heated Cob bench & thermal mass

I am really really starting to love the concept of thermal mass. The first time I heard about thermal mass was from Earthships. The tires and the berm around an Earthship provide thermal mass that acts as a temperature battery storing the heat or cold that you expose it to (integrating passive solar/south facing windows etc. to heat it up in cold times).

Deanne introduced me to a rocket stove DVD with Ernie & Erica Wisner and Paul Wheaton. It is expensive, but is a 4 DVD set with lots of information. In the DVD they discuss all sorts of good stuff relating to heat, fire, thermal mass, convection/conduction/radiation, and efficient heating. I went in with a friend to get the DVD and feel it was very worth it. I have started to think of heating homes differently.

I used to be one of those people who felt slightly frozen in the winter because heated air just didn't seem like enough to me. I felt I needed to soak in warm water or touch something warm to really soak in the heat (or gather my ambition for some kundalini yoga). Now I have learned that heating the air (convection) is likely the least efficient form of heating. Then we seal up houses to keep the warm air in and end up with stale allergen populated air.  No wonder everyone has allergies.

Heating thermal mass, which slowly releases the heat is heating by radiation and is very efficient. My body really likes this. Who doesn't like sitting on a warm bench in the winter . . . not counting menopausal women. Also, the heat is more regulated.  In the DVD someone mentions a house in Norway or Sweden that is heated with a masonry heater (using the concept of thermal mass & heating with radiation) and has free airflow to the outside just below the roof, staying plenty warm.  There are all sorts of ways to heat thermal mass from fire, to passive solar & glycol panels with in floor heating, and even in floor electrical heating mats (ease of installation & use but less efficient).   There are varying densities of thermal mass, from cement slab, even tile, to cob, and stone .  . . and so much more.

This all works up to: we are working on a heated cob bench, or two. The cob and stone help to store heat inside the house so it is not whisked out of the house if the door is opened or windows are not perfectly sealed.  The more thermal mass you have the more your desired temperature wants to stick to your living space.

One is in the entry room/inner almost-soon-to-be greenhouse.
The thermal mass is made of local limestone from a quarry and cob (also a nice sand & clay mix from a local quarry).

 Top picture is what we started with. We decided to take out the closet & table (doors are already off of the closet).

Everything is out. We tiled the walls. The bench goes in in a "U" shape.

Beginnings of a bench. We are having a cob mixing party tomorrow to bulk this up before sculpting and putting on a finish plaster coat. I'm not completely sure we will have enough materials to finish right now. The local quarries said that their stone is not accessible because it was frozen solid . . . our weather station said it was -17 degrees out this morning (without windchill factored in)! I hear this will be over soon though and I can access materials again.

The window between the bathroom and the entry room. I found these used glass floor tiles at the Habitat for Humanity Restore and knew they would fit the empty window frame perfectly; I just mortared them in. I thought about using bottle bricks but the frame is only about 1 1/2-2 in and the outsides slope. This was quick, easy, and fun. I like how it looks.

I will post a follow-up when the bench is finished!

the Strawbale Studio part II

Here is a video I found online where Deanne gives a brief tour of The Strawbale Studio.

She is offering internships in January and Feburuary!

This is a picture inside The Strawbale Studio sculpted out of cob. I like the branch added at the top. 

Deanne and Phoenix in front of the in-progress hobbit sauna.

Holes for pipe inside the sauna where the wood burning stove will go. 

A fish sculpted on the side of the rocket stove.

Rocket Stove (rocket mass heater)! This is inside a storage building, but still beautiful.

A spiral hut

A soon to be children's house 

Inside the children's house. The floor has the exhaust of the rocket stove running through heating it.

 Deanne at her rocket cookstove made of thrown together bricks

One thing I love about Deanne--everything is useful and everything is art.

Building with Cob

This year I participated in the Natural Cottage Workshop from September 28-Oct 11.  http://naturalcottageproject.com/wordpress/

We built a cob cottage from foundation to rafters during this time and learned about how to go about putting in, or having the main systems put in, as well as discussing building permits and codes.  There were design nights where individuals presented their plans an got feedback from the experts and other members of the group. Overall the course was thorough and informative and we all left feeling we had gained family. 

 We started with the foundation. The purpose of the foundation is to keep water away from the cob.  Start by digging a trench, next add drainage with gravel and a drainage pipe/hose that slants away from the structure. The stem wall/knee wall needs to be 14-24 inches above grade.  We completed the stem wall with natural stone and a basic cement mortar.

 On day 2 we began mixing cob by foot. The mix was 2:1. 2 buckets of a sharp sand (here manufactured sand because it is very sharp and will hold together well) and 1 bucket of clay. Add water to desired consistency. We stomped and pushed the mix until it began to burrito when we lifted the tarp over. Next straw was added. To mix in the straw we used twisting movements.

 The stone was wet with a brush or sponge and cob was laid onto it ensuring a level surface with no slumping shoulders. We left overhang on purpose so that it could be trimmed back to a more level surface and reduce the number of plaster coats required later.

 At the end of the day this "spine and ribs" pattern left on top allowed quicker drying and quicker building the next day. Each day we could plan to build about 2ft higher. If too much wet cob is added the wall may slump and/or fall.

 Here is a gringo block. This wooden block set in the wall allows for attachments. Gringo blocks may be set in a cob wall every 2ft where an interior wall will be to allow for attachment.

 This is a drawing from lecture. On the bottom is a drawing of how to build on cob walls. The center of the three pillars shows shouldering (bad).

 Here Christina is showing window placement with leveling an temporary supports until the windows are cobbed in.  The windows have extra wood on the sides to key into the cob. A lintel will be placed over the windows to spread the load of the roof. Every column of cob that carries a load needs to be at least 2ft.

 Here Christina is showing us "speed cobbing" where someone is throwing her chunks of tractor mixed cob and she is quickly thumbing in large amounts.

 Our wall is growing!

 Gringo blocks are attached to the side of this cabinet that is being cobbed into the wall, saving time and space.  The wooden blocks securely key the cabinet into the cob.

 The back of the cabinet has strings and wood to hold the cob. The smooth wood on the back of the cabinet will not hold the cob as well as the pointy sticks and string.

 The front window area will have a built in bench.

 We stripped, snedded, cleaned, and ground these poles. Then we learned to gouge the rafters to fit onto the main beams.

 Here a cedar post was cut and sanded then oiled with a linseed oil blend to act as a lintel.

 I snuck this picture in from another building. This cob fireplace heated the room on a rainy night and at breakfast the next morning the thermal mass of the fireplace and the roof were still letting off heat even though the building had open doors and windows. Here we worked on a cob floor and laid some earthen tile into the cob as well.

 The bench and window area with lintels. I got to put in a shallow niche for some unsuspecting window bench reader to place her coffee on in the future.

My first niche!

 This is where we got! Looking beautiful.

This workshop was a great experience and I plan to be blogging soon about my cob adventures at moonCatlife!