Norfolk: A County Guide (Barnabys Relocation Guides S Book 5)

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The first edition of Curators and Collections , published in , was based on interviews and features published in the quarterly review, Cv Journal of Art and Crafts The essay focuses on the makeup of a provocative and original personality acutely reflexive, intelligent, and pathologically driven. This guide explores the county of Cumbria. The journey starts in Kendal, and moves to Windermere, Bowness and Ambleside.

The beautiful environment of tarns and fells opens many varied experiences for the traveler. The guide includes information and histories from local sources. The fifth of Cv's English County Guides Norfolk is characterized by the breadth and variation of its countryside, known for its arched skies and expansive landscape.

In a series of journeys that crisscrossed the county, author Nicholas James recorded over villages and market towns, ranging from Cromer to Hunstanton on the "Norfolk Riviera" to the King's Lynn by "The Wash". It considers varied aspects of the artist, the circumstances of his social milieu, his painting methods, and the iconography of his work comparing him with predecessors in Western art from Goya to Picasso as well as contemporaries such as Lucian Freud.

A second part reviews works in an exhibition held at the Hayward Gallery London Viewing works by Rubens, van Gyck, Mantegna, and Holbein, with comments and responses of the spectators. Painter Claudia Carr describes her surreal landscapes, composed from reflections of found objects that suggest imaginative scenarios of play and dreams. Interview recorded with Rachel Howard at the artist's studio in July Explores her childhood and upbringing, awareness of "God", and experience of a Quaker schooling. Recent exhibition in Italy, the "Via Dolorosa"; discussion of her paintings and drawings; the desired effect of her work.

Interview conducted with Christiane Baumgartner in , by emailed questions and replies, in which she describes the process of her graphic and video work; incorporating ideas of stop-motion time frames applied to subjects of landscape, travelling, traffic, highways, and military installations.

She describes her training at Kingston University and at The Pratt Institute New York; with the development of an intricate play between figure, ground and light in an intimate process of accumulation and elision of elements. Listen as descriptions of human physiology are illustrated in the eBook edition with 80 panel paintings by Philip James ROI. A viscous surface of pulped and washed colour interprets the intricate framework of muscles, arteries, bone and soft tissue, all infused with an internal dynamic of potent nervous energy.

First published in , the volume carried 80 colour plates of art works with descriptions of the location and function of portrayed parts. She describes her travels in Nepal and Thailand, and the works produced from a fellowship in Barcelona, Spain. She focuses on "The Envelope Series", votive objects made with wax and encaustic, and works made with Nepalese bark paper. She considers their source and her excursions in London and elsewhere, and their bearing on her work.

An interview with the author J. He describes his formative experience of Dublin, with exhibitions there in , '50, and '51, the catalogue manifestos, for these were his first published writings, leading to work on his first renowned novel, The Ginger Man. She describes her interest in souvenirs and votive settings found in the Catholic Church, and acknowledges an influence from the art of Velazquez and Zurbaran in her refined and ethereal paintings. The conversation revolves around a recent set of still life studies; tableaux of nature morte, that carry implications of transient existence in their subtle conception.

Showing results by author "Nicholas James". Under 1 Hour While this design is not wrong, it transfers substantial load to the cross-laminated timber structure which must then be accounted for in its design. This increases costs and complexities to the design, which could be avoided by making the cladding self supporting. Self-supporting cladding must then be tied back to the crosslaminated timber structure to provide it with lateral restraint. This is normally achieved with stainless steel ties specifically designed for use with timber structure.

Depending on factors such as the amount of differential movement expected between the brick cladding and the crosslam structure, and the type of insulation used, one of three different types of ties would normally be used. The choice of ties is discussed later in this article. Insulation Another key consideration is the type of insulation that is to be used and its location.

Rigid, foil-faced foam insulation installed on the outer face of the crosslam structure appears to be a popular choice in the UK where brick-clad crosslam buildings are concerned. While this type of insulation does offer the best thermal performance per unit of thickness, it also has potential drawbacks to be considered. The foil facings on the insulation. Gaps around the perimeter of the boards can allow air infiltration past the boards and into any spaces between the insulation and the structure behind; this effect is referred to as thermal bypass.

The use of rigid insulation boards should be based on a favourable condensation risk analysis. As an alternative to rigid foam insulation, mineral or wood-fibre insulation quilt or slabs can be used. These insulation materials either need to be sufficiently dense to be used in an unsupported application, or a support network of battens or studs needs to be created. Protection from moisture The cross-laminated timber structure of the building needs to be protected from exposure to any moisture which penetrates the brick cladding.

This is achieved by incorporating a drained and vented cavity between the cladding and the outer face of the insulation, as well as the installation of a breather membrane. We often see the breather membrane installed to the face of the crosslam panels with the insulation installed outside of this. In this location, the breather membrane may not be able to repel water efficiently due to water being held against the breather membrane by the insulation.

Wind washing or thermal bypass may also occur in and around the insulation without an external wind barrier in place. BM TRADA has seen instances where taping of the joints between outer foil faces of the insulation boards has been specified.

