GLOSSARY OF TERMS
Mataverde® Decking and Rain Screen Siding
This glossary was created as a helpful guide to explain some of the industry terminology particular to the decking, siding, rainscreen, construction and architectural design communities. We hope you will find the siding and decking terminology helpful. Please browse the definitions and terms on this page. If you would like your own copy please download a complimentary PDF here.
Please feel free to contact us with any questions you may have relating to any Mataverde products or an upcoming decking or siding project requiring our assistance.
DECKING AND SIDING GLOSSARY OF TERMS
Mataverde® Decking, Lumber and Siding
Acclimation: Allowing wood materials to adjust naturally to their new environment. Most of the acclimation of outdoor wood species occurs rather quickly, although it can take years for wood to fully acclimate to the EMC (Equilibrium Moisture Content) of its new environment. Generally, the thicker the wood, the longer the acclimation time required to achieve EMC.
Air dried: Refers to wood that is allowed to dry naturally, without using kilns. Some wood species, such as Ipe hardwood, air dry exceptionally well with minimal movement.
Apuleia leiocarpa: Scientific name for Garapa, a high density tropical hardwood native to Brazil and other regions of South America. (see Garapa)
Beam: Refers to a horizontal framing member, often supporting joists or other horizontal structural components.
Building envelope: The outside boundary of the insulated portion of a building or structure.
Bull Nosing: Rounded edge feature often used for stair treads and sometimes for top railing edges.
Butt Joint: Where the ends of two decking or wood siding boards meet. On a deck, these “butts’ will typically share the same deck joist.
Chatter marks: Marks made on boards during the planing or surfacing process when the material is milled. They occur perpendicular to the length of the board. Also referred to ‘skip planing’, ‘planer marks’ or ‘mill marks’, excessive “chatter” is a milling imperfection. Minor chatter marks can be sanded out. Deep chatter marks are typically ‘defected’ out of a board by cutting the board to a usable length.
Composite decking: The name for wood plastic composite material (WPC). WPC is composed of a mixture of finely ground plastic (virgin or recycled) and finely ground wood particles, referred to as ‘wood flour’. Due to its microscopic size, wood flour is highly reactive to moisture, mold and mildew. Unlike natural wood boards, composite decking has no graining and fiber strength, making it very weak with extremely low span capacity.
Compressive strength: The measure of how strong a wood species is when put under stress along its length.
Contraction: Refers to the size change (shrinkage) experienced when boards lose their moisture. Natural wood boards contract only slightly along their length (linear) and more so along their width (radial). Composite and plastic decking expand and contract significantly along their length and width dependent on temperature. During cold temperatures, synthetic decking will shrink significantly, often creating large gaps. In hot weather, plastic decking shows major expansion, sometimes causing buckling at butt joints and miters.
Cumaru: is a high density exotic hardwood species with the scientific name Dipteryx odorata. This species is extremely hard and dense, coarsely grained and ranges in color from yellow brown to reddish brown to an almost purplish cordovan. Due to its amazing physical characteristics and exotic beauty, Cumaru is often used for boardwalks, walkways, esplanades and outdoor decks.
Cupping: The uplifting of the edges of decking or other boards due to excessive moisture below the material. When decks are designed and built too low to the ground or without proper ventilation, the boards may ‘cup’ towards the sun (like a flower petal) as a result of the stress of too much moisture on one side of the board and too little on the other side. This condition can be minimized by providing adequate ventilation and using screws for installation.
Deck Joists: Structural members that support the decking material above them. Generally they are spaced 12”, 16” or 24” apart from one another (on center). Because hardwood decking is significantly stronger than other decking material options, wider joist spans can be successfully used while maintaining the strength of the deck structure. Synthetic decking requires joist to be spaced much closer together.
Decking material: Describes the actual surface of the deck structure. As this portion of the deck is the most visible portion of the deck, care should be taken to assure that the right material is selected.
Defecting: The process of cutting a board to its usable length by removing any defects such as worm holes, knots, chatter marks, mill marks, or any other undesirable appearance concerns.
