Friday, January 2, 2015

Ready-mix concrete

                                                               Ready-mix concrete

             Ready-mix concrete is concrete that is manufactured in a factory or batching plant, according to a set recipe, and then delivered to a work site, by truck mountedin–transit mixers. This results in a precise mixture, allowing specialty concrete mixtures to be developed and implemented on construction sites. The first ready-mix factory was built in the 1930s, but the industry did not begin to expand significantly until the 1980s, and it has continued to grow since then.

              Ready-mix concrete is sometimes preferred over on-site concrete mixing because of the precision of the mixture and reduced work site confusion. However, using a pre-determined concrete mixture reduces flexibility, both in the supply chain and in the actual components of the concrete.
Ready-mix concrete is also referred as the customized concrete products for commercial purpose. Ready-mix concrete, or RMC as it is popularly called, refers to concrete that is specifically manufactured for delivery to the customer's construction site in a freshly mixed and plastic or unhardened state. Concrete itself is a mixture of Portland cement, water and aggregates comprising sand and gravel or crushed stone. In traditional work sites, each of these materials is procured separately and mixed in specified proportions at site to make concrete. Read-mix concrete is bought and sold by volume - usually expressed in cubic meters (cubic yards in the US).

           Ready-mix concrete is manufactured under controlled operations and transported and placed at site using sophisticated equipment and methods. In 2011, there were 2,223 companies employing 72,924 workers that produced RMC in the United States.

TMT Bars

                                                                    TMT BARS

 Thermomechanical processing, also known as thermo-mechanical treatment (TMT), is a metallurgical process that integrates work hardening and heat-treatment into a single process.[1] A description of its application in rebar steel follows.
The quenching process produces a high strength bar from inexpensive low carbon steel. The process quenches the surface layer of the bar, which pressurizes and deforms the crystal structure of intermediate layers, and simultaneously begins to temper the quenched layers using the heat from the bar's core.
     Steel billets 125mm² ("pencil ingots") are heated to approximately 1100°C in a reheat furnace. Then, they are progressively rolled to reduce the billets to the final size and shape of reinforcing bar. After the last rolling stand, the billet moves through a quench box. The quenching converts the billet's surface layer to martensite, and causes it to shrink. The shrinkage pressurizes the core, helping to form the correct crystal structures. The core remains hot, and austenitic. A microprocessor controls the water flow to the quench box, to manage the temperature difference through the cross-section of the bars. The correct temperature difference assures that all processes occur, and bars have the necessary mechanical properties.
      The bar leaves the quench box with a temperature gradient through its cross section. As the bar cools, heat flows from the bar's centre to its surface so that the bar's heat and pressure correctly tempers an intermediate ring of martensite andbainite.
Finally, the slow cooling after quenching automatically tempers the austenitic core to ferrite and pearlite on the cooling bed.

     These bars therefore exhibit a variation in microstructure in their cross section, having strong, tough, tempered martensite in the surface layer of the bar, an intermediate layer of martensite and bainite, and a refined, tough and ductile ferrite and pearlite core.
When the cut ends of TMT bars are etched in Nital (a mixture of nitric acid and methanol), three distinct rings appear: 1. A tempered outer ring of martensite, 2. A semi-tempered middle ring of martensite and bainite, and 3. a mild circular core of bainite, ferrite and pearlite. This is the desired micro structure for quality construction rebar.
     In contrast, lower grades of rebar are twisted when cold, work hardening them to increase their strength. However, after thermo mechanical treatment (TMT), bars do not need more work hardening. As there is no twisting during TMT, no torsional stress occurs, and so torsional stress cannot form surface defects in TMT bars. Therefore TMT bars resist corrosion better than cold, twisted and deformed (CTD) bars.

wall panel

                                                                        wall panel

   A wall panel is single piece of material, usually flat and cut into a rectangular shape, that serves as the visible and exposed covering for a wall. Wall panels are functional as well as decorative, providing insulation and soundproofing, combined with uniformity of appearance, along with some measure of durability or ease of replaceability. While there is no set size limit for a piece of material fulfilling these functions, the maximum practical size for wall panels has been suggested to be 24 feet by 8 feet, to allow for transportation.
       Use of wall panels can reduce construction costs by providing a consistent appearance to the panelled surface without requiring the application of paint or another finishing material. Wall panels may be finished on only one side, if the other side is going to be against a brick or concrete wall, or a comparable structure. Alternately, the panels may, if assembled to an appropriate framework, substitute for having any other kind of wall at all. Holes may be cut or drilled into a wall panel to accommodate electrical outlets and other devices coming out of the wall.
       There is a new type of eco friendly 3d wall panel made out of the fibrous residue of sugarcane. This fibres of crushed sugarcane stalks, remaining after raw sugar is extracted from the juice of the sugarcane by shredding it, is now the raw material, called bagasse, that forms the base of this easily installed eco friendly product. The raw material used for these 3d wall panel is 100% recycled, compostable and is therefore 100% biodegradable.