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If the joints are taped with foil tape, a vapour control layer is then effectively formed on the outer cold in the UK climate face of the insulation which may result in an interstitial condensation risk. To recap at this point, a typical brick-clad, cross-laminated timber structure would typically consist of: These holes in the insulation and breather membrane would need to be filled and sealed to maintain the thermal and moisture tightness of the structure. The effects of differential movement would also need to be considered. Similarly, high-movement ties would result in substantial disruption to the insulation and breather membrane and the buildability of the structure needs to be carefully considered.

Solid timber battens or studs could be incorporated into the insulation zone to allow the wall ties to be fixed to them but on the outside of the breather membrane. This would avoid the need to make holes in the insulation. In summary, masonry clad cross-laminated timber structures offer good thermal and structural performance, but the connection of the masonry to the timber panels through the insulation can be problematic.

Where conditions allow, the use of simple straight helical ties helps to easily solve these issues. Wall ties The three main types of wall ties suitable for masonry-clad timber structures are: The choice of tie is normally dictated by how much differential movement is expected to occur and the type of insulation which is to be used.

If the amount of differential movement anticipated between the crosslam structure and the brick cladding does not exceed the movement allowance of the ties this can be obtained from the tie manufacturer , then helical can be used. Helical ties can be inserted through the breather membrane and insulation and into the crosslaminated timber structure. Plastic insulation retaining rings are normally available that can be used to help hold the insulation material tight to the cross-laminated timber panel.

The repeat thermal bridging of the wall ties should be considered in any U-value calculation for the wall. If an alternative type of tie needs to be used for movement or structural reasons, problems can result with their installation. The standard timber frame wall ties must be connected to the crosslam structure. If battens or studs have been used to support insulation, the ties could be fixed to these, subject to the approval of the structural engineer.

Its use in wide-span arches, gridshell domes and even bridges for roads without load restrictions has given it a reputation for public structures with a great visual impact, but it is equally at home in industrial and commercial buildings where a wide span and low weight are important.

Glulam is a construction product capable of carrying significant structural loads where failure of a single member could be catastrophic. Since its performance relies on the quality of the glue bonds between the laminations and in the finger joints, strict production controls are vital. Glued laminated timber and glued solid timber. Requirements, with the close involvement of a Notified Body.

However it does supersede six other standards, namely BS ENs , , , , and These standards dealt with performance,. Structural finger jointed solid timber. Performance requirements and minimum production requirements, the new harmonised Standard for finger-jointed timber. The scope of the new standard has been expanded to include new product variations such as block glued glulam, where glulam components are bonded together to form a larger member with a rectangular cross-section, and glued solid timber, where the individual laminations are between 45mm and 85mm in thickness.

Isocyanate and gap-filling adhesives are also included.

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The laminations are now assigned to a tension class, although equivalent bending strength classes are given for most of the tension classes, for example C24 is equivalent to T This change reflects the understanding that the performance of the lamination at the tension edge of a glulam beam is critical to the performance of the whole member.

In one important respect, the scope of the new standard is narrower than the old standard, to the extent that the UK submitted a negative vote at the approval stage. The standard now contains a list of approved species; so if the species is not on the list, it is outside the scope of the standard. There are no hardwoods on the list and hardwoods are specifically excluded from the scope, with the exception of poplar which is treated as a softwood. The National Annex NA to the standard notes that UK general practice has been to allow the use of hardwoods, and a table is provided of hardwood species that are suitable for glue laminating.

It recommends that the quality of the timber should be sufficient to achieve a C24 strength class allocation according to BS EN Assignment of visual grades and species. Despite the UK reservations the new standard has been adopted throughout Europe, and will govern the way glulam is produced for the foreseeable future. Classification of adhesives for structural use Hugh Mansfield-Williams summarises how recent changes to standards are helping to make the classification of structural adhesives easier.

These innovations are made possible by the increasing use of engineered wood products that rely upon the strength and durability of modern adhesive bonds between large timber surfaces. Well, there are many good reasons: Stresses are transferred over the whole contact area of an adhesive joint, without damaging the structure of the timber, whereas stresses in mechanically fastened joints are concentrated where each fastener penetrates the timber. Adhesive joints are resistant to corrosive atmospheres and connections made with thermosetting resins may last longer in a fire than those made with metal fasteners.

However, all these benefits are lost if the adhesive bond is not up to scratch. A quality control check will pick up a mechanical fastener that is missing or poorly installed, but a poor adhesive bond cannot be identified by visual inspection. A poor bond may be strong enough to survive handling and installation, but that will be of little comfort if it fails under a high load, a very rare occurrence fortunately. Factories manufacturing structural products that rely on adhesive bonds tend to automate the process as far as possible, as consistent performance follows a consistent process.

