A building’s thermal performance is now as important an aspect of the building’s design and construction as its structure. Energy prices and climate change are often cited as the principal reasons for the increased energy and CO2 reduction standards required of our built environment. Less known is the fact that insulation can also play a major role in our health, safety, comfort and wellbeing.
When higher levels of thermal performance are required, this has a significant impact on building physics and other dynamic elements of a building’s performance.
Woodfibre insulation has a number of properties that enables it to provide a multifunctional role within the construction of a home. When specified and installed correctly, woodfibre provides protection against summertime overheating, enhanced acoustic performance and moisture control. The latter provides a building fabric with additional insurance against potential moisture problems that could otherwise undermine the integrity of the building and the health of the occupants.
Woodfibre is highly sustainable, locking up considerably more CO2 than is produced in manufacture. It can therefore play an essential part of a strategy for mitigating climate change.
This document provides information for specifiers and procurement specialists working on social housing projects. It is designed to help with the specification of wood fibre insulation within a social housing context. It provides performance criteria and indicates what needs to be considered when specifying woodfibre insulation.
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Building Elements
Zero Carbon Homes—Zero Carbon Timber Solutions for Wales
What is the zero carbon timber housing solution for Wales?
This document proposes a range of timber build solutions. Results are based on the analysis of an appropriate and future proofed definition for ‘zero carbon’, followed by design and calculation to develop an understanding of the quantifiable factors of embodied and operational carbon. Using a fabric first approach, an examination of existing and alternative timber construction methods, materials and systems offers a range of developed timber solutions that are capable of meeting the target fabric specification. These include information on whole carbon emission and offsetting calculations for a range of key typologies demonstrating the routes to Zero.
The detailed report presents findings from the Home-Grown Homes Project including actions for further detailed design, training and skills, technical development and testing, design and modelling tools. These may be relevant for designers, manufacturers, specifiers and clients.
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The role of our own conifer forests for building a sustainable society in Wales
Despite wide recognition of their value, plantation forests are critically misunderstood and undervalued in Wales. Plantation forests comprise around 7% of the planet’s forest area whilst sustainably supplying over 50% of industrial roundwood. This report looks at myths and tropes around home-grown timber and considers research results from wood science and socio-economic aspects across planting, forest management, timber grading and processing.
Modern British sustainable forest management techniques were established 150 years ago and are still appropriate for efficiently growing construction grade softwoods. Exemplar stands of high grade Douglas fir in north Wales grow some of the largest conifer trees existing in Europe. Older conifer stands across Wales have great potential to produce high grade joinery softwood. Sitka spruce forests are routinely denigrated, nevertheless over 95% of Welsh spruce sawlogs can be graded to strength class from C16 to C27 because of Sitka spruce’s high strength to weight ratio. Yet, quality is regularly used as a weasel word in order to reinforce negative views about Welsh homegrown softwoods.
The FAO reported in 2013 that current trends in European forest management could result in an over-supply of wood from broadleaved species, as well as a shortfall of coniferous timber. Planted forests are exposed to socio-economic risks due to governance failures. These risks comprise a weak or inadequate forest policy framework including insecure investment conditions.
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Wooden Windows-Specification guidance for timber windows
Windows provide an outlook on the world. They help set the tone and character for a building and the area in which it stands. Windows define natural lighting levels and thermal comfort essential for the wellbeing of residents. They offer sound protection and keep homes safe from intrusion. Windows are an essential part of the building fabric and as such contribute to a development’s overall energy performance.
Modern factory-finished timber windows have a better environmental performance than any other window material. They have a longer service life and lower whole life costs than uPVC windows. Wooden windows can be repaired and recoated throughout their lifetime and are the best option for achieving zero carbon buildings. They can be sourced from local manufacturers using home-grown timber and support economic recovery in Wales.
The multiple benefits wooden windows deliver over their life-span in terms of maintenance, durability, embodied carbon, and other social and environmental aspects make them excellent value for money.
This document provides information for specifiers and procurement specialists working on social housing projects. It is designed to help with the specification of low-carbon timber windows in a social housing context. It provides performance criteria and indicates what needs to be considered to achieve these in practice. Windows are an essential element of the building fabric and should not be discussed in isolation. They should be considered very early in the design process when deciding what build system to use.
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Timber Cladding—Specification Guidance for Social Housing
Timber cladding has become increasingly popular, mainly for its sustainability credentials and low environmental impact: It has a low carbon footprint as it requires less energy to produce than any other construction material and helps lock carbon into the building fabric. It is made from renewable material – wood – and can be reused, recycled or used as fuel at the end of its service life. Timber cladding is widely available from sustainably managed forests and can be sourced locally.
With correct detailing, proper installation and appropriate materials, timber cladding will provide a long lasting decorative and functional façade to any type of development, new build or existing stock.
This document provides information for specifiers and procurement specialists working on social housing projects. It is designed to help with the strategic selection of timber cladding as an external rainscreen in a social housing context. It provides performance criteria for specifying timber cladding and indicates what needs to be considered to achieve these in practice. The document highlights performance benefits across a range of intended design outcomes and is designed to help ensure that timber cladding is used appropriately. Timber cladding should not be viewed in isolation and should be considered very early on in the design process when specifying details and deciding on what build system to use.
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Wood Fibre Insulation in the UK
A relatively old report written in 2013 on wood fibre insulation in the UK authored by our now Chief Executive, Gary Newman, when acting as an independent consultant for Forestry Commission Scotland and Woodknowledge Wales. The report was never published but we consider it highly relevant to today’s discussions about how Wales can become a high value forest nation and delivery zero carbon housing (both new and existing) by 2050. Access to the full report here.
