7 Reasons to Keep Your Old Plaster or Plaster New Walls

You could say that lime plaster forms the foundation of our company, or at least of our origin story. The three of us met on a big lime plaster job in the mountains west of Boulder, CO. We each contacted our mentor, Ryan Chivers, because we had heard of his reputation in the natural building community as a lime plaster expert. Frank had worked with him for a year at that time, and this project was mine and Ben’s first time meeting Ryan. He brought us on to help him sling plaster on both the exterior and interior of this strawbale mountain home. And, as they say, the rest is history.

Here are a few of the reasons we love lime. Whether it’s found in a historic home where plaster was the primary choice for wall building at the time (lime or gypsum), or a new build or remodel where the homeowner chooses to use plaster, this material is definitely not out of style.

1. Beauty

Have you heard the word birefringence? I hadn’t either, until I met Frank. Wikipedia defines it as so: “Birefringence is the optical property of a material having a refractive index that depends on the polarization and propagation direction of light.” Well, maybe that cleared things up for some of us…

The point is, because lime plaster cures back to it’s original material of limestone, it maintains some of the aesthetically enchanting qualities and depth of a natural gemstone or mineral, while being customizable in texture and color.

2. Durability

We all know that something that’s rock solid is very dependable. So, if someone gave you the choice to have walls that are literally rock solid, wouldn’t you take them up on that? It sounds like a no brainer to me.

3. Easy to Repair

One miraculous feature of lime plaster is that it is actually constantly repairing itself on a microscopic level. When small cracks form, new lime is exposed to air and moisture, which causes a continuing reaction which can self-heal smaller cracks. In case your lime plastered walls do get some bigger cracks, or a couple scratches, or an historic wall system needs repair, lime plaster can be repaired by a skilled plasterer. There are even artisans replicating plaster relief art in historic renovation.

4. It’s got History

Today, I told a material supplier that the products I was picking up were going to be used on a exterior plaster job, using lime plaster. He looked surprised and said, “Now that’s old school.” And he is not wrong! But the best thing about an old school material like lime it that it’s tried and true. And lime has been used in building mortars and plasters since the Greek and Roman heydays.

5. Low Carbon Footprint

As lime cures, it actually absorbs CO2 from the atmosphere. While there is still energy input during the production and shipping of lime (we call this it’s embodied energy), the curing process helps to offset this carbon footprint. Plus, lime is a more local product in many locations, particularly here in the Denver area, which means less fuel is burned for transportation than a cement stucco or paint.

6. Support your Local Craftsmen and Craftswomen

Many trade groups and magazines are extolling the virtues of skilled craftspeople in construction. The hashtag #keepcraftalive is one example I saw recently. Like many trades in the building industry, the workforce of skilled plasterers is diminishing. Hiring a local plaster company is one way to help rekindle the movement of skilled laborers coming up in the workforce. Plus, dollars spent on local products and with small businesses are more likely to stay in the community.

7. Improve Indoor Air Quality

Plaster improves indoor air quality in a few ways. One is that lime plaster contains no chemicals that can off-gas into the indoor atmosphere. Those are things like VOCs (found in some paints and stains). Instead, plaster is made of solely natural materials like sand and lime, with nothing that will emit noxious chemicals into the home.

Another way plasters improve air quality is managing humidity levels. We wrote a full blog on plaster and humidity over at our plaster specific website, Living Plasters. The general idea is that whether humidity is too low or too high, it can be bad for indoor air quality, or make your home feel uncomfortable. Plasters act as a buffer to moderate humidity levels in the “Goldilocks Zone” of just-right.

lime plaster door

Personally, I’m excited to be part of reviving the lime plaster movement and beautifying our homes and buildings.

Our Lime Plasters Featured in Modern in Denver Magazine

Living Craft’s work at The Bindery Restaurant in Denver was recently featured in an article in Modern in Denver magazine. The focus is on the sustainable and cultural elements that the owner, Linda, brought to her new business venture. Our custom traditional lime plasters are one component of the sustainability practices that they prioritized during their design and build process. Read the full article to find out more, or stop by for an up close look at the walls.

The Ties That Bind


“Lime Plaster is a natural product. It’s a true craftsman’s product… it’s more alive than stucco. It allows light to interact, to dance.”

Read the Full Article 

Case Study: Healthy Basement

We were approached by a family that was hoping to have their currently unfinished basement built out to include a bedroom, bathroom, storage, living area, and home office/meditation space. This extra space will accommodate a family with up-and-coming teenagers.