The classification of structural adhesives is the tool that specifiers can use to understand if the adhesive is suitable for the intended end use. The recent publication of new editions of the European Standards for adhesives for load-bearing timber structures has made major changes to the classification systems for these adhesives. Classification codes combine information about the type of adhesive and its intended end use. Adhesive groups Adhesives can be placed into one of six groups, based on their composition, but only four of the groups are generally suitable for load-bearing connections: The two groups that are not generally suitable for structural applications are not considered here.

Adhesives can also be grouped according to their behaviour under elevated temperature as thermosetting or thermoplastic. Thermosetting adhesives are polymers that cannot easily be softened or dissolved once set. The chemical reactions during curing tend to form a network of bonds, so the gluelines are strong and rigid under load. Some adhesives cure more quickly or their properties change when heat is applied during curing. Thermoplastic adhesives are polymers that even after curing will soften when they become hot and harden when they cool.

Some are less rigid when cured than thermosetting adhesives, or more inclined to creep under load, in which case they are not suitable for structural use, but others are similar to thermosets and can be suitable for structural use. Classification Standards The Standards containing classification systems for adhesives for load-bearing timber structures have recently been revised.

In practice this means heated interior use only. A new Standard has been published for emulsion polymerized isocyanate adhesives: Type I EPI adhesives are assigned to service classes 1 and 2, but not to service class 3. An equivalent classification system is provided for one-component polyurethane adhesives in BS EN The classification does yet not match the revised BS EN or the new BS EN since it still allows Type II adhesives to be used in service class 2 conditions, where there may be occasional wetting. Tests are for close contact gluelines of 0.

Manufacturers should undertake these programmes to demonstrate that their adhesives meet the performance requirements of the standards. Not all combinations are allowed. Maximum glueline thickness mm 0. Adhesive and hardener mixed before application S: Separate application of adhesive and hardener. Laminated veneer lumber LVL: Supporting services Visit the Wood Information section at www.

What is clear from the types of enquiry is that there is a concerning lack of understanding about passive fire protection. This is particularly apparent for individuals that have been tasked with responding to the findings of a fire risk assessment. It is certain that, despite the RRFSO having been in force for eight years, the number of queries related to passive fire protection that it generates has not abated.

One of the reasons why the RRFSO continues to raise questions with respect to passive fire protection is the general lack of building information available during the fire risk assessment process. Among other duties placed upon them by the RRFSO, the responsible person must conduct a suitable and sufficient risk assessment article 9 and take any general fire precautions to ensure, so far as is reasonably practicable article 8 , the safety of relevant persons.

The highlighted terms are subjective but are intended to allow risk-based solutions that are tailored to the building type, business undertaking and the occupants. Built-in protection Passive fire protection is the primary safety measure built into the fabric of a building.

It helps to ensure the stability of the building and protect the means of escape in fire conditions. Unsurprisingly, therefore, it is one of the key aspects of a fire risk assessment. This assessment often has to be made in the absence of supporting test evidence and within buildings that pre-date current building regulations and design codes. In the absence of information on the fire resistance properties and design of the building, the fire risk assessment can take various paths. These are normally a function of the competency of the risk assessor.

The element of construction is assumed to have the required level of fire resistance or is not addressed within the fire risk assessment at all, reliance on the building structure is misplaced undermining the suitability of the fire risk assessment. Risk adverse, the default position is to replace or upgrade passive fire protection to meet current regulations. Recognition of limits of knowledge and referral to an independent expert for a third party opinion on likely fire resistance performance of an element of construction.

A risk-based approach is adopted based on the likely performance of construction set against the overall risk and occupancy of the building. The examination of buildings during the fire risk assessment process has not only highlighted competency issues among those carrying out the assessments Responsible Persons and professionals but also within the building industry. To name just a few of the more common issues, many risk assessments find compartment lines breached by the installation of pipes and cables; deficient fire doors, which are poorly maintained; glazing incorrectly specified and installed; and poor fire-stopping practices.

In fact, as some specialists operating in the passive fire protection industry have known for some time, the RRFSO has highlighted wideranging concerns including: A great deal of construction work is directly or indirectly linked to passive fire protection and many of the more specialist systems are incorrectly installed or specified. Unfortunately, these mistakes are not always picked up in the building approvals process. Since inspections are subjective in their nature, this has led to inconsistent enforcement by different regions, and sometimes within the same fire and rescue service.

What is deemed acceptable in the absence of supporting test evidence to some inspecting officers is not always acceptable to others. This has led to frustration for some Responsible Persons who view this as a shifting of the rules, making it even more difficult to comply. As with any new legislation, there is a period of adjustment as businesses, enforcers and the law courts become familiar with the. Judging by statistics released by the Department for Communities and Local Government DCLG for the period , there are still a large number of businesses that are either not aware of their legal obligations or choose to put profit before safety.

The statistics for England showed that during this period 2, enforcement notices and prohibition notices were issued and 58 prosecutions undertaken. Nevertheless, the RRFSO is slowly becoming accepted and understood as part of the landscape of fire safety legislation. Driving improvement During the last eight years, the RRFSO has highlighted a number of challenges related to our existing building stock. These are now being addressed in a number of ways: This not only provides confidence in the performance of a product but also assists with identifying the provenance of the product, which is useful for future maintenance and fire risk assessment.