Wednesday, May 14, 2014

Green building Materials

Green building (also known as green construction or sustainable building) refers to a structure and using process that is environmentally responsible and resource-efficient throughout a building's life-cycle: from siting to design, construction, operation, maintenance, renovation, and demolition. This requires close cooperation of the design team, the architects, the engineers, and the client at all project stages. The Green Building practice expands and complements the classical building design concerns of economy, utility, durability, and comfort.
Although new technologies are constantly being developed to complement current practices in creating greener structures, the common objective is that green buildings are designed to reduce the overall impact of the built environment on human health and the natural environment by:
  • Efficiently using energy, water, and other resources
  • Protecting occupant health and improving employee productivity
  • Reducing waste, pollution and environmental degradation[2]
A similar concept is natural building, which is usually on a smaller scale and tends to focus on the use of natural materials that are available locally. Other related topics include sustainable design and green architecture. Sustainability may be defined as meeting the needs of present generations without compromising the ability of future generations to meet their needs.Although some green building programs don't address the issue of the retrofitting existing homes, others do. Green construction principles can easily be applied to retrofit work as well as new construction.
A 2009 report by the U.S. General Services Administration found 12 sustainably designed buildings cost less to operate and have excellent energy performance. In addition, occupants were more satisfied with the overall building than those in typical commercial buildings
The opportunities to reduce the environmental and health impacts of our homes span from big decisions, like location, to seemingly small decisions, like paint and light bulbs. The products we use to clean, light, furnish, renovate, and build our homes must be a part of the greening process. Reducing our environmental impacts requires thinking and learning about not just how we use products, but where they came from and where they're going. Consider factors like:
  • Energy used to make, ship, and use a product;
  • The product's contents and the sources of its raw materials;
  • Emissions during manufacturing the product and the level and type of toxins in the final product; and
  • The product's durability (lifespan) and recyclability.
These are just some of the impacts a product has on the environment from "cradle to grave" during its "lifecycle." The five main stages in the lifecycle of a material or product are: raw material acquisition, manufacturing, distribution, use, and end-of-life management. Attributes of a product at different stages of its lifecycle to consider may include:
Waste and materials:
  • Reduced waste
  • Biobased content
  • Recyclable or reusable components
  • Recycled-content
  • Water efficient
  • Water reuse and recycling
  • Responsible stormwater management
Other environmental & health impacts:
  • Enhanced indoor environmental quality
  • Reduced environmental impact over the lifecycle
  • Reduced or eliminated toxic substances
  • Sustainable development, smart growth

Recycled-Content Building Materials

Buying recycled-content materials helps ensure that the materials collected in recycling programs will be used again in the manufacture of new products. Examples of construction materials that can be readily found with recycled content include: 
  • Drywall (many utilize recycled paper and post-industrial gypsum)
  • Insulation (including cellulose, mineral wool, fiberglass, and recycled cotton insulation)
  • Plastic lumber
  • Kitchen countertops
  • Glass tiles
  • Landscaping materials
  • Carpet and carpet padding
  • Steel
Recycled content products are often labeled with percentages of postconsumer and recovered material. If a product is labeled "recycled" because it contains used, rebuilt, reconditioned, or remanufactured parts, the label must say so - unless it's obvious to the consumer (e.g. when purchasing used building materials at a used construction materials resale store).
For information on recycled-content construction products, visit EPA's Comprehensive Procurement Guidelines (CPG) Web site. The CPG program is part of EPA's continuing effort to promote the use of materials recovered from solid waste. EPA provides a list of designated products and the accompanying recycled-content recommendations. EPA has already designated or is proposing to designate a number of building construction products, such as carpet, floor tiles, insulation, patio blocks and other landscaping materials, and roofing materials. Note: When reviewing these product lists, bear in mind that some of the products are designed for use in commercial or industrial buildings, rather than for homes.
For a complete list of EPA's recommended construction materials and for additional information on these materials, go to:

EPA's Environmentally Preferable Purchasing (EPP) Program

EPA launched the EPP program to help the federal government "buy green," and to stimulate demand for green products and services. Environmentally preferable purchasing means adding environmental considerations to buying decisions, along with traditional factors such as performance and price. Environmentally preferable products are those that are considered to be "greener" overall than their conventional counterparts.
EPA's EPP Program has summarized information about popular environmentally preferable products and services, including environmental attributes to look for, procurement guidance, tools, case studies, and other useful resources. Although geared towards the federal government (and its own institutional, mainly non-residential, buildings), this program can also help consumers identify environmentally preferable products and places to buy them.
For information on environmentally preferable products, including building and construction materials, carpeting, and landscaping materials, go to:
For the complete database of standards and contract language for environmentally preferable building materials,
Click here
For Model Green Product Specifications, go to the Federal Green Construction Guide for Specifiers - EPA Disclaimer
PLEASE NOTE: Linking to these lists does not constitute "endorsement" of these products or companies on the part of the EPA.

