HAND
MADE ADOBE BRICKS, WALLS AND FLOORS -
QUESTION: Is it
possible to make your own bricks using adobe, or possibly fibrous cement formed
in molds like brick? How low could you get the cost?
EXPERT: Sure
you can do it and get the price down too. Mix Adobe with straw for better
insulation and largely-unneeded tensile strength, not as strong as synthetic
fibres(they don't insulate much in the quantities used) but more than strong
enough for walls in one or two story structures---disregarding labor cost, but
with purchased straw (chop it), purchased sand and onsite screened-clay, my
estimate for a 4" x 10" x 14" would be ten cents for hand-mixed
small quantities. Add for purchase or rental of a pugmill for mixing clay
and straw (the hardest part of the operation). Running the straw through a
garden-shredder would be easier and more readily available than an electric or
hydraulic shear (rotary cylinder or reciprocating four-foot paper-cutter)
Add
another five to ten cents for other additives---slaked lime, Portland and
asphalt emulsion, depending on how you want to balance out the characteristics.
Portland adds compressive strength, straw tensile strength, asphalt
water-resistance.
Just
one problem for me. I like the idea of brick in certain areas mud room, garden
rooms, green house etc. but that surface is pretty hard on your
legs, hurts a lot more if you fall on it, can be slippery, and dishes etc.
will break. It can also appear quite cold. While rugs would help. I'm not
sure that condensation, temperature differentials might not cause molds
etc. to flourish under carpet, or padding.
EXPERT: The purpose of vapor-barrier is to prevent
capillarity-wicking or vapor-transmission from earth (which would otherwise keep floor surfaces damp).
QUERENT:
It's the damned dirt, airborne, spilled, tracked-in and ground into carpeting
that transforms it into your own private Love Canal for living room, hallways
and bedrooms. No wonder allergists get rich. Did I say I hate carpeting? That
goes for padding too! A few small braided throw-rugs that you can wash, take
outside in bright sunlight, hang over a clothesline or wall and beat hell out
of is still my favorite way of putting something soft (and clean) underfoot.
Don't know who sells carpet-beaters nowadays though---have to make your own if
Lehman's doesn't carry them. In the interior living rooms I'd prefer wood, or
possibly laminated wood surfaces, which appear warmer, are easier on the
feet, can be covered with area rugs for interest, and are fairly easily maintained
if properly sealed, and glazed. Again just my preferences.
EXPERT:
Traditional full-thickness hardwood-strip flooring doesn't buckle, is level
(unlike most wood-tiles), comfortable and good for low-traffic areas. If you do
it, pay the price and do it right. And get those braided throw-rugs (with
non-slip backing so you don't inintentionally go skiing)
However
if fibrous cement were possible. and somehow could be cushioned by adding some
other ingedients with a little give, colored and or patterned it might prove
very exciting for groundfloor considerations. HMM...is that possible?
EXPERT:
Yup. The Steen or Swearingen earthen floors are softer-feeling than wood, wear
well, are easily repaired or replaced. Enjoy the luxury of Cordovan leather
floors without the cost.
Wouldn't
it be possible to build our own and save 5$ a block? Tiv, Gene, know of any
formula for taking REAL ADOBE SOIL which is gummy, adding some concrete type
product that is cheap to purchase by the truckload...and making a block which
would either dry stack or mortar up and be strong. Any files out there, recipes
for making our own HOMEY looking, rustic blocks out of clay soil?
EXPERT:
if by "gummy", you mean clay, cheap lime is a better binder than
Portland. Portland is more effective with clean, sharp sand and gravel. There's
lots of ways to make adobe brick or formed walls, and any of them good enough
if you have a wide roof overhang (which you should have anyway). You can
"puddle" brick or a wall, add chopped straw for lighter weight and
more strength.
Buy
the Ken Kern book, "The Owner Built Home"---your best builders'
library investment.
