Wednesday, September 17, 2014

Review Notes: Building Materials - Building Boards


Building Boards – a group of sheets of building materials often faced with paper or vinyl, suitable for use as a finished surface on walls, ceiling, etc.

Kinds of Building Boards:
1. Plywood – made by bonding together thin layers of wood in a way that the grain of each layer is at right angles to the grain of each adjacent layer.
Veneer - each layer of plywood
Rotary Cutting – a method of cutting wood veneer in which a log is fixed in a lathe and rotated against a knife so that the veneer is peeled from the log in a continuous sheet.
2. Hardboard – made from processed wood chips.
Three grades of board:
a. Standard – flexible to be quite easily bent
b. Tempered hardboard – made by impregnated standard board with a tempering compound of oils and resin and baking it to polymerize the tempering material.
c. Low-density hardboard – not as strong and durable as standard hardboard.
3. Insulating Fiberboard – made from three types of fiber – wood, sugar cane, and asbestos, and binder, formed into a board.
4. Chipboard – a large class of building board made from wood and particles and a binder, often faced with veneer.
5. Particle Board – a hardboard made from relatively small particles.
6. Gypsum Board – a wall board having a gypsum core.
7. Straw Board – a hardboard made of compressed wheat straw, processed at 350 to 400 degree Fahrenheit and covered with a tough kraft paper.
8. Asbestos-cement Board – a dense, rigid board containing a high proportion of asbestos fibers bonded with Portland cement, resistant to fire, flame, and weathering, has low resistance to heat flow.
9. Corkboard – from the outer bark of the cork oak tree, cork granules is mixed with synthetic resin, compressed and formed into sheet from 1 to 6 inches thick and baked under pressure into rigid boards.
10. Paperboard – made into two different types: a paper pulp pressed into boards 3/16, or ¼ in. thick, 4 ft. wide, and 6, 7 or 8 ft. long. Usually one surface is primed for easier finishing. The other is a layer of stiff paper folded into corrugated from and faced on both sides with a thick paper backing, cemented to the core.
11. Mineral Fiberground – thick mats of mineral fibers, usually glass or rock wool are covered with a backing of stiff paper on one or both sides to form rigid boards, ranging in thickness from ½ to 2 in. The usual board size is 24 x 48 inches.
12. Plastic Foamboards – polystrene and polyurethane plastics are formed by a patented process to about 40 times their original volume. Used for perimeter insulation for concrete floor slabs, for wall and roof deck insulation, and for roof decks when properly supported.

Building Papers – in building construction, paper is used for sheathing, roofing and insulation, in making asphalt shingles, laminated and corrugated building products, and concrete form materials, as a moisture and vapor barrier; as cushioning material; as wallpaper; as an envelope or sheath for other materials; and as a fireproofing material.

Type of Wood Pulp:
1. Mechanical Pulp – or groundwood, is produced by grinding blocks of wood against a revolving abrasive stone or by grinding steamed wood chips in a grinding mill.
2. Chemical Pulp – produced by digesting wood chips in various chemicals to free the cellulose fibers from the liquid binding.
3. Semi-chemical Pulp – wood chips are first subjected to a mild chemical treatment and then mechanically disintegrated in rotating disk refiners.

Types of Paper:
1. Sheathing Paper – used to provide an airtight barrier over walls, floors, etc.
2. Roofing Paper – A. roofing felts - used in making a built-up roof and are usually produced in 36 in. wide rolls, in various weights from 3 to 20 lb/square. B. Rolled roofing – a heavy, mineral surfaced paper used as a final roof covering, made 18 and 36 in. wide, in various weights from 45 to 120 lb/square.
3. Insulating Paper – used to secure bulk and entrapped air with as much strength as possible. Insulating papers are made from both wood-fiber insulating paper and asbestos fibers.
4. Cushioning Paper – similar to wood-fiber insulating paper, but less attention is paid to strength. Its chief use is for cushioning under linoleum, carpets, or slate roofing.
5. Vapor Barrier Paper- intended to prevent the passage of moisture vapor through walls, ceilings and floors.
6. Laminating Paper – a special, high strength kraft paper made for use in the production of plastic laminates. The thin, strong paper is impregnated with liquid plastic resin and several sheet are laminated together under heat and pressure to form the base for the plastic sheet.
7. Concrete Form Paper – made from strong kraft paper in the form of a spiral tube and boxlike from made from corrugated container paper.
8. Wallpaper – paper from which decorative wallpaper is made.
9. Envelope Paper – used as an outer covering or envelope for a number of building materials. One of these is gypsum board, composed of a layer of calcined gypsum covered in both sides by a sheet of kraft paper.
10. Fire Proofing Paper – made from asbestos fibers, since this is an incombustible material. This material maybe in the form of matted paper, similar to asbestos insulating or roofing paper, or it may be in the form of a cloth woven from thread spun from asbestos fibers.


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