Timber pilings serve as the foundations of many historic structures such as canneries, wharves, and shore buildings. The old pilings present challenging problems during restoration as they age and are destroyed by organisms and decay. Replacing the foundation entirely is possible but expensive. Regularly inspecting and maintaining timber piles may extend the life of the foundation.
Timber pile construction in the aquatic and marine environment has a long history in Europe dating as far back as the bronze and Stone Age in Switzerland. [1]
During severe droughts in Switzerland in the mid-nineteenth century, lake areas that had been previously inundated with water were exposed to reveal ancient archaeological remains of various types of timber piling support assemblies that served as foundations for both individual houses and community buildings. The design of these timber assemblies varied by the time of occupation, whether during the bronze or Stone Age, and also by geological conditions where the timbers rested. [1]
The communities were called the Swiss Lake Dwellers and were located in various fresh water lakes around Zürich and other areas in Switzerland. During the archaeological excavations, many of the piles dissolved after being in contact with air. [1]
In Venice, some of the early piling foundations were built on timber piles. The early Venetian constructors used building techniques that included using impermeable stone supported by wooden rafts and timber piles. [2] The timber piles did not rot because they were set into the mud at the bottom of the lagoon which prevented oxygen and harmful microbes from reaching them. [2]
Over 2,000 years ago, wood builders were aware of marine borers and decay and protected wood using crude extracts and various chemicals. [3] Further study on how to address marine borer activity and decay accelerated in the 18th century.
In the 18th and 19th centuries the study of wood preservation was revived due to the deterioration of the timber pile dikes that protected Holland as well as the high level of decay and marine borer activity in English Navy ships. [3] The early dikes in Holland were supported by timber piles. [4] Creosote derived from coal processing, was discovered in the mid-18th century to prevent timber pile decay. [3] The development of Creosote pressure treatment by John Bethel was also an important advancement in timber piling construction. [3] Historic buildings supported by timber piles may either be treated with creosote or chromated copper arsenate.
In the United States, Douglas-Fir timber piles are used most often in the Pacific Northwest while Southern Pine are used most commonly on the East Coast. Douglas-Fir is used most commonly on the west coast due to its high strength, renewability and low cost. [5]
There are three groups of marine borers in West Coast waters including gribbles, shipworms, and pholads, and each differs in the type of damage it causes. [6]
A Gribble (Limnoria) is a destructive crustacean that burrows into the wood surfaces. [6] Unlike other marine borers, gribbles travel easily from timber to timber using the wood for food and shelter. [6] Gribbles burrow to a shallow depth but can still reduce pile diameter by one inch per year; a gribble infested pile typically has an hour-glass shape at the tide line. [6]
Shipworms (Teredolite) are wood-boring bivalves that burrow deeply into submerged wood. [7] Although piles attacked by shipworms may appear sound on the surface, they may be completely riddled with a maze of tunnels. [6] Shipworms can spread to new wood only when they are in the free-swimming larval stage. [8] Once they attack and bore into the wood, they become imprisoned within it. [8] Ancient mariners, realizing that shipworms were imprisoned in the wood of their ships, would sail far up river and remain in fresh water for a number of months to kill the shipworms. [8] Experienced divers look for siphons that project from the wood or use sonic devices to estimate the extent of internal damage. [8] Shipworm and gribble attacks can also be detected by immersing untreated wood panels and destructively sampling them at monthly intervals. [8]
Pholads, rock-burrowing clams, burrow into and damage untreated wood in warmer waters near Hawaii and Mexico and along Oregon beaches boring only into the surface of the wood. [8] Ensuring that the shell of the wood is undamaged will keep this Pholad borer at bay.
Wood above the waterline may be attacked by a number of insects, including termites, carpenter ants, and beetles. [9] One beetle, the wharf borer (Nacedes melanura), can attack untreated or damaged treated hardwoods and conifers with high moisture contents by tunneling extensively and leaving behind dark brown fecal matter that further degrades the wood. [9]
Wood decay describes wood in all stages of fungal attack, from the initial invasion of hyphae into the cell walls to the complete destruction of the wood. [10] Wood-inhabiting fungi are most common on timber piles above the water surface since the lack of oxygen below water inhibits fungal growth. [10]
Incipient decay may develop in untreated pile tops within 1 year and reach the visible, advanced stage, termed rot, within 2 to 4 years and can extend 4 feet or more from the internally rotting areas of a Douglas-fir pile. [9] A triangular blade scraper, a sharp shovel, or a dull probe are useful when inspecting piles for surface deterioration or marine borer attack because they allow the inspector to estimate the depth of deterioration. [9] Because untreated wood can often be exposed while these tools are being used, a preservative solution or paste should be applied to exposed areas. [9]
Cracks that have developed after the wood has been treated are highly susceptible to borers, insects and decay in the right conditions. Cracks need to be evaluated during an initial pile inspection to ascertain depth, location and treatment condition.