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The guide places emphasis on prioritising assessment of the passive fire protection systems on the means of escape in order to evaluate what is needed for occupants to evacuate the building in the event of fire. Fire risk assessments for insurance and property protection may need to consider the performance of passive fire protection systems that go beyond that required as a minimum for evacuation and life safety. Aimed at ensuring that building owners have all the necessary information on the fire safety systems that are incorporated within the building, this regulation is not always complied with, despite having been in place since the RRFSO came into force.

Access to this vital information not only assists with the safe operation of a building on a day-today basis but is obviously valuable when it comes to undertaking a fire risk assessment under the RRFSO. In summary, the RRFSO has had a huge and mainly positive impact on the passive fire protection industry, by highlighting competency issues at every level of the supply chain and revealing some of the fire safety concerns prevalent within our existing building stock. This has raised the profile of passive fire protection and the industry has responded by introducing qualifications and benchmark standards for professionals working with passive fire protection.

However, there is still a considerable amount of work to be done to further improve understanding of the RRFSO and the role of passive fire protection, so that everyone is aware of their fire safety obligations. Rapid fire spread, with an extremely quick increase in temperature and the development of large volumes of smoke, is possible within a matter of minutes of a fire starting. Left unchecked, a fire will continue to grow and exploit weaknesses in the building structure and, once a fire has engulfed a building, it has the potential to spread to adjacent buildings through radiated heat.

The need to limit fire and smoke spread, to protect the lives of people living and working in and around buildings, has been recognised for many years. Sections B2, B3 and B4 outline how the construction should limit fire growth B2 , contain fire growth to the room of origin and provide structural stability B3 and prevent fire spreading over the envelope of the building and travelling to adjacent buildings B4.

This is reflected in the increasing number of construction projects using modern methods of construction MMCs , particularly in the education, healthcare and housing sectors. Occasionally, MMCs are now integrated with traditional buildings that may pre-date our current building regulations, in order to enhance environmental performance. Irrespective of what materials or methods are used for a building, the building regulations require that the building must be constructed to secure reasonable levels of health or safety in case of fire.

For the same systems to continue to provide the required level of fire resistance throughout the design life of the building they must also be adequately repaired and maintained. As a result of the increase in fire risk assessment, now a legal requirement for individuals responsible.

Understanding buildings — past, present and future Guidance documents such as Approved Document B are based primarily on construction methods such as brick and block, and draw on expertise specific to this method.

Often the controlling authorities, construction industry, insurers, fire and rescue services, property managers and homeowners are most familiar with traditional methods of construction. However, to meet increasing demands for sustainable buildings that can achieve higher standards of energy efficiency, coupled with faster completion times, timber and innovative construction products and. Problems are being identified in traditionally constructed buildings as well as MMC, some are a result of: In the majority of cases, the people that occupy these buildings would be under the assumption that they could make their way to a place of safety in reasonable time in the event of fire, when in reality that might not be the case.

System-based approach Fire will always find the weakest link and the opportunity for weak links in the construction process is vast. For an individual item of passive fire protection to work as tested it must be constructed with the correct components and be installed correctly. The products must then be correctly specified throughout the building in order to complement. There is little point in using linings that limit the growth of fire and smoke if other aspects of the building design allow the fire and smoke to travel freely.

Although the Q1 RICS Construction Market survey highlights a continuing improvement in activity, contractors are acutely aware that projects need to be delivered on time and to budget to maintain their profile within the industry and continue to win work. The pressure on time and money occasionally results in deviations from the original building design and corners being cut, which can have the potential to seriously undermine the assumed performance of the building in a real fire event.

In some cases, cheaper alternatives are being used as construction materials that may not carry any fire resistance performance or may not have been tested for the application, thus reducing any safety margin of performance or, worse still, completely undermining the fire resistance of the building. In addition to time and cost pressures there is a recognised shortage of skilled individuals working specifically within the field of passive fire protection within the construction sector.

This has become more prevalent during the recession and, now that we are beginning to see an upturn in construction, there is a concern that a lack of skills in the sector could affect the quality of installed passive fire protection measures. For the MMC sector, there are some additional challenges posed by the shortage of skills in the construction sector.

As for any innovative product, knowledge of the system and how it works is particularly important as there will be less industry experience of the product. Applying traditional building practices to MMC may be inappropriate and could compromise the structure of the building in a fire event.

For any individual working on a project that uses MMC, demonstrable experience of working with the system should be required, which must include understanding how the passive fire protection features of the system work. Increasing knowledge of passive fire protection within the construction industry is essential but really this should include building owners, occupants and trades people that are likely to have an impact on the structure of the building during its design life.

There is no point in constructing buildings that are safe in the event of fire if there is a significant risk that this will be quickly diminished by the management and use of the building. This aims to ensure that fire stopping solutions are being fitted correctly and to verify the competence of installation companies. Representatives of companies certified under the scheme will place a label next to each installation to confirm that it meets the requirements of the scheme and each will be registered with BM TRADA through their web-based database.