Design

Our clients already had a design for the new space and emptied the basement of most things, minus a piano which would be too difficult to move upstairs – so we built the basement around it! The bathroom design was tweaked a little by us and our plumber to make it easy to drain everything and provide required clearances and access for pipe clean-outs.

We also made some modifications to the office/meditation space, which ended up with a very cool and versatile corner of sliding barn doors.

Indoor Air Quality

Basements in older homes are notorious for being moldy, damp, and having stale air. Because we build healthy homes, breaking from the stereotype was necessary. This featured heavily in our materials selection and building method criteria.

This house has luckily not had any problems with bulk moisture in the basement (i.e. flooding). In order to create an air and vapor barrier inside the permeable concrete foundation walls, we used a polyiso foam board (a case of least-bad when it comes to foams). We foil taped all joints and caulked along the bottom. This barrier was completed using spray foam along the rim joist at the top of the wall to seal that area from air infiltration, both from outside and from the garage. Its very important to keep car fumes out of living spaces!

We also installed a small, two unit, balanced ERV, with one unit in the bedroom and the other in the living area, on the other side of the basement. These ceramic-core fans alternate drawing air in and pushing it out. The ceramic is a heat sink, designed to keep the air temperature inside the same and prevent energy loss.

A nearly silent, motion activated bathroom fan keeps excess moisture down. Clay plaster also plays a big role in managing humidity and keeping air quality high.

 

The existing wood-burning fireplace was replaced with a new gas insert. This is cleaner burning, and no more having to sweep dusty ashes.

Finally, we used a paperless drywall in all areas of the basement. This choice is mold resistant, since it’s actually the paper that provides the food for the mold spores. The only place that’s different is the shower, which we fully waterproofed using Schluter Kerdi products. Here, the longevity and mold resistance in the wet environment of a shower is valuable for a long lasting home. It will prevent unnecessary water damage and further remodeling work later on.

Insulation and Sound

Because of the possibility of moisture, we used mineral wool batts within the 2×4 framed walls to insulate the basement further. This insulation is rot-resistant, since it’s basically just rock, turned into fibers. Up in the ceiling, we used cellulose in mesh bags to insulate the top of the outside walls, between each joist, before the drywall went in.

Extra insulation batts went into the interior walls surrounding the bathroom and bedroom. This will allow the family to use the space in multiple ways without disturbing each other if someone is sleeping or showering.

Finishes

As part of a healthy indoor environment, all the surfaces are treated with VOC-free finishes. Custom clay plasters cover all the walls and ceilings except the bathroom. The bathroom has a lime plaster on the walls and ceilings, and a groutless tadelakt shower, which will never have issues with mildew in grout lines.

All trim is custom milled beetle kill pine. Doors are from used building supply stores, and are all solid alder wood. All of the wood in the home is treated with a VOC-free and plant based oil finish.

The floor is the original slab of the basement, polished and tinted and then sealed. This is easy to keep clean, and will also keep air quality higher than if we’d used carpet. Area rugs can be used in places of high traffic or where you might be walking barefoot.

A Healthy, Natural Basement

This family was great to work with and be around, as we worked in their home. We’re excited to see how the space lives up to their needs. We are glad that this basement offers them some extra living space, without having to worry about the problems of unhealthy indoor air quality.

basement before
Before
basement after
After

Check out finished photos of the job over at the projects page.

The Hemp Clay Experience

We’re working in a home where we used a hemp and clay mixture between timbers to add insulation and thermal mass. Why did we choose this, and how is it different from the hemp-lime or hempcrete building processes?

Typical Hempcrete

Hempcrete, or hemp-lime, as you may know, is a popular form of wall infill that’s a mixture of hemp hurd, hydraulic lime, and water. As it cures, the lime in hempcrete chemically changes back into the same composition as limestone, making it rock solid. Frank has taught at a few hempcrete workshops around Colorado with John Patterson of Tiny Hemp Houses.

hemp building workshop
At a hempcrete workshop Frank co-taught at in Colorado.