From garden sleeper to beautiful window. Challenging perceptions about Welsh timber
Custom Precision Joinery rose to the challenge laid down by Dainis Dauksta at a Woodknowledge Wales knowledge event on Developing the Welsh Joinery Sector – Barriers and Opportunities for Windows by offering to make a demonstration window from (1) local Welsh timber (2) to a specification acceptable to housing associations and (3) have it ready for WoodBUILD 2019. We were not disappointed!
This second knowledge event in our “Campaign for Wood Windows” looked at how the Welsh Joinery sector can respond to the real and growing demand from the social housing sector to supply wood windows and ultimately how the joinery sector can access home-grown timber to be used in making those windows.
Larch for the windows on planner. This photo shows the straightness of the grain after the first 20-30cm which can be removed.
During the event Dainis Dauksta (sawmiller, designer and consultant) had challenged perceptions that Welsh (and UK) forest plantations provide low grade softwood which is only fit for fence posts and biofuel. He urged us all to learn more and not to make the mistaken judgement that fast grown is always inferior to slow grown or that large ring width means low density. His talk illustrated how large Welsh logs which are currently being used in low value markets such as fencing and bio-fuel can provide high grade joinery timber.
The Timber
Two reject larch garden sleepers (2.4m*250mm*125mm) obtained from BSW were resawn (by Dainis Dauksta) into joinery sizes as specified by Custom Precision Joinery. The sleepers, which had been air dried were cut so that the juvenile corewood [1] was specifically sawn out and excluded from the final joinery grade product, this is because the core wood can have properties which are significantly different, and variable compared to the mature wood.
“Home grown larch is currently such an under-utilised joinery timber” said Dainis Dauksta who supplied the material used by Custom Precision Joinery. “High quality joinery grade timber is currently going into low value end markets which is such a waste of our resources. This project showed just how easy it was to select and cut joinery grade timber from larch that was being sold as reject garden sleepers.”
Custom Precision Joinery checked the joinery grade larch on delivery and confirmed that it was fit for purpose. The scantlings where then conditioned in their workshop for two weeks before machining into the required profiles.
| British grown larch is a moderately durable softwood with a colour that ranges from a light to dark brown heartwood to a white sapwood. It has a density of around 550kg/m3 at a moisture content of 12%. When wet it has a tendency to distort but once dry it is generally stable. Potentially large volumes of larch could become available in Wales because of the Phytophthora ramorum epidemic. Larch is a very useful construction timber and larch grown in Wales can already be visually strength graded to C24. It can be used for cladding, structural and joinery applications. High-quality stainless-steel fixings should be used to avoid corrosion of fixings. |
The Windows
Two windows made by Custom Precision Joinery from Welsh larch and on display at WoodBUILD 2019.
Two windows were made at Custom Precision Joinery in Buckley, north Wales, they were the same design but had different paint finishes. The windows were made to a design supplied by Coastal Specialist Ironmongery Ltd (also participants in our windows workshop). The design used was one which has already been approved as suitable for social housing.
“We are very pleased with how these windows turned out” said Colin Morris from Custom Precision Joinery. ”A large percentage of home grown timbers are generally of a higher standard than that of imported timbers. However, the Welsh supply chain is an issue for manufacturers in the joinery sector like us. But with the right investment and perseverance Wales has a unique opportunity to enhance this sector.”
What next?
Profile detail of window made by Custom Precision Joinery, fixtures by Coastal Specialist Ironmongery and paint finish by Remmers (UK) Lrd.
This project has shown that high quality joinery items can be made from Welsh timber that is currently being sawn and sold for low value garden sleepers. Just by grading and sawing that same material in a different way it has been transformed into a high value joinery grade timber.
Simple interventions like this could help develop the supply chain for Welsh timber and offer smaller sawmills opportunities to diversify and provide higher value products into the joinery sector. However, the demand for joinery products made from Welsh timbers need to developed. One way to do this is by working with housing associations and local authorities. This is being done through the Home-Grown Homes Project, led by Powys County Council which is exploring supply chain interventions to encourage growth of the timber sector in Wales.
At the end of the Home-Grown Homes Project a set of recommendations will be presented to Welsh Government with case studies to demonstrate how interventions could help improve the supply of Welsh timber to Welsh house building manufactures to build more and better homes.
| Woodknowledge Wales would like to thank Custom Precision Joinery for offering to make these windows from Welsh timber and putting them on show at WoodBUILD 2019. We would also like to thank Coastal Specialist Ironmongery for their part in providing the specification for the window design and Craig Lovatt, formally of Custom Precision Joinery and now of Remmers (UK) Ltd for initiating the project. |
[1] Corewood or ‘juvenile wood’ is found within the first 10–20 annual rings adjacent to the pith.
Professor Callum Hill’s update on the positive environmental impact of wood 2016
In a review of the environmental impact of wood products, leading Welsh wood scientist, Callum Hill shows that timber products lock-up more carbon than is used in their production. The study also shows that generic embodied carbon data quoted from independent databases such as the Inventory of Carbon and Energy (ICE) tend to underestimate the benefit of wood.
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Welsh Softwoods in Construction – Revised edition, March 2016
This research was undertaken by Woodknowledge Wales to identify the range of timber construction systems or techniques that are available for use in Wales and to identify the extent to which Welsh-grown softwoods could be utilised in their production.
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Homegrown Timber in UK Construction – Case Studies, Volume. 1
The projects showcased here represent a snap-shot of what’s happening throughout the whole of the UK, but with an emphasis on projects in Wales – from housing to retail, simple homes and social housing to high end self-build, as well as offices and schools.
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