NZ760241A

NZ760241A - A Structural Laminated Post

Info

Publication number: NZ760241A
Application number: NZ760241A
Authority: NZ
Inventors: Dennis Woodman John
Original assignee: Rippleaffect Trust Ltd
Priority date: 2018-12-17
Filing date: 2018-12-17
Publication date: 2021-01-29
Also published as: NZ771690A

Abstract

A difficulty with glued laminated timber is maintaining durability and strength when used for in-ground situations. Described herein is a structural laminated post, the post manufactured from a combination of shooks, the shooks having a generally planar shape with random length and ending and a width, the shooks being laminated together about their planar surfaces to collectively form the post shape, the post further comprising an above ground portion and an in-ground portion. In one aspect, at least the external surface of the in-ground portion of the post is chemically sealed. In an alternative aspect, the shooks of the above ground and in-ground portions are adhered together using at least one common adhesive and no sealing is required. Methods of manufacturing the posts are also described. The configurations described provide a structural laminated post for in ground applications for strength and longevity that meets code of compliance.

Description

A STRUCTURAL LAMINATED POST FIELD OF THE INVENTION Described herein is an upright supporting structure. In particular, a structural laminated post manufactured from a combination of shooks bonded together with durable, moisture-resistant structural adhesives.

BACKGROUND Structural members such as wooden posts often rot quickly because of the prolonged exposure to moisture in the soil. Without stable posts, fences and other construction members attached to the posts fall over and often the posts have to be replaced every few years. It is well known that dampness favours the growth of fungi which destroy wood. Untreated wood of many species’ decays in any situation where it can collect moisture and remain damp for a long time or where it is alternatively wet and dry.

Therefore, many posts such as solid sawn fence posts in environments in which decay hazards are great are pressure-treated with a wood preservative to make them last longer in the ground, but when fasteners (i.e. nails, bolts, and the like) or other attachments penetrate deeper into the wood than the preservatives, a condition is set up whereby water can work its way into the untreated portion of the wood and decay fungus growth can become established.

Also, solid sawn fence posts often do not have the requisite strength or longevity when the above ground portion of the post is exposed to the environment.

Glued laminated timber, also called glulam, is a structural timber product composed of several layers of dimensioned lumber bonded or glued together. By laminating a number of smaller pieces of lumber, a single large, strong, structural member is manufactured from smaller pieces. These structural members are used as vertical columns or posts, horizontal beams, as well as curved, arched shapes. Glulam provides the strength and versatility of large wood members without relying on the old growth-dependent solid-sawn timbers. As with other engineered wood products, glulam products reduce the overall amount of wood used when compared to solid sawn timbers by diminishing the negative impact of knots and other small defects in each component board.

A difficulty with glued laminated timber may be maintaining the integrity of the glue or adhesive used in the manufacture of the timber, especially that the glue remains durable when used for in-ground situations. For example, casein glues which are waterproof but have low shear strengths struggle with detachment due to inherent stresses in the wood.

The development of synthetic adhesives has enabled versatile use of glulam construction. In some cases, using adhesives characterised by resistance to temperature, climate changes, chemicals, and microorganisms can give glulam construction an advantage over reinforced concrete and steel structures. The adhesive bonds wood into a new material. The adhesive must have mechanical characteristics such that the joint is practically non-deformable.

Laminates must be joined lengthwise together in order to achieve the necessary length of the post. The most common is a finger joint glue line.

In New Zealand the requirements for timber use in construction are defined by NZS 3602:2003.

This standard also specifies the minimum preservative treatment levels for given end uses. The requirements of specific treatment regimes are contained in NZS 3640:2003. It contains detailed treatment specifications, the types of chemicals that may be used, the minimum preservative retention and penetration into the timber, identification of treated timber and quality control requirements.

