How to Build a Global Model Earthship
Operation II: Concrete Work
by Michael Reynolds
Copyright 2013 Michael Reynolds
All rights reserved
Published in eBook format by eBookIt.com
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ISBN-13: 978-1-4566-1581-9
No part of this book may be reproduced in any form or by any electronic or mechanical means including
information storage and retrieval systems, without permission in writing from the author. The only
exception is by a reviewer, who may quote short excerpts in a review.
DISCLAIMER:
Codes vary from state to state, county to county and city to city. The required inspections needed (per
your local planning department) will vary according to the location of your build. The required building
techniques (i.e. width/depth of footings, placement of bond beams, etc.) in order to meet code may vary
according to your city/county/state codes and local soil conditions.
Contents
Introduction
Operation 2: Concrete Work Overview
Buttress Footings
Buttresses
Concrete Bond Beam
Structural FrontFace Footing
Interior Footings
Exterior Footings
Conclusion
Introduction
Operation Two covers the concrete and steel strength of the building. For a two bedroom Earthship,
20 people can stay busy and accomplish more, taking advantage of the “group effort”.
As with any construction project, there are many things going on at once. This book is meant to be a
step by step guide, therefore, it is important to follow these directions and proceed accordingly, step-bystep.
This guide and the Global Model Earthship itself is the result of over 40 years of research and
development, both in the field and ‘on the drawing board’ - all over the world, in every climate. Many
books and videos are available that were produced during this forty years of development. It is advisable
to become familiar with them all.
DISCLAIMER: Codes vary from state to state, county to county and city to city. The required
inspections needed (per your local Planning Department) will vary according to the location of your
build. The required building techniques (i.e. width/depth of footings, placement of bond beams, etc.)
may also vary in order to meet code depending on your location and soil conditions.
Operation 2: Concrete Work Overview
The first part of constructing your building is the most important part. Take your time, double check
your work, then triple check your work.
• Buttress Footings
• Buttresses
• Concrete Bond Beam
• Structural Front Face Footing
• Interior Footings
• Exterior Footings
Buttress Footings
Step 1
Buttresses are like a “spur out” to help support a straight linear wall that is about 20’ or more and are
typically located along the North wall in Earthship designs (in the northern hemisphere). They are
designed into the building to line up with a wall or other features within the home so as not to have too
much affect in the living spaces.
Locate the footprint of your buttresses from your specific construction drawings. You will be digging
a hole large enough to place a 24”x 36” rebar grid, digging down 10 inches deep below grade (the size
of the footings will vary according to soil conditions and local codes, for this information contact your
local building authority). This hole is centered on where your buttresses will be. The general rule of
thumb for the spacing of buttresses to aid in the support of a tire wall construction is to place the
buttresses no more than 14 feet apart. See your construction drawings for specific placement.
See Image: A & HH
Step 2
Mark the location and dimensions of the hole. You don’t have to use a string line as you will be
digging this out quickly and the string will just get in the way. Dig down 10 inches below subfloor and
level out the bottom. Be sure to protect the edges and corners of the buttress footing dig out See Image: B & HH
Step 3
The buttress footing must have steel in the bottom to spread and take the load. Using 1/2 inch #4
rebar, cut rebar to size (three lengths of 32” and four lengths of 20”). Using bailing wire, make a grid
with the rebar pieces spaced equidistant to create an evenly spaced grid pattern. When the buttress
footing grid is placed in the dug out hole, rebar should not touch the dirt. (The dimensions of the hole
and the rebar grid may vary depending on local codes and soil conditions).
See Image: C & D & E
Cut four more pieces of rebar at 3 foot lengths Bend all pieces in the middle to 90 degree to create
four ‘L’ shaped pieces of rebar, each with each edge of the ‘L’ at least 18 inches in length
Connect the two ‘L’ shaped pieces to the steel grid footing with bailing wire. This allows for four
pieces of rebar sticking up vertically into the middle of the buttress and and will connect the footing to
the buttress and to the bond beam. Many codes pertaining to the overlap of tied in steel rebar (also called
‘splicing’) in reinforced masonry construction call for an overlap of 18 inches of rebar (refer to your
local building codes for specific code requirements pertaining to steel reinforced masonry construction
but the general rule of thumb for “tying” together or “splicing” together two pieces of rebar is the
overlap should be at least 32 times the rebar diameter). This ‘L’ shaped connector piece will allow for
the buttress footing, buttress and the bond beam to be connected by continuous lengths of #4 steal rebar,
aiding in the stability and strength of the overall construction.