My
favorite website on your particular question of numerous specialty adobe mixes
is gone. Try googling the words ‘adobe mix’
http://shell.rmi.net/~adobeman/index.html
(this is an 8 hour video on all phases of making and using adobe brick)---and
any book by Paul Graham McHenry will be of great help.
http://www.adobebuilder.com/cgi-bin/id?ab/navab.html,ab/pumice_adobe.htm
(pumice, clay, bitumil (asphalt emulsion) makes a great adobe brick)
http://www.snowcrest.net/smb/mudfloors.htm
(and don't forget mud floors---a
favorite of mine)
http://www.deatech.com/canelo/pics/
(Canelo project---note the straw brick
and two-layered Carrizo (straw with light clay and perlite slip) with 3
inches of concrete over it in a vaulted roof.)
http://www.zetatalk.com/shelter/tshlt04c.htm
(adobe recipe)
http://newdeal.feri.org/library/i_c_t.htm
(adobe brickmaking in 1940 New
Mexico)
http://www2.cr.nps.gov/tps/briefs/brief05.htm
(preservation of historic
adobe buildings---and description of original processes)
http://www.homeownernet.com/articles/adobe.html
(simple local materials
transformed into a work of art---the adobe, viga and latia way)
http://www.selfhelphousing.org.za/mudbrick.html
(Australian introduction of
asphalt emulsion in South Africa adobe brick)
The Wood Burning Adobe Barbecue
By AZ rancher, Boyd Crick
This
adobe barbecue features a wood heated oven which is large enough to hold a
turkey pan. The adobe fire box and main body of this barbecue can provide the
grommet cook with any style of cooked meat: from steamy pit roasted to smoked
(for authentic machaca). The choice is yours. This versatile barbecue also
allows for regular up-draft cooking on wood or charcoal. (After three years of
using mine, I find that I usually just
put some charcoal in the built in hibachi and barbecue on it). I only roast
on special occasions. The oven cooks a turkey in the same time as a regular
oven. Do not be fooled by the slightly pink color of the meat. Smoked meat will
give this appearance. Of course how long you cook it is up to you--only you. Do
not let a committee help you.
The
inside of the adobe fire box and heat vents will harden with use, unlike
concrete which will only get soft when it has been heated. Also the adobe is
easier to shape than fire bricks and can be formed into pleasing and functional
shapes. Furthermore the adobe can always be altered or added on to. If you have ever tried to add new concrete
to concrete which is already cured, you will know that it doesn't work well--even if you use the white concrete
adhesive form the lumber yard. However, unfired adobe is not water-proof so some
precautions must be taken.
The
first precaution is the masonry base. Just like a house, the barbecue needs a
masonry base because adobe will not support much weight when it is really wet
through and through. The masonry base keeps the adobe elevated where it will
not stand in water. You should consider the drainage of your yard when you
locate your barbecue. The other necessity is a patio roof or colored stucco, or
both. The patio roof is the most effective way of keeping the rain from
gradually eroding your barbecue. If stucco is used, one must decide whether to
use crack-control strips (lumber yard)--the barbecue will expand with
heat--just enough to crack the stucco. I rather like the cracks as they make it
look rustic. You can let the cracks develop and then just fill then with
flexible tile grout. My choice was to just let the barbecue age a few years
then build a roof over it. This way it looks like an Indian ruin which has been
preserved. The look is just right for my yard. You can also whitewash the
barbecue with quicklime and water. Ancient peoples kept their adobe structures
protected by regular whitewashing. (A little red iron oxide or stucco coloring
can be used for color). Some building codes require that houses built of adobe
are really bitadobe. This means that a small amount of asphalt oil is added to
the mixture to improve water resistance. I do not recommend this type of adobe
for a barbecue because I think it would make the meat taste weird. ( would also
caution against burning much pine or pitch pine for the same reason. Mesquite,
Oak, other hard woods and prunings from nut or fruit trees work best. Even mulberry and hackberry work. )
Take
time to think about work surfaces, sinks, storage and such things before you
start. It always pays to spend plenty of time planning. Most of all, think and
re-think about where you want to place your barbecue. If you have a portable
barbecue you can test out parts of the yard before you commit to a location.
Remember, you may even want to build a roof over it (make it tall enough or
vented)
My
barbecue is built on a concrete slab which is at least 6'x8' and 3" thick.