When specifying timber treatment, the most important requirement is that an appropriate treatment level is specified for the particular situation. This can be done by reference to the appropriate hazard class as defined by NZS 3640. For example, see table below of exemplary timber treatment levels, treatment options and suitable applications: Timber and Timber treatment Exposure Comments Typical uses treatment CCA Copper quaternary (including Not suitable for micronized critical major Fence posts, Treated to hazard In contact with copper structural horizontal timbers class H4 ground or concrete quaternary) components in for retaining walls Copper azole ground contact (including micronized copper azole) Treated to hazard Suitable for critical House piles and As above As above class H5 major structural poles, crib components in walling, retaining ground contact wall poles As above, it would be useful to have a laminated post for in-ground structural use for over 15 years without any evidence of failure (systemic or episodic) and to meet and/or exceed code of compliance along with a product certification scheme such as CodeMark™.

CodeMark™ is a voluntary product certification scheme that provides an easily understood and robust way to show a building or construction product meets the requirements of the New Zealand Building code. Building Consent Authorities (BCAs, usually councils) must accept a product certificate as evidence of compliance with the Building Code - that is, as long as the product is used in accordance with the use and limitations defined on the certificate. Currently, CodeMark™ will not provide certification for laminated posts for in ground applications that utilise polyurethane resin (PUR) for both the laminate line as well as the finger joint line during manufacture.

It is an object of the invention to provide a structural laminated post for in ground applications with strength and longevity that meets or exceeds code of compliance, or at least to provide the public with a useful choice.

SUMMARY In a first aspect, there is provided a structural laminated post, the post manufactured from a combination of shooks, the shooks having a generally planar shape with opposing ends and a width, the shooks being laminated together about their planar surfaces to collectively form the post shape, the post further comprising an above ground portion and an in-ground portion wherein, at least the external surface of the in-ground portion of the post is chemically sealed.

In a second aspect, there is provided a method of manufacturing a structural laminated post, the method comprising the steps of: selecting a combination of shooks, the shooks having a generally planar shape with opposing ends and a width; laminating the shooks together about their planar surfaces to collectively form the post shape, the post further comprising an above ground portion and an in-ground portion; and chemically sealing at least, the external surface of the in-ground portion of the post.

In a third aspect there is provided a structural laminated post, the post manufactured from a combination of shooks, the shooks having a generally planar shape with opposing ends and a width, the shooks being laminated together about their planar surfaces to collectively form the post shape, the post further comprising an above ground portion and an in-ground portion, wherein the shooks of the above ground and in-ground portions are adhered together using at least one common adhesive.

In a fourth aspect, there is provided a method of manufacturing a structural laminated post, the method comprising the steps of: selecting a combination of shooks, the shooks having a generally planar shape with opposing ends and a width; laminating the shooks together about their planar surfaces to collectively form the post shape, the post further comprising an above ground portion and an in-ground portion; and completing lamination using a common adhesive throughout the post length.

Advantages of the above include a laminated post for in-ground applications having the requisite strength and longevity to meet or exceed code of compliance. Where used, the adhesive used to laminate the shooks provides the requisite bond strength for in-ground applications and for in-ground applications for strength and longevity that meets or exceeds code of compliance and protection for portions of the post that are exposed to UV light on a continuous and long-term basis. Adhesive use may not be essential. Where chemical sealing is optionally used, the external surface of the post may be chemically sealed, thus no physical or other sealant is required and the post once chemically sealed may be inserted into the ground and achieve desired longevity (> 15 years). Where a common adhesive is used for the above and in-ground portions of the post, the adhesive may be an easily available resin and there is no need to separately manufacture or treat different portions of the post thereby reducing manufacturing cost and complexity.

BRIEF DESCRIPTION OF THE DRAWING The invention will be described by way of example only, with reference to the accompanying drawing in which: Figure 1 is a fragmentary perspective view of a structural laminated post constructed using multiple adhesives and a chemical seal; Figure 2 is a fragmentary perspective view of an alternative embodiment of structural laminated post constructed using mechanical fasteners and a chemical seal; and Figure 3 is a fragmentary perspective view of a further alternative embodiment of structural laminated post constructed manufactured using a common adhesive throughout the post.

DETAILED DESCRIPTION For the purposes of this specification, the term ‘about’ or ‘approximately’ and grammatical variations thereof mean a quantity, level, degree, value, number, frequency, percentage, dimension, size, amount, weight or length that varies by as much as 30, 25, 20, 15, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% to a reference quantity, level, degree, value, number, frequency, percentage, dimension, size, amount, weight or length.