Additional Guidance on Residential Green Building Products

EPA has developed guidance for many green building products:

For guidance on flooring, carpets, cabinetry, and countertops, see the kitchenbathroom, and/or living areas sections of this Web site.

For general guidance on building and construction products -

For extensive guidance on carpets - 

ENERGY STAR® qualified products -

WaterSense® labeled products -

Household Goods and Practices

Making smarter building material choices during renovation or new home development is a key way that you can help green your home. In addition, everyday decisions about household products (e.g., furniture, furnishings, appliances, electronics, and other goods) can also green your home and lifestyle. Keep in mind that sometimes it takes a little work to make the greenest choices. Different green goals may conflict with one another, and just because a product is advertised as "green" doesn't mean that it really is the most environmentally friendly choice. But the more you learn and the more questions you ask, the better equipped you will be to find greener products. Below are some strategies to help you make smarter material choices. 
  • Salvage and reuse material - Salvaging building materials and reusing them saves energy and reduces greenhouse gas emissions by minimizing the need to extract and process raw materials and ship new material long distances; and reduces the economic and environmental impact of waste disposal (for example, greenhouse gases generated from waste decomposition, the need to build new landfills or the emission of air pollutants from waste incineration). Also, some salvaged building materials are rare and sought-after, such as marble mantles, antique fixtures, old growth hardwoods, wide-plank lumber and knot-free, fine-grain wood.

    The Building Materials Reuse Association's Web siteExit EPA Disclaimer contains a directory of member reuse stores. Habitat for Humanity operates many reuse stores around the country and their reuse store directory Exit EPA Disclaimercan also be found on their Web site. There are also online marketplaces for these materials, such as PlanetReuse.comExit EPA Disclaimer and EPA Disclaimer

    For more information on using reclaimed building materials, see EPA's resource guide on lifecycle construction: EPA Disclaimer
  • Choose durable products and materials and maximize their lifespan - Choose durable items (including clothing, tires, furniture, luggage, appliances, and electronics) that are less likely to wear out or break prematurely. Although durable products sometimes cost more initially, their extended life span often offsets the higher cost and saves money over the product's life. Also keep building materials maintained and repair broken goods whenever possible, to maximize their useful life.
  • Buy locally or regionally produced materials - Using locally produced or salvaged materials reduces the demand to ship materials typically sourced and manufactured long distances from their ultimate use. This helps support the local economy as well as reduce air emissions.
  • Consider reusable products - Instead of using disposable products, consider using reusable products such as cloth napkins, dishcloths, rechargeable batteries, refillable containers, and washable utensils. This can save you money, as well as reduce the environmental impacts related to producing, transporting, and disposing of single-use products.
  • Buy Recycled - "Close the loop" by choosing products that have recycled content. These materials perform as well if not better than virgin materials and buying recycled content products helps sustain the market for recycled materials.
  • Choose sustainably grown/harvested materials - Choose sustainably harvested wood and materials made of a rapidly renewable resource ( e.g., bamboo flooring, wool carpets and bedding, bamboo fiber clothing), agricultural waste materials (e.g., strawboard), or organically grown materials (e.g., organic cotton bedding).
  • Use less-toxic products - Use less-toxic and non-toxic cleaning products, personal care products, and pest control products. If you have to use a toxic or hazardous product, read the instructions on its label carefully, and use the smallest amount necessary. Protect Your Health.
  • Choose products with minimal packaging - Packaging materials account for a significant amount of the trash we generate, and consume resources and energy to produce. Consider buying items in bulk or those with minimal packaging.
  • Choose recyclable products - Identify items and/or packaging that can be recycled, and then be sure to recycle them! Our landfills are full of recyclable products that were discarded.
  • Choose energy-efficient appliances and electronics - Look for the ENERGY STAR® label on home appliances and electronics, including refrigerators, room air conditioners, dishwashers, clothes washers, dehumidifiers, TVs, DVD players, stereos, computers, monitors, and cordless telephones. ENERGY STAR® products meet strict efficiency guidelines set by the U.S. Environmental Protection Agency and theU.S. Department of Energy.
  • Choose water-efficient fixtures and appliances WaterSense® and ENERGY STAR®, programs sponsored by EPA, have identified high-performance, water-efficient appliances, fixtures, water systems, and accessories that reduce water use in the home and help preserve the nation's water resources.
  • Recycle! - Remember, many products (and most packaging waste) can be recycled into new products. Although the recycling process uses some energy and raw materials, it generally uses less than manufacturing virgin products and also avoids environmental issues related to disposal.
  • Borrow, rent, or share items used infrequently - - Before you buy seldom-used items, like certain power tools and party goods, first consider renting or borrowing them.

