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118-430: A blockhouse is a small fortification , usually consisting of one or more rooms with loopholes , allowing its defenders to fire in various directions. It is usually an isolated fort in the form of a single building, serving as a defensive strong point against any enemy that does not possess siege equipment or, in modern times, artillery , air force or cruise missiles . A fortification intended to resist these weapons

236-828: A palisade with the blockhouse at one corner, and possibly a second tower at the opposite corner. Many historical stone blockhouses have survived, and a few timber ones have been restored at historical sites. In New Zealand, the Cameron Blockhouse , near Whanganui , is one of the few blockhouses to survive from the New Zealand Wars . During the Second Boer War the British forces built a large number of fortifications in South Africa . Around 441 were solid masonry blockhouses, many of which stand today. Different designs were used in

354-430: A ravelin like angular gun platform screening one of the curtain walls which is protected from flanking fire from the towers of the main part of the fort. Another example is the fortifications of Rhodes which were frozen in 1522 so that Rhodes is the only European walled town that still shows the transition between the classical medieval fortification and the modern ones. A manual about the construction of fortification

472-647: A rip saw is the most common method, because sawing allows logs of lower quality, with irregular grain and large knots, to be used and is more economical. There are various types of sawing: Dimensional lumber is lumber that is cut to standardized width and depth, often specified in millimetres or inches (but see below for information on nominal dimensions vs. actual dimensions). Carpenters extensively use dimensional lumber in framing wooden buildings. Common sizes include 2×4 (pictured) (also two-by-four and other variants, such as four-by-two in Australia, New Zealand, and

590-455: A "class 1 flame spread rating of 25 or less, when tested in accordance with ASTM standard E 84," which means it burns more slowly than almost all treated wood lumber. A timber mark is a code beaten on to cut wood by a specially made hammer to show the logging licence. The basic understanding of lumber, or "sawn planks", came about in North America in the seventeenth century. Lumber is

708-400: A 1-inch-thick (25 mm) board, 8/4 (eight quarter) is a 2-inch-thick (51 mm) board, etc. This "quarter" system is rarely used for softwood lumber; although softwood decking is sometimes sold as 5/4, even though it is actually one inch thick (from milling 1 ⁄ 8  in or 3.2 mm off each side in a motorized planing step of production). The "quarter" system of reference is

826-534: A 10-foot-long (3.0 m) 2×4 ( 1 + 1 ⁄ 2 by 3 + 1 ⁄ 2  in or 38 by 89 mm) into two 1×4s ( 3 ⁄ 4 by 3 + 1 ⁄ 2  in or 19 by 89 mm) of the same length is considered re-sawing. Structural lumber may also be produced from recycled plastic and new plastic stock. Its introduction has been strongly opposed by the forestry industry. Blending fiberglass in plastic lumber enhances its strength, durability, and fire resistance. Plastic fiberglass structural lumber can have

944-512: A double wall of trenches and ramparts, and in the Congo forests concealed ditches and paths, along with the main works, often bristled with rows of sharpened stakes. Inner defenses were laid out to blunt an enemy penetration with a maze of defensive walls allowing for entrapment and crossfire on opposing forces. A military tactic of the Ashanti was to create powerful log stockades at key points. This

1062-500: A few had semi-circular or rectangular platforms. Surviving redoubts with blockhouses include Baħar iċ-Ċagħaq Redoubt and Briconet Redoubt , both of which have a pentagonal plan. A few of the redoubts consisted of a single tower-like blockhouse without a platform, and were known as tour-reduits . Of the four tour-reduits that were built, only the Vendôme Tower survives today. Originally blockhouses were often constructed as part of

1180-467: A framer much time, because they are pre-cut by the manufacturer for use in 8-, 9-, and 10-foot ceiling applications, which means the manufacturer has removed a few inches or centimetres of the piece to allow for the sill plate and the double top plate with no additional sizing necessary. In the Americas, two-bys (2×4s, 2×6s, 2×8s, 2×10s, and 2×12s), named for traditional board thickness in inches, along with

1298-522: A large plan, to "block" access to vital points in the scheme. But from the Age of Exploration to the nineteenth century standard patterns of blockhouses were constructed for defence in frontier areas, particularly South Africa , New Zealand , Canada , and the United States . Blockhouses may be made of masonry where available, but were commonly made from very heavy timbers , sometimes even logs arranged in

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1416-587: A modern blockhouse and a bunker is that a bunker is constructed mostly below ground level while a blockhouse is constructed mostly above ground level. Some blockhouses like those constructed in England in 1940 were built in anticipation of a German invasion ; they were often hexagonal in shape and were called " pillboxes ". About 28,000 pillboxes and other hardened field fortifications were constructed, of which about 6,500 still survive. The Admiralty Citadel in London

1534-413: A necessity for many cities. Amnya Fort in western Siberia has been described by archaeologists as one of the oldest known fortified settlements, as well as the northernmost Stone Age fort. In Bulgaria, near the town of Provadia a walled fortified settlement today called Solnitsata starting from 4700 BC had a diameter of about 300 feet (91 m), was home to 350 people living in two-storey houses, and

1652-399: A relatively small set of specified lengths; in all cases hardwoods are sold to the consumer by the board-foot (144 cubic inches or 2,360 cubic centimetres), whereas that measure is not used for softwoods at the retailer (to the cognizance of the buyer). Also in North America, hardwood lumber is commonly sold in a "quarter" system, when referring to thickness; 4/4 (four quarter) refers to

