Ben, Frank and Cheryl were a pleasure to work with on the project. Our plan was to alter a brick wood burning fireplace with a gas insert and to redefine and modernize its appearance and shape. Our first thought was concrete, which proved to be too heavy and expensive. Living Plasters’ suggestion of a finish mimicking Marmorino was perfect. They met their deadlines, arrived when they said they would, and followed up consistently to ensure they met our and their quality standards. In other words, everything you want in a contractor.
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.
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.
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.
Personally, I’m excited to be part of reviving the lime plaster movement and beautifying our homes and buildings.
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.
Our clients for this project had finished building their own straw-bale home in the mountains west of Boulder about a decade ago. However, the harsh mountain climate and some details of the design and material selection had led to failures in areas of plaster, particularly around windows and in places where the roof drainage lacked adequate gutter systems.
We worked with them to come up with a solution that would allow them to participate in the repair work, while using our experience and tools to speed up the process and get the home ready for winter.
First steps were to remove the lime plaster where it had begun to delaminate from the clay plaster base coat below. This happens because of a reaction between the two materials that creates a silt layer which prevents them from bonding, weakening the walls. In some areas, water had eroded the clay base coats, and we needed to mix and apply a clay plaster to build out everything to the same level. Next, we mixed up an intermediate lime-stabilized earth plaster to apply on top of the clay base coat. This in-between layer helps bond the two materials by creating a transition. The homeowners applied both of these layers by hand after we mixed up several batches and staged them around the house. They also took the opportunity to enhance and add some sculptural elements, including the house number in relief on the side of the wall.
We also added metal flashing around windows and below siding to move any water running off the building out to the surface of the wall and keep it from infiltrating into the plaster again. A final sponge-finished lime plaster over the whole house covers up any differences between the old and new and seals boundaries to prevent water from eroding the surface.
We will be able to go back in the spring next year, once temperatures are consistently above freezing, to apply a final colored coat over their home. This entire process will ensure that the will last for many decades to come, even in the harsh mountain winters.