Historicorps Job

If you’ve got some building knowledge but are excited to get a hands-on chance to learn more, as well as lead crews and live in the backcountry which repairing historic buildings, check out this job opportunity with HistoriCorps.

Crew Leader

School Bus Stop Cob Bench

Last week we wrapped up the cob school bus stop bench in Arvada that we built in the spring. we gave it a quick coat of lime plaster to protect it this winter, and plan on coming back to do a finer finish next spring.

We are considering making the final coat a tadelakt – a traditional Moroccan water-resistant style of lime finishing. At the work party we tried out tadelakt samples on AAC – Aerated Autoclaved Concrete. They worked great and volunteers got a chance to learn about the process and science behind creating this shiny and smooth finish, plus a small tadelakt tile to take home.

For this coat, we hand mixed a small batch of lime plaster, using a combination of Type S lime and NHL (Natural Hydraulic Lime). The NHL helps to make the curing time faster, which is ideal when plastering late in the season when frosty overnight temperatures might arrive anytime.  Ideally, this coat will have at least a week of frost-free nights as it cures for the best durability.

This coat went on quickly. After wetting down the bench, we hand applied a layer then used sponge floats to roughen up the surface so water won’t erode it as easily. Extra lime plaster was recycled into the soil around the base of the bench as a temporary weed barrier.


Thanks to everyone who made it out! We’re feeling great about this project and hope that it gets use by neighbors and children while waiting for their morning bus.

mixing lime plaster

Mixing the lime plaster with a mortar hoe in a wheelbarrow. For small batches this is very efficient.


Before bench

Before: lime stabilized clay base coat plaster.





bench after lime plaster

After: a light yellow sponge coated lime plaster finish.

Earth Day Recap

Thanks to everyone who came by our table at Union Station as part of Denver’s Earth Day Celebration. We talked with a load of folks about natural building on the Front Range, baked an absurd amount of cookies in the Colorado Straw Bale Association’s solar oven, and had a fantastic time. Check out some of the photos below!

On Saturday & Sunday, we had a work party at Tonita Young’s home. We built a cob bench school bus stop that is now ready for plaster. After slinging all the cob, we had a delicious dinner with all of her neighbors followed by some street luging with the neighborhood kids! Photos below and info on the bench plaster party here.


Legalizing Sustainability: Part 1

Natural buildings have long been restricted to code-less municipalities (mainly rural, libertarian areas), and to those who have the financial resources to pay for extensive engineering. Even with approved, stamped engineer plans, building officials still have retained the power to say no to natural homes.

Webb_Municipal_BuildingThat has been changing all over the United States recently, and here in Denver it looks like we are further opening the door.

Within the next year, the City of Denver will be adopting the 2015 International Building Codes (I-Codes). The I-Codes are a huge set of rules to help ensure buildings are built safely, and they will mean an enormous overhaul to the current building codes in Denver.

Due to the hard work of a lot of devoted individuals, the 2015 I-Codes include two appendices related to natural building. One of these is on strawbale and the other is on light straw clay. These appendices give folks parameters on which to design code-approved strawbale homes and use light straw clay insulation. This means you can not only receive a permit for this type of construction, but also that the city MUST issue you a permit if you are following the code.

Here is the catch. Municipalities are not required to adopt the appendices of the I-Codes.

20150320_152214Advocacy is one of Common Earth’s main goals, so we jumped right on in to this process and submitted a proposal to the City of Denver requesting that they outright adopt both of these appendices. The proposal was accepted and reviewed by a committe on March 20th, 2015. There were some important concerns raised around how to inspect these unfamiliar construction techniques, but the committee overwhelmingly supported these appendices and approved both of them! If these appendices make it through the rest of the review process (more on that to come), we hope to be able to fill in the gaps and offer the city inspectors a training on how to properly inspect for these appendices.

This is a huge step towards natural building becoming more widely accepted, and it can’t be said enough that we are building on the hard work of a lot of individuals who came before us. Not just the folks who ingeniously started stacking bales over 130 years ago, or the generations of builders and craftsmen that refined wattle & daub into light straw clay as we know it today, but we particularly owe enormous gratitude to those who have labored over writing and gathering support for these appendices. To name just a couple: Martin Hammer and Paula Baker-Laporte. Please check back in to hear about the public review process as the codes continue on to City Council. We invite you to become more involved and help us build on the exciting momentum towards change in the building industry!



Why Natural Building?