Avoid Greenwashing

Manufacturers are increasingly making environmental claims about all types of products, including building products. Unfortunately, some claims are misleading, unverified, or downright untrue. When manufacturers make unsubstantiated claims about the environmental attributes of a product, it's called "greenwashing," and consumers need to be on the lookout for it. Here are some tips to help:
  • Just because something is packaged like a green product doesn't mean that it is. Don't be taken in by natural looking scenes and "green" branding.
  • Read labels carefully and look for the environmental attributes discussed in this Web site, such as recycled content (the higher the percent, the better, and post-consumer is better than pre-consumer), low or no VOC, or reduced toxicity or non-toxic, and sustainably harvested (for wood products). The word "natural" has no legal meaning and is not a reliable indicator of environmental attributes
  • "Recycled" means that the product was made with recycled content, whereas "recyclable" just means that the product can be recycled. Recycled is preferable.
  • If the product has a green label, research the label if it's one that you trust, especially for big purchases.
  • Consider shipping distance. Transportation emissions are a big factor in considering how green a product is, especially for heavier products. A locally or regionally produced product with no environmental claims may be better for the environment than a product with a green label that traveled a long distance.

Monday, June 17, 2013


     Flooring Information

    Flooring is the general term for a permanent covering of a floor, or for the work of installing such a floor covering. Floor covering is a term to generically describe any finish material applied over a floor structure to provide a walking surface. Both terms are used interchangeably but floor covering refers more to loose-laid materials.
     Materials almost always classified as floor covering include carpet, area rugs, and resilient flooring such as linoleum or vinyl flooring. Materials commonly called flooring include wood flooring, ceramic tile, stone, terrazzo, and various seamless chemical floor coatings.

Flooring materials


The choice of material for floor covering is affected by factors such as cost, endurance, noise insulation, comfort and cleaning effort. Some types of flooring must not be installed below grade (lower than ground level), and laminate or hardwood should be avoided where there may be moisture or condensation.
The sub-floor may be finished in a way that makes it usable without any extra work, see:

Soft coverings

Carpet is a floor covering woven or felted from natural or man-made fibers. Fitted carpet is attached to the floor structure, extends wall-to-wall, and cannot be moved from place to place. An underlay will extend carpet life and improve comfort.
Rugs are also woven or felted from fibers, but are smaller than the room in which they are located, have a finished edge, and usually lie over another finished floor such as wood flooring. Rugs may either be temporarily attached to the flooring below by adhesive tape or other methods to prevent creep, or may be loose-laid.

Wood flooring

Many different species of wood are fabricated into wood flooring in two primary forms: plank and parquet. Hardwoods are typically much more durable than softwoods. Reclaimed lumber has a unique appearance and is used in green (environmentally responsible) building.
Laminate is a floor covering that appears similar to hardwood but is made with a plywood or medium density fiberboard ("MDF") core with a plastic laminate top layer. HDF laminate consists of high density fiberboard topped by one or more layers of decorative paper and a transparent protective layer. Laminate may be more durable than hardwood, but cannot be refinished like hardwood. Laminate flooring is available in many different patterns which can resemble different woods or even ceramic tile. It usually locks or taps together.
Bamboo flooring is a floor manufactured from the bamboo plant and is a type of hardwood flooring, though technically not a wood. Bamboo is known to be durable and environmentally friendly. It is available in many different patterns, colors, and textures.
Cork Flooring is a flooring material manufactured from the by-product of the cork oak tree. Cork floors are considered to be eco-friendly since the cork oak tree bark is stripped every nine to ten years and doesn't damage the tree. Cork flooring comes in both tiles and planks, and can have glue or glues-less installation.

Resilient flooring

Resilient flooring is made of material that has some elasticity. It includes many different manufactured products including linoleum, sheet vinyl, vinyl composition tile (VCT), cork (sheet or tile), rubber, and others. Performance surfaces used for dance or athletics are made of either wood or resilient flooring.

Hard flooring

Ceramic tiles flooring in Istanbul street
Ceramic tile includes a wide variety of clay products fired into thin units which are set in beds of mortar or mastic with the joints between tiles grouted. Varieties include quarry tile, porcelain tile, terracotta tile, and others.
Many different natural stones are cut into a variety of sizes, shapes, and thicknesses for use as flooring. Stone flooring is usually set in mortar and grouted similar to ceramic tile. Slate and marble are popular types of stone flooring.
New technologies are emerging since 2004 to produce hard floorings having the ability to light up when needed. These security glazing materials contain transparent LED embedded films laminated between glass.

Seamless chemical flooring

Many different seamless flooring materials are available. These are usually latex, polyester, urethane or epoxy compounds which are applied in liquid form to provide a completely seamless floor covering. These are usually found in wet areas such as laboratories or food processing plants. These may have granular or rubberized particles added to give better traction.