Deflection: A measurement of how far a structural member will bend along its length when placed under pressure. High density hardwoods are extremely difficult to bend and therefore show minimum deflection, even under great pressure. Due to their low strength, synthetic plastics and composites bend significantly, exhibiting maximum deflection.
Density: The measure of how much a wood species weighs compared to a specific volume. This measurement is often expressed in grams per cubic centimeter (g/cm³). Due to their exceptional density, high density hardwoods are remarkably strong, hard and durable.
Dimensional lumber: Refers to wood materials that are thicker than one inch.
Dipteryx odorata: Scientific name for Cumaru, a high density tropical hardwood indigenous to areas of South America. (See Cumaru)
Durability: Refers to how long a wood material will last when exposed to outdoor elements and weather conditions. It is also a measure of a wood species' resistance to decay, rot and insects. The US Forest Product laboratory rates materials they test from the highest rating of highly durable, meaning the material should last at least 25 years in an exterior exposure, to the lowest rating of non-durable, which means the wood is not expected to last for more than 5 years of exposure. Most high density hardwood species are rated as durable to highly durable.
Equilibrium Moisture Content: Equilibrium Moisture Content (EMC) is the moisture level achieved when a wood species is considered fully acclimated to its new environment. Wood is a naturally hygroscopic (water absorbing) material and will change the amount of moisture it will absorb based on a number of factors and conditions; changes in the relative humidity, where the wood is located on a structure, the amount of ventilation, exposure to UV rays and more.
Expansion: This is the opposite of contraction. Wood will naturally expand with an increase in moisture. This can be noticed mostly along the width of the board. Synthetic decking boards are known to expand dramatically along their length and width, with an increase in temperature. Increased temperatures can also cause synthetic decking to buckle at butt joints and become extremely hot and exhibit some distortion.
Fiber bending strength: Measurement of how strong a wood species is and how many pounds per square inch of stress is required to break it. High density hardwood species such as Ipe, Cumaru, Machiche and Garapa have amazingly high fiber bending strength. That is why hardwood decking can span so far and still be incredibly strong. Synthetic decking has no wood fiber strength and therefore can span only very short distances and with marginal strength.
Figuring: Describes the amount of lively graining and patterns found in wood. Most domestic hardwood species that have figuring, such as curly maple, burled walnut and other figuring cost significantly more than standard stock of the same species. High density tropical hardwoods typically have a significant of lively graining at no extra charge.
Flat sawn: (See Plain sawn)
Forest Stewardship Council®: FSC® is a worldwide organization that is dedicated to the preservation of sound ecological and environmental practices. FSC was an early pioneer and proponent of sustainable yield forestry practices.
Garapa: High density hardwood native to much of South America. Garapa has golden yellow to light honey brown tones and finer, moiré-like graining. Due to its beauty and stability, Garapa hardwood is often selected for decking, siding and outdoor furniture.
Good side: Denotes the face of an appearance board that the wood is graded to.
Graded side: appearance lumber is graded to the best side of the material.
Grading rules: Vary from species to species and country to country. There are no consistent grading rules throughout Central and South America. Mataverde decking, siding and lumber has developed their own strict criteria that are very similar to hardwood grading rules used in the US. This ensures that lower quality material is “graded out” of Mataverde hardwoods. Mataverde has established guidelines that ensure acceptable tolerances of width, thickness, length, the number and nature of mill marks, worm holes and other imperfections.
Grain: Describes the appearance of the interlocking wood fibers that give various wood species different looks and strength characteristics. Wood species are often described as fine-grained, coarse grained or other descriptions.
Hardwood: Describes non-coniferous, deciduous (leaf bearing) trees. Generally speaking, hardwoods are harder, denser, stronger and more durable than softwood species. Ipe, Cumaru, Machiche and Garapa hardwoods are extremely dense, durable and strong.
Heartwood: The area of log that is away from the bark and softer sapwood. Heartwood is typically significantly more stable and durable than sapwood.
High density hardwood: Term used to describe various species that exhibit extraordinarily high specific gravities. Hardwood species with a density higher than oak are often referred to as high density hardwoods.
IBAMA: Government agency in Brazil that is responsible for the selection of forest parcels to conduct sustainable yield forestry practices. Over the past decade this agency and others have virtually eliminated the illegal cutting of trees in Brazil.