The Good:

Hemp! It’s great. It grows fast, and needs less chemicals while growing: all reasons it may be more ecological than other building materials. Hemp is also better for soils than most other plants, with its deep roots that aerate soil. Additionally, the hemp stalk is composed of about 50% carbon by dry weight. This means that the carbon sequestered from the atmosphere during photosynthesis can be locked into our building like a carbon sink, not being released until the building is demolished much further down the line. This enables us the possibility to build a “carbon negative” wall system. If you’d like to learn more about carbon sequestering and building for climate change, we will be posting a blog soon.

The Not-So-Good:

Lime, while a natural and healthy building material, requires a lot of energy input to be created. Also, we import a lot of the natural hydraulic limes from overseas, increasing the embodied energy of the material. Alternately, a mix with cement is used, which also has very high embodied energy and accounts for an absurd amount of greenhouse gas emissions. There are other additives that can be mixed with lime to make it hydraulic, such as different types of pozzolans and geopolymers. These have their own benefits and drawbacks, but it comes down to manufacturing processes, local availability, and toxicity.

What about Hemp-Clay?

Colorado is blessed with beautiful and strong clay, an alternative binder to lime or cement. The best part of this is that the energy required to dig up and screen local clay is minuscule compared to burning lime.

We made a test brick with hemp hurd and clay slip, and the result was strong and lightweight – a perfect combination of insulation and thermal mass (especially once clay plaster is added).

The Installation

The hemp clay installation process went very similarly to hemp-lime. Forms were packed with wet material and then moved up. It goes pretty quickly if you can make your mix dry enough, but still sticky and workable. That way, forms are moved up and the packed in hemp-clay sticks in place without slumping.

hemp building process
Forms and the tamped hemp-clay mixture.

Drying

Since clay does not set chemically, like lime or cement, it has to dry naturally, with time. With several fans and dehumidifiers placed around the home, it still took a while to fully dry. We used a moisture meter to check deep within the walls, and later patched those spots where we had to put the probe in.

hemp wall drying
Hemp wall drying in the basement. Some forms had to stay up a little longer for extra reinforcement of thinner areas.

This step is very important because if you seal the hemp up with plasters before it’s dry, although it can still breathe through the plasters, there is a greater chance that some moisture will get stuck deep in the wall. Over time, this could lead to mold.

Another thing to note is the clay tends to shrink as it dries. This led to some cracking and pulling away from timbers. We took an extra half day to come back and fill those cracks in to prevent thermal bridges and loss of insulation in those places.

hemp clay dried
The dried hemp-clay infill shrunk and pulled away slightly from the timbers. Nothing plaster can’t cover.

Plaster Prep and Plastering

This step is again just about the same as with hemp-lime or hempcrete. We had a few places where the mix was too dry or didn’t have enough clay, as well as fragile corners around windows where we used an expanded metal lath to shore up the hemp clay. Landscape staples were used to attach the lath to the hemp, where needed.

We used clay plaster and our sprayer to get a base coat up first. The texture is perfect for plaster to stick to. Although clay plaster is the safest bet for a strong bond, a lime plaster or lime stabilized clay mix would also key in well to the rough surface.

hemp clay wall
Before
hemp plastered wall timber frame
After

We’re pretty happy with the results and process. It’s not too dissimilar to a woodchip-clay infill wall. The fact that it’s a low embodied energy and carbon sequestering solution is exciting, but the amount of time it takes to dry is a challenge. However, working in the summer could speed that up easily. We would also consider adding a small amount of cement or lime to the mix in order to create that chemical set and allow us to fill higher and faster.

We used a mortar mixer for mixing, which only allows a certain amount of minimum moisture. If you wanted the mix dryer, a horizontal drum mixer would be a better option.

Unsurprisingly, we’re not the first to try this. Check out Chris Magwood and the Endeavour Centre Blog below for their experience.  Scroll to the bottom if you just want to read the hemp-clay part. I think that the hemp-clay block shows the most promise. Because they are small, that minimizes the risks of cracking and pulling away that can happen during the drying of a large wall.

Hempcrete developments

Thanks for reading, and let us know your latest hemp building experience, or if you are interested in trying it out for yourself, or in your home, backyard studio, or shed!

Green and Low Carbon Building Interview

lime plaster skylight

Frank participated in a brief interview on green building in Colorado with Boulder, CO radio station KGNU. Both Living Craft and Rodwin Architecture were represented after our joint presentation at The Eco-Social Solutions 2018 conference at CU Boulder. Click below to give it a listen, and be sure to read the whole article at KGNU’s site, linked below.

Green Building and Carbon Reduction

lime plaster skylight

What is “Building Science”?