Sustainable flooring

 Sustainable flooring is produced from sustainable materials (and by a sustainable process) that reduces demands on ecosystems during its life-cycle. Some think that sustainable flooring creates safer and healthier buildings and guarantees a future for traditional producers of renewable resources that many communities depend onBrowse our materials guide to find the right carpeting and flooring for your home. Living rooms, bedrooms, kitchens, bathrooms, basements, and entryways all have unique flooring needs: wet spaces versus dry spaces, high-traffic versus low-traffic, subflooring differences, insulation needs. Our flooring guides and tips help to uncover those details that you might not have considered before. The differences between tile, carpet, hardwood, laminate, vinyl, linoleum, engineered flooring, and eco-friendly alternatives are vast, and our handy flooring guides help to ease some of the pressure of selecting a flooring material for your space that reflects your personal style and project budget. Cleaning, care, and upkeep also come into consideration when selecting the perfect flooring for you; learn about the pros and cons for each flooring type here. Discover the differences between ceramic, porcelain, and hard-bodied tile before you complete a do-it-yourself tile installation. Carpet tiles and area rugs are also good options for fickle tastes or for cushioning high-traffic areas; cleanable and replaceable, both options are easily switched out depending on taste, trends, and wear. 


Kitchen Flooring


 Flooring is an especially noticeable characteristic in the often-used space of a kitchen. Find the material that is right for your kitchen's style and for your budget by reading our buying guides and taking our flooring finder quiz. If you are a serious cook and spend a lot of time on your feet in the kitchen, one key consideration is to find materials for kitchen flooring with a cushioning effect such as wood, laminate, cork, and vinyl. Brick, ceramic tile, and stone are durable but hard to stand on for extended periods of time without a cushioned mat on top. Another tip about making the right kitchen flooring selection is to look for materials low in maintenance and high in durability. Think about the time you have for cleaning and maintaining your kitchen flooring. Know that high-maintenance flooring might look great, but it also requires pampering to stay that way. Finally, select kitchen flooring complementary to the cabinets, wall coverings, furniture, and other design elements in the room. Wood blends into any decorating scheme, and there are a variety of eco-friendly options such as bamboo and engineered wood that up your style quotient. Laminates and vinyl are ideal choices if you're after a patterned or colorful contemporary look. And stone and concrete add fun to a neutral or tone-on-tone color scheme

Flooring Tiles

A tile is a manufactured piece of hard-wearing material such as ceramic, stone, metal, or even glass. Tiles are generally used for covering roofs, floors, walls, showers, or other objects such as tabletops. Alternatively, tile can sometimes refer to similar units made from lightweight materials such as perlite, wood, and mineral wool, typically used for wall and ceiling applications. In another sense, a tile is a construction tile or similar object, such as rectangular counters used in playing games (see tile-based game). The word is derived from the French word tuile, which is, in turn, from the Latin word tegula, meaning a roof tile composed of fired clay. Tiles are often used to form wall and floor coverings, and can range from simple square tiles to complex mosaics. Tiles are most often made from porcelain, fired clay or ceramic with a hard glaze, but other materials are also commonly used, such as glass, metal, cork, and stone. Tiling stone is typically marble, onyx, granite or slate. Thinner tiles can be used on walls than on floors, which require thicker, more durable surfaces.

These are commonly made of ceramic or stone, although recent technological advances have resulted in rubber or glass tiles for floors as well. Ceramic tiles may be painted and glazed. Small mosaic tiles may be laid in various patterns. Floor tiles are typically set into mortar consisting of sand, cement and often a latex additive for extra adhesion. The spaces between the tiles are nowadays filled with sanded or unsanded floor grout, but traditionally mortar was used.
Natural stone tiles can be beautiful but as a natural product they are less uniform in color and pattern, and require more planning for use and installation. Mass-produced stone tiles are uniform in width and length. Granite or marble tiles are sawn on both sides and then polished or finished on the facing up side, so that they have a uniform thickness. Other natural stone tiles such as slate are typically "riven" (split) on the facing up side so that the thickness of the tile varies slightly from one spot on the tile to another and from one tile to another. Variations in tile thickness can be handled by adjusting the amount of mortar under each part of the tile, by using wide grout lines that "ramp" between different thicknesses, or by using a cold chisel to knock off high spots.
Some stone tiles such as polished granite, marble, and travertine are very slippery when wet. Stone tiles with a riven (split) surface such as slate or with a sawn and then sandblasted or honed surface will be more slip resistant. Ceramic tiles for use in wet areas can be made more slip resistant either by using very small tiles so that the grout lines acts as grooves or by imprinting a contour pattern onto the face of the tile.
The hardness of natural stone tiles varies such that some of the softer stone (e.g. limestone) tiles are not suitable for very heavy traffic floor areas. On the other hand, ceramic tiles typically have a glazed upper surface and when that becomes scratched or pitted the floor looks worn, whereas the same amount of wear on natural stone tiles will not show, or will be less noticeable.
Natural stone tiles can be stained by spilled liquids; they must be sealed and periodically resealed with a sealant in contrast to ceramic tiles which only need their grout lines sealed. However, because of the complex, non repeating patterns in natural stone, small amounts of dirt on many natural stone floor tiles do not show.
Most vendors of stone tiles emphasize that there will be variation in color and pattern from one batch of tiles to another of the same description and variation within the same batch. Stone floor tiles tend to be heavier than ceramic tiles and somewhat more prone to breakage during shipment.
Rubber floor tiles have a variety of uses, both in residential and commercial settings. They are especially useful in situations where it is desired to have high-traction floors or protection for an easily breakable floor. Some common uses include flooring of garage, workshops, patios, swimming pool decks, sport courts, gyms, and dance floors.
Plastic floor tiles including interlocking floor tiles that can be installed without adhesive or glue are a recent innovation and are suitable for areas subject to heavy traffic, wet areas and floors that are subject to movement, damp or contamination from oil, grease or other substances that may prevent adhesion to the substrate. Common uses include old factory floors, garages, gyms and sports complexes, schools and shops.