Once this has been completed, BM TRADA will email a certificate to the responsible person, confirming details of what has been installed. MMCs are expected to reduce the housing shortage within the UK and therefore we must have a skilled work force within the construction industry that understands the systems, how they differ from traditional methods of construction, and the importance of detailing the passive fire protection systems correctly.

The solution is to close this knowledge gap through offering training and continuous professional development to all those involved in the construction process and throughout the life of a building. Manufacturers must offer training and guidance to those tasked with building these structures.

Such courses should highlight the key features of MMC that may impact on the fire performance. Third party certification schemes for products and personnel can go a long way to ensuring that the system-based approach required for passive fire protection is correct when the building is completed and throughout its design life. They not only demonstrate the quality that should be expected but allow traceability for future fire risk assessments and maintenance.

Such schemes require products to meet established test performance and require ongoing production audits. Installer schemes require operatives to demonstrate their skills and knowledge with site installations regularly audited. Supporting services BM TRADA can test and certify the fire resistance of various construction materials and provide site surveys for passive fire protection.

The Lifecycle Database aims to provide independent data on the environmental performance of wood products to stakeholders including architects, engineers and material specifiers, as well as the timber industry itself. It is available at www. This can help make timber a natural first choice for the market. Life cycle assessment LCA data Life cycle assessment LCA is currently the most appropriate tool for determining the environmental performance of products. LCA considers impacts throughout the product supply chain and addresses a range.

As such, LCA gives a rounded understanding of the environmental performance of products and can be used to illustrate the trade-offs associated with different design choices such as selection of different materials. Given the large number and geographic distribution of suppliers of wood products to the UK, the costs and time required to collect and generate specific data for the products covered in the Database would be very high.

Using generic data offers a practical way to accurately estimate the impacts of timber products consumed in the UK market and we consider this to be appropriate considering the goals of the Wood for Good Lifecycle Database. Generic data is as useful as proprietary data for a particular manufacturer and product which may be available in manufacturerspecific EPD at the early design stage when making choices about material types rather than product. This database is designed to bridge an existing gap and provide generic information to construction professionals to help inform their early thinking.

Support for the timber industry The database will support the timber industry as, in the near future, it will be necessary to provide this form of data as new rules and regulations start normalising the use of LCA data in building projects across Europe. The Netherlands already requires building-level lifecycle assessment for all new homes and offices over m2; Germany has done the same for all public sector buildings, while Belgium and France have similar regulations coming into force.

By providing the generic product information from across the industry we can help ensure that timber-based projects are realised and seen as first choice options. So far, the reporting requirements at building level have mainly been for structural elements and the database contains information on structural timber products. However, the data can be used to calculate the impacts for a wide range of other joinery items. In the future we hope to be able to add to this list with many other items which could not be included in this first phase of the project.

First phase LCA datasets are available for the following products: The data has also mapped and highlighted the impacts across the supply chain. This allows the timber industry to look more closely at where its own processes can be improved in order to reduce environmental impact.

Perhaps the most important advantage of this project is to be able to communicate quickly and with confidence the environmental benefits that building with timber can bring. A greater use of timber can help make significant savings. Our animations are designed to clearly show how these savings can be made.

We will continue to push this agenda, using LCA data to qualify our campaigns, to ensure that the construction industry, policy makers and the general public are all aware of the benefits of using timber. We hope we can build on this and use the data to usher in a new era of truly sustainable construction.

Such timbers are often those highly valued for their unique properties, for being particularly attractive, being highly durable or having excellent mechanical properties, or producing extractives which provide a natural source of aromas for use in perfumery. The perceived value of species such as ramin or Brazilian rosewood means they have become overexploited, often leading to sustainable forest management placing harvesting restrictions on these species in their countries of origin. Timber properties testing For lesser-used timbers to become more widely accepted for use in markets outside their regions of origin, it is important that their properties be understood.

The properties of many commercial species are well documented and understood following extensive testing, usually using standard test methods. Properties described include ease of processing sawing, planing, sanding, gluing and finishing , strength, hardness, abrasion resistance, movement, interaction with fixings, weathering performance and durability against biological agents. This information is valuable to manufacturers and to specifiers, since both need to understand how the wood they select is likely to perform, either during manufacture or in its intended end use.

Access to this information also allows them to select a species that has the appropriate combination of properties for an intended end use. As some traditionally used species become more difficult to source, there is increased interest in using more readily available lesser-known timber species, sometimes described as lesser-used species LUS or secondary timber species.

Many of these timbers might have been used locally but are not accepted by the wider timber market. BM TRADA is able to access information about properties and uses of individual species from a very wide range of sources, interpret the relevance of test methods used in relation to current standards and interpret data to determine likely timber properties. TRADA also maintains a species database which guides specification based on wood properties. Timber properties testing can be expensive, in terms of time and money. A full suite of tests may cost tens of thousands of pounds and can take up to five years to complete.