See Image: D & E & J & K
Step 4
Place the steel grid with its connected ‘L’ pieces into the dug out buttress footing hole. The steel grid
must be 3 inches up from the bottom of the footing dig out (this can be accomplished using.rebar
“chairs”).
See Image: F
Step 5
INSPECTION REQUIRED
*At this point an inspection will be required. Your local inspector will want to see all of your steel
work PRIOR to pouring concrete. If you can coordinate the completion of your pre-pour bondbeam
work (see the bond beam section of this manual), and the bond bond beam it is possible to have all steel
inspections done at once, which will save you a lot of time. Also, remember that the required inspections
may vary according to the location of your build site.
When the steel rebar for the footings have been signed off by the inspector, pour the concrete into
the footing dig out, with rebar in place, (each footing must be poured all at once to maintain structural
integrity of the footing). The top of the pour is at sub-floor. agitate the concrete so that it is evenly
distributed.
See Image: G
Step 6
Shoot in the top of the buttress pour to be at sub-floor. (using your site level). This measurement is
where the top of your Structural Frontface Footing is.
When the top of the pour is measured at sub-floor, make the four ‘L’ pieces of steel rebar sticking out
vertically plumb.
See Image: H
Buttresses
Buttresses are like a “spur out” to help support a straight linear wall that is about 20 feet+ in length
and are typically located along the North wall in Earthship designs (in the northern hemisphere at least).
They are designed into the building to line up with a wall or other features within the home so as not to
have too much affect in the living spaces.
In the previous section, four pieces of steel rebar stick out of each of the buttress footings. These are
to be connected with steel rebar inside of the buttresses in a continuos length of rebar extending through
the bond beam. This creates connected steel all around the building and down through the buttresses.
Step 1
Every 20 or so inches on center vertically you will pound 36 inch pieces of steel rebar horizontally
between the the grooves of the tires sticking out into the buttress attaching (using baling wire) to the
long vertical pieces of steel rebar running from the footing up through the buttress (there should be two
lengths of rebar 6 inches apart on center at each interval). These pieces of steel rebar will protrude from
the tire wall anywhere from 12 inches to 18 inches into the formed buttress to help stabilize the long
vertical pieces of steel rebar during the pour. The long pieces of vertical steel rebar must remain in the
relative middle of the buttress forms during the pour.
See Image: A & B & I
Step 2
Cut and bend four ‘L’ shaped pieces of steel rebar to ‘splice’ with bailing wire to the steel rebar
sticking out of the footing (overlapping at least 18 inches). The other side of the ‘L’ overlaps 18 inches
with the vertical steel rebar inside of the bond beam. (If your bond beam rebar is not in place yet. Don’t
worry. Simply have the rebar ready to be tied into the bond beam)
See Image: J & K & L & R & X
Step 3
Build a form to pour the concrete buttress. See your specific construction drawings for the
dimensions and construction details for the buttress forms.
Be sure these forms are VERY STRONG. They will need to withstand a lot of force pushing out. Be
sure to seal the connection between the buttress forms and the tire wall so the concrete in the pour does
not leak out.
See Image: A & B & M & N & O & P & Q & R
Step 4
Where there is a door-buck at the end of the buttress, every 2’ vertically, drill a hole in the wood
form and place an anchor bolt in the end. The anchor bolt will be in the poured concrete and bolted to
the door-buck.
Where there is a can wall at the end of the buttress, every 2’ vertically, drill a hole in the wood form
and place a piece of steel rebar 18 inches long. This piece of steel will be in the poured concrete and in
the concrete of the can wall, connecting the two.
See your specific construction drawings for locations of the doors and can walls in your home,
relative to the buttress locations.