We use the term building science a lot. For those who may have never heard the term, or fully explored it, here is a quick debrief.

Building Science

Taking into account experiences of architects, engineers, and builders, building science explores the way that a building responds over time to environmental factors and natural phenomena. Or, a detailed study of a building with the goal of increasing its life span, health, and/or performance, and applying those lessons to new buildings.

Big Topics

Indoor Air Quality/Indoor Environmental Quality

This covers things like sound/acoustics, lighting, indoor air pollutants and how to control them. Ever heard of “sick building syndrome”? In those cases, actually being inside a building will negatively affect a person’s health, whether from stale or toxic air, lack of good ventilation, noise levels, or a number of other factors.

Mechanical Systems

Air conditioning, heating, and ventilation are some of the important mechanical systems. Without proper systems, filtration, and flow, a building will not function well and keep its inhabitants comfortable. We prefer balanced ventilation, like an energy recovery ventilation system that is continuously alternating between bringing fresh air in and venting stale air out, while maintaining the temperature indoors to prevent energy loss.

ENCLOSURES and Air/Moisture Barriers

An enclosure is simply the surfaces of a building that separate indoors and outdoors. Walls, ceilings, windows, and soffits. Not surprisingly, better methods for keeping moisture out of building materials will prolong their life and reduce problems like mold and rot. So, things like air and vapor barriers are very important. They also increase the energy efficiency of buildings, and reduce operating costs from heating and cooling. However, its all connected. Since a home with a “tight envelope” or a continuous air or moisture barrier doesn’t allow air to flow through cracks, it will also need to be closely monitored and have a good, balanced ventilation system in place to circulate fresh air and reduce indoor air pollutants.

Building Sustainability

With the increasing awareness of the pressures that humans are placing on the global environment, we recognize the role that the construction industry needs to take on in reducing our impact. Big changes can be made with a choice of materials that have a low carbon footprint, or by building using carbon rich materials like wood, hemp, and straw that sequester the carbon out of the atmosphere. Things like passive solar design and an integrated landscape and water management plan also help to greatly reduce a building’s need for external energy inputs.

Modern Building Science, Traditional Materials

Hopefully it’s all coming together for you. At Living Craft, we are always trying to educate ourselves on the latest innovations in building science. We are doing the work of researching and picking out the best solutions which honor the traditions of building and respect the environment on all levels. If you have questions, we would love to hear them!

Why Design and Build?

We called our company Living Craft DESIGN + BUILD. But why?

Firstly, we each love to get our hands into the design phase of a remodel or new build. It is super fun to geek out about air barriers, passive solar, material selections, mechanical systems, and floor plans that will result in the best and healthiest home possible to meet the client’s needs.

Additionally, when the builders join the design team early, or simply are the design team, small tweaks to the design made early on can result in huge cost savings down the line, when the project is under construction.

For example, when designing a straw bale house (one of many types of construction we specialize in), it is so important to take into account the dimensions of the bale when deciding the wall height and length. If your straw bale walls are always the length of x number of bales, plus a half bale, this reduces the labor when it comes time to build. Why’s that? Because then the cutting of bales is reduced and simplified (always into 1/2’s). It also eliminates wasted bales, since every half bale left over from one course will be used on the next!

This is just one example of many as to why builders who are interested and involved in the design of a project will save money, time, and materials. We make it even simpler, by offering both!

Bioneers Event

Frank will be speaking on a panel about natural and ecological building, and ways to revamp the green construction industry to serve the needs of the people, place, and economy, at the Front Range EcoSocial Solutions Conference, a.k.a. Bioneers, this year.

Add it to your calendar because it’s coming up soon: February 9-10, 2018.

Located at CU Boulder in their new SEEC Building, look forward to a wide range of speakers discussing topics of environmental and social concern. Check out their full schedule for more topics and speakers.

Here’s the official description:

15th Annual Front Range Eco- Social Solutions: A Bioneers Network Event
February 9 + 10, 2018 ~ University of Colorado at Boulder

In its 15th year, Front Range Eco-Social Solutions is two days of sharing, learning and action, and is a uniquely affordable community event that brings together the progressive thinkers of this colorful region.

Front Range Eco-Social Solutions features re-broadcasts of the national Bioneers plenaries. The national presentations set a global context for the local conference, which features over 30 options of workshops and sessions with over 80 local presenters that focus on topics of regional importance. Bioneers is the preeminent international gathering of leading innovators and visionaries who offer practical solutions to the most pressing environmental and social issues of our time. In its 28th year, Bioneers continues to
uniquely and authentically articulate the relationships between environment, health, social justice and spirit.