The term ‘substantially’ or grammatical variations thereof refers to at least about 50%, for example 75%, 85%, 95% or 98%.

The term 'comprise' and grammatical variations thereof shall have an inclusive meaning - i.e. that it will be taken to mean an inclusion of not only the listed components it directly references, but also other non-specified components or elements.

The term ‘adhesive’ or grammatical variations thereof may be used interchangeably with the terms ‘glue’ or ‘paste’ and encompasses unless otherwise stated, any non-metallic substance applied to one surface, or both surfaces, of two separate items that is typically applied as a liquid or semi-liquid and which post application cures and once cured, binds the items together and resists item separation via chemical bonding, physical bond or a mixture of chemical and physical bonding.

The term ‘finger glue line’ or grammatical variations thereof refers to the interface between opposing shook endings.

The term ‘shook’ or grammatical variations thereof refers to a short piece of timber ready to be assembled to form a laminated structure comprised of a plurality of elongated laminated together in side-by-side relationship to form an elongated timber structure. The cross-sectional areas of the respective elongated timbers are of a generally uniform shape and size. The respective elongated timbers are disposed in side-by-side relationship and glued along the sides of the timber as well as across the ends, giving rise to both edge and face joints.

The term ‘laminate glue line’ or grammatical variations thereof refers to the interface between opposing planar shook regions.

Post with Chemical Sealing In a first aspect, there is provided a structural laminated post, the post manufactured from a combination of shooks, the shooks having a generally planar shape with opposing ends and a width, the shooks being laminated together about their planar surfaces to collectively form the post shape, the post further comprising an above ground portion and an in-ground portion wherein, at least the external surface of the in-ground portion of the post is chemically sealed.

Shook Lamination In the above aspect, the shooks may be laminated together using a first adhesive about the laminate join. The first adhesive may be resorcinol glue also known as resorcinol- formaldehyde. Resorcinol is manufactured from natural or synthetic methods and is a relatively simple compound comprising a benzene ring and two hydroxide groups.

Resorcinol glue is an adhesive combination of resin and hardener that withstands long term water immersion and has a high resistance to UV light. Resorcinol glue was historically used in the marine industry but fell out of favour with the rise of epoxy resins.

Epoxy resins however lack long term UV resistance and this aspect of resorcinol glue makes resorcinol a useful choice for laminated posts such as those described herein that are exposed to UV light on a continuous and long-term basis. The bond strength is also significant for resorcinol (superior to epoxy) hence making this adhesive good for structural applications.

Further, resorcinol has excellent water resistance.

In an alternative embodiment, the shooks may be laminated together using mechanical fasteners. For example, the shooks may be nailed, screwed or bolted together about a post width.

In a further embodiment, shook lamination may occur by a combination of both adhesive use and mechanical fasteners.

Shook lamination in the in-ground portion of a post may occur via a different method to shook lamination for the above ground portion. For example, the in-ground portion shook and above ground portion shooks may be laminated together using combinations as follows: (a) In-ground portion laminated by mechanical fastener(s) and above ground portion laminated by adhesive; (b) In-ground portion laminated by adhesive and above ground portion laminated by mechanical fastener(s); (c) In-ground portion and above ground portion laminated by adhesive; (d) In-ground portion and above ground portion laminated by mechanical fasteners; (e) In-ground portion laminated by adhesive and mechanical fastener(s) and above ground portion laminated by adhesive; (f) In-ground portion laminated by adhesive and mechanical fastener(s) and above ground portion laminated by mechanical fastener(s); (g) In-ground portion laminated by mechanical fastener(s) and above ground portion laminated by adhesive and mechanical fastener(s); (h) In-ground portion laminated by adhesive and above ground portion laminated by adhesive and mechanical fastener(s); Finger Glue Line Adhesive The shooks may be joined together about the finger glue line via a second adhesive different to the first adhesive.

The second adhesive used in the above ground portion may comprise a resin.

The resin may, at room temperature when in a pure form, be a solid or highly viscous substance. The resin may typically be a mixture of organic compounds.

The resin may be natural or synthetic in origin.

The natural based resin may be a terpene compound, with non-limiting examples including pinene compounds, and monocyclic terpene compound such as limonene.