See Image: U (an example of what the set up bondbeam looks like with the anchor bolts in place)
Step 5
Before pouring your buttress check your construction drawings to see if a chase is needed (PVC pipe
running behind the formed buttress.). The chase is needed in cases where your utilities closet is located
along the north wall and you need to run your plumbing behind the bondbeam. In most Global Model
Earthships the utilities closet is located through the greenhouse making the chase running behind the
buttress unnecessary. Electrical can be run along the top of the buttress making a chase unnecessary in
many cases.
See Image U (an example of a chase running behind buttress)
Step 6
*** STOP: Steel inspection needed prior to the concrete pour.
Mix a lot of concrete and pour. You must pour an entire buttress at once, in one hit. So think ahead
and don’t get stuck running out of time or running out of materials. There are two options at this point;
have three mixers going continuously with an army of people, or contact your local Concrete Ready Mix
Company to come to your site with cement truck and pumping apparatus.
CONCRETE FORMULA: 3:4:5 = concrete: sand: gravel
As you fill up the buttress form, be sure to agitate the concrete so it is evenly distributed within the
buttress form.
See Image: S (an example of “agitating the concrete”)
See Image: T (an example of buttress pour done prior to bond beam pour)
See Image: U (an example of Set Up and completed buttress and bond beam)
Concrete Bond Beam
The Concrete Bond Beam is on top of the last tire course. It has steel inside for strength, that ties in
with the buttresses and receives the roof beams.
You can have a large team of people working on the concrete bond beam. The entire bond beam
must be poured at once. You cannot pour part of the bond beam, then do the other. This will cause the
concrete to dry in chunks which compromises the strength.
The Concrete Bond Beam pour form is created with short can walls. You will need a lot of 1/2” rebar
for this part of the building construction.
Step 1
Insert 3’ painted rebar pins into the dirt in the tires alternating sides at least 3” in from the can wall
form. Each rebar pin cannot be closer than 3 inches to the string lines. This is what your two horizontal
lengths of rebar (running the entire span of the bond beam) will tie to.
See Image: V & W
Step 2
Run two rows of horizontal rebar, 3” up from the tires. Attach the horizontal rebar to the vertical 3’
pins with bailing wire or rebar ties. Every vertical 3’ pin should be attached to a horizontal rebar. Two
people can bend the rebar lengths following the curves of the tire wall so the two rows of rebar run
parallel and in the center of the tires.
See Image: V
Step 3
The horizontal rebar in the Concrete Bond Beam must tie into the rebar in the buttresses. To tie into
the rebar in the Buttresses, use four pieces of 90 degree angled rebar, one for each horizontal row. The
90 degree ‘L’ shaped rebar must be at least 18” in length for each ‘side’ of the angled ‘L’ to meet code
for splicing together two pieces of rebar. Use bailing wire or rebar ties to attached the rebar together.
See Image: R & X & Y
Step 4
Wing-walls. The bond beam on the east and west tire walls step up to meet the wood plate of the
inner greenhouse. See Operation Three for details and construction guidelines for the inner greenhouse.
The last course on the side tire wing walls steps up another course. The can walls and horizontal
rebar is bent to accommodate this step up. Depending on your construction drawings, this step up on
each side may be one or two tire courses or more, or no step up at all.
See Image: Z & Z2
Step 5
After all of the horizontal rebar is in place and a grade pin is set every 10’ in the tires to mark the
height of the bond beam, (see your construction drawings). Note: The bond beam should be no less than
10” deep.
‘Porcupine’ the tires with 8d galvanized nails sticking out where the can wall will create the bond
beam form. The nails should be approximately 4 - 6 inches apart. The concrete will be able to grab onto
the nails and connect to the tires for the can wall. NOTE: The gap between the tires, where the can wall
will be laid can be packed out with concrete, or if the pack-out has not been done yet you can lay metal
lath kept in place by the ‘porcupined’ nails.
See Image: AA & AA2
Step 6
Now it is time to bring up the vertical can walls. Run both little can walls up almost to the height of
the grade pins. A cement cap on the can wall will be leveled to the height of the grade pins so the entire
can wall is level with the grade pins.