Ipe: Known by the scientific term Tabebuia spp., Lapacho group, Ipe is one of the hardest, strongest and most versatile hardwoods on earth. Sometimes referred to as Brazilian Walnut, Ipe is prized for its high density, incredible fiber strength, superior hardness, scratch resistance, decay resistance, natural slip resistance, fire resistance and imperviousness to most insects. Ipe is commonly selected for boardwalks, bridges, piers, decks, docks, walkways, rainscreen siding and more.
Janka scale: A measurement of hardness of a wood species that measures the amount of pressure required to embed a .4444” inch diameter steel ball, half of its width into a piece of wood. This so-called “high heel test” was established so an accurate gauge could be used to measure flooring and other materials for suitable usages. Oak flooring has a Janka hardness of 980 and is considered an appropriate species for wood flooring. High density hardwood species like Ipe, Cumaru, Machiche, Garapa and others are up to three times harder than oak. That’s why many of these species are selected for high traffic areas such as boardwalks, walkways, bridges and more.
Kerfs: Slots that can be routed into a board for any number of purposes, typically to receive some type of fastener. Cutting kerfs into the edge of decking boards is the most common way to install hidden fasteners.
Kiln dried: Method of drying wood to a uniform moisture content by putting the “green” wood material into a specially configured drying area.
Lateral Bracing: Describes a structural member that is fastened to another structure member to create a stronger structure than either member would provide independently. For example when decking is screwed to deck joists, it provides lateral bracing, which make the deck stronger as a whole.
Life Cycle Cost: Defined as the total cost of building, operating, maintaining and disposing of an asset or structure over its lifetime. Owners and architects are concerned with the overall lifetime of their design and also analyze the overall cost per year.
Lonchocarpus castilloi: Scientific name for Machiche high density hardwood tree. (See Machiche)
Machiche: Common name for the high density hardwood species with the scientific name Lonchocarpus castilloi. This species has beautiful chocolaty brown colors and moderate graining, sometimes exhibiting tropical striping and exotic figuring. Machiche is a beautiful, sustainably harvested and is used for decking, outdoor furniture, rainscreen siding and more.
Mataverde®: The registered trade name for many high quality, high density hardwood decking, lumber and siding species. Mataverde means green forest in Portuguese. All Mataverde hardwood species are harvested in an eco-friendly manner including FSC and IBAMA/SEMA sustainable yield forestry guidelines. Mataverde has developed its own grading standards to ensure consistently high quality materials. Mataverde Ipe, Cumaru, Garapa and Machiche Decking species are covered by a 25 year limited warranty against decay and insects.
Mill marks: Any imperfections or blemishes left on the surface of wood from the planing process. (See ‘chatter marks’)
Moisture content: A measure of how much moisture is in a particular piece of wood and is expressed as a percent of its overall content.
Moisture Meter: Tool used to measure the amount of moisture contained in wood and other materials. The measurements are expressed in terms of percent of moisture content, e.g. 16% moisture content.
OC: (or O.C.) is construction shorthand for ‘on center’. (See On Center)
On Center: Denotes the distance between two structural members, measured from the center of one piece to the center of the next piece. The term is often used to describe the relative positioning of joists, rafters and other framing members. For example, deck joists are often spaced 12”, 16’ or 24” ‘on center'.
Plain sawn: (or flat sawn) Describes the method of cutting a log into straight slices (like a loaf of bread except lengthwise). The resulting boards have a lot of flat and horizontal graining.
Plastic decking: Refers to any number of synthetic plastic or PVC decking materials that are available in a number of colors. This material has limited structural strength (requires joists to be from 12” OC or 16” OC) and can become overheated in direct sunlight. Plastic decking material exhibits significant expansion and contraction with temperature.
Pre-grooved: Also known as ‘slotted’ material, pre-grooved refers to kerfs which are milled into the sides of decking boards to accommodate a hidden fastener. Full one inch thick material is suggested for this type of installation. While decking can be grooved in the field with a biscuit cutter, pre-grooved decking is typically used to save labor costs and provide consistent, uniform sizing for fastening strength.