Synthetic based resins may be chemically synthesised materials with properties similar to natural resins. They are generally viscous liquids capable of hardening permanently.

The synthetic resins may be of differing classes. For example, the resin may be manufactured by esterification or soaping to organic compounds. Some may be thermosetting plastics.

The resin may be applied in a copolymer form being mixed at application with a hardener, one example being an epoxy resin mixture.

Thermosetting polymers may include only one monomer that polymerises and ‘sets’ or hardens on application.

One example of a thermoset polymer resin may be polyurethane resin (PUR resin).

Polyurethane is a polymer composed of organic units joined by carbamate (urethane) links.

Most polyurethanes are thermosetting polymers that do not melt when heated.

The resin noted above may also comprise blend additives such as chain extenders, cross-linking agents, surfactants, flame retardants, pigments, fillers, UV retardants and/or combinations thereof.

In one embodiment, the above described second adhesive is not used in-ground or is fully sealed by the chemical sealant described below.

Sealant As noted, in the first aspect, sealant may be used. Sealant may be used on at least the external surface of the in-ground portion of the post is chemically sealed.

In one embodiment, no physical or other sealant is needed and the post once chemically sealed may be inserted into the ground and achieve desired longevity.

The chemical sealant may be a polymer-based coating material with a curing time of less than 12, or 11, or 10, or 9, or 8, or 7, or 6, or 5, or 4, or 3 hours. A problem in the art of many polymer systems used for coatings was that they had curing times longer than 12 hours, examples being polymer systems based on modified polyurethanes, epoxies, methacrylate’s, polysulfides or silicones.

The chemical sealant may be applied to at least the in-ground portion of the post as a spray.

The chemical sealant may be a polyurea elastomer polymer (clearly distinct from polyurethane). Polyurea polymers may be useful as they: • have fast and consistent reactivity and cure; • are not sensitive to moisture and temperature during processing; • have excellent physical properties / elastomeric qualities; • have very low water absorption qualities and are hydrolytically stable; and • have a high thermal stability; Furthermore, they are auto-catalytic and do not require solvents to harden or cure.

Typical properties of a polyurea spray elastomer system may be as follows: ASTM Test Typical Physical Properties Shore Hardness Shore A 30 to Shore D 65 Elongation, % Up to 800 Tensile strength, psi Up to 4000 Tear strength, pli 250 - 600 100% Modulus, psi 900 - 2000 300% Modulus, psi 1000 - 3000 Taber Abrasion, mg loss < 200 (1000 gms, 1000 revs, H-18 wheels) Flexibility / Crack Bridging -26°C > 1/8 inch, pass Moisture Vapor Transmission, 0.025 perms @ 30 mils CLTE 4 - 13.4 X 10-5 mm/mm/ ° C Dielectric constant 1Mhz 3.5 - 4.5 Gel time, sec 2 - 15 Tack free, sec 10 - 60 Full curing time, hours 1 Polyurea elastomer systems contain no catalyst for cure development even down to ambient temperatures of at least -20°C. Systems which require a type of catalyst for cure, i.e. polyurethanes and some epoxies, are adversely affected by low ambient temperatures. In this way, polyurea elastomer systems cure readily at a broad range of ambient temperature conditions.

The lack of a catalyst also gives improved performance when exposed to UV light. The catalyst in a system will promote polymer degradation when the system is exposed to high temperatures or UV light. Polyurea elastomer systems exhibit exceptional performance with only slight colour changes being noted in accelerated weatherometer testing. Elastomer physical property retention is excellent.

Polyurea elastomer systems are amorphous in nature, not crystalline like polyurethane systems. This amorphous nature is similar to that of epoxy type systems except that polyurea systems do not have a true glass transition temperature. Instead, two distinct Glass Transition Temperatures (Tg) can be noted, one corresponding to the melting point of the soft block in the polymer and the other corresponding to the melting point of the hard block in the polymer.

From Dynamic Mechanical Spectroscopy evaluations of typical polyurea elastomer systems, a low temperature Tg is noted at about -50°C with a high temperature Tg of about 230°C to 260°C. The response curve between these two points remains relatively flat. This would be the performance range, temperature wise, for a polyurea elastomer system. In lay terms, the polyurea elastomer systems would tend to show some significant stiffening at temperatures less than -50°C with some polymer softening, or possible decomposition, at temperatures above 230°C to 260°C.