Where clients have several lesser-used timbers to evaluate, these costs can be prohibitive. These include specialist publications such as scientific papers published in wood journals, reports from local forestry and wood science departments and specialist databases, many of which are held by BM TRADA. Specialist publications can provide information on lesser-used timber species. A review of literature relating to a specific timber species enables us to establish what is already understood regarding its properties. Similarly, those timbers that have been used locally for furniture are likely to have suitable working properties and appearance for this end use elsewhere.

Research data In some cases testing has been carried out by universities in the country of origin. Although the methods used may be non-standard, and the work has not been peer-reviewed and therefore the reliability of the findings must sometimes be viewed with caution, in the absence of further information they can provide a useful insight. Geographic range Where the natural range of a tree species extends across several countries so that information is available from more than one source, then if it can be established that researchers in different countries find a specific property of the species to be similar, this provides extra confidence about the reliability of these findings relating to the property in question.

Some properties are assessed using very similar methods irrespective of test laboratory. One such property is density. Understanding the level of variation in density data is useful since density influences other wood properties such as strength, hardness and wear-resistance. Where density data is available for trees taken from across a geographic range, an examination of the level of variation provides an insight into likely variation in other properties such as strength and hardness for the timber species.

An understanding of the level of variation in timber properties is important to the end user who, in some cases, may require consistency or may need to be conservative in their selection of timber. The variation in properties between trees is one of the reasons that Standards require testing of timber taken from several trees and this is one of the aspects we seek to verify when reviewing local test methods used.

Nomenclature Sourcing information based on local names for timbers can be challenging with more than one local name used in some countries; where a tree species grows across several countries this can lead to a multitude of names to search under. In addition, the botanic nomenclature for certain species can be confusing. For that reason where searches are done by botanic name you also need to consider what it may have been called in other publications, to avoid missing information. Where this information is available it provides an insight into how well the LUS is likely to perform.

Visit the Wood Information section at www. Although the methods used are sometimes time consuming, work of this type demonstrates the value of international networks of wood scientists, specialist databases and warrants the shelf and filing cabinet space given up to specialist texts dating back as far as the early s.

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WPA Director Steve Young explains the importance of this project to the UK timber industry and why those with an interest in growing the use of British softwoods are backing the project. PA has contracted the Building Research Establishment BRE to conduct a long-term, controlled field trial of sawn and pressure-treated British softwood posts at two sites with differing soil conditions — one in Scotland and one in England. In all, some 1, samples of treated and untreated Sitka spruce, Scots pine, Douglas fir and larch posts will be installed across the two sites.

The performance of the posts will be monitored for up to 15 years. A growing awareness about variability in the natural durability of heartwood, particularly in fastgrown plantation softwoods, contributed to this specification change. Any process that results in achieving the new heartwood penetration requirement may be used but, as in other parts of the world, it is expected that incising prior to treatment may be the only practical method currently available for commercial use — particularly for species that are difficult to treat.

The WPA believes that strengthening the year specification should only be based on data derived from a controlled field trial of commercially sized sawn posts of spruce, pine, Douglas fir and larch from UK forests. This project uses commercially available incising patterns and is independently audited and assessed. In all there will be approximately 1, 75mm x 75mm treated samples incised and untreated controls in the field trial, across both sites. In addition, the project will also include some smaller EN samples to characterise the test sites against other UK test site locations.

This is a low-cost addition that will provide some very useful additional data. The project will run for up to 15 years. Publicity about the field trial has, however, revealed a growing industry interest in this commercially relevant project and WPA is inviting other organisations and individual companies to back the initiative and become either a Project Associate or an Associate Sponsor.

Project associates This category enables other timber trade associations a stake in the first reporting phase of the project. The field site in Scotland is provided courtesy of James Jones. The wood preservatives used in this field trial have all been approved by the WPA after independent scrutiny of efficacy data under our Benchmark Product Approval scheme. Who is backing this WPA project? This WPA initiative has been a long time in the planning but successful bids for matching funding support from Forestry Commission Scotland and Scottish Enterprise and a financial contribution from the Grown in Britain campaign have made this important project possible, together with the sponsorship support of WPA members involved in homegrown timber supply, incising and wood preservation.

This project is not a comparative assessment of the different preservatives used; it is a trial of natural durability first and foremost, and of the effects of different preservative loadings. However, the performance data on a specific preservative will be made available to the manufacturer of that preservative. Post preparation, quality control, project logistics and management will be carried out by WPA, in partnership with key commercial organisations that have an interest in the market for British softwoods. The key role of auditing these activities, the establishment and monitoring of the two test sites, and annual reporting on the condition of test stakes, will be the responsibility of BRE.

This sponsorship opportunity is renewable for each major reporting stage of the field trial as it progresses over the years. Details of the sponsorship cost are available from the WPA. Associate sponsorships are renewable on an annual basis.