Quartersawn: Refers to cutting a log into four sections (like a pie slice). The logs are then re-sawn perpendicular to the tree’s growth rings, creating vertical grain patterns on the boards or lumber. This often results in more beautiful figuring to the grain pattern than found in flat sawn lumber. This usually increases the stability of the lumber and reduces expansion and contraction.
Radial movement: A measure of the amount of expansion and contraction along the width of a board. With wood species, the amount of radial expansion and contraction depends on the moisture content of the wood. After wood acclimates and reaches its equilibrium moisture content, there is minimal expansion and contraction of material. Synthetic decking materials experience significant expansion and contraction with temperature. Synthetic decking does not ‘acclimate’ and will experience expansion and contraction throughout its usable life time.
Rain Screen: A method of cladding the building envelope by placing the siding way from the structure. By distancing the siding from the structure, the siding creates a shield or ‘rain screen’, keeping the external elements away from the building envelope. The space that is created behind the siding is called the wall cavity.
Rain Screen Siding: Refers to the exterior cladding material that is spaced away from the building envelope. This cladding protects the structure from rain, snow, sleet and other elements.
Rift sawn: Refers to the method of cutting a log that is similar to quarter-sawn material. The result is wood material that is a lot of vertical graining and higher stability than flat sawn or plain sawn material.
Santa Maria: A medium-high density hardwood species found throughout much of Central America. Santa Maria is a lighter tan to pinkish color and looks very similar to genuine Mahogany with fine darker grained exotic striping.
Sapwood: The wood from the softer area of the tree found closest to the bark. Sapwood is usually not as strong or durable as ‘heartwood’ and is often lighter in appearance.
Scarf Joint: 45° angle commonly cut into the butt end of flooring, decking and siding boards to provide for any expansion and contraction of the ends of wood.
Screws: Threaded metal fasteners and are the strongest form of mechanical fastening typically used in construction. The holding strength of a screw into a stable substrate is remarkably stronger than a nail and most chemical bonding agents.
Softwood: Any species of coniferous or evergreen trees. Most softwood species yield wood that has a very low density and hardness. Most softwood species have a very low durability rating.
Species: Refers to the scientific classification of various trees.
Sticker marks: These can be left on the surface of decking boards when dirt or water contacts a unit of decking material during shipment. These marks are easily removed with washing at the completion of a project.
Sustainable yield forestry: An environmentally friendly and responsible method used to ensure that there are as many mature trees 20 years later as there were at the beginning of a harvesting cycle.
Stability: The measurement for the amount of movement, including expansion and contraction of an exterior building material. Highly stable material shows minimal movement.
Tabebuia: Scientific name for Ipe high density tropical hardwood. (See Ipe)
Thermal bridging: Describes the transmission of heat or cold from the outside of a structure into or through the building envelope. In a rain screen system, it is a preferred design and construction practice to minimize the amount of area that materials come into contact with the building envelope to reduce thermal transmission.
Timbers: Describes heavier wood components that can be use for posts, beams and other heavy structural members.
Tongue and groove: Also referred to as T&G, it describes a milling profile where two pieces can be joined with a minimal joint reveal. The male ‘tongue’ inserts into the female ‘groove’ on alternate edges of the boards creating an interlocking joint.
Usable lifetime: Refers to the number of years a material will last and still be serviceable. This can refer to the amount of time that a material is stable enough to perform adequately. It can also be a subjective term in that many exterior materials can ‘ugly out’ before they actually wear out.
UV: Shorthand for Ultraviolet and refers to the harmful ultraviolet rays from direct sunlight. Protecting wood exterior building materials form harmful rays is very important, particularly during the initial acclimation period when the wood is exposed to the elements.
Wall cavity: Refers to the space created behind the back of a siding material that is spaced away from the building envelope. this space allows for drainage and eleimination fo moisture.
Wood siding: Refers to any exterior cladding material that is made from wood. In a rain screen system, stability and durability are the two most important functional criteria for selecting the proper species for a particular project. Due to their beauty and physical characteristics, high density and medium high density hardwood species such as Santa Maria, Garapa, Machiche and Ipe are often selected for exterior wood cladding.