All About Slip Straw

Workshops throughout this process. If you want to be involved, ask!

This Saturday and Sunday mornings the 24th and 25th, I will be collecting clay at the river.  I haven’t figured out where…but I know I can.  Anyone want to come, you are totally welcome. Let me know.  Saturday will be more of a search, hopefully with results.  Both days probably around 9am

Awesome finished slip straw wall. This would then be plastered after the straw completely dried. Plaster to keep water out!

Slip Straw is also known as Light Straw-Clay.  This is coming from the German “Leichtlehm” which means light-loam.  So we have three names for the same thing:

  • Slip Straw
  • Light Straw-Clay
  • Leichtlehm (light-loam)

I like Slip Straw the best.  It is fun to say and the most descriptive of the technique. Literally, Straw put in a slip.

Light Straw-Clay can lead you on.  It is HEAVY straw content to light clay content. It is neither particularly light nor heavy in weight.

I like Leichtlehm because I like to speak German, again very descriptive (light loam content, to straw).

So Slip Straw.  You take a bunch of straw.  NOT hay as that can seed in your walls and lead to living walls which, unfortunately you don’t want in this case.  Leads to rot.  Also, less tensile strength than straw, as straw is all stalks.  Also! Hay is a food source (nutritional as it has the seed and grain content) for many animals around here! So let the animals have theirs and you can have yours.

You take any amount of earth loam with a high clay content, sift it to get rocks and larger pieces out, and mix water into it.  Water is mixed until it is kind of syrupy or creamy in consistency.  It really doesn’t matter, the thicker (milkshake-ish)  it is, the more slip you will have to straw, the heavier the straw will be and the longer it will take to dry.  Some people are fine with this.  In this project, it will not be a thick mixture as it is very important that the drying process does not take very long.  As it gets colder, the longer something will take to dry as it will start freezing first. Then it will start molding and I will live in a mold house.

After you mix the slip, you throw straw over it and throw it around so that every bit of straw is lightly coated in slip.  THIS MIX IS SOMETHING LIKE 90% STRAW 10% CLAY.

I have used a wheelbarrow for this process in the past.  I like this way a lot because the slip will settle at the triangular bottom, so you just keep folding the straw in on itself down into the slip while being able to keep parts that you feel have been sufficiently wet down on the sloping sides.  I don’t have a wheelbarrow and would appreciate  if anyone who has access to one could let me know!

So apparently, some people then leave the straw that has been put in the slip on a tarp to soak for a few days.  I don’t really think this is necessary and won’t be doing this.  I’ve come to this decision because I didn’t let the slip straw soak in the last project I worked on and it was fine and soaking will make the project take longer and I am on a tight time schedule.

So after you pile your available slip straw on a tarp at your work site, collect yourself a good study stick from the forest. Diameter of 1.5-2 inches/~4-5 centimeters. Three feet or under a meter long. Or whatever you like after you know what you like.

So you have all this.  Now let’s go back in time to what you did to prepare the work site.

As mentioned in an earlier post, the structure I am working on is a three walled, raised hut.  Before you can create walls made out of slip straw, you need a frame.  So, we already have one side of the frame in each of the three existing exterior wall.  The other side of the frame will be about 3 or 4 feet/1 meter high, running the length of each wall.  It should be a piece of plywood or something similarly light-ish, thin and easily put in place.    Since I want walls with a thickness of 9-10inches/22-25 cm, I will be placing the plywood about that width from the existing walls.  Stabilize this in any way possible, most likely screwing it into the support beams, so you can remove it easily.

So now you have a 3 or 4 foot/ 1meter  high pocket.  This is where the slip straw comes in.  Start throwing some down in the pocket and tamp it with the stick you collected.  It is important to compress the slip straw as much as possible and get it into every corner and cranny. As the slip straw dries, it shrinks.  The more compact it is, the less shrinkage, the less holes to fill in.  And as one of our frames is an exterior wall that will not be coming off, it is even more important to compress it fully because we will not have access to the other side of the slip straw wall when we are done.  Also, the more compact it is, the better an insulator the wall is.  And that is the whole point.

After tamping ~2 feet, you want to take the form off and  let it dry for a few days.  Really, I don’t know how well this is going to work out.  Mostly I am worried about it not drying out properly.  Also, depending on what I experience, perhaps more than 2 feet high can be done at a time.  You can decide this by the amount of splooging occurring.  Splooging is a very technical term used in cob building…It is when you have put too much cob clay up at once, and the walls start bulging and sliding down.  Splooging is bad.  It means that you have put too much on top of a layer and it will therefore take much much longer to dry and it will mean more sawing (yes with a saw) of the wall in order to make it even (Because it has to be even!).   After the few days, place the 3-4 foot form you used for the bottom layer of insulation above it, going along the length of the wall again, same distance from wall, and over lapping the first finished part of the wall a bit so straw is tamped directly on top of  the first layer. Repeat what you did before, tamping slip straw into the form until it is about 2 feet high. The reason why I suggest a 3 foot high form is so that you can tamp down more than 2 feet if you decide that it is working ok, and not splooging in the same way as cob.  At points in the growing wall, put in horizontal beams.