Much of the activity involved in establishing this field trial is being facilitated through WPA members who have a direct commercial interest in the information that will be produced:. Achieving longlasting timber fencing through specification Ben Sharples looks at the considerations for durable timber fencing. Easily worked and readily available in a variety of types, shapes and sizes, it can last longer and perform better than many alternative materials — either in its natural form or with preservative treatment.

Choosing a specific fence type could be down to personal preference where the function of the fence is primarily based on aesthetics, for example a garden border. A fence may need to serve a particular purpose for which a specific type would be more appropriate, such as a closed panel fence acting as an acoustic barrier along a motorway or stock fencing for farming.

Once the fence type is determined, then a robust design and specification process will ensure that the fence will fulfil its requirements. Provided that the fence is designed and specified properly there should be no reason for the fence to fail prematurely. Risk of decay The service life of most fences is governed by the resistance to decay of those timber components that are in ground contact, for example posts.

Many timber species used for posts do not have sufficient natural resistance to decay to last for more than five years in ground contact. The heartwood of tropical and temperate hardwoods is generally sufficiently durable to be used without treatment; however their sapwood is not durable and should therefore be excluded. Other less durable but readily available timbers require preservative treatment to achieve desired service lives of 15 or 30 years.

Two such UK hardwoods that have traditionally been used for fencing are European oak and sweet chestnut. Preservative treatments Desired service lives of 15 to 30 years may be achieved with correct timber treatment, which requires a rigorously controlled treatment process. Wood must be of appropriate moisture content, and process parameters must be closely monitored including preservative solution strength and vacuum pressure cycle times.

A list of preservatives approved for different use classes is given in the Manual: Although this may be acceptable in many situations, it may be desirable to protect the timber from this effect. A finish can protect the surface of the timber from weathering and reduce rate of wetting but this requires the coating to be maintained and it cannot be applied to protect bases of posts.

It is most frequently applied where aesthetics of fences are important. Detailing and design Careful design and detailing can extend the service life of fencing — for example, designing to allow for water shedding will reduce the risk of it trapping around joints. To protect the exposed end grain of fence posts from wetting, the tops of the posts should be capped or sloped to shed rainwater away from the end grain. Erection Using professional fencing contractors to install fencing is more likely to achieve a better quality installation and improve the service life of the fence.

An added benefit of this is that good aesthetics and better security can be achieved. It is recommended that posts be installed in accordance with the relevant British Standards, such as BS — Fences. The standard gives specific dimensions for fencing components and spacing intervals. In some instances strengthgraded timber set to specific depths in appropriate foundations is advised.

For closed panel fences wind loads may need to be considered. Specialist contractors provide installation services for farm fencing and highways fencing. Where preservative-treated posts are cut to length during installation, the untreated section of the timber will be exposed. To prevent the occurrence of fungal decay, it is essential that any exposed untreated timber does not come into contact with the ground. Treat cut ends with a liberal application of preservative to restore the treated zone.

Inspection and maintenance Routine inspections particularly for fencing where failure poses a problem, such as stock fencing and acoustic barriers and regular maintenance are essential, to ensure the fence remains in good condition, safe, and fit for purpose. Finishes and preservatives may, over time, fail due to factors that inevitably occur when a natural material is used in an outdoor environment.

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Maintaining the protective finish by regular re-application of a stain or paint will help keep the fence components above ground level structurally sound free from decay for an extended period of time. The Fencing Contractors Association www. This is particularly important when the condition of the fence is imperative to the use such as stock fencing or acoustic barriers. Top ten tips for timber cladding Timber cladding provides an attractive, economic and environmentally friendly way to enclose buildings. Lewis Taylor offers tips for specifiers.

Here are some of the key points to help you to get the best from this versatile material. Species The choice of timber species is normally based on three main considerations: It is normal to start with the consideration of durability and then look at cost and aesthetics of the species available which offer the required service life. Code of practice provides guidance on the minimum anticipated service life of timbers in various different applications. Table 3 of this standard lists the anticipated service life of coated and uncoated timber cladding depending on the durability of the timber used.

This table extracts this information for cladding. These durability classes refer to the heartwood only. The sapwood of any timber species is considered not durable. When specifying timber for external cladding, the specification must exclude sapwood. It should also be understood that these are minimum anticipated service life predictions, and many factors such as design can prolong or shorten the service life. Common softwood species used for timber cladding are: Due to its natural durability, western red cedar is a common and popular choice for uncoated external cladding and can provide a year service life.

Douglas fir and larch can also be used uncoated, but will typically only achieve a year service life. Whitewood and redwood can also be used for external cladding but would normally be preservative treated and coated — it is important that the surface coating is appropriate and well maintained. Common hardwood species are oak and sweet chestnut, both of which are durable. There are many other hardwood species which could be considered, and information on their durability can be found on the TRADA Wood species database at www.

Modified woods are also available for use as external cladding. These are either thermally or chemically modified to enhance their natural durability. The durability classes are: The choice of profile predominantly comes down to aesthetics. There are two things to consider however, the first being the width of the cladding boards.

