Monday, October 14, 2013

Learning how to build with Clay/Straw

Why clay/straw, you ask?   Good question.  Regular cob adobe type buildings like they have in the desert don't work in the subarctic.  1.  the clay walls conduct the cold (which is good in the desert, not so good in the cold) and 2. the freezing of the walls in the winter turns the cob mushy and it can't hold a roof or any structure.  So insulating with clay/straw in a timber frame structure is what works best for Alaska.  There are problems however.  Alaska's short summer means that anything thicker than a 12 inch wall can't get dry before winter.  If it's not dry, mold starts to appear and then rot.

So to make a house with clay/straw you have to start by making clay/straw bricks.  With a form, you can stuff the form with clay/straw and make an 8 inch brick.  The bricks are added to the clay/straw walls on each side.  So as soon as summer's over, or the next spring, the bricks are added and the wall becomes a very warm 28 inches thick.  That works---well, at least below the Alaska Range.

All homes in Alaska are made extremely air tight.  We have fancy air-exchangers to move the air out of the house and back in again to stay healthy.  With clay/straw, the walls breathe.  Moisture is wicked in and out of the house as the humidity inside and outside of the house fluctuates.  It's natural.  There's no off-gassing from the sheet rock, paint, or other man-made building materials.  And when you go into a clay/straw structure, you can just feel the difference.

These are only a few things we learned in the Clay/Straw Workshop taught by Lasse. All of us gathered Saturday morning in the bioshelter for an introduction to building with straw and clay.  We took notes, learned theory and learned about building with clay/straw bricks.   And then we went to work.                                            

The first task was to break up the clay.  We dug the clay out of the mountain in chunks and it needed to be turned into powder----an arduous task!

 Next, Lasse had us doing it the ancient way----mixing clay and water with a hoe in a bucket.  That, too, was arduous.  It's important to understand how much we take electricity for granted.  

Then Lasse got out the drill with a big paddle on the end and started mixing the clay with water in various thicknesses to teach us about different slips for different projects.  

Look at his fingers---they are just coated.
That's a cream consistency, so it's #2 slip---
just want we wanted for our clay/straw.

Look at how thick that is---like a milk-
shake.  That is a #3 slip

Next came the straw..... local straw from Palmer.
Out came the pitchforks and we went to town tossing the straw in the air while another person poured clay like dressing over a salad. We tossed and tossed and added more clay and tossed and tossed. 

More tossing!

Bridget tests the straw to see if it is
completely coated, but not too much.

Auri tests it too!

Finally the time came to start on the wall.  The lathe should have been 1x strips cut from any lumber using a table saw, but since I had no clue---I bought lathe.  Don't do that.  It's way too expensive.

First we had to "water proof" the bottom of the wall.  It would have been much easier to do this BEFORE we built the wall, but again---we didn't know.  So we snaked some EDPM rubberized membrane between the rocks in the trench and the 2x4s.  We needed to make sure that no water came up from the ground into the clay/straw walls.    
The trick is to get any water to go under the rubberized membrane, not on top of it.                                                                                                                                                                                                         We mixed perlite with #1.5 slip until it had the consistency of a rice crispy bar.  We tamped down the clay/perlite between the 2x4s.
OKAY!  We were finally ready for the clay/straw.  One of the other cool reasons to use clay/straw is that mice don't come in.  They don't like the clay.  The other reason is that you can take a lighter to clay/straw and it will not burn.  That is a huge advantage.   
Lasse explains what to do with the clay/straw and how to stuff it.

A very interested class

Avoid the voids---stuff the corners well,
but don't stuff the rest of it---
The more stuffed in it is,
the less it insulates.
Liz starts stuffing/placing

Notice how we put the lathe up the back side of the wall before we starting putting straw in.  The walls have to be ready before               clay/straw can go in.

These are the CHASES.  The rocket stove pipes
will come in and leave the greenhouse
through these holes.  
And now you can watch the wall go up.

Curt's checking the loftiness of it to make sure folks aren't getting carried away in their stuffing.

 The stuffers continued stuffing while the rest of us kept tossing straw or churning clay slip, or breaking up the clay chunks.  We had a great assembly line.

The sun came out that afternoon and we couldn't help but sit down and soak it in.  Most of us still sun-deprived from the dark winter.
Good Conversation.
Tea Time---reflecting on the process.
Poor Liz is tuckered out!

And we finally called it a day!  Everyone was tired and sore and inspired.

What 10 people finished in a weekend.  A great start!  

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