As I get closer to the roof, this will be harder to do as the roof was not secured to the structure with cob in mind.  What I will most likely do for this is leave a frame up near the roof and fill it with dry straw as thickly as possible.

If this process continues every 4 days, this part of the project should be done in about two weeks.

Things to remember while working on these walls:

where windows are going (don’t put slip straw there, accommodate with a wooden frame WITH LINTLE!) (later windows to be put in using cob and or corbel cob)

The pieces of wood extending to the right and left of the window on the top and bottom are lintles. They displace pressure or that the window doesn't crack!!!

Other things to do while doing this:

  • reinforce floor especially on open wall of structure as this will be where the stove is going
  • attach door to open wall from corner beam.

The Wall that does not yet exist must have a non-combustible component on wall and floor as this is where the wood burning stove will be.  Rock/bricks on floor, rock/brick wall for half of it. Don’t really know what to do.  IDEAS APPRECIATED!

A Look at the Original Structure

The original structure was built sometime in the late summer or fall by a friend of an old tenant.  All I know is that he never finished it, originally planning on living in it in through the winter but after hurting his ankle, he was unable to work on the project anymore and moved in with his girlfriend.  This might not even be true.  I don’t know. Anyway, it is abandoned and available, so I am not taking over someone else’s space.

So this is a side view above there.  As you can see, it is a sloping roof.  The roof is completely waterproof using some sort of wavy plastic board that is used for roofing or perhaps not used for roofing at all.  It is extremely stable, using standing trees as supplementary support. Latter included! The roof is covered strategically placed branches.  I am pretty sure this is for camouflage.  The shorter end faces towards the house on the property.  In the winter the structure may almost be visible with less trees so the branches on the roof could cover it up pretty well.

So, the structure is completely situated off the ground which is great and what is necessary (no sinking, water entering through the floor, etc.). Look at the roofing material there!  I would want to reinforce the floor in the place where I would put the stove so that it doesn’t collapse under the weight.  If I buy a stove, it will be around 120 pounds/54 kilos.  This will be does with concrete blocks most likely or stones.

Here is the interior.  Those wood pallets are regular sized pallets and would perfectly fit a twin bed.  I would insulate the floor with rugs and inside the pallets to reduce airflow under my bed therefore reducing cold and keeping my and Diesel’s bodies warmer at night. You can see a window in the corner.  On the other side of the inside, there is any other window as well as a door. Door and stove will be on the wall that does not yet exist.  As you can see, the structure is drafty…what with no wall on one side and cracks between the boards.  This will all be changed soon.

Better view of roof.  White under branches is the plastic wavy board. Blanket there for draft control I guess. Again, another view of how the trees already standing at acting upon this structure in some way.

First thing to work on is covering the cracks in the existing walls with wooden “band-aids”.  Once there is a solid exterior wall, I can begin slip straw.

Example of Slip straw without exterior wall or finish


When you walk through the yard and into the woods, you come across a wooden skunk cut in half. One half nailed to a stump of here, one half nailed to a stump over there. Then you notice the wooden structure with the camouflage roof, advertisements near by for tomatoes and basile. Though, why anyone would come lloing for these tastes here, I do not know.

I am moving into a three walled hut in the woods.

       I live in a house where the rent is too expensive, the bus stop is too far, it is (inconveniently) without internet, and the exterior walls are filled with mice instead of insulation. Really, a whole house that is uninsulated.  However, it is a great house.  It was built in 1740, there are some aging gnarly looking chickens, a wood burning stove for winter heat and it is a month to month lease.  The landlord seems communicative and open; I could approach him with any project ideas and use the expansive property with its years of left-by-past-house-livers’ resources.
        I guess the biggest problem is that there is no wood for the wood stove and no one really wants to buy/put the time into finding wood.  It is not even cold out yet, lows at night being in the 40sF/≈7C and it is cold in there.  I moved there September 1st.  The person who lived in the room before me said that he knew it was cold when he woke up to find his water bottle frozen next to his bed.  With a North/East facing room, it is going to be cold not matter what.
        I started thinking about exterior insulation for the bedroom but realized I don’t have much energy for a project in that room because I don’t feel connected to the house or most of the people in it.  Not true of two folks I love a lot who do/will live there.  I was planning on moving out in November/December time to live with two beautiful people coming back East.  So I am not interested in putting time into making my space there comfortable or warm because it isn’t worth it to me.
       So I am giving my landlord my month’s notice.  I will live there through the end of October.  The rest of September and all of October will be spent winterizing a three walled plywood hut in the wood behind my friends’ house.This blog will cover the process of winterizing a “summer shelter” using earth building methods including Slip straw, earth bag, and a small bit of cob as well as brick or stone work.  This will be a space for me to process my ideas and show the progress.  Eventually, this structure which is a three sided, plywood shack will be properly insulated structure with a wood burning stove.
       Things I will accomplish through this (beyond having a space that will be rent free, warm and cozy, much closer to friends I want to see everyday) will be becoming a more confident slip-straw builder, builder in general, learning how to cheaply winterize an already standing structure, learning how to properly install a factory made wood burning stove or (if I am brave) how to make one myself, I will be able to run my first workshop about earth building through this project which would be rewarding for everyone involved. An infinite amount of things to learn; let’s see what happens.