Roof Tiles 

Roof tiles are designed mainly to keep out rain, and are traditionally made from locally available materials such as clay or slate. Modern materials such as concrete and plastic are also used and some clay tiles have a waterproof glaze. A large number of shapes (or "profiles") of roof tiles have evolved. These include:

  • Flat tiles - the simplest type, which are laid in regular overlapping rows. An example of this is the clay-made "beaver-tail" tile (German Biberschwanz), common in Southern Germany. Flat roof tiles are usually made of clay but also may be made of stone, wood, plastic, concrete, or solar cells.
  • Imbrex and tegula, an ancient Roman pattern of curved and flat tiles that make rain channels on a roof.
  • Roman tiles - flat in the middle, with a concave curve at one end at a convex curve at the other, to allow interlocking.
  • Pantiles - with an S-shaped profile, allowing adjacent tiles to interlock. These result in a ridged pattern resembling a ploughed field. An example of this is the "double Roman" tile, dating from the late 19th century in England and USA.
  • Mission or barrel tiles are semi-cylindrical tiles laid in alternating columns of convex and concave tiles. Originally they were made by forming clay around a curved surface, often a log or the maker's thigh. Today barrel tiles are mass-produced from clay, metal, concrete or plastic.
  • Interlocking roof tiles are similar to pantile with side and top locking to improve protection from water and wind.
  • Antefixes: vertical blocks which terminate the covering tiles of a tiled roof.
Roof tiles are 'hung' from the framework of a roof by fixing them with nails. The tiles are usually hung in parallel rows, with each row overlapping the row below it to exclude rainwater and to cover the nails that hold the row below. There are also roof tiles for special positions, particularly where the planes of the several pitches meet. They include ridge, hip and valley tiles.These can either be bedded and pointed in cement mortar or mechanically fixed.
Similarly to roof tiling, tiling has been used to provide a protective weather envelope to the sides of timber frame buildings. These are hung on laths nailed to wall timbers, with tiles specially moulded to cover corners and jambs. Often these tiles are shaped at the exposed end to give a decorative effect. Another form of this is the so-called mathematical tile, which was hung on laths, nailed and then grouted. This form of tiling gives an imitation of brickwork and was developed to give the appearance of brick, but avoided the Brick Taxes of the 18th century.




 Plywood is a manufactured wood panel made from thin sheets of wood veneer. It is one of the most widely used wood products. It is flexible, inexpensive, workable, and re-usable, and usually can be manufactured locally. Plywood is used instead of plain wood because of plywood's resistance to cracking, shrinkage, splitting, and twisting/warping, and because of its generally high strength.
Plywood layers (called veneers) are glued together, with adjacent plies having their wood grain at right angles to each other, to form a composite material. This alternation of the grain is called cross-graining and has several important benefits: it reduces the tendency of wood to split when nailed at the edges; it reduces expansion and shrinkage, providing improved dimensional stability; and it makes the strength of the panel consistent across both directions. There is usually an odd number of plies, so that the sheet is balanced—this reduces warping. Because plywood is bonded with grains running against one another and with an odd number of composite parts, it is very hard to bend it perpendicular to the grain direction.