If you already have a good patio you can skip part #1. If you live where it
gets really cold, you should build your barbecue on a deep footing so ice
cannot form between the slab and the base of the barbecue. If are careful when
you finish the slab, you can make sure that it drains away from the barbecue.
(See illustration #1 the basic concept of the updraft barbecue).
#(1).
Be sure to prepare the sub-grade as necessary depending on the site. I use
6" of sub-grade. This means that you need a rectangular excavation at
least six feet wide, eight feet long and nine inches deep. The first six inches
of the excavation is filled with sub-grade. Contractors use stuff called ABC
which is a compressible mixture of gravel, sand, and silt. They pack it with a
pneumatic tamper or a special tractor roller. I use rammed concrete. Mix about
three parts gravel + two parts sand (sub-grade sand does not need to be
perfect) and one-half part Portland cement. Add ONLY enough water to dampen the
mix. The trick here is to pack the crumbly mix with wooden tamps, or get your
friends to stomp on it as it is added to the hole. COMPRESSION is the key and
fluid mix will not compress. After all the sub-grade is in you can start
pouring the slab. If you want to pour the slab later, be sure to sprinkle the
rammed sub-grade as soon as you have packed it in. Sprinkle it every thirty
minutes for about two hours, then cover it with water. Keep it wet until you
pour the concrete. This sub-grade tends to suck the water out of concrete.
Which is why I like to get the concrete poured before the sub-grade cures. If
you want your slab to be elevated you can use more sub-grade and build a form
for the concrete. The form can be made of oiled 2x4s. The form is supported
with wooden or metal stakes inside and out. Earth from the excavation can be
packed against the outside of the form. The wet concrete you will fill the form
with is heavy and will exert pressure on your form. You should use a concrete
mixer so the form can be filled quickly. For the slab, use just enough water to
make the mix flow in the mixer. I start with a mixture of 2 parts pea gravel+1
part sand + 1 part cement. I fill the form evenly across the bottom. When I get
close to the top, I use equal parts sand, pea gravel, and cement. This makes it
easier to knock the gravel down below the surface (the end of a good rock rake
will suffice if you do not have a tamper). You can strike off the concrete with
a 2x4 which is worked across the form from one end to the other (get a helper
to work the other end and use a sawing motion ) and finish it as much as you
like. Obviously, most of your slab will be under the barbecue anyway. I like to
add some extra concrete to the middle and work it with a finishing trowel so
that the middle is raised slightly. Water should drain away from the barbecue
base although it is also masonry.
Be
sure to have plenty of help when you pour the slab. It takes at least one
person to run the mixer, and one person to spread and pack the concrete.
Otherwise, the concrete in the form might harden before you can spread it out
and pack it down.
If
all this seems like too much, you can just get some concrete blocks or large
granite rocks to build your barbecue on. The idea is to keep the adobe elevated
from rain water on the ground. I just built enough slab for my barbecue--then
added other sections gradually to make a patio.
All
concrete must be kept WET and cool. Depending on the weather, it will take
about 4 weeks to cure the slab--the slower, the better. I use wet blankets and
straw to keep concrete wet and cool. Remember, concrete gets hard because some
of the water in the mix combines with the cement to form hard crystals. If the
concrete is allowed to dry out before it is finished forming the crystals, it
will just crumble. This is why concrete gets crumbly after it is exposed to too
much heat. When the chemical water is driven out of the hydrate crystals, the
concrete is ruined. On the other hand, adobe gets hard when it dries out. The
clay in the mixture gets harder when it is dry. The silt and sand just reduce
the shrinkage enough to prevent cracking. When heated, the adobe just gets
harder.
A
word or two about cement stabilized adobe. Rammed earth is a sandy soil which
is stabilized by the addition of a little Portland cement. It gets its hardness
by virtue of compression. (It can even be water proof). The catch is that you
need really strong forms to withstand the pressure. DO NOT add Portland cement
to your adobe. Rammed earth is packed into place as soon as it is mixed.