The poured dimensions of the bond beam should be at least 10” deep by 10” wide, so make sure
your can wall form meets this criteria.
Can Wall Mix Formula:
• One single hand-full of structural engineering fibers for bonding.
• Three full 5 gallon buckets of sand
• 1/2 bag of cement
• This is an approximation of the formula- as it will vary depending on local conditions but the mix
should have a ‘sticky’ consistency.
How to lay a can wall
Always wear rubber gloves whenever you are working with portland cement. It will irritate your
skin. Note: If you happen to get concrete on your skin white vinegar works well for neutralizing cement
burns.
The mortar should be a stiff mix, so that it does not ooze out from around the cans. A loose wet mix
would make this operation very difficult.
Drive a few nails into the tires where the cans and cement will make contact with the tires. This
anchors the cement work to the tires.
Now, lay an approximately 1-1/2” patty of mortar that is about 3-1/2” wide in a strip where the can
wall will go up. This isn’t a precise process. Generally, grabbing a couple of handfuls of concrete and
spreading it like a tube in the center of where you want the cans to lay is good practice.
Slightly crimp each can, so that once the mortar is dry, it cannot be pushed out of the wall. Lay the
cans level about 3/4” apart, and flush with each prior row of cans.
Lay another bed of mortar on the center of the first course of cans, and add another row of cans. If
the mortar is oozing out and running, it is too wet.
Continue the process until you reach the string. Use a scrap board for a straight edge to assure that
you have cement coming up to the line of the decking which will be applied later.
This process should be done with hands only (wearing rubber gloves). Trowels and regular masonry
tools will simply slow you down.
See Image: BB
Step 7
When the can walls are capped and leveled with can-wall mix to the grade pins, let the entire
concrete bond beam form dry (setup) for 24 hours.
See Image: CC & DD
Step 8
****STOP: Steal inspection will be required PRIOR to pouring concrete
A team of people with three mixers going can pour the entire concrete bond beam in one day easy,
possibly a half day. or contact your local Concrete Ready Mix Company to come to your site with a
cement truck and pumping apparatus. Remember, the entire pour must be done at once, at the same time.
Prepare your mixing area with easy access to sand, gravel, cement and water. Be sure to allow for easy
access to the mixers for the wheel barrels delivering concrete up to the bond beam.
Concrete Bond Beam Mix Formula: 3:4:5 = cement: sand : gravel
Set up with a wheel barrow for each mixer and a runner for the wheel barrow. The wheel barrows
deliver the concrete mix to the bond beam. You can have two delivery points when filling the bond beam
with concrete. As you are filling the bond beam, to be sure the concrete is distributed properly, you will
need to agitate the concrete. This means using any kind of thing rod/stick that is strong and won’t break.
Poke and stir-in the concrete that is filling the can form. The concrete locks everything in creating a
concrete and steel ring (bond beam) around the entire building.
See Image: EE
Step 9
Anchor bolts are added roughly every two feet on-center. The anchor bolts are 1/2” x 8”, they
receive the plates that sit on top of the bond beam. Be sure to leave the anchor bolts sticking up enough
to receive the bolts and the thickness of the wood (2”-2-1/2”). The vigas (roof beams) sit on these plates.
See Image: FF
Structural FrontFace Footing
The structural frontface footing is supporting the interior frontface (the wall that divides the living
space from the greenhouse) and the weight from the roof structure. The footing is similar to the concrete
bond beam on the tire wall but is deeper and wider due to the difference in structural support.
Step 1
Locate the inside of the frontface footing as per your construction drawings. This is the dimension
from the inside of the back tire wall to the frontface footing. Typically this dimension is 16’10”. Be sure
to take the dimension to the inside of the frontface footing.
See Image: HH
Step 2
Mark off the location of the frontface footing digout with string.
Dig a trench the length of the building for the frontface footing. This trench is 20” deep and 16”
wide. Be sure the edges are straight and vertical and the corners remain with the floor and sides of the
trench at 90 degree angles to each other and do not get hit and knocked away deforming the shape of the
footing trench.