Plywood was invented about 3400 B.C. by the Ancient Mesopotamians, who attached several thinner layers of wood together to make one thick layer. They originally did this during a shortage of quality wood, gluing very thin layers of quality wood over lesser-quality wood.
Different varieties of plywood exist for different applications:
Softwood plywood
Softwood panel is usually made either of cedar, Douglas fir or spruce, pine, and fir (collectively known as spruce-pine-fir or SPF) or redwood and is typically used for construction and industrial purposes

Hardwood plywood

Used for demanding end uses. Birch plywood is characterized by its excellent strength, stiffness and resistance to creep. It has a high planar shear strength and impact resistance, which make it especially suitable for heavy-duty floor and wall structures. Oriented plywood construction has a high wheel-carrying capacity. Birch plywood has excellent surface hardness, and damage- and wear-resistance

Tropical plywood

Tropical plywood is made of mixed species of tropical wood. Originally from the Asian region, it is now also manufactured in African and South American countries. Tropical plywood is superior to softwood plywood due to its density, strength, evenness of layers, and high quality.

Special-purpose plywood

Certain plywoods do not have alternating plies. These are designed for specific purposes

Aircraft plywood

High-strength plywood also known as aircraft plywood, is made from mahogany and/or birch, and uses adhesives with increased resistance to heat and humidity. It was used for several World War II fighter aircraft. Although the British-built Mosquito bomber, nicknamed "The Wooden Wonder", was constructed of a plywood monocoque, this was formed in moulds from individual veneers of birch, balsa and birch  rather than machined from pre-laminated plywood sheets.

Decorative plywood (overlaid plywood)


Usually faced with hardwood, including ash, oak, red oak, birch, maple, mahogany, Philippine mahogany (often called lauan, luan or meranti and having no relation to true mahogany), rose wood, teak and a large number of other hardwoods. However, Formica, metal and resin-impregnated paper or fabric bonded are also added on top of plywood at both side as a kind of ready for use in the decoration field. This plywood is a lot easier to dye and draw on than any other plywoods.

Flexible plywood

Flexible plywood is very flexible and is designed for making curved parts. In the UK this is sometimes known as "Hatters Ply" as it was used to make stovepipe hats in Victorian times .It is also often referred to as "Bendy Ply" due to its flexibility. However these may not be termed plywood in some countries because the basic description of plywood is layers of veneered wood laid on top of each other with the grain of each layer perpendicular to the grain of the next. In the U.S., the terms "Bender Board" and "Wiggle Board" are commonly used.

Marine plywood

Marine plywood is manufactured from durable face and core veneers, with few defects so it performs longer in humid and wet conditions and resists delaminating and fungal attack. Its construction is such that it can be used in environments where it is exposed to moisture for long periods. More recently, tropical producers have become dominant in the marine plywood market. Okoumé from Gabon is now the accepted standard for marine plywood, even though the wood is not very resistant to rot and decay. Each wood veneer will be from tropical hardwoods, have negligible core gap, limiting the chance of trapping water in the plywood and hence providing a solid and stable glue bond. It uses an exterior Water and Boil Proof (WBP) glue similar to most exterior plywoods.

Other plywoods

Other types of plywoods include fire-retardant, moisture-resistant, sign-grade and pressure-treated. However, the plywood may be treated with various chemicals to improve the plywood's fireproofing. Each of these products is designed to fill a need in industry.



Plywood is used in many applications that need high-quality, high-strength sheet material. Quality in this context means resistance to cracking, breaking, shrinkage, twisting and warping.
Exterior glued plywood is suitable for outdoor use, but because moisture affects the strength of wood, optimal performance is achieved in end uses where the wood's moisture content remains relatively low. On the other hand, subzero conditions don't affect plywood's dimensional or strength properties, which makes some special applications possible.
Typical end uses of spruce plywood are:
  • Floors, walls and roofs in house constructions
  • Wind bracing panels
  • Vehicle internal body work
  • Packages and boxes
  • Fencing

  •    There are many different types of wood-based man-made materials on the market. Each has its own purpose, drawbacks, and benefits. When most people hear the term plywood, they think of CDX (or whatever...) which is used to build houses. Yet in the wholesale wood products industry, plywood is a generic term for any sheet product regardless of construction (for example; MDF, VC, CDX.) The two terms are interchangeable, more-or-less.
    Medium Density Fiber Core Hardwood Plywood (MDF)

    MDF is made from fine wood dust mixed with a binder and heat-pressed into panels. The sheets can be sold as-is, or a veneer skin, like oak or maple, can be laid up on the sheet. (The veneered sheet is the most common form, but blank MDF sheets are available as Paint-Grade)
    This material is extremely stable to work with, and is typically very consistent from batch to batch. A 3/4" thick sheet purchased over a year ago is exactly the same thickness as a new sheet purchased today. The surface below the veneer is typically free of voids and blisters, resulting in a better veneer consistency and bond. With this better bonding of the wood veneer, there is less chipping during a crosscut operation. I have also observed that this material is easy to machine either by saw or router, and the cut edges are excellent for glue adhesion. (I have heard it mentioned that MDF is hard on cutters, but personally, I disagree with this statement. I feel that MDF is rather easy on the cutters.)
    The primary drawback to this product is weight. A 3/4" x 4' x 8' sheet can weigh as much as 70 to 90 pounds per sheet. The density of the core is expressed as the weight of a one cubic foot (1'x1'x1') block of the material. Therefore, an MDF sheet using a 48# (pound) core, will weigh 96 pounds. (48"x96"x3/4"= 2 cubic feet)
    Medium- and High-Density Overlay Plywood (MDO and HDO)