Post with Common Adhesive In a third aspect there is provided a structural laminated post, the post manufactured from a combination of shooks, the shooks having a generally planar shape with opposing ends and a width, the shooks being laminated together about their planar surfaces to collectively form the post shape, the post further comprising an above ground portion and an in-ground portion, wherein the shooks of the above ground and in-ground portions are adhered together using at least one common adhesive.

Common Adhesive As noted above, the post described herein may comprise one common adhesive for the post in both the above and below ground portions.

The common adhesive may be used for both shook lamination and/or finger glue line adhesion.

The common adhesive may in one embodiment be resorcinol glue also known as resorcinol- formaldehyde. Resorcinol is manufactured from natural or synthetic methods and is a relatively simple compound comprising a benzene ring and two hydroxide groups.

Resorcinol glue is an adhesive combination of resin and hardener that withstands long term water immersion and has a high resistance to UV light. Resorcinol glue was historically used in the marine industry but fell out of favour with the rise of epoxy resins. Epoxy resins however lack long term UV resistance and this aspect of resorcinol glue makes resorcinol a useful choice for laminated posts such as those described herein that are exposed to UV light on a continuous and long-term basis. The bond strength is also significant for resorcinol (superior to epoxy) hence making this adhesive good for structural applications. Further, resorcinol has excellent water resistance.

In an alternative embodiment, the common adhesive used for the post above and below ground portions may comprise a resin.

The resin may be natural or synthetic in origin.

One example of a thermoset polymer resin may be polyurethane resin (PUR resin).

Most polyurethanes are thermosetting polymers that do not melt when heated.

In selected embodiments, a blend or mix of both resorcinol and thermoset resin e.g. PUR may be used as the post common adhesive. For example, the shook lamination surfaces throughout the post may be adhered using resorcinol and the finger glue lines throughout the post may be adhered using PUR.

Shooks Only Adhered Together The shooks described to form the post in the above second aspect may only be retained together via the common adhesive described above.

The shooks described may not use mechanical fasteners for lamination. For example, the shooks are not nailed, screwed or bolted together about a post width.

No Sealing The post described above in the second aspect may be used in the form described with the common adhesive above and below ground and the post or parts thereof are not also subjected to chemical sealing or physical sealing. The inventor has found that by selection of the correct adhesive, the longevity desired for an in-ground post section in articular may be achieved without need to rely on sealants be they chemical or physical e.g. a rubber boot. This is contrary to much of the art and building standards that have traditionally required further wood preservation steps to ensure the desired longevity (50 years +). Avoiding sealants also minimises the material costs and may help to avoid unwanted changes occurring to the wood such as wood stiffening.

Despite the above, optionally, the post or a part thereof described in the second aspect may be subjected to sealing although this is not envisaged as being necessary in the inventor’s experience.

Additives The above noted common adhesive may also comprise blend additives such as chain extenders, cross-linking agents, surfactants, flame retardants, pigments, fillers, UV retardants and/or combinations thereof.

Shooks In one embodiment, the above ground portion, in-ground portion or both the above ground and in-ground portions may comprise a series of shooks of random length and ending.

Multiple shooks may be joined together in series and linked together about each shook ending to form the above ground portion, or in-ground portion or both the above ground and in- ground portion post length.

At least 2, or 3, or 4, or 5, or 6, or 7, or 8, or 9, or 10 shooks may be joined together to form part or all of the full post length.

Where multiple shooks are used in series, the shooks may comprise complementing finger joints about the interface between the shooks.

The shook length from end to end where multiple shooks are used may be 180 to 900mm long with an average length of approximately 350 to 650mm. It should be appreciated by those skilled in the art that the quality of the wood may determine the length of the shooks. For example, poor quality wood may result in the use of shorter length shooks while better quality wood might result in the use of longer than average length shooks.