1770-579: A result, very very few kotas still stand to this day. Notable kotas: During Muhammad 's era in Arabia, many tribes made use of fortifications. In the Battle of the Trench , the largely outnumbered defenders of Medina, mainly Muslims led by Islamic prophet Muhammad, dug a trench , which together with Medina's natural fortifications, rendered the confederate cavalry (consisting of horses and camels ) useless, locking

1888-434: A series of straight lines creating the central fortified area that gives this style of fortification its name. Timber Lumber is wood that has been processed into uniform and useful sizes (dimensional lumber), including beams and planks or boards . Lumber is mainly used for construction framing , as well as finishing (floors, wall panels , window frames ). Lumber has many uses beyond home building. Lumber

2006-449: A timber is referred to as one "timber" (材), and the dimensions of other structural components were quoted in multiples of "timber"; thus, as the width of the actual timber varied, the dimensions of other components were easily calculated, without resorting to specific figures for each scale. The dimensions of timbers in similar applications show a gradual diminution from the Sui dynasty (580–618) to

2124-443: A traditional North American lumber industry nomenclature used specifically to indicate the thickness of rough sawn hardwood lumber. In rough-sawn lumber it immediately clarifies that the lumber is not yet milled, avoiding confusion with milled dimension lumber which is measured as actual thickness after machining. Examples – 3 ⁄ 4 -inch, 19 mm, or 1x. In recent years architects, designers, and builders have begun to use

2242-426: A unit of dimensional lumber is limited by the height and girth of the tree it is milled from. In general the maximum length is 24 ft (7.32 m). Engineered wood products, manufactured by binding the strands, particles, fibers, or veneers of wood, together with adhesives, to form composite materials, offer more flexibility and greater structural strength than typical wood building materials. Pre-cut studs save

2360-549: Is also an intermediate branch known as semi-permanent fortification. Castles are fortifications which are regarded as being distinct from the generic fort or fortress in that they are a residence of a monarch or noble and command a specific defensive territory. Roman forts and hill forts were the main antecedents of castles in Europe, which emerged in the 9th century in the Carolingian Empire . The Early Middle Ages saw

2478-428: Is another example of a Gaulish fortified settlement. The term casemate wall is used in the archaeology of Israel and the wider Near East , having the meaning of a double wall protecting a city or fortress, with transverse walls separating the space between the walls into chambers. These could be used as such, for storage or residential purposes, or could be filled with soil and rocks during siege in order to raise

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2596-419: Is available in many species, including hardwoods and softwoods , such as white pine and red pine , because of their low cost. Finished lumber is supplied in standard sizes, mostly for the construction industry – primarily softwood , from coniferous species, including pine , fir and spruce (collectively spruce-pine-fir ), cedar , and hemlock , but also some hardwood, for high-grade flooring. It

2714-543: Is critical, such as trusses , rafters , laminating stock, I-beams and web joints. Machine grading measures a characteristic such as stiffness or density that correlates with the structural properties of interest, such as bending strength . The result is a more precise understanding of the strength of each piece of lumber than is possible with visually graded lumber, which allows designers to use full-design strength and avoid overbuilding. In Europe, strength grading of rectangular sawn lumber/timber (both softwood and hardwood)

2832-633: Is done according to EN-14081 and commonly sorted into classes defined by EN-338. For softwoods, the common classes are (in increasing strength) C16, C18, C24, and C30. There are also classes specifically for hardwoods and those in most common use (in increasing strength) are D24, D30, D40, D50, D60, and D70. For these classes, the number refers to the required 5th percentile bending strength in newtons per square millimetre. There are other strength classes, including T-classes based on tension intended for use in glulam . Grading rules for African and South American sawn lumber have been developed by ATIBT according to

2950-493: Is employed when in the course of a campaign it becomes desirable to protect some locality with the best imitation of permanent defences that can be made in a short time, ample resources and skilled civilian labour being available. An example of this is the construction of Roman forts in England and in other Roman territories where camps were set up with the intention of staying for some time, but not permanently. Castles are fortifications which are regarded as being distinct from

3068-519: Is formally known as poliorcetics . In some texts, this latter term also applies to the art of building a fortification. Fortification is usually divided into two branches: permanent fortification and field fortification. Permanent fortifications are erected at leisure, with all the resources that a state can supply of constructive and mechanical skill, and are built of enduring materials. Field fortifications—for example breastworks —and often known as fieldworks or earthworks, are extemporized by troops in

3186-406: Is minimally 1 + 1 ⁄ 2 by 3 + 1 ⁄ 2 inches (38 mm × 89 mm). As previously noted, less wood is needed to produce a given finished size than when standards called for the green lumber to be the full nominal dimension. However, even the dimensions for finished lumber of a given nominal size have changed over time. In 1910, a typical finished 1-inch (25 mm) board

3304-607: Is more commonly made from softwood than hardwoods, and 80% of lumber comes from softwood. In the United States and Canada, milled boards are called lumber , while timber describes standing or felled trees. In contrast, in Britain, and some other Commonwealth nations and Ireland, the term timber is used in both senses. (In the UK, the word lumber is rarely used in relation to wood and has several other meanings.) Re-manufactured lumber

3422-411: Is more likely to qualify as a fortress or a redoubt , or in modern times, be an underground bunker . However, a blockhouse may also refer to a room within a larger fortification, usually a battery or redoubt. The term blockhouse is of uncertain origin, perhaps related to Middle Dutch blokhus and 18th-century French blocus (blockade). Blockhouses existed in ancient Greece, for example

3540-651: Is one of the sturdiest above-ground structures built during World War II. It was constructed in 1940–1941 as a bomb-proof operations centre for the Admiralty , with foundations nine metres deep and a concrete roof six metres thick. It too was intended to serve as a strongpoint in defending against the feared invasion. In Berlin and other cities during World War II some massive blockhouses were built as air-raid shelters and anti-aircraft artillery platforms. They were called Hochbunker (literally, "high bunkers"; better translated as "above ground bunkers", to distinguish them from

