Words and Meaning
Many terms, words, and acronyms are used in The Last Straw to describe construction methods, materials, tools, and processes. This section of the Resource Guide is intended to help define those unfamiliar to some. We hope you will add to this list, and correct us if our definition is slightly wrong!
Aliz, a clay slip applied to an earth-plastered wall, almost like paint is used on other surfaces, to seal and beautify the surface; after it has become soiled or damaged, another coat may easily be applied to renew its fresh look. Traditionally, aliz was applied with a sheepskin in a very thin layer.
Bale is a large bundle of straw bound with cord or wire while Bail is the temporary release of a prisoner in exchange for security.
Cast Earth uses gypsum (plaster of paris) and set-retarding additives with soils to form walls with greater tensile strength than adobe and rammed earth.
Cob, moistened earth containing suitable clay and sand content, mixed with straw; formed into stiff loaves of movable size; piled onto a wall and blended with previous layers. Produces a monolithic, load-bearing mud wall. Used to fill voids in straw-bale walls prior to applying exterior/interior coatings.
Comealong/come-a-long, a tool, similar to a winch, that gives one person the ability to pull or lift objects that are very heavy; also used to stretch wire.
Cord of wood, the amount of wood in a stack of 48-inch logs (or cut logs equaling 48 inches) that is 4 feet high and 8 feet wide. A half-cord or face-cord or rick describes a stack of the same dimensions as a cord, except the logs are 24 inches long. Many fireplaces and woodstoves cannot accommodate this length so are cut to 20 inches to fit. – Mother Earth News, October/November 2004
Cordwood (or stackwall) uses split or whole sections of
softwood (without bark) as masonry units laid in two cement mortar tracks (one
on the outside, one on the inside) filled with sawdust and lime or cob
Durawall, a brand name for a welded metal wire product used in reinforcing concrete, sometimes laid between bale courses and tied into the support structure and bales to add lateral strength to the wall.
Earthbags (also called Superadobe) are filled with mostened clay-bearing soil, laid in courses, tamped solid and held together by long-point barbed wire to prevent slippage. Used for domes, walls, fills and foundations.
Ecocomposites. The combination of two or more materials, typically with fibers that remain identifiable combined with a matrix that together are stronger than either material alone.
Fines, finely crushed or powdered material (as ore, rock, stone); very small particles in a mixture of various sizes.
Forb (something you do not want to have in your bales). A broad-leaved herb other than a grass, especially one growing in a field, prairie, or meadow.
Gabions are used for thermal mass and in foundation systems. Containers of wire filed with stone, sometimes supported by upright posts when stacked on the vertical.
Gringo Grip, a product consisting of heavy metal wire and a grasping mechanism wrapped around materials to hold them together securely. Can be used to secure/support hundreds of pounds of weight; works on any thickness straw-bale wall as tie-down. Simple, inexpensive through-the-bale anchor for fastening cabinets, interior wall sections, electrical boxes, fixtures, and pipe/conduit to straw-bale walls.
Gypsum, the raw material (minerals alabaster, satin spar, selenite) used for gypsum plasters, wallboard/drywall; gypsum plaster, unlike cement, expands on setting, does not crack unless there are faults in the backing; must never be mixed with Portland cement.
Hay is not straw. Hay is grass, clover, alfalfa mown and dried for fodder.
HVAC, heating, ventilation, air conditioning.
Insolation is the rate of solar radiation per unit of horizontal surface.
LSL, Laminated Strand Lumber, used as load-bearing header material.
MDF (medium density fiberboard) is a board made of wood fiber and glue. MDF is often used for moldings, casing, finish trim and cabinets. MDF will not split or crack easily.
Nicho/Niche, a recess in a wall, especially for a statue; creates a small shelf space used for display, and sometimes used as a “truth” window in bale walls.
Papercrete (also called padobe or fidobe) is waste paper mixed with water, sand, cement (or clay for padobe and fidobe).