    MDO and HDO consist of a core material, like laminated fir veneer, overlaid with a pressed fiber material. In short, this is a typical veneer core plywood (common plywood) with an MDF surface. This gives the best of both worlds; the weight is lower than a full MDF, but the surface is more stable than a veneer core plywood.
    Veneer Core Hardwood Plywood (VC)

    Veneer Core plywood is made from alternating layers of fir slices (common plywood) with a surface veneer of a finished woodgrain such as oak or maple. This construction gives VC plywood a distinct advantage over others in strength. This is a light weight material, and easy to handle.
    The drawbacks of VC plywood are:
    • Voids in the core and face are common.
    • VC is not always consistent in thickness from sheet to sheet, or within the same sheet.
    • The pre-veneered surface is coarser, and does not accept veneer as well. This results in excessive chipping and tearout during machining.
    • No matter how you cut it, you will be ripping some layers, and crosscutting others. This makes cutting this material with a fine laminate blade more difficult, with a greater tendency to burn.
    • The saw-cut edges are not as clean and smooth as the other products, so this material does not take edge gluing as well.
    • The inconsistency in the pre-veneered surface can result in thin spots in the veneer.
    Lumber Core Plywood

    Lumber Core Plywood is manufactured from strips of solid lumber, typically basswood. The core is then surfaced and a veneer layer is applied. This is one of the most expensive plywood types to make, and is commonly used for applications where the edges cannot be concealed or need to be routed.
    As the popularity of this product diminishes, it is becoming more and more difficult to locate suppliers who are willing to carry high grade sheets. The quality of the core lumber is dropping in all but the best of grades. Most grades machine poorly. If the core is not glued up with consistent stock, voids can be present which will run the full length, or at least a portion of the full length, of the entire sheet.
    Because of this, care must be taken in selecting sheets if they are to be used for matched and sequenced door material, as a flaw in the core can wipe out an entire set of doors if they need to maintain grain matching from one to another.
    Particle Board Core Plywood (PBC)
    PBC uses a coarser wood dust than MDF. Because of this, it has a slightly lower weight, but the edges and surfaces are not as smooth and consistent. Most melamine products use PBC as the substrate.


    Melamine plywood is a thermally fused, resin saturated paper finish over a particle board core. It is highly stain and abrasion resistant. As a cabinet maker, I use a lot of this material. Even though glue manufactures claim to have developed an adhesive which bonds to the surface, I (personally) am not willing to take the chance; after all, this is a "paper" surface. (My personal recommendation to any one using this product is to dado the joints for better bonding.)
    Contrary to popular belief among many woodworkers, melamine is not the name of the paper finish; it's the name of the resin used to impregnate the paper liner (chemically C3H6N6). Even among manufacturers of this type of sheet product, however, it is still called melamine.
    This material comes in a variety of colors, is highly stain and mar resistant, and is commonly used in the cabinet industry for carcass construction.
    Depending on the grade of melamine, it can be brittle or soft, coarse or smooth. Typically, the higher grades of melamine are more brittle and will chip during machining but have a thicker surface and greater resistance to abrasion.
    I have found that the best blade for cutting melamine is a triple-chip laminate blade set with a blade height of about 1" above the top of the wood. With a higher blade height, there will be excessive chipping on the back of the sheet, and with a lower blade height, there will be some chipping on the top of the sheet. The reason for the top-side chipping with a low blade height is due to the teeth striking the surface veneer nearly perpendicular, and throwing chips forward.
    High Density Maple/Birch (Baltic Birch or Appleply)

    High density plywoods (HDP) typically come in either maple or birch specie. Unlike common plywood, HDP has many more plies, is generally void free, and uses a stronger species than fir. HDP is commonly used for drawer side material as it is strong, stable, and has a moderately attractive edge
    Baltic Birch

    Baltic birch is probably the most common type of HDP, and uses birch as the substrate. This will come in 5' x 5' sheets. For a 1/2" sheet, there are typically 7 to 9 plies. Being birch, the surface does not finish as nicely as the maple counterpart, and there is a tendency for splintering at the edge of a machined cut.

    Appleply is a manufacturer's name for high density maple plywood. From a fabrication stand point, it is similar to Baltic Birch, in that it carries about the same number of plies, except Appleply comes in standard 4'x8' sheets. Because the surface is maple, there will be slightly more grain pattern on the surface, and the surface will sand much smoother. There is less splintering of the machined edges, and those splinters which do appear will be shorter and less inclined to align with the edge.