3658-552: Is referred to as timber in the United Kingdom, Europe, Australia, and New Zealand, while in other parts of the world (mainly the United States and Canada) the term timber refers specifically to unprocessed wood fiber , such as cut logs or standing trees that have yet to be cut. Lumber may be supplied either rough- sawn , or surfaced on one or more of its faces. Rough lumber is the raw material for furniture-making, and manufacture of other items requiring cutting and shaping. It

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3776-591: Is required. Under the prescription of the Method of Construction (營造法式) issued by the Song dynasty government in the early twelfth century, timbers were standardized to eight cross-sectional dimensions. Regardless of the actual dimensions of the timber, the ratio between width and height was maintained at 1:1.5. Units are in Song dynasty inches (31.2 mm). Timber smaller than the 8th class were called "unclassed" (等外). The width of

3894-459: Is smaller than the nominal dimensions because modern technology makes it possible to use the logs more efficiently. For example, a "2×4" board historically started out as a green, rough board actually 2 by 4 inches (51 mm × 102 mm). After drying and planing, it would be smaller by a nonstandard amount. Today, a "2×4" board starts out as something smaller than 2 inches by 4 inches and not specified by standards, and after drying and planing

4012-422: Is still continued in some places. Otherwise, logs were sawn using a two-person whipsaw, or pit-saw, using saddleblocks to hold the log, and a pit for the pitman who worked below. In 1420 the island of Madeira  – an archipelago comprising four islands off the northwest coast of Africa and an autonomous region of Portugal – was discovered. King Henry VI sent settlers to Madeira and

4130-437: Is the result of secondary or tertiary processing of previously milled lumber. Specifically, it refers to lumber cut for industrial or wood-packaging use. Lumber is cut by ripsaw or resaw to create dimensions that are not usually processed by a primary sawmill . Re-sawing is the splitting of 1-to-12-inch (25–305 mm) hardwood or softwood lumber into two or more thinner pieces of full-length boards. For example, splitting

4248-605: Is well utilised in the construction industry. Attempts to maintain lumber quality over time have been challenged by historical changes in the timber resources of the United States – from the slow-growing virgin forests common over a century ago to the fast-growing plantations now common in today's commercial forests. Resulting declines in lumber quality have been of concern to both the lumber industry and consumers and have caused increased use of alternative construction products. Machine stress-rated and machine-evaluated lumber are readily available for end-uses where high strength

4366-503: The American Lumber Standard Committee , appointed by the U.S. Secretary of Commerce . Design values for most species and grades of visually graded structural products are determined in accordance with ASTM standards, which consider the effect of strength reducing characteristics, load duration, safety, and other influencing factors. The applicable standards are based on results of tests conducted in cooperation with

4484-702: The American colonies began in 1607 when the Jamestown settlers cut timber to build the first settlement in the new world. America's first sawmill was built at the Falls of Piscatauqua , on the line between the Province of Maine and the Province of New Hampshire , in 1634. Unauthenticated records, however, claim that as early as 1633 several mills were operating in New Netherland . The American colonies were essential to England in

4602-732: The British Raj are found in the mainland Indian subcontinent (modern day India , Pakistan , Bangladesh and Nepal ). "Fort" is the word used in India for all old fortifications. Numerous Indus Valley Civilization sites exhibit evidence of fortifications. By about 3500 BC, hundreds of small farming villages dotted the Indus floodplain. Many of these settlements had fortifications and planned streets. The stone and mud brick houses of Kot Diji were clustered behind massive stone flood dykes and defensive walls, for neighbouring communities bickered constantly about

4720-614: The Indus Valley Civilization were the first small cities to be fortified. In ancient Greece , large stone walls had been built in Mycenaean Greece , such as the ancient site of Mycenae (known for the huge stone blocks of its ' cyclopean ' walls). A Greek phrourion was a fortified collection of buildings used as a military garrison , and is the equivalent of the Roman castellum or fortress. These constructions mainly served

4838-1147: The Maratha Empire . A large majority of forts in India are in North India. The most notable forts are the Red Fort at Old Delhi , the Red Fort at Agra , the Chittor Fort and Mehrangarh Fort in Rajasthan , the Ranthambhor Fort , Amer Fort and Jaisalmer Fort also in Rajasthan and Gwalior Fort in Madhya Pradesh . Arthashastra , the Indian treatise on military strategy describes six major types of forts differentiated by their major modes of defenses. Forts in Sri Lanka date back thousands of years, with many being built by Sri Lankan kings. These include several walled cities. With

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4956-574: The Mediterranean . The fortifications were continuously being expanded and improved. Around 600 BC, in Heuneburg , Germany, forts were constructed with a limestone foundation supported by a mudbrick wall approximately 4 metres tall, probably topped by a roofed walkway, thus reaching a total height of 6 metres. The wall was clad with lime plaster, regularly renewed. Towers protruded outwards from it. The Oppidum of Manching (German: Oppidum von Manching)

5074-552: The Napoleonic wars . Most of the colonial forts were garrisoned up until the early 20th century. The coastal forts had coastal artillery manned by the Ceylon Garrison Artillery during the two world wars. Most of these were abandoned by the military but retained civil administrative officers, while others retained military garrisons, which were more administrative than operational. Some were reoccupied by military units with