Parging, coating with plaster; especially applying ornamental or waterproofing plaster.
generic name for a polybutelene or
polyethylene tubing commonly used for radiant floor heating and increasingly for domestic water supplies. Comes in long rolls like garden hose. Less expensive than copper, more costly than PVC; no glues, fewer fittings. Various brand names including Wirsbo.
Pise (Pneumatically Impacted Stabilized Earth) (pise de terre means rammed earth) uses formwork to contain a stabilized earth mixture poured at high pressure from gunite machines.
Plinth, a block or slab forming the base of a column.
PSL, Parallel Strand Lumber, made from long, thin strands of wood structurally bonded together in a patented microwave process to make large cross section columns and beams.
PVC, polyvinyl chloride plastic piping; shown to outgas harmful gases, and not used for water supply piping in a healthy home.
Pozzolan, a siliceous volcanic ash used to produce hydraulic cement; any of various artificially produced substances resembling pozzuolana ash.
Purlin, Timber used to support roofing sheets. Usually fixed on top of rafters; a horizontal structural member spanning between beams or trusses to support a roof deck; a horizontal member attached perpendicular to the truss top chord for support of the roofing (i.e., corrugated roofing or plywood and shingles).
Rubble trench foundations eliminate frost heave by the use of
loose stone or rubble to minimize the use of concrete and improve drainage,
more environmentally friendly because cement manufacturing requires the use of enormous amounts of energy. To construct a rubble trench foundation, a trench is dug down below the frost line and then filled with drainage tile and loose stone. A concrete cap is poured to provide ground clearance.
Scoria, a light-weight, dark-colored, glassy, pyroclastic igneous rock containing many vesicles (bubblelike cavities). Foamlike scoria, in which the bubbles are very thin shells of solidified basaltic magma, occurs as a product of explosive eruptions (as on Hawaii) and as frothy crusts on some pahoehoe (smooth- or billowy-surfaced) lavas. Other scoria, sometimes called volcanic cinder, resembles clinkers, or cinders from a coal furnace.
Spalling, the spider-web kind of cracking often associated with freezing damage or water expansion damage.
Stem Wall, anchors the foundation to the ground, usually constructed of cinder block reinforced with steel and concrete, typically three courses high, and poured at the same time as the slab in one continuous pour, marrying the slab to the foundation and the walls to the slab and stem wall.
Strapping, metal bands used to tie down bale walls in the process of compressing the walls.
Straw is the dry cut stalks of grain (wheat, oats, rye, rice, etc.) used as a material for bedding, thatching, and straw-bale construction.
Straw/clay or Light Straw-clay (from the German Leichtlehm), lightweight mixture of straw and clay slurry which coats each strand of straw; the wet material is compacted into a formwork (removed the same day) resulting in a precise wall with enough texture to accept mud plaster without further preparation or lathing. Often used as an “outsulating” wall around a timber-frame structure; can also be used an as infill material between deep structural members.
Toe-ups, a combination of wood and fill (e.g., pea gravel, rigid insulation, blocks) attached to the slab or floor deck to protect the bales from water that might pool on the floor during construction or a plumbing or drainage problem.
Toed-up Foundation. The stem wall is elevated above the floor slab approximately 4 inches. (See Stem Wall)
Truss, a type of framework, usually comprising straight struts and ties, designed to be stiff. This is achieved by the inclusion of a sufficient number of triangles. Some or all of the joints may be fixed rather than pinned, but the main contribution to the stiffness is provided by the triangulation.
Truth Window, an exposed portion of a bale wall allowing a view of the bale so that people know “in truth” there is baled material (straw, grasses, hay) in the wall. Truth windows are a creative addition to any straw-bale building, framed with a variety of materials such as small windows, doors, metalwork, and more.
Urbanite, broken concrete used in foundations, walls and floors. Reuse keeps it out of landfills; it is a free (usually) and strong building material.
Wattle-and-Daub, a substrate for earthen materials made from small branches or twigs woven into a lattice.