In an alternative embodiment, the above ground portion or in-ground portion may comprise a series of shooks of generally common length laminated together to form the entirety of the above ground portion or the entirety of the in-ground portion. In other words, in this embodiment, the shooks run along the whole length of the in-ground portion or alternatively, the above ground portion of the post. The shooks described as above may in fact run slightly above the ground as well or slightly below the ground as well depending on the location of the longer shooks described. It should be understood that reference to slightly above may be around 1-100mm beyond the transition of the above ground and in-ground portions.

In the above embodiment, the shooks may have a common first end and random opposing ends, the random opposing ends complementing an end point of an above ground or in-ground shook ending.

Also, in the above embodiment, the shooks may for example be anything from 1 to 2m long or in one embodiment 1.3 to 1.5m long.

The shook width in the above embodiments may be approximately 30 to 500mm wide.

The shook depth in the above embodiments may be approximately 5 to 100mm deep.

Overall Post The post dimensions such as post width and depth may be common throughout the post length i.e. the in-ground and above ground portions may have a common size cross-section.

In alternative embodiments, variations in cross-section shape may occur such as a wider in- ground portion relative to the above ground portion or vice versa. For example, the cross- section size may taper from a smaller to a wider size along the post length.

The overall post shape may be square in cross-section, but conceivably other shapes such as oblong cross-sections may easily be achieved through varying shook dimensions and shook placement.

The overall post shape cross-section may in one embodiment be anything from 88 to 300mm , the dimensions depending on the structural properties required (the bigger the post, the greater the strength but also the greater the number of shooks needed to form the post).

The post or parts thereof may be treated timber. The treatment may meet hazard class ratings H4 (non-structural), H5 (structural) or H6 (Marine).

Uses Including Posts and Other Applications It should be appreciated by those skilled in the art that the invention is not limited to a structural laminated post as conceivably it could be used for other building constructions such as decking, exterior cladding, fence lines, retaining walls and so on.

Advantages Selected advantages of the above include a laminated post for in-ground applications having the requisite strength and longevity to meet or exceed code of compliance. Where used, the adhesive used to laminate the shooks provides the requisite bond strength for in-ground applications and for in-ground applications for strength and longevity that meets or exceeds code of compliance and protection for portions of the post that are exposed to UV light on a continuous and long-term basis. Adhesive use may not be essential. Where chemical sealing is optionally used, the external surface of the post may be chemically sealed, thus no physical or other sealant is required and the post once chemically sealed may be inserted into the ground and achieve desired longevity (> 15 years). Where a common adhesive is used for the above and in-ground portions of the post, the adhesive may be an easily available resin and there is no need to separately manufacture or treat different portions of the post thereby reducing manufacturing cost and complexity.

The embodiments described above may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features.

Further, where specific integers are mentioned herein which have known equivalents in the art to which the embodiments relate, such known equivalents are deemed to be incorporated herein as of individually set forth.

WORKING EXAMPLES The above aspects are now described with reference to specific examples.

Example 1 The above post of the first aspect is now described by reference to a specific example.

With further reference to Figure 1, a laminated timber structure in the form of an in-ground laminated bracing post is shown therein and indicated generally by the numeral 1.

The laminated timber structure 1 includes a plurality of timber shook laminations 2 secured together in a side-by-side relationship. The timber shook laminations 2 are elongated and extend in generally parallel relationship to a neutral axis of the laminated timber structure 1.

The timber shook laminations 2 are of a generally uniform width (30mm to 45mm), but of varying or random lengths. The average ‘short’ 3 shook length is 350mm (typically 180mm to 900mm) and a ‘long’ 4 shook length ranges in length from 1.3m to 1.5m. As shown in this example, the cross-sectional area is square and 135mm , but typically may range from 88 to 300mm for a post.

As illustrated in Figure 1, the timber laminations include five upright elongate laminated members with both edge and face joints where the respective members are glued there between. In particular, the laminated timber structure 1 comprises a plurality of timber laminations 2 glued in an end to end relationship. To form the joint about the respective ends, which are referred to as edge joints, finger joints or finger glue lines, in the contemplated design there is provided a finger joint 5. To form this joint, a respective end portion of certain timber shook laminations 2 are provided with complementary wedge cuts. To receive the point end, other respective shook laminations 2 are provided with a triangular or wedge-shaped cavity that is particularly formed to receive the point end in a very tight and secure relationship. To form this finger joint, polyurethane resin (PUR) glue is interposed between the point end and the triangular cavity.