See Image: HH & KK
Step 3
Place two horizontal pieces of rebar at the bottom of the trench. These two pieces must be 3 inches
UP from the bottom of the trench and 3 inches IN from the sides of the trench. Each horizontal piece
must overlap 2 feet with the next horizontal piece. “stirrups” or “chairs” can be used to elevate the rebar
from the bottom of trench and the two upper lengths of rebar can be suspended with wire from above.
There will be two more pieces of rebar at the top of the pour. 3 inches DOWN from the top of the
pour and 3 inches IN from the sides of the trench. The following images shows the two, topmost lengths
of rebar being held in place by suspending them with wire from rebar resting across the width of the dug
out trench.
See Image: II & LL & MM & MM2
Step 4
Place grade stakes. These are vertical pieces of steel rebar. Pound them in and stop to the point
where the top of the grade stake steel rebar pieces are at subfloor (or pound them in and cut them to the
level of the subfloor). Place one grade beam every six to eight feet. Use the builder’s level to shoot in
the top of these grade beams for an accurate measurement.
See Image: II & NN
Step 5
Cut pieces of #4 rebar to be placed in the front face footing after the concrete has been poured and
before the concrete has setup. These 12” lengths of rebar will be placed where you will build up the stem
wall and placed approximately every 16” on center. Also have the anchor bolts on hand to place where
the door bucks are going to be located in the interior front face footing. These anchor bolts receive the
wood plates for the door-bucks in the interior structural front face..
See Image: HH to locate stem wall pour and door buck placement on Structural Front Face
Footing
Step 6
STOP: A steel inspection may be required prior to pouring your concrete, check with your local
building authority for required inspections in your area.
Double check all measurements and pour the concrete into the trench. The top of the pour is at subfloor. This measurement is taken by shooting in the level of the top of the footing using a builder’s level.
You will be consistently shooting in this measurement for multiple footings outlined in this book. Be
sure to rod the concrete as you pour it in. The pour must be done all at once.
See Image: NN
Step 7
When the pour is complete and to the proper level, place the 12” vertical pieces of rebar to receive
the stem wall pour. Place the rebar every 16” on center. These vertical pieces of rebar should protrude 5”
above subfloor. See your specific construction drawings for locations of the stem wall poor. Place
anchor bolts in the structural frontface footing to receive the Trex (where the door-bucks are located).
(The anchor bolts should be placed every 18”-24”). The anchor bolts should protrude 2+” above
subfloor. Be sure all vertical pieces of rebar and anchor bolts are sitting vertically plumb as they stick
out of the frontface footing.
See Image: HH & II & JJ & OO
Step 8
After the concrete has set up (about 24 hours) affix the 2x6 Trex to the anchor bolts (where door
bucks occur). Holes are drilled into the Trex where the anchor bolts occur (using a 1/2”- 5/8” drill bit).
Make sure the Trex is level. A second piece of Trex is affixed using 2-1/2” screws. And again make sure
the Trex is level.
See Image: JJ & PP
Step 9
At this point you must frame out the rough openings where the door bucks occur on the front face
footing.. Be sure to brace the framed out rough openings in order to keep them vertically plumb and
stable until the rest of the front face is framed out (Operation III).
See Image: HH & PP & QQ & UU & XX
Step 10
Finish building the stem pour mould using 2x8 wood. The nominal dimensions of the stem pour will
be 7-1/4” deep by 8” wide. Make sure that the created wooden form is level from every direction and
very strong.
See Image: HH & II & QQ & RR & SS & TT & UU & VV & WW
Step 11
Once the stem pour mould is complete, run one length of horizontal #4 rebar along the length of the
stem pour, making sure that the horizontal rebar is 3” up from the bottom and 3” in from each side.
Usually it is easiest to attach the horizontal rebar to the vertical pieces of rebar that are already
protruding from the initial pour using baling wire.