5192-518: The Nordic states and in Britain , the fortifications of Berwick-upon-Tweed and the harbour archipelago of Suomenlinna at Helsinki being fine examples. During the 18th century, it was found that the continuous enceinte , or main defensive enclosure of a bastion fortress, could not be made large enough to accommodate the enormous field armies which were increasingly being employed in Europe; neither could

5310-677: The Old City of Shanghai , Suzhou , Xi'an and the walled villages of Hong Kong . The famous walls of the Forbidden City in Beijing were established in the early 15th century by the Yongle Emperor . The Forbidden City made up the inner portion of the Beijing city fortifications . During the Spanish Era several forts and outposts were built throughout the archipelago. Most notable is Intramuros ,

5428-605: The Siege of Ta'if in January 630, Muhammad ordered his followers to attack enemies who fled from the Battle of Hunayn and sought refuge in the fortress of Taif. The entire city of Kerma in Nubia (present day Sudan) was encompassed by fortified walls surrounded by a ditch. Archaeology has revealed various Bronze Age bastions and foundations constructed of stone together with either baked or unfired brick. The walls of Benin are described as

5546-617: The Tang dynasty (618–907 AD). The Great Wall of China had been built since the Qin dynasty (221–207 BC), although its present form was mostly an engineering feat and remodelling of the Ming dynasty (1368–1644 AD). In addition to the Great Wall, a number of Chinese cities also employed the use of defensive walls to defend their cities. Notable Chinese city walls include the city walls of Hangzhou , Nanjing ,

5664-629: The Thames Estuary , the Solent , and Plymouth . Often sited in pairs, the blockhouses were not built to a common design, but usually consisted of a stone tower and bastion or gun platform, which could be semi-circular, rectangular or irregular in shape. The last blockhouse of this type was Cromwell's Castle , built in Scilly in 1651. Blockhouses were an ubiquitous feature in Malta 's coastal fortifications built in

5782-787: The Theodosian Walls of Constantinople , together with partial remains elsewhere. These are mostly city gates, like the Porta Nigra in Trier or Newport Arch in Lincoln . Hadrian's Wall was built by the Roman Empire across the width of what is now northern England following a visit by Roman Emperor Hadrian (AD 76–138) in AD ;122. A number of forts dating from the Later Stone Age to

5900-539: The USDA Forest Products Laboratory. Design Values for Wood Construction, which is a supplement to the ANSI/AF&;PA National Design Specification® for Wood Construction, provides these lumber design values, which are recognized by the model building codes. Canada has grading rules that maintain a standard among mills manufacturing similar woods to assure customers of uniform quality. Grades standardize

6018-401: The "Great Wall of Brodgar" it was 4 metres (13 ft) thick and 4 metres tall. The wall had some symbolic or ritualistic function. The Assyrians deployed large labour forces to build new palaces , temples and defensive walls. In Bronze Age Malta , some settlements also began to be fortified. The most notable surviving example is Borġ in-Nadur , where a bastion built in around 1500 BC

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6136-404: The "quarter" system in specifications as a vogue of insider knowledge, though the materials being specified are finished lumber, thus conflating the separate systems and causing confusion. Hardwoods cut for furniture are cut in the fall and winter, after the sap has stopped running in the trees. If hardwoods are cut in the spring or summer the sap ruins the natural color of the lumber and decreases

6254-552: The 18th century by the Order of St. John . Between 1714 and 1716, dozens of batteries and redoubts were built around the coasts of the Maltese Islands, while a few others were built in the subsequent decades. Almost every battery and redoubt had a blockhouse, which served as gun crew accommodation and a place to store munitions. Many of the batteries consisted of a semi-circular or polygonal gun platform, with one or two blockhouses at

6372-530: The 19th and early 20th centuries. The advances in modern warfare since World War I have made large-scale fortifications obsolete in most situations. Many United States Army installations are known as forts, although they are not always fortified. During the pioneering era of North America, many outposts on the frontiers, even non-military outposts, were referred to generically as forts. Larger military installations may be called fortresses; smaller ones were once known as fortalices. The word fortification can refer to

6490-409: The 4×4 (89 mm × 89 mm), are common lumber sizes used in modern construction. They are the basic building blocks for such common structures as balloon-frame or platform-frame housing. Dimensional lumber made from softwood is typically used for construction, while hardwood boards are more commonly used for making cabinets or furniture. Lumber's nominal dimensions are larger than

6608-577: The Indus Valley Civilization were fortified. Forts also appeared in urban cities of the Gangetic valley during the second urbanisation period between 600 and 200 BC, and as many as 15 fortification sites have been identified by archaeologists throughout the Gangetic valley, such as Kaushambi , Mahasthangarh , Pataliputra , Mathura , Ahichchhatra , Rajgir , and Lauria Nandangarh . The earliest Mauryan period brick fortification occurs in one of

6726-621: The Iron Age and peaking in Iron Age II (10th–6th century BC). However, the construction of casemate walls had begun to be replaced by sturdier solid walls by the 9th century BC , probably due the development of more effective battering rams by the Neo-Assyrian Empire . Casemate walls could surround an entire settlement, but most only protected part of it. The three different types included freestanding casemate walls, then integrated ones where

6844-825: The UK), 2×6 , and 4×4 . The length of a board is usually specified separately from the width and depth. It is thus possible to find 2×4s that are four, eight, and twelve feet in length. In Canada and the United States, the standard lengths of lumber are 6, 8, 10, 12, 14, 16, 18, 20, 22 and 24 feet (1.8, 2.4, 3.0, 3.7, 4.3, 4.9, 5.5, 6.1, 6.7 and 7.3 m). For wall framing, precut "stud" lengths are available, and are commonly used. For ceilings heights of 8, 9 or 10 feet (2.4, 2.7 or 3.0 m), studs are available in 92 + 5 ⁄ 8 inches (2.35 m), 104 + 5 ⁄ 8 inches (2.66 m), and 116 + 5 ⁄ 8 inches (2.96 m). The length of