The Materials:

natural building in ColoradoNatural building often calls to something deep within people: The feel of earthen floors, heated by the southern exposure of the sun underneath your feet, the solid, reassurance of a straw bale wall insulating you from the cold north winds, the late western sun heating the earthen plastered wall as you lean against it, “the cathedral of the forest” sense you get when standing in a structure framed from hewn lumber, the ingenuity of a greywater system that uses waste water from your sink to nourish fruit trees growing inside your kitchen. The technologies are ancient and simple. The process of building with them hones the craftsman just as surely as it hones the material.

The Design:

The process of design taps into patterns that our modern mind has forgotten. It requires communities to co-create structures that are vibrant and alive with the relationships and cultures of the people who crafted them. It retraces laws of nature that should be etched in our minds from birth and revealed to us through play with the elements- not memorized from a text book in science class. As designers, we face the challenge of remembering the patterns of science and nature that we have forgotten. Sequestered from the elements and bound inside of “ticky tacky” boxes, we have forgotten the innate wisdom that humans used to inherit through stewardship of their ecosystem:

  • How the sun works- now called “passive solar design,”

The science of materials – for example, what insulates versus what serves as thermal mass

  • Patterns in nature that solve design problems efficiently- for example, why does a river move nutrients most efficiently, why does fine sediment fall out when the flow lessens, how does gravity over distance move all materials so that we can conserve energy?

Many ancient civilizations knew all of these things innately. They taught their children and lived their lives by these natural sciences. Now we are reclaiming our natural ability to read our landscapes and our drive to design. We are reviving our relationship with the patterns all around us. As an educator and a designer, I believe that pattern literacy and engineering is JUST as crucial as numerical or linguistic literacy, but it is a science we have neglected to teach children. Nowhere in current educational standards do we teach design or engineering until students are selected into specialized colleges. Why? Children are naturally attuned to patterns and design. Let’s capture their wisdom, hone it and shape it before they forget their first language as observers & stewards of their natural world.

Light Straw Clay Workshop Report

Slip straw is a great beginning natural building technique because it is quick to learn, simple, Light Straw Clayand can be used in new buildings or to add non-toxic insulation to existing buildings. Ben Waldman, contractor and natural builder, taught a slip straw workshop at the GrowHaus in Denver last month.
Workshop participants included permaculture students, landscapers, farmers, and people who wanted to explore options for building projects they have coming up.

Mixing Clay SlipSlip straw is made by combining fiber (preferably wheat straw) with a runny clay slip. The hollow shaft of the straw creates air pockets, while the clay binds the fiber together and adds thermal properties.

Once the straw and clay slip have been mixed to the right consistency, the mixture is added into a wall’s framing and then tamped down.

Slip straw is not load bearing on its own, but is meant to be used as an infill for framed walls. Different framing designs were discussed, along with their advantages and disadvantages for combination with this technique.

Once the straw has been fully tamped into the wall, it will be finished with a clay or lime plaster. Clay is able to control moisture on its own, which helps protect infill of the wall against mold or Mixing Plasterrot.

Clay plaster is another huge topic that will be taught at a future workshop, but students in this class got to have some hands-on introduction.

Burlap coated in clay slip was added over wood framing members to help bind the plaster to the wall.

Students left the workshop having gained firsthand experience with natural materials, knowledge of how to achieve the right mixtures for slip-straw and the steps involved in applying this method for better wall insulation, and access to additional resources.

January Open House

We’ll be gathering at Robin Eden and Mike Wird’s home this month. As usual this will be a drop in style potluck. Hope you can make it.

Wednesday, Jan. 28, 6:30 p.m.

Light Straw Clay Workshop

In this hands-on workshop, participants will learn how to use straw and clay in combination to create a low cost, low impact non-toxic insulation called “light 6a013487c4922b970c017743005b5f970d-800wistraw clay”. Participants will understand the variety of applications light straw clay can be used in. The hands-on portion of the workshop will include mixing and installing light straw clay in a conventional wall system, and installing a basic clay plaster finish over the light straw clay wall system.




In this hands-on workshop, participants will learn about the following topics:

  • Properties of slip-straw construction
  • Properties of clay plasters
  • How to retrofit an existing home
  • How to install in a new home
  • Building code compatibility
Saturday, January 24th 2015
10:00am to 1:00pm
The GrowHaus – 4751 York Street, Denver CO 80216
$35 for DPG members
$40 for non-members

October 22: Open House

natural city builders open houseYou are cordially invited to NCB’s monthly open house (6:30 – 8:30p). This month we’ll be doing it Southern style and having a fry out.

Please bring whatever you’d like to deep fry – chicken, french fries, onions, mushrooms, okra, twinkies. . . your imagination is the limit. We’ll have a separate pot for veggies too.

Get directions HERE

The goal of the open house is to share NCB’s work and explain how to get involved.