BM TRADA recommends that board widths are limited to mm maximum to reduce the overall shrinkage or swelling which will occur with moisture content changes. Tongued and grooved boards should be limited to a maximum width of mm to reduce the risk of the tongues disengaging from the grooves when the boards shrink. The second consideration is whether it is an open- or closed-jointed cladding system. Open-jointed cladding systems can allow substantial water penetration and exposure of the substructure to UV.

Special consideration needs to be given to waterproofing details around window and door openings and it may be necessary to use a specialist UV-resistant breather membrane on the substructure behind. Hardwood cladding boards are normally screwed to the battens using stainless steel screws — again two fixings used at quarter points across the board. Holes should be pre-drilled in the cladding board and slightly oversized to allow expansion and shrinkage of the board. Support battens Cladding boards are usually fixed to preservative-treated softwood cladding battens. These will normally be oriented perpendicular to the cladding boards: Depending on the board profile and installation method, vertical counter battens may be installed first to provide drainage and ventilation.

Horizontal battens should have their top edge angled to shed water. Fixings Softwood cladding boards are normally nailed onto timber support battens with stainless steel nails. It may be possible to use galvanised nails if the boards are to be painted, but BM TRADA recommends that stainless steel nails be used. If using plain wire nails, the nails should be long enough to achieve a point-side penetration of 2. For example, when fixing a 20mm thickness board, there should be 50mm of nail penetration into the batten using nails of 70mm length.

Annular ring shank nails sometimes called improved nails only require point-side penetration of 2x the board thickness. For example, 40mm of nail penetration for a 20mm thickness board using 60mm length nails. Two nails are normally used at quarter points across the width of the board. The space behind the cladding created by the cladding battens should be drained and ventilated.

This serves three purposes: Flashing details at the base of the cladding and around windows and doors should be designed to shed water away from the building while maintaining the required ventilation. Check the requirements for fireresistant cavity barriers with local building control and consider using third-party approved, ventilated cavity barriers where needed. Coatings Before specifying the application of a surface coating, consider the anticipated service life of the coating and the required maintenance regime, and make sure that the building owner understands what maintenance is required.

Clear coatings such as oils and varnishes will normally require pre-emptive re-application approximately every 12 months and, for that reason, BM TRADA does not recommend their use. In addition, if the surface coating does fail leading to discolouration or weathering of the wood, simply reapplying the coating will not be sufficient and will seal in the discolouration and trap moisture. Paints and stains will have a longer service life but will still require periodic and pre-emptive re-application.

The design of the cladding should avoid moisture traps and projections which will allow splash back onto the cladding. Cutting the ends of vertical cladding board to an angle will allow moisture to drip from the ends of the boards more easily. Where end grain of boards is present,. Normally rainwater running down the cladding would wash these extractives away potentially discolouring other cladding, such as render, below. If the timber cladding is sheltered fully or partially from rain water, these extractives will still come to the surface but will not be washed away and can result in surface staining.

Cutting the ends of vertical cladding board to an angle allows moisture to drip from the ends of the boards more easily. Installation Store cladding boards spread out on stickers small timber strips to spread and separate the boards and cover loosely to reduce the exposure to moisture and allow air flow around all boards. This will greatly reduce the risk of discolouration to the timber.

This will reduce the likelihood of significant movement or distortion of the cladding. If surface coatings are to be used, they should be applied to all faces before the cladding is fitted. Finishing the cladding after installation may result in areas of unfinished wood becoming visible when the cladding swells or shrinks. This staining can be removed and the surface of the wood brought back to a natural colour, or it may naturally fade over time if the area in question is only partially sheltered.

Weathering If the external timber cladding is to be left uncoated, it will weather naturally and turn silver-grey over time, due to exposure to moisture and sunlight. Uncoated external timber cladding will always weather and this should be expected. As discussed above, the use of clear surface finishes to preserve colour is not recommended due to the maintenance required. Discolouration During the weathering process, discolouration or differential weathering of the cladding can sometimes occur, leading to staining or an uneven colour.

There can be many reasons for this, but one of the more common reasons is extractive staining sometimes called tannin staining. Some timbers, such as oak and western red cedar, have far more extractives, and are more prone to this type of discolouration. When the cladding is wetted, these extractives are mobilised and brought to the. How to design a pitched roof Aron Searle discusses the design of pitched roofs, with particular reference to condensation, fire resistance and durability.

Within these two categories there are several different build methods, typically consisting of either trusses, timber rafters with ridge beams and purlins, or using prefabricated structural insulated panels SIPs. Roofs with a non-habitable space are normally constructed using prefabricated wooden trusses made with pressed metal nail plates. The design and manufacture of these trusses is normally carried out by a specialist company using bespoke truss design software. Once fabricated, they are delivered to site and lifted into place on top of a masonry, steel or timber-framed structure.

In England and Wales, these trusses are normally braced with longitudinal braces fitted to the ridge and ceiling ties, and with diagonal braces fitted to the rafters to act as wind bracing.

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