6962-499: The United States began with the publication of the American Lumber Standard in 1924, which set specifications for lumber dimensions, grade, and moisture content; it also developed inspection and accreditation programs. These standards have changed over the years to meet the changing needs of manufacturers and distributors, with the goal of keeping lumber competitive with other construction products. Current standards are set by

7080-422: The actual standard dimensions of finished lumber. Historically, the nominal dimensions were the size of the green (not dried), rough (unfinished) boards that eventually became smaller finished lumber through drying and planing (to smooth the wood). Today, the standards specify the final finished dimensions and the mill cuts the logs to whatever size it needs to achieve those final dimensions. Typically, that rough cut

7198-508: The ancient site of Mycenae (famous for the huge stone blocks of its ' cyclopean ' walls). In classical era Greece , the city of Athens built two parallel stone walls, called the Long Walls , that reached their fortified seaport at Piraeus a few miles away. In Central Europe , the Celts built large fortified settlements known as oppida , whose walls seem partially influenced by those built in

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7316-410: The arrival of cannons on the 14th century battlefield . Fortifications in the age of black powder evolved into much lower structures with greater use of ditches and earth ramparts that would absorb and disperse the energy of cannon fire. Walls exposed to direct cannon fire were very vulnerable, so were sunk into ditches fronted by earth slopes. This placed a heavy emphasis on the geometry of

7434-439: The ceiling, with a bench lining the walls inside for defenders to stand on, so that attackers could not easily reach the loopholes. Blockhouses were normally entered via a sturdy, barred door at ground level. Most blockhouses were roughly square in plan , but some of the more elaborate ones were hexagonal or octagonal , to provide better all-around fire. In some cases, blockhouses became the basis for complete forts, by building

7552-571: The construction of these blockhouses, but most were either two or three story structures built using locally quarried stone. However the vast scale of British strategy led the British to develop cheaper, double-skinned corrugated iron structures. These could be prefabricated, delivered to site by armoured train, and then have locally sourced rocks or rubble packed inside the double skin to provide improved protection. A circular design developed by Major Rice in February 1901 had good all round visibility, and

7670-560: The control of prime agricultural land. The fortification varies by site. While Dholavira has stone-built fortification walls, Harrapa is fortified using baked bricks; sites such as Kalibangan exhibit mudbrick fortifications with bastions and Lothal has a quadrangular fortified layout. Evidence also suggested of fortifications in Mohenjo-daro . Even a small town—for instance, Kotada Bhadli, exhibiting sophisticated fortification-like bastions—shows that nearly all major and minor towns of

7788-402: The conversion of log timber into planks 30 times faster than previously. The circular saw, as used in modern sawmills, was invented by an Englishman named Miller in 1777. It was not until the nineteenth century, however, that it was generally applied, and its great work belongs to that period. The first insertable teeth for this saw were invented by W. Kendal, an American, in 1826. Logging in

7906-421: The cost to build a blockhouse dropped down to £16, compared to several hundred pounds for masonry ones. These blockhouses played a vital role in the protection of the railway lines and bridges that were key to the British military supply lines. During World War I and World War II , many types of blockhouses were built, when time allowed usually constructed of reinforced concrete . The major difference between

8024-408: The countries with significant sawmilling industries. Historical wood-frame home building regions are: Europe, North America, Japan. Different areas of the world are recognized as significant timber suppliers; however, these areas (Indonesia, Sarawak, New Guinea, etc.) are exporters of raw logs and do not have a significant domestic lumber producing industry. The largest lumber manufacturing regions in

8142-407: The creation of some towns built around castles. Medieval-style fortifications were largely made obsolete by the arrival of cannons in the 14th century. Fortifications in the age of black powder evolved into much lower structures with greater use of ditches and earth ramparts that would absorb and disperse the energy of cannon fire. Walls exposed to direct cannon fire were very vulnerable, so

8260-931: The current level of military development. During the Renaissance era , the Venetian Republic raised great walls around cities, and the finest examples, among others, are in Nicosia (Cyprus), Rocca di Manerba del Garda (Lombardy), and Palmanova (Italy), or Dubrovnik (Croatia), which proved to be futile against attacks but still stand to this day. Unlike the Venetians, the Ottomans used to build smaller fortifications but in greater numbers, and only rarely fortified entire settlements such as Počitelj , Vratnik , and Jajce in Bosnia . Medieval-style fortifications were largely made obsolete by

8378-435: The defences be constructed far enough away from the fortress town to protect the inhabitants from bombardment by the besiegers, the range of whose guns was steadily increasing as better manufactured weapons were introduced. Threfore, since refortifying the Prussian fortress cities of Koblenz and Cologne after 1815, the principle of the ring fortress or girdle fortress was used: forts, each several hundred metres out from

8496-704: The escalation of the Sri Lankan Civil War ; Jaffna fort , for example, came under siege several times. Large tempered earth (i.e. rammed earth ) walls were built in ancient China since the Shang dynasty ( c.  1600 –1050 BC); the capital at ancient Ao had enormous walls built in this fashion (see siege for more info). Although stone walls were built in China during the Warring States (481–221 BC), mass conversion to stone architecture did not begin in earnest until

8614-400: The field, perhaps assisted by such local labour and tools as may be procurable and with materials that do not require much preparation, such as soil, brushwood, and light timber , or sandbags (see sangar ). An example of field fortification was the construction of Fort Necessity by George Washington in 1754. There is also an intermediate branch known as semi-permanent fortification. This

