Unit 1 Building Materials Modern carpentry Building construction

Building materials Many different types of materials go into the construction of a modern residence. A carpenter needs to be familiar with these materials. All of these materials have special properties that makes it suitable for it’s application. This includes natural and man made (composites) products.

Common Construction materials Sawed lumber Engineered lumber Plywood Particleboard, Hardboard, and Waferboard Steel and Aluminum Metal fasteners Concrete Wood and non wood materials for shingles and flooring Adhesives and Sealers Gypsum board and other interior covering

Sawed Lumber Lumber is one of the greatest natural resources in the world today. Because it is easy to saw and rework on the job site makes it one of the best choices for residential construction.

Sawed Lumber Once a tree is harvested and cut in to uniform thicknesses, width, and length it becomes lumber. Lumber is the name given to natural or engineered products of a sawmill.

Lumber includes Boards used for flooring, sheathing, paneling and trim. Dimension lumber used for sills, plates, studs, joists, rafters, and other framing members Timbers used for posts, beams, and heavy stringers.

Wood Structure and Growth The growing parts of a tree are: The tips and roots The leaves The layer of cells just under the bark called the Cambium

Wood Structure and Growth nutrients and water absorbed by the roots travels in a layer under the bark known as sap wood to the leaves, and combines with carbon dioxide from the air. through a process called photosynthesis, sunlight changes these elements in to food. The sap caries this food back to various parts of the tree.

Annual rings The rings of a tree are made up of two layers: spring wood and summerwood. Growth of the rings takes place in the cambium layer in the spring and fall. In the spring growth is fastest and slows during the summer and fall seasons

Annual rings

Kinds of Wood Lumber is either softwood or hardwood. Softwoods come from the evergreen, or needle-bearing trees. Another name for evergreen is conifers because many of them bear cones. Hardwood comes from broadleaf (deciduous) trees that loose their leaves at the end of the growing season.

Kinds of Wood Soft woods Douglas Fir Southern Pine Western Larch Hemlock White Fir Spruce Ponderosa Pine Western Red Cedar Redwood Hardwoods Maple Oak Walnut Cherry Birch Beech Willow Elm Mahogany

Kinds of Wood When it comes to the rough framing of residential construction softwood is more commonly used with Douglas Fir being most commonly used. Hardwoods are most commonly used for finishing such as; flooring, trim, casing, cabinets, and furniture.

Moisture Content and Wood A piece of wood will give off or take on moisture from the air around it until the moisture in the wood is ballanced with that in the air. As the moisture in wood changes so does the wood size and shape. The average moisture content of lumber in an homes is 8%.

Moisture Content and Wood

Lumber Defects A defect is an irregularity occurring in or on wood that reduces its strength, durability, or usefulness. Types of defects Knot Split and Checks Wane Blue Stain Decay Holes Warp

Lumber Defects Knots are caused by an embedded branch or limb. Knots reduce the strength of the lumber. Split and Checks is the separation of the wood fibers which run along the grain across the annual growth rings. Wane is the presence of bark or the absence of wood along the edge of a board. Wane forms a bevel and may reduce width.

Lumber Defects Blue Stain is the discoloration caused by a mold like fungus, blue stain has little or no affect on wood strength. Decay the disintegration of wood fibers due to fungi, decay is often difficult to recognize in its early stages.

Lumber Defects Holes are caused by handling equipment or boring insects and worms. Severe holes can weaken lumber greatly. Warp any variation from a true plane surface. Warp may include any one or a combination of Cup, Bow, Crook, and Twist

A; Crook B; Twist C; Bow

Wood Grades Wood grades are divided into two categories one for soft woods and another for hard woods. The carpenter must understand that quality construction does not require that all lumber be of the best grade. In a given structure, several grades may be appropriate. The key to good economical construction is matching the proper grade with its function

Lumber size When listing and calculating the size and amount of lumber, the nominal size is always used. Ex 2x4, 2x6, 2x8, ect. The nominal size is the lumbers rough unfinished size. The dressed size is less than the nominal size as a result of seasoning and surfacing. Dressed sizes are enforced across North America and must be maintained through the industry.

Panel Material Panel materials for construction purposes are constructed in several different ways. Plywood Softwood Plywood Grades Wafer board Oriented Strand Board

Plywood Plywood is constructed by gluing together a number of layers (plies) of wood. Each layers wood grain is turned at a right angle to the one before it. There is always an odd number of layers so the panel is balanced. This is so the grain runs in the same direction on either side of the sheet. The thicker the panel the more layers required.

Exterior plywood Exterior ply wood is bonded using a waterproof glue. It can be used for siding, concrete forms, and other constructions where it will be exposed to the weather or excessive moisture.

Softwood plywood grades Softwood plywood is for general construction purposes It must be noted that many species of softwoods are used in making plywood. There are 5 separate plywood groups based on stiffness and strength. Group #1 is the stiffest and strongest.

Waferboard Is produced from High quality flakes (chips) of wood that is about 1 ½” square. The chips are bonded together under heat and pressure with resins. The 4’x8’ sheets range in thicknesses from ¼” to 1 1/8”

Oriented Strand Board (OSB) Similar in appearance to waferboard and also made up of wood fibers (chips). The fibers of OSB are placed in successive layers arranged at right angles to each other.

Engineered Lumber It once took more than 80 years to saw mill size. Tree farming has shortened this to 27 years but has had a great affect on the spacing of the annual rings. Lumber today have annual rings further apart making it weaker and not suitable for spanning long distances.

Engineered Lumber Some engineered lumbers include Laminated-Veneer Lumber (LVL) Glue-Laminated Beams Wooden I-Beams Open-Web Trusses

Laminated-Veneer Lumber (LVL) Constructed much like plywood with many lavers of wood. Each laver is 8” wide and 1/8” thick Each laver is coated with glue, stacked, placed under pressure and heated until dry

Glue-Laminated Beams Glue-laminated beams are made from a stack of 2x4 or 2x6 to form a beam up to 30” deep. These beams are used when long distances must be spanned.

Glue-Laminated Beams

Wooden I-Beams Wood I-Beams are constructed of laminated veneer lumber while the web is made of plywood or oriented strand board (OSB) Wooden I beams are light, strong, and straight. They are often used as floor Joists

Wooden I-Beams

Open-Web Trusses Open-web trusses are also often used in place of floor Joists. They are used when long spans are demanded. They are constructed from solid 2x4s

Open-Web Trusses

Steel framing P.37