Front Range Eco-Social Solutions is a Bioneers Network Event produced by the CU Environmental Center in collaboration with Naropa University, Woodbine Ecology Center, Denver Permaculture Guild, and Earth Guardians.

Let’s create some solutions in the Front Range, together!

The Story of the Truth Window


When you’re new to straw bale building, one of the first things you may notice or hear about is the “truth window.”

What exactly is this feature? It seems to me like a fun little joke within the community of straw bale builders and/or homeowners, where a small part of the wall (interior or exterior) is left without plaster, so that the straw is visible. This acts as proof to unbelieving guests and visitors that the walls are actually insulated with straw bales.

The truth window opening is covered with non-removable glass, left open, or has a door that opens and closes to allow the straw to be both seen and touched. However, we STRONGLY recommend sealing this section of the wall and detailing it well to prevent air and moisture from moving through the walls via this penetration. A simple pane of glass embedded in the plaster should do the trick.

Designing a truth window is a fun process where you can express your style and individuality by customizing the trim, shape, or other features. A quick online image search can give you inspiration, or check out a few we’ve worked on and around.

RMNBC 2017 Recap

Living Craft owners were recently proud to be speakers, sponsors, planners, and attendees of the 2017 Rocky Mountain Natural Building Conference, co-hosted by the Colorado Straw Bale Association and Common Earth. It’s been a fun and exhausting process through which we learned a lot, both about hosting a conference, as well as all the learning opportunities from speakers and other attendees of the event.

This year’s event was a blast, where we finally had a chance to meet other straw bale and natural building enthusiasts and reconnect with our mentors and friends from past natural building endeavors. The scope of the conference was broader than similar events put on by COSBA in the past, as we were striving to connect straw bale with other building techniques and ideas which can offer their own unique benefits. Speakers and attendees included earthen and adobe builders, hemp builders, building scientists and passive house experts, timber framers, architects, permaculturists, and landscape and greywater systems designers.

Frank was the emcee for the event, and Ben and Frank gave a presentation titled: Natural Building in the Urban Environment – Low Hanging Fruit. Cheryl was on a panel with several of her mentors and peers, discussing Intergenerationality in Natural Building.

Other highlights were Deva Racusin of New Frameworks Natural Design Build discussing building science and the important role of natural building materials and techniques in the green building movement. There is a huge opportunity for natural builders to promote building homes that not only have low energy use during their operation, but are also made of materials that sequester carbon within the structure of the building itself. By using plant based materials like straw, wood, cellulose, and hemp, instead of carbon emitters like steel, concrete, and mineral wool, the immediate carbon footprint of the building is significantly lower. This is absolutely essential to fight climate change in the moment, rather than waiting for benefits to offset inputs after 20-30 years or more. His business partner wrote a great article that goes into more detail about sequestering carbon in buildings.

The Friday night panel discussion with Deva, Mike Wird, Brian Fuentes, Emily Niehaus, and Derek Roff was also a really fun and informative discussion. The crowd was able to get involved by asking question via a website, which other audience members could vote on to lead the topic of conversation to areas of highest interest. Mike’s discussion of leverage points was inspiring and artful, as was Emily’s reminder that we all have more to give, as her upcoming role as mayor of the town of Moab illustrates.

An impromptu 5×5 panel on Saturday night allowed some of our friends for CASBA (California Straw Building Association) to share the results of wildfires on several straw bale homes which were impacted in recent wildfires across the state. We are truly impressed again and again by the durability of straw buildings with lime plaster, as several homes were left intact even after other non-straw structures nearby were damaged or destroyed.

Finally, COSBA and other anonymous donors, along with event attendees, were able to raise a significant donation to Liz Johndrow’s Pueblo Project, a non-profit that teaches local Central American people how to build with adobe and clay, and improve their homes’ durability, beauty, and comfort with these simple and affordable techniques. She’s hosting a natural building conference of her own in Guatemala this year.

There was too much fun to fully recount here, but Living Craft would like to fully extend our gratitude and love to our community for joining us on this amazing weekend. We hope to continue to work with all the folks we met and those we didn’t get a chance to talk with.

‘Til the next one, friends! #RMNBC2017