8732-467: The fortification to allow defensive cannonry interlocking fields of fire to cover all approaches to the lower and thus more vulnerable walls. The evolution of this new style of fortification can be seen in transitional forts such as Sarzanello in North West Italy which was built between 1492 and 1502. Sarzanello consists of both crenellated walls with towers typical of the medieval period but also has

8850-521: The frontiers of the Nile Valley to protect against invaders from neighbouring territories, as well as circle-shaped mud brick walls around their cities. Many of the fortifications of the ancient world were built with mud brick, often leaving them no more than mounds of dirt for today's archaeologists. A massive prehistoric stone wall surrounded the ancient temple of Ness of Brodgar 3200 BC in Scotland . Named

8968-504: The generic fort or fortress in that it describes a residence of a monarch or noble and commands a specific defensive territory. An example of this is the massive medieval castle of Carcassonne . Defensive fences for protecting humans and domestic animals against predators was used long before the appearance of writing and began "perhaps with primitive man blocking the entrances of his caves for security from large carnivores ". From very early history to modern times, walls have been

9086-518: The height of the Maguindanao Sultanate 's power, they blanketed the areas around Western Mindanao with kotas and other fortifications to block the Spanish advance into the region. These kotas were usually made of stone and bamboo or other light materials and surrounded by trench networks. As a result, some of these kotas were burned easily or destroyed. With further Spanish campaigns in the region,

9204-413: The inner wall was part of the outer buildings of the settlement, and finally filled casemate walls, where the rooms between the walls were filled with soil right away, allowing for a quick, but nevertheless stable construction of particularly high walls. The Romans fortified their cities with massive, mortar-bound stone walls. The most famous of these are the largely extant Aurelian Walls of Rome and

9322-402: The intervals between them. The arrival of explosive shells in the 19th century led to yet another stage in the evolution of fortification. Star forts did not fare well against the effects of high explosives and the intricate arrangements of bastions, flanking batteries and the carefully constructed lines of fire for the defending cannon could be rapidly disrupted by explosive shells. Worse,

9440-448: The lack of corners did away with the need for a substructure. Failure due to wood rot and splintering when hit by bullets or shrapnel were eliminated. The steel door to the blockhouse was sheltered by another piece of corrugated iron. The Major Rice blockhouse could be erected in six hours by six trained men. With the change from square gabled roofs to a circular design, they were given the nickname "Pepperpot blockhouse". With mass production

9558-413: The large open ditches surrounding forts of this type were an integral part of the defensive scheme, as was the covered way at the edge of the counter scarp . The ditch was extremely vulnerable to bombardment with explosive shells. In response, military engineers evolved the polygonal style of fortification. The ditch became deep and vertically sided, cut directly into the native rock or soil, laid out as

9676-476: The main antecedents of castles in Europe , which emerged in the 9th century in the Carolingian Empire . The Early Middle Ages saw the creation of some towns built around castles. These cities were only rarely protected by simple stone walls and more usually by a combination of both walls and ditches . From the 12th century, hundreds of settlements of all sizes were founded all across Europe, which very often obtained

9794-471: The manner of a log cabin . They were usually two or even three floors , with all storeys being provided with embrasures or loopholes, and the uppermost storey would be roofed. If the structure was of timber, usually the upper storey would project outward from the lower so the upper storey defenders could fire on enemies attacking the lower storey, or perhaps pour water on any fires. When the structure had only one storey, its loopholes were often placed close to

9912-543: The modern era; a 1st class timber during the Sui was reconstructed as 15×10 (Sui dynasty inches, or 29.4 mm). Defects occurring in lumber are grouped into the following four divisions: During the process of converting timber to commercial forms of lumber the following defects may occur: Fungi attack wood (both timber and lumber) when these conditions are all present: Wood with less than 25% moisture (dry weight basis) can remain free of decay for centuries. Similarly, wood submerged in water may not be attacked by fungi if

10030-491: The most common and widely used method of sawing logs. Plain sawn lumber is produced by making the first cut on a tangent to the circumference of the log. Each additional cut is then made parallel to the one before. This method produces the widest possible boards with the least amount of log waste. Lumber manufacturing globally is determined by the preferred style of building; areas with a "wood building culture" (homes were built from wood rather than other materials like brick) are

10148-525: The old walled city of Manila located along the southern bank of the Pasig River . The historic city was home to centuries-old churches, schools, convents, government buildings and residences, the best collection of Spanish colonial architecture before much of it was destroyed by the bombs of World War II . Of all the buildings within the 67-acre city, only one building, the San Agustin Church, survived

10266-578: The one near Mycenae . Early blockhouses were designed solely to protect a particular area by the use of artillery, and they had accommodation only for the short-term use of the garrison. The first known example is the Cow Tower, Norwich , built in 1398, which was of brick and had three storeys with the upper storeys pierced for six guns each. The major period of construction was in the maritime defence programmes of Henry VIII between 1539 and 1545. They were built to protect important maritime approaches such as

10384-440: The original enceinte, were carefully sited so as to make best use of the terrain and to be capable of mutual support with the neighbouring forts. Gone were citadels surrounding towns: forts were to be moved to the outside of the cities some 12 km to keep the enemy at a distance so their artillery could not bombard the city center. From now on a ring of forts were to be built at a spacing that would allow them to effectively cover

10502-711: The outset of colonial rule in the Indian Ocean , Sri Lanka was occupied by several major colonial empires that from time to time became the dominant power in the Indian Ocean. The colonists built several western-style forts, mostly in and around the coast of the island. The first to build colonial forts in Sri Lanka were the Portuguese ; these forts were captured and later expanded by the Dutch . The British occupied these Dutch forts during