However, your adobe will be added gradually. If you mix quicklime or cement to
your adobe you will end up with a pile of hard mud which you cannot use. If you
try to re-wet or reuse this stuff, it will just crumble. That is why you will
see a good brick or stone mason really cleaning the old mortar out of the
mixing boat between batches. You can add water to mortar only once. After that
it must be dumped. The old mix will contaminate any new mix. Moreover, it will
absolutely ruin your adobe. There it is: Masonry or concrete to protect against
water and adobe to withstand heat and sculpt or form with. Remember, you need
helpers--not a committee of "experts."
#2.When
the slab is cured, construction of the actual barbecue can begin. The first
step is to draw a rectangle on the slab where the barbecue goes. .Make it at
least 6" oversized so you can see the lines. After the mortar is down. I
use colored chalk. At this point you could use blocks or even fire bricks, but
I have access to good hard granite rocks (actually they are Pinal Schist). You
need good hard stones without cracks. Sedimentary rocks like sandstone or slate
will also work. Just be sure to use rocks which are used for building or
paving. Do not try untested rocks. In my area, one can get permission from the
forest service to get rocks by the road-side in parts of the public lands. If
you have a truck, it can make a fun outing.
The
rocks should be soaked in water for at least 48 hours, then scrubbed with a
stiff brush and a little dish soap. Rinse them well. This will insure that the
rocks stick well and prevent them from sucking the vital water out of the mortar.
Take your time and dry fit the rocks before you mix the mortar. Then remove the
rocks from the slab and mix some mortar. You can then replace the rocks on the
bed of mortar. I mix one part Portland cement to three parts coarse sand with
the minimum amount of water. If your rocks are smooth, one-fourth part of
quicklime can be added to make the mortar sticky. Hand mixing requires less
water than the concrete mixer and is therefor preferable. If you must use a
machine, A mortar mixer is better than a concrete mixer. Good mortar is just
too sticky in a concrete mixer. I mix by hand in a wheelbarrow. The mortar must
be stiff enough to stand at least 6" tall when shoveled onto the slab.
Contractors use a slump test. The idea is that if you mix it long enough, it
will be able to stand vertically instead of just running. Do not add excess
water. It is best if you add water gradually as you mix. I know people who make
a slurry and then add dry ingredients to stiffen the mix. While this will work,
your mix will be better if you avoid it (more chemical reasons). Also this
mortar can be colored by the addition of stucco color which you can get at a
lumber yard.
The
rocks can be placed in the perimeter. They should have at least 3" of
mortar under them, and 2-3" of mortar between them. Once the perimeter is
complete, the inside can be filled with rocks and mortar. This masonry base
must be at least 12" high around the perimeter and elsewhere except
beneath the fire box. Leave room for the 4 to 6" of adobe which insulates
the masonry form the bottom of the fire box. Remember, heat is not good for
cement. Also, don't allow any rocks to project up past the mortar (see
illustration#2)
#3.
While waiting for the base to cure, you can begin working on your adobe.
Traditionally, adobe was very practical stuff. It was made from the earth which
was dug-up as a result of digging a basement or other necessary hole. The
fortunate builder found layers of clay, silt, and sand as he dug. The separate
earth components were placed in separate piles. These piles would provide the
equal parts of sand, silt, and clay which form the optional mix. When the best
proportions are not present, straw or cow manure is used to bind the mix. I do
not resort this method unless I want light-weight adobe. Bugs and small
creatures like to make earth sheltered homes in the straw type adobe. If you
use this method, make sure the barbecue is in a place where bugs will not bug
you. You can make test batches of this type of mixture and test it by: Dropping,
crushing, and heating it. I used equal parts of red clay, coarse sand, and
silt. This is the strongest mixture. If you have a truck, you can haul the
ingredients you need. Contractors and road crews often dig-up good clay. Sand
and silt can be found in dry washes. Screen out rocks and clay lumps. You will
probably find that your sand contains some silt, or that the clay (not always
red) contains some sand ect. The way to sort this out is with the settlement
test. Take each of your ingredients and dry it out completely. The clay should
be broken into small pieces and dried then crushed and dried more. Dry it in a
warm oven if you have to, but keep it below 200 F or it will blow little bits
of clay all over the place. Do not even think about drying it in a microwave.