See Image: II & SS & UU & VV
Step 12
Pour concrete for the stem walls. But make sure once again that the wooden form is level. Pour the
concrete for each section of stem pour all at once. Pour the concrete up to the top of the the wooden
form, agitate the concrete to make sure it is evenly distributed, and then the concrete is troweled smooth
to a level and uniform finish.
Place anchor bolts in the poured and leveled concrete every 18” on center. Making sure that they
protrude 2+” out of the concrete pour and are vertically plumb.
See Image: II & XX
Interior Footings
See your specific construction drawings for the location of the interior footings for your building.
They are labeled under interior, non-structural walls. These are the can walls that create the walls for the
bedrooms, and the mechanical/plumbing walls that create the kitchen and bathroom spaces.
Step 1
Layout the interior footings with string lines and dig. The interior footings are 8 inches deep by 10
inches wide. Be sure to protect the edges and corners of the buttress footing dig out.
See Image: HH & YY
Step 2
Place two horizontal rows of steel rebar into the bottom of the footings. The horizontal steel rebar
must be 3” up from the bottom of the footings.
See Image: ZZ & AAA & BBB & CCC
Step 3
The interior footings support the interior walls. Some of the walls the interior footings support are
made of cans (these walls function as space dividers only) and some are framed out with wood (to create
mechanical/plumbing walls). Please see image HH, the interior footings are color coded to call out
which interior walls are can walls and which are mechanical/plumbing walls.
When the interior footing supports a can wall, you place the first course of cans directly into the
footing.
See Image: HH & BBB
When the interior footing supports a mechanical/plumbing wall, anchor bolts are placed every 18”
into the poured concrete (which will receive 2/6 Trex once the concrete has set up).
See Image: HH & CCC
Step 4
Pour the concrete into the dug out footings. Make sure the steel rebar in the bottom of the footing
remains 3” up from the bottom of the footing. Shoot in the top of the pour for the interior footings. This
is at subfloor. Use a builder’s level and tape measure. Be sure the top of your pour is level and at
subfloor before the concrete has set up.
Step 5
WHERE INTERIOR FOOTINGS SUPPORT A CAN WALL:
Place first layer of cans directly into the still wet concrete, see image HH to determine which walls
are can walls.
See Image: HH & BBB
WHERE INTERIOR FOOTINGS SUPPORT A MECHANICAL WALL:
Place anchor bolts into the wet footing spaced 18”-24” staggered off of the center line. Be sure the
anchor bolts are protruding from the concrete 2+” above subfloor and are vertically plumb.
See Image: HH & CCC
Exterior Footings
The exterior footings act as a frost barrier and as the support for the entrances to the building. See
your specific construction drawings for the exact location of the exterior footings.
Step 1
Layout the exterior footings with string lines and dig. There are two sets of exterior footings on the
east side of the building and two sets of exterior footings on the west side of the building. All exterior
footings are 1’ wide. The inner most exterior footings are 1’ deep. The outermost exterior footings depth
is determined by local codes (check with your local building authority to determine the depth that
exterior footings must be to reach below frost line). In New Mexico our outermost exterior footings are
generally 24” deep.
See Image: FFF
Step 2
Place two horizontal rows of #4 steel rebar into the bottom of the footings. The horizontal steel rebar
must be 3” up from the bottom of the footings. Two more horizontal rows of #4 steel rebar will be
placed at the top of the pour three inches in and down from the sides and top of the pour.
At the outermost edge of the outer exterior footings a piece of 2” rigid insulation must be placed into
the footing.
See Image: GGG
Step 3
Mix concrete and pour it into the dug out trenches with rebar and rigid insulation in place. Be sure to
do the concrete pour all at once to maintain structural integrity. Use your site level to pour the concrete
to the level of subfloor, and trowel smooth.
See Image: GGG
Step 4
Place anchor bolts into the poured concrete where the exterior footing will receive a door buck
(placed every 12” on center protruding 2+” above subfloor).
If you will be building bottle walls or can walls to either side of the entrance, insert 12” steel rebar
into the exterior footing pour (protruding 5” above subfloor) to connect the masonry wall to the footing.
See Image: HHH
Conclusion
Operation III will include: window and door structural boxes, timbers, bond beam and front stem
wall plates.