Apply a liquid preservative to cutoff tops of piles and timbers by flooding them with hot creosote (150 to 200 °F), pentachlorophenol in diesel oil, or copper naphthenate in mineral spirits. [11]
A solid preservative, such as Fluor-Chrome-Arsenic-Phenol (FCAP), can be applied dry or as a paste where hawsers rip off caps and expose wood to moisture and decay organisms. [11]
Creosote effectively prevents attack by marine borers in coastal waters north of San Francisco and inorganic salts [Chromated Copper Arsenate (CCA) or Ammoniacal Copper Arsenate (ACA) are recommended south of San Francisco because of the likelihood of attack by the wood borer that is predominantly located in warmer waters. [12]
Impermeable barriers can protect preservative-treated wood piles under the waterline from marine borer attack by inhibiting the entry of borers into the wood and creating anaerobic conditions that kill established borers by limiting the available oxygen. [13]
A heavily damaged piling structure can be reinforced by cutting out the damaged section and replacing it with preservative-treated wood. [14] Wrapping piles with plastic barriers can provide protection from marine borers for 25 years or more. [14] Pile reinforcement with concrete can be sufficient by filling the void with coarse stone and mortar. [14] Where damage is more severe, forms made of metal, wood, concrete, woven nylon, or pitch-impregnated fiber are attached to the pile as far down as 2 feet below the mudline. [14]
In order to effectively preserve and maintain timber piles, regular inspection is required to detect deteriorating structures before replacement is necessary. [5] Pile inspections should take place every five years. [5]
One of the best ways to ascertain the cause of deterioration as well as what stage the deterioration is in, is to inspect a piling that has been removed from service. [5] The loss of one piling used for inspection might save the remaining timber pilings and members from being replaced. In order to diagnose the problems, cut the timbers into short sections and longitudinally split each section in order to see how far the preservative has penetrated. [5] Reuse of any treated timber pile supplied by an outside source is not recommended. Not knowing the applied treatment, past use, or if diesel fuels have been applied to the surface used to give the appearance of a recent retreatment could decrease the life of the pile. Some unscrupulous suppliers of used timber piles should be avoided, because some contractors have applied diesel fuel to the outside of the piles to bring the embedded creosote to the surface.
Lumber is wood that has been processed into uniform and useful sizes, including beams and planks or boards. Lumber is mainly used for construction framing, as well as finishing. Lumber has many uses beyond home building. Lumber is referred to as timber in the United Kingdom, Europe, Australia, and New Zealand, while in other parts of the world the term timber refers specifically to unprocessed wood fiber, such as cut logs or standing trees that have yet to be cut.
Creosote is a category of carbonaceous chemicals formed by the distillation of various tars and pyrolysis of plant-derived material, such as wood, or fossil fuel. They are typically used as preservatives or antiseptics.
The shipworms, also called Teredo worms or simply Teredo, are marine bivalve molluscs in the family Teredinidae, a group of saltwater clams with long, soft, naked bodies. They are notorious for boring into wood that is immersed in seawater, including such structures as wooden piers, docks, and ships; they drill passages by means of a pair of very small shells ("valves") borne at one end, with which they rasp their way through. They are sometimes called "termites of the sea". Carl Linnaeus assigned the common name Teredo to the best-known genus of shipworms in the 10th edition of his taxonomic magnum opus, Systema Naturæ (1758).
Wood easily degrades without sufficient preservation. Apart from structural wood preservation measures, there are a number of different chemical preservatives and processes that can extend the life of wood, timber, and their associated products, including engineered wood. These generally increase the durability and resistance from being destroyed by insects or fungi.
Chlorocardium rodiei (greenheart) is a species of flowering plant in the family Lauraceae. It is one of two species in the genus Chlorocardium. It is native to Guyana and Suriname in South America. Other common names include cogwood, demerara greenheart, greenhart, ispingo moena, sipiri, bebeeru and bibiru.
A utility pole is a column or post, usually made out of wood or aluminum alloy, used to support overhead power lines and various other public utilities, such as electrical cable, fiber optic cable, and related equipment such as transformers and street lights. It can be referred to as a transmission pole, telephone pole, telecommunication pole, power pole, hydro pole, telegraph pole, or telegraph post, depending on its application. A Stobie pole is a multi-purpose pole made of two steel joists held apart by a slab of concrete in the middle, generally found in South Australia.