10620-409: The practice of improving an area's defense with defensive works. City walls are fortifications but are not necessarily called fortresses. The art of setting out a military camp or constructing a fortification traditionally has been called castrametation since the time of the Roman legions . Laying siege to a fortification and of destroying it is commonly called siegecraft or siege warfare and

10738-471: The purpose of a watch tower, to guard certain roads, passes, and borders. Though smaller than a real fortress, they acted as a border guard rather than a real strongpoint to watch and maintain the border. The art of setting out a military camp or constructing a fortification traditionally has been called "castrametation" since the time of the Roman legions . Fortification is usually divided into two branches: permanent fortification and field fortification. There

10856-505: The quality of lumber at different levels and are based on moisture content, size, and manufacture at the time of grading, shipping, and unloading by the buyer. The National Lumber Grades Authority (NLGA) is responsible for writing, interpreting and maintaining Canadian lumber grading rules and standards. The Canadian Lumber Standards Accreditation Board (CLSAB) monitors the quality of Canada's lumber grading and identification system. Their common grade abbrievation, CLS, Canadian Lumber Standard

10974-411: The rear. The blockhouses usually had musketry loopholes, and in some cases were linked together by redans . Surviving batteries include Mistra Battery and Ferretti Battery , which both have two blockhouses, and Saint Mary's Battery and Saint Anthony's Battery , which have a single blockhouse. Many of the redoubts consisted of a pentagonal platform with a rectangular blockhouse at the rear, although

11092-636: The resistance of the outer wall against battering rams. Originally thought to have been introduced to the region by the Hittites , this has been disproved by the discovery of examples predating their arrival, the earliest being at Ti'inik (Taanach) where such a wall has been dated to the 16th century BC . Casemate walls became a common type of fortification in the Southern Levant between the Middle Bronze Age (MB) and Iron Age II, being more numerous during

11210-429: The right of fortification soon afterward. The founding of urban centres was an important means of territorial expansion and many cities, especially in eastern Europe , were founded precisely for this purpose during the period of Eastern Colonisation . These cities are easy to recognise due to their regular layout and large market spaces. The fortifications of these settlements were continuously improved to reflect

11328-603: The role of supplier of lumber for the British fleet. By the 1790s, New England was exporting 36 million feet of pine boards and at least 300 ship masts per year to the British Empire. The timber supply began to dwindle at the start of the twentieth century due to significant harvest volumes, so the logging industry was forced to seek timber elsewhere; hence, the expansion into the American West. Logs are converted into lumber by being sawn, hewn , or split . Sawing with

11446-511: The rules of the Sciages Avivés Tropicaux Africains (SATA) and is based on clear cuttings – established by the percentage of the clear surface. In North America, market practices for dimensional lumber made from hardwoods varies significantly from the regularized standardized ' dimension lumber ' sizes used for sales and specification of softwoods – hardwood boards are often sold totally rough cut, or machine planed only on

11564-496: The settlers started clearing the huge expanses of forest in order to grow crops. Felled trees were made into planks by water-powered mills and the timber (cedar and yew) was shipped to Portugal and Spain. About 1427, the first sawmill in Germany was built. Cornelis Corneliszoon (or Krelis Lootjes) was a Dutch windmill owner from Uitgeest who invented the first mechanical sawmill, which was wind-powered, on 15 December 1593. This made

11682-484: The stockades by mounting old-fashioned bayonet charges, after laying down some covering fire. Defensive works were of importance in the tropical African Kingdoms. In the Kingdom of Kongo field fortifications were characterized by trenches and low earthen embankments. Such strongpoints ironically, sometimes held up much better against European cannon than taller, more imposing structures. Roman forts and hill forts were

11800-438: The stupa mounds of Lauria Nandangarh, which is 1.6 km in perimeter and oval in plan and encloses a habitation area. Mundigak ( c.  2500 BC ) in present-day south-east Afghanistan has defensive walls and square bastions of sun dried bricks. India currently has over 180 forts, with the state of Maharashtra alone having over 70 forts, which are also known as durg , many of them built by Shivaji , founder of

11918-626: The sultanate was subdued and a majority of kotas dismantled or destroyed. kotas were not only used by the Muslims as defense against Spaniards and other foreigners, renegades and rebels also built fortifications in defiance of other chiefs in the area. During the American occupation, rebels built strongholds and the datus, rajahs, or sultans often built and reinforced their kotas in a desperate bid to maintain rule over their subjects and their land. Many of these forts were also destroyed by American expeditions, as

12036-453: The two (broader) face sides. When hardwood boards are also supplied with planed faces, it is usually both by random widths of a specified thickness (normally matching milling of softwood dimensional lumber) and somewhat random lengths. But besides those older (traditional and normal) situations, in recent years some product lines have been widened to also market boards in standard stock sizes; these usually retail in big-box stores and using only

12154-474: The two sides in a stalemate. Hoping to make several attacks at once, the confederates persuaded the Medina-allied Banu Qurayza to attack the city from the south. However, Muhammad's diplomacy derailed the negotiations, and broke up the confederacy against him. The well-organized defenders, the sinking of confederate morale, and poor weather conditions caused the siege to end in a fiasco. During

12272-511: The usual deep i.e. underground air raid shelters) and those that functioned as anti-aircraft artillery platforms were also called Flak towers . Some were over six stories high; several survive to this day because of the high cost of demolition. The Hochbunker Pallasstraße  [ de ] in Berlin- Schöneberg has a post-war block of flats built over it. During the Cold War the shelter