It is appreciated that for a laminated post substitute of the character being described herein, in use, the stress about certain cross-sectional areas will vary depending on the location thereof and the application and orientation of the laminated timber structure 1. This means that certain areas of the laminated timber structure 1 will not be required to withstand stresses that other areas will require e.g. above or below ground level 6. This means that the laminated timber structure 1 can be more economically designed by selectively placing high grade timber or longer shooks 4 at selected locations while at the same time placing relatively lower grade timbers at other locations – hence the variation in shook lengths.

Also, it is appreciated that where the laminated timber structure includes face joints or laminate joints 7 i.e. between the interface opposing planar shook regions (five upright elongate laminated shook members 2), the shooks 2 are laminated together using an adhesive about the laminate join 7. This adhesive may be resorcinol-formaldehyde glue that withstands long term water immersion and has a high resistance to UV light for both in-ground and above ground applications.

By providing a laminated timber structure 1 such as discussed hereinabove, it is appreciated that higher grade timber (longer shooks 4) can be placed in areas of higher stress. In addition, natural defects such as knots, wane, and checks can be removed from the respective timber laminations with the use of lower grade timber (shorter shooks 3).

The external surface of the post (in-ground portion or all) is chemically sealed by spraying a polyurea elastomer polymer-based coating material. Therefore, no physical or other sealant is needed and the post once chemically sealed may be inserted into the ground and achieve the desired longevity.

Example 2 The above post of the first aspect is now described by reference to an alternative example.

With reference to Figure 2, a laminated timber structure in the form of an in-ground laminated bracing post is shown therein and indicated generally by the numeral 1.

As illustrated in Figure 2, the timber laminations include five upright elongate laminated members with both edge and face joints where the respective members are laminated together using mechanical fasteners 10. The laminated timber structure 1 comprises a plurality of timber laminations 2 glued in an end to end relationship. To form the joint about the respective ends, which are referred to as edge joints, finger joints or finger glue lines, in the contemplated design there is provided a finger joint 5. To form this joint, a respective end portion of certain timber shook laminations 2 are provided with complementary wedge cuts.

To receive the point end, other respective shook laminations 2 are provided with a triangular or wedge-shaped cavity that is particularly formed to receive the point end in a very tight and secure relationship. To form this finger joint, polyurethane resin (PUR) glue is interposed between the point end and the triangular cavity.

It is appreciated that for a laminated post substitute of the character being described herein, that in use the stress about certain cross-sectional areas will vary depending on the location thereof and the application and orientation of the laminated timber structure 1. This means that certain areas of the laminated timber structure 1 will not be required to withstand stresses that other areas will require e.g. above or below ground level 6. This means that the laminated timber structure 1 can be more economically designed by selectively placing high grade timber or longer shooks 4 at selected locations while at the same time placing relatively lower grade timbers at other locations – hence the variation in shook lengths.

Also, it is appreciated that where the laminated timber structure includes face joints or laminate joints 7 i.e. between the interface opposing planar shook regions (five upright elongate laminated shook members 2), the shooks 2 are laminated together using mechanical fasteners about the laminate join 7.

The external surface of the post is chemically sealed by spraying a polyurea elastomer polymer- based coating material. Therefore, no physical or other sealant is needed and the post once chemically sealed may be inserted into the ground and achieve desired longevity.

Example 3 The above described apparatus is now described by reference to a specific example with particular relevance to the post of the second aspect described above.

With further reference to Figure 3, a laminated timber structure in the form of an in-ground laminated bracing post is shown therein and indicated generally by the numeral 1.

As illustrated in Figure 3, the timber laminations include five upright elongate laminated members with both edge and face joints where the respective members are glued there between. In particular, the laminated timber structure 1 comprises a plurality of timber laminations 2 glued in an end to end relationship. To form the joint about the respective ends, which are referred to as edge joints, finger joints or finger glue lines, in the contemplated design there is provided a finger joint 5. To form this joint, a respective end portion of certain timber shook laminations 2 are provided with complementary wedge cuts. To receive the point end, other respective shook laminations 2 are provided with a triangular or wedge-shaped cavity that is particularly formed to receive the point end in a very tight and secure relationship. To form this finger joint, polyurethane resin (PUR) glue is interposed between the point end and the triangular cavity.

