably harvested hemlock fascia boards from Mountain Works installed this week.

If you’re interested in volunteering for the Nauhaus Prototype Project, please contact Billy.

Click here to view the entire Nauhaus Prototype Construction Chronology.

Wall with Custom Hemcrete Forms
Wall with Custom Hemcrete Forms
Wall after Hemcrete Forms are Removed
Wall after Hemcrete Forms are Removed
Serious Materials Windows Have Arrived
Serious Materials Windows Have Arrived
Serious Materials Windows Waiting for Installation
Serious Materials Windows Waiting for Installation
Head and Jamb of Hemcrete Window Opening
Head and Jamb of Hemcrete Window Opening
Jamb and Sill of Hemcrete Window Opening
Jamb and Sill of Hemcrete Window Opening

Sustainably Harvested Hemlock Fascia
Sustainably Harvested Hemlock Fascia

Closeup of Future Patio Connection at West Wall
Closeup of Future Patio Connection at West Wall
Nauhaus Prototype as of December 31, 2009
Nauhaus Prototype as of December 31, 2009