12390-459: The value of the wood for furniture. Engineered lumber is lumber created by a manufacturer and designed for a certain structural purpose. The main categories of engineered lumber are: In the United States, pilings are mainly cut from southern yellow pines and Douglas-fir . Treated pilings are available in chromated copper arsenate retentions of 0.60, 0.80 and 2.50 pounds per cubic foot (9.6, 12.8 and 40.0 kg/m ) if treatment

12508-499: The walls were sunk into ditches fronted by earth slopes to improve protection. The arrival of explosive shells in the 19th century led to another stage in the evolution of fortification. Star forts did not fare well against the effects of high explosives, and the intricate arrangements of bastions, flanking batteries and the carefully constructed lines of fire for the defending cannon could be rapidly disrupted by explosive shells. Steel -and- concrete fortifications were common during

12626-559: The war. Partial listing of Spanish forts: The Ivatan people of the northern islands of Batanes built their so-called idjang on hills and elevated areas to protect themselves during times of war. These fortifications were likened to European castles because of their purpose. Usually, the only entrance to the castles would be via a rope ladder that would only be lowered for the villagers and could be kept away when invaders arrived. The Igorots built forts made of stone walls that averaged several meters in width and about two to three times

12744-410: The width in height around 2000 BC. The Muslim Filipinos of the south built strong fortresses called kota or moong to protect their communities. Usually, many of the occupants of these kotas are entire families rather than just warriors. Lords often had their own kotas to assert their right to rule, it served not only as a military installation but as a palace for the local Lord. It is said that at

12862-424: The world are: China (18%); United States (17%); Canada (10%); Russia (9%); Germany (5%); Sweden (4%). In early periods of society, to make wood for building, the trunks of trees were split with wedges into as many and as thin pieces as possible. If it was necessary to have them still thinner, they were hewn, by some sharp instrument, on both sides, to the proper size. This simple but wasteful manner of making boards

12980-627: The world's second longest man-made structure, as well as the most extensive earthwork in the world, by the Guinness Book of Records, 1974 . The walls may have been constructed between the thirteenth and mid-fifteenth century CE or, during the first millennium CE. Strong citadels were also built other in areas of Africa. Yorubaland for example had several sites surrounded by the full range of earthworks and ramparts seen elsewhere, and sited on ground. This improved defensive potential—such as hills and ridges. Yoruba fortifications were often protected with

13098-514: Was 13 ⁄ 16  in (21 mm). In 1928, that was reduced by 4%, and yet again by 4% in 1956. In 1961, at a meeting in Scottsdale, Arizona, the Committee on Grade Simplification and Standardization agreed to what is now the current U.S. standard: in part, the dressed size of a 1-inch (nominal) board was fixed at 3 ⁄ 4  inch; while the dressed size of 2 inch (nominal) lumber

13216-516: Was reduced from 1 + 5 ⁄ 8  inch to the current 1 + 1 ⁄ 2  inch. Dimensional lumber is available in green, unfinished state, and for that kind of lumber, the nominal dimensions are the actual dimensions. Individual pieces of lumber exhibit a wide range in quality and appearance with respect to knots, slope of grain, shakes and other natural characteristics. Therefore, they vary considerably in strength, utility, and value. The move to set national standards for lumber in

13334-430: Was a large Celtic proto-urban or city-like settlement at modern-day Manching (near Ingolstadt), Bavaria (Germany). The settlement was founded in the 3rd century BC and existed until c.  50–30 BC . It reached its largest extent during the late La Tène period (late 2nd century BC), when it had a size of 380 hectares. At that time, 5,000 to 10,000 people lived within its 7.2 km long walls. The oppidum of Bibracte

13452-598: Was employed in later wars against the British to block British advances. Some of these fortifications were over a hundred yards long, with heavy parallel tree trunks. They were impervious to destruction by artillery fire. Behind these stockades, numerous Ashanti soldiers were mobilized to check enemy movement. While formidable in construction, many of these strongpoints failed because Ashanti guns, gunpowder and bullets were poor, and provided little sustained killing power in defense. Time and time again British troops overcame or bypassed

13570-517: Was encircled by a fortified wall. The huge walls around the settlement, which were built very tall and with stone blocks which are 6 feet (1.8 m) high and 4.5 feet (1.4 m) thick, make it one of the earliest walled settlements in Europe but it is younger than the walled town of Sesklo in Greece from 6800 BC. Uruk in ancient Sumer ( Mesopotamia ) is one of the world's oldest known walled cities . The Ancient Egyptians also built fortresses on

13688-435: Was found. Exceptions were few—notably, ancient Sparta and ancient Rome did not have walls for a long time, choosing to rely on their militaries for defence instead. Initially, these fortifications were simple constructions of wood and earth, which were later replaced by mixed constructions of stones piled on top of each other without mortar . In ancient Greece , large stone walls had been built in Mycenaean Greece , such as

13806-660: Was in use as a NATO foodstore. In the guerrilla phase of the Irish Civil War (1922–1923), a network of blockhouses was constructed to protect the railways from guerrilla attacks. Blockhouses and coordinated road systems were used in the encirclement campaigns of Chiang Kai-shek against the Chinese Communist Party . Fortification From very early history to modern times, defensive walls have often been necessary for cities to survive in an ever-changing world of invasion and conquest . Some settlements in

13924-478: Was published by Giovanni Battista Zanchi in 1554. Fortifications also extended in depth, with protected batteries for defensive cannonry, to allow them to engage attacking cannons to keep them at a distance and prevent them from bearing directly on the vulnerable walls. The result was star shaped fortifications with tier upon tier of hornworks and bastions , of which Fort Bourtange is an excellent example. There are also extensive fortifications from this era in

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