Next get a jar with straight sides --like a graduated cylinder. Put enough of
the sample and water in the jar to fill it about 2/3 full. Next, shake it, let
it sit, and shake it again. You will have to shake the clay sample over and
over. When the sample has been completely mixed, let it sit on a level surface
until it is completely settled. The different components will settle into
distinct layers. The sand will fall to the bottom. The next layer will be the
silt, and the top layer will be clay. Now you can figure out the portions you
need to get equal parts. Write down the portions you try and give the mixture
the settlement test. When you get equal parts, you will know what it takes to
get equal parts of clay, silt and sand. Now you can use a shovel to measure out
the adobe mix. Good adobe does not have to be perfect. Just remember, if it has
too much clay it will shrink a lot when it dries and this can cause it to
crack. On the other hand if it has too much silt or sand, it will tend to
crumble. Furthermore, if you cannot get your sediment test to work (ie the
sample jells and will not settle into layers, you probably have soluble salts
in the soil. this soil can make good adobe, but you need to test it. You can
make test blocks by packing the mud into a small form made of 2x4's. I once
used soil with a little caliche (calcium carbonate) to build a very nice adobe
fireplace. Once you become accustomed to your local ingredients you can do like
the primitive people and just eyeball it. Where I live there is red clay with
decomposing granite sand in it (its called adobe soil). I just mix it with
about two parts of silty sand from a dry wash, and I have a very strong
mixture.
Once
you have your dry ingredients on hand and have a little experience with them,
you are ready to start mixing mud. After your piles of ingredients are
screened, they can be mixed with plenty of water in a mixing boat with a mixing
hoe or it can be mixed in a bowl shaped hole with the feet. Some people buy
beer or sodas and invite some friends to stomp around in the mud. After the mud
is completely mixed, take it out and pile it up for a while to cure. After it
has dried and stiffened up a bit it will be easy to handle and pile on the
base. I start a new batch soaking in the hole while the previous batch is
curing on a slab. The adobe can be kept fresh by covering it with a plastic
drop cloth.
After
the base has about four inches of adobe on it, it is time to start building the
sand form. You need damp sand which is sticky enough to hold its shape. Some
adobe can be added to accomplish this. (Some artists use a few drops of the
previously mentioned concrete adhesive in a shovel full of sand, but do not
over do). Do not add more adobe than is needed, because you will have to dig the
sand form out after the adobe has hardened. The sand should handle like
sand-castle sand. The sand will form the needed cavities in the barbecue. The
outside perimeter can be supported by forms made of concrete blocks and dirt
stacked around it anything heavy. Don't worry about the outside much. It can be
sculpted into shape after the main mass is built. In fact even the fire-box and
the heat channels can be carved into it after the adobe mass is built, however
that is the hard way. The beauty of this method is that the sticky sand is
shaped to create the fire box and the heat vents. When the adobe is cured, the
sand is removed and the inner parts are finished. once you get used to
visualizing the empty spaces as solid, you can use this method to make neat sculptural
stuff with adobe and concrete
If
desired, this barbecue can be built without the oven or it can be added later.
The great thing about adobe is that one can always alter it. I like the option
of building in stages as I get the time and money. I can upgrade and use my
barbecue at the same time. Your choice is not " set in stone," just
be sure to leave plenty of room for possible expansion .
# 4
The oven arch can be built of light-weight adobe. This can be made by adding
straw, wood chips, cow manure, or vermiculite to the basic mix. (Adobe mixed
with some vermiculite can also be used to line the bottom of the fire-box for
better heating). However, I prefer to use fired bricks for this part. I was
fortunate to locate some good bricks from a quicklime plant. These are safe to
use because they have only been used to heat calcium carbonate into calcium
oxide. Never use bricks which have been used for smelting or other questionable
purposes--they absorb impurities. New clay arch-bricks can be purchased. Or
fired adobes can be bought inexpensively. If you want to make fired adobes for
the oven arch, you can mix two parts clay, one part silica sand (#30 lumber
yard) and one part wood chips or vermiculite. I use equal parts kaolin and ball
clay (pottery supply) for my clay--if you use adobe clay, you should test fire
a brick to be sure it will fire good. To fire the bricks, you will need a large
kiln or a place where you can stack a "clutch" and make a lot of
smoke. The bricks are stacked on edge with wood between them the whole thing is
fired like a bon fire. The bricks in the middle get hotter than the ones at the
perimeter. Instructions for firing the bricks can be found in a book called
"Pioneer Pottery" by Cardew. It is a common book should be in your local
library.