Barmouth Bridge, or Barmouth Viaduct is a Grade II* listed single-track wooden railway viaduct across the estuary of the River Mawddach near Barmouth, Wales. It is 900 yards (820 m) long and carries the Cambrian Line. It is the longest timber viaduct in Wales and one of the oldest in regular use in Britain.
A gribble /ˈgɹɪbəl/ is any of about 56 species of marine isopod from the family Limnoriidae. They are mostly pale white and small crustaceans, although Limnoria stephenseni from subantarctic waters can reach 10 mm (0.4 in).
Teredo navalis, commonly called the naval shipworm or turu, is a species of saltwater clam, a marine bivalve mollusc in the family Teredinidae. This species is the type species of the genus Teredo. Like other species in this family, this bivalve is called a shipworm because it resembles a worm in general appearance while at the anterior end it has a small shell with two valves, and it is adept at boring through wood.
Chromated copper arsenate (CCA) is a wood preservative containing compounds of chromium, copper, and arsenic, in various proportions. It is used to impregnate timber and other wood products, especially those intended for outdoor use, in order to protect them from attack by microbes and insects. Like other copper-based wood preservatives, it imparts a greenish tint to treated timber.
A pile driver is a heavy-duty tool used to drive piles into soil to build piers, bridges, cofferdams, and other "pole" supported structures, and patterns of pilings as part of permanent deep foundations for buildings or other structures. Pilings may be made of wood, solid steel, or tubular steel, and may be driven entirely underwater/underground, or remain partially aboveground as elements of a finished structure.
A deep foundation is a type of foundation that transfers building loads to the earth farther down from the surface than a shallow foundation does to a subsurface layer or a range of depths. A pile or piling is a vertical structural element of a deep foundation, driven or drilled deep into the ground at the building site.
A wood-decay or xylophagous fungus is any species of fungus that digests moist wood, causing it to rot. Some species of wood-decay fungi attack dead wood, such as brown rot, and some, such as Armillaria, are parasitic and colonize living trees. Excessive moisture above the fibre saturation point in wood is required for fungal colonization and proliferation. In nature, this process causes the breakdown of complex molecules and leads to the return of nutrients to the soil. Wood-decay fungi consume wood in various ways; for example, some attack the carbohydrates in wood, and some others decay lignin. The rate of decay of wooden materials in various climates can be estimated by empirical models.
The wharf borer, Nacerdes melanura, belongs to the insect order Coleoptera, the beetles. They belong to the family Oedemeridae, known as false blister beetles. Wharf borers are present in all the states of the USA except for Florida. It takes about a year to develop from an egg to an adult. The name 'wharf borer' comes from the larval stage of this insect, which often lingers on pilings and timbers of wharves, especially along coastal areas. The adult beetles are identifiable via a black band across the end of both elytra. In addition, wharf borers are distinct from other members of the family Oedemeridae due to the presence of a single spur on the tibia of the forelegs and the distance between both eyes. The female beetle oviposits eggs on rotten wood, on which the larvae hatch, burrow, then feed. Adults do not eat and depend on stored energy reserves accumulated as a larva. They are considered a pest because they damage wood used in building infrastructures.
Dry rot treatment refers to techniques used to eliminate dry rot fungus and alleviate the damage done by the fungus to human-built wooden structures.
Copper naphthenate is a copper derivative of naphthenic acid. Although commonly called salts of naphthenic acid, copper naphthenate is not ionic, but is a covalent coordination complex, hence its lipophilic character. Copper naphthenate is most widely used in wood preservation and for protecting other cellulosic materials such as textiles and cordage from damage by decay fungi and insects. Other metal naphthenates are used as paint driers, rubber adhesion promoters, lubricant additives, and catalysts where oil solubility is required.
Teredora princesae is a species of marine bivalve mollusc in the family Teredinidae, the shipworms. This species lives in timber that is floating in the western Pacific Ocean.
Limnoria lignorum, commonly known as the gribble, is a species of isopod in the family Limnoriidae. It is found in shallow water in the North Atlantic and North Pacific Ocean where it tunnels into wood and attacks and destroys submerged wooden structures.
Institute of Wood Science and Technology (IWST) is a Research institute situated in Bangalore in Karnataka. It works under the Indian Council of Forestry Research and Education (ICFRE) of the Ministry of Environment and Forests, Govt. of India. It is recognized to be a Centre of Excellence for Sandalwood Research and Wood Science
The wood industry or timber industry is the industry concerned with forestry, logging, timber trade, and the production of primary forest products and wood products and secondary products like wood pulp for the pulp and paper industry. Some of the largest producers are also among the biggest owners of timberland. The wood industry has historically been and continues to be an important sector in many economies.
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