Also, it is appreciated that where the laminated timber structure includes face joints or laminate joints 7 i.e. between the interface opposing planar shook regions (five upright elongate laminated shook members 2), the shooks 2 are laminated together using an adhesive about the laminate join 7. This common adhesive used throughout the post may be resorcinol- formaldehyde glue that withstands long term water immersion and has a high resistance to UV light for both in-ground and above ground applications.

No chemical or other sealing is needed in the inventor’s experience but could optionally be used.

From the foregoing specification and description, it is appreciated that the laminated timber structure of the present invention presents a practical solution for in ground applications with the requisite strength and longevity that meets code of compliance. Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope of the claims herein.

Claims

WHAT IS CLAIMED IS:

1. A structural laminated post, the post manufactured from a combination of shooks, the shooks having a generally planar shape with opposing ends and a width, the shooks being laminated together about their planar surfaces to collectively form the post shape, the post further comprising an above ground portion and an in-ground portion, wherein the above ground portion, in-ground portion or both the above ground and in-ground portions comprise a series of shooks of random length and ending, and wherein the in-ground portion of the exterior of the post is chemically sealed.

2. The post as claimed in claim 1, wherein the shooks are laminated together using a first adhesive about a laminate join.

3. The post as claimed in claim 2, wherein the first adhesive is resorcinol-formaldehyde.

4. The post as claimed in claim 2 or claim 3 wherein the adhesive is used to laminate the above ground or in-ground portion of the post.

5. The post as claimed in claim 1, wherein the post or an in-ground or above ground portion of the post is laminated using at least one mechanical fastener.

6. The post as claimed in claim 1 wherein adhesive is used along with at least one mechanical fastener to laminate the post or an in-ground or above ground portion of the post.

7. The post as claimed in any one of claims 2 to 6, wherein the shooks are joined together about a finger glue line via a second adhesive different to the first adhesive.

8. The post as claimed in claim 7, wherein the second adhesive is polyurethane resin.

9. The post as claimed in any one of claims 7 to 8, wherein the second adhesive is not used in- ground and/or is fully sealed by a chemical sealant.

10. The post as claimed in any one of the above claims, wherein the chemical sealant is a polyurea elastomer polymer that is amorphous and has elastomeric properties once applied.

11. A structural laminated post, the post manufactured from a combination of shooks, the shooks having a generally planar shape with opposing ends and a width, the shooks being laminated together about their planar surfaces to collectively form the post shape, the post further comprising an above ground portion and an in-ground portion, wherein the above ground portion, in-ground portion or both the above ground and in-ground portions comprise a series of shooks of random length and ending, and wherein the shooks of the above ground and in-ground portions are adhered together using resorcinol-formaldehyde as a common adhesive for both shook lamination and finger glue line adhesion.

12. The post as claimed in claim 11 wherein the post is retained together only via the common adhesive.

13. The post as claimed in claim 11 or claim 12 wherein the post or parts thereof are not subjected to chemical sealing or physical sealing.

14. The post as claimed in any one of the above claims, the in-ground and above ground portions have a common size cross-section.

15. A method of manufacturing a structural laminated post, the method comprising the steps selecting a combination of shooks, the shooks having a generally planar shape with opposing ends and a width; laminating the shooks together about their planar surfaces to collectively form the post shape, the post further comprising an above ground portion and an in-ground portion and where the in-ground portion or both the above ground and in-ground portions comprise shooks of random length and ending; and chemically sealing the in-ground portion of the exterior of the of the post.

16. A method of manufacturing a structural laminated post, the method comprising the steps selecting a combination of shooks, the shooks having a generally planar shape with opposing ends and a width; laminating the shooks together about their planar surfaces to collectively form the post shape, the post further comprising an above ground portion and an in-ground portion and where the in-ground portion or both the above ground and in-ground portions comprise shooks of random length and ending; and completing lamination using resorcinol-formaldehyde as a common adhesive for both shook lamination and finger glue line adhesion.