Arch
method #1
Like the arch for the fire box, the arch
for the oven can be made with a sand form. An arch this big will need some
support. You can simply place a piece of 1/2 inch plyboard at the front and
back of the arch. These pieces can be supported by the use of 2x4's which are
angle cut at the ends and staked at the ground. Use nails to hold them at the
pylwood (fig 5). This form can be covered with lightweight adobe or straight
bricks which are adjusted with mud (see fig 3-b). After it dries awhile you can
take the sand out.
Arch method #2
I do not recommend this method for this project, but I have included it for
those who may need it. One easy way to use either fired or unfired adobes is to
build a bent plywood arch form. This will make a barrel arch. take a piece of
1/4 inch pylwood and bend it so that the ends can be screwed onto the ends of
two 2x4s The bricks are placed edge-wise. The mortar between the bricks will
adjust the shape to the arch. In other words the mortar will be wedge shaped.
This way you need not make arch bricks. You only need a block mold or a gang
mold made of 2x4's to make the bricks. The gang mold looks like a ladder but
the 2x4's are on edge. Use cement mortar for fired bricks, and adobe mortar for
unfired adobes. The same adobe which is used for the bricks should be used for
the mortar. If you choose this method, make your oven arch form first then
build the adobe base to fit it. I test it with a turkey pan with the lid on.
One
neat way to design a template for an arch is to hang a limp small-link chain in
front of a piece of card board. First, draw a line which is as long as the base
of the arch. Next, find the middle of this line and use a square to make a
perpendicular line from the center point. This is the center line. This center
line is as long an the arch is high. Next, hang the cardboard upside down on a
wall and use a plumb bob to get the center line vertical. Now you can secure
the cardboard and recheck for plumb. Next drive a small nail at each end to the
base line. Now you can hang a limp-small-link chain from the nails. let it hang
down to the end of the center line. Now you can make some marks or trace out
the line made by the hanging chain. You now have a cantonary arch. Gravity will
make it for you. If you cut out the arch, the remaining template can be dragged
over the sand arch to check it.
For
the front and back of the oven arch. make a cardboard template of the finished
arch and lay it on a 3-1/2 inch slab of firm brick clay.
Cut out the form with an old butcher knife. Then cut the slab into bricks these
can be fired. I glazed and fired mine in a small kiln. (If you know a potter, you have it made). If you
fire bricks, be sure you dry them completely before firing. The wood chips and
or vermiculite will help prevent them from exploding as the steam escapes. The
bricks in the back of the oven part were mortared in except three at the top.
They are removed during cooking for smoke draft. If you do not want to fire
them, you can just stick them with adobe. The bricks in the front are left
loose, I just remove them, put the meat in and restack them for cooking. This
setup drafts perfectly and no chimney is needed--if you follow the diagrams.
You may want to build an oven door if you want to cook bread. (I did not want
to change the looks with iron parts). You can also just stack light weight
adobe bricks and fresh lightweight mud in front after you put the meat into the
oven. This provides the steamy atmosphere needed for pit roasting. It may be a
bit of trouble, but it is way easier to close the oven with fresh adobe than it
is to dig a hole in the ground for pit roasting. Be sure to leave a good ledge
at the front of the oven so you can use a double course of bricks this will
better insulate the oven. In designing this barbecue, I used my years of
experience as a kiln builder to calculate the size and shape of the fire box
and the heat chambers. You will actually see the fire drafting horizontally
into the chambers. The oven will heat up quickly if you follow the plan for the
innards. Do with the outside as you will. Do remember to let the barbecue dry
good and break in with a small fire at first. And remember it is normal for it
to crack a little.
Good
luck, and if you need advise just write me or send me an email.
Boyd Crick boyd@boyd-crick.com
RT 2 box 78
Globe, AZ 85501
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