Latest innovations and products in the offsite sections of the construction industry.

Fassa Bortolo brings its Fassarend timber frame system to the UK market

Fassa Bortolo, one of the leading Italian manufacturers of renders and integrated building systems has brought its popular Fassarend timber frame system to the UK market, making off site construction easier than ever.

To meet the soaring demand for timber frame and modular builds, this system is made with the potential to be installed off or onsite. Using a four-stage application process, light-weight carrier boards are mechanically fixed onto the frame batons and finished on site with Fassa’s high quality, thin-coat render, either by hand or by machine once the project reaches the final stages.

With superb insulation options, this system can be combined with a mechanical external wall insulation (EWI) rail system, in the form of mineral wool or Expanded Polystyrene (EPS) inside the timber frame, to help the build reach a required u-value and reduce emissions, as well as protect the structural integrity of the frame from any foreseeable damage.

The Fassarend timber frame system has been third party certified by KIWA BDA and approved by the National Housebuilding Council (NHBC).

For more information please visit www.fassabortolo.com.
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‘Flight’ connections at Manchester Airport

Invisible Connections is currently working with precast concrete and DfMA specialist SCC Design Build to construct stair cores at Manchester Airport.

Manchester Airports Group (MAG) is undertaking a transformation programme that will position the airport as a ‘Global Gateway’, offering more routes and creating increased economic growth in line with aviation forecasts.

As part of this development the airport is expanding its terminal facilities, apron space and customer car parking facilities to accommodate increased demand.

With many MSCP projects already to its name, SCC Design Build (working for BAM) successfully manufactured and constructed the precast concrete frame and cores (incorporating flights and landings) at the newly completed 6,500 space ‘meet and greet’ MSCP at Terminal 1 and Terminal 3.

As part of its innovative build process, SCC Design Build (‘SCC’) used telescopic connectors by Invisible Connections extensively throughout the structural frame and cores, being SCC’s tried and trusted connection solution for rapid construction.

With a clear pedigree in car park construction and an existing presence on the airport, SCC was the natural choice by Galliford Try for the newest 7,669 space car park that will link to Terminal 3 and have buses to the other terminals.

Although a steel frame was chosen for this latest car park, SCC was appointed to construct the stair cores in precast concrete, chosen for its fire properties and the stabilisation of the structural steel frame.

There are 10 stair cores in total, which vary in height up to 5 storeys. All 10 cores incorporate precast flights and landings, with 6 of the cores also housing the lift-shafts.

Building on the success of several previous project collaborations, Invisible Connections was chosen by SCC for its landing-to-wall system of telescopic connectors. The RVK101-30 pinned connection detail was specified to tie landings to the core walls (tying into REDiBOX PIN recess formers) thereby satisfying the Engineer’s design requirements for robustness.

It’s increasingly common to combine precast concrete stairs and landings with core walls which are either precast or poured in-situ. When connection methods are left as an afterthought, using traditional rolled steel support angles is often the only practical, yet inefficient, fixing solution.

With a little up-front planning, there’s much to gain by incorporating telescopic connectors, which come with a host of advantages; such as improved health and safety, robustness compliance, and significantly improved cost effectiveness. Indeed, a recent study found that using telescopic connectors instead of rolled steel angles reduced man hours by 80%, which contributed to a total 33% reduction in direct costs.

For more information please visit www.invisibleconnections.co.uk.
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The importance of Heat Air Moisture Management in DfMA

In this article Adam Taylor, Business Development Manager – Building Envelope of the A. Proctor Group outlines the need for designers and manufacturers to understand and embrace a best practice approach to heat, air, moisture management in DfMA.

As the construction industry seeks to address the challenges which relate to the UK’s housing shortage and deliver more energy-efficient buildings across the residential and commercial sectors, it is clear that Design for Manufacture and Assembly (DfMA) will form an essential part of the delivery process.

The application of DfMA is ideally suited towards offsite modular construction, with its focus on ease and efficiency of both manufacture and assembly. The benefits of fast-track offsite manufacture for assembly onsite can lead to higher outputs, whilst significantly reducing the project programme time, with less material waste and costs, and fewer delays in relation to snagging and re-working on site.

The A. Proctor Group Ltd as a leading manufacturer of vapour permeable membranes and vapour control layers provides essential best practice advice to designers and manufacturers of offsite modular buildings based upon the proven model of Heat Air Moisture Management (HAMM).

The importance of Heat Air Moisture Management (HAMM) to DfMA

Based upon over 50 years of providing solutions and products for the construction sector we understand that a totally holistic approach is required to DfMA building design. In doing so, the points below consider six core aspects in the process:

  • Building
  • Weather
  • Occupants
  • Heat
  • Air
  • Moisture

For any building to be an energy efficient, healthy, moisture free building envelope there is a clear need to manage the balance of Heat, Air and Moisture movement throughout the process of the building’s life cycle from design, construction, completion and use.

Understanding the importance of these key elements upon the building envelope is crucial to the successful construction and operation of a building. Architects, designers, and off-site construction manufacturers must seek to understand the science behind our buildings, managing the external and internal forces, which impact on the quality of the completed building, its performance in use, as well as the health of its occupants and the wider environment.

Airtightness and modular building design

There is absolutely no question that an integral part of modern building design is influenced by energy efficiency. In the EU it is estimated that buildings account for approximately 40% of energy consumption and are responsible for some 36% of CO2 emissions. Closer to home, around 45% of UK CO2 emissions come from the built environment, (27% from domestic dwellings and 18% from non-domestic).

As thermal insulation requirements have increased over the last few years, the proportion of energy lost through air leakage has become more evident. The ever-increasing thermal insulation required will, however, be rendered largely ineffective unless the airtightness of the structure itself is addressed. Air leakage greatly reduces the effect of thermal insulation; therefore if energy efficiency is to be improved within buildings, this is the most critical area to focus on.

In addition to improved insulation, energy efficient heating systems will also be ineffective if warm air can escape the building and cold air can seep in. This is reflected in the fact that total space heating costs in an airtight construction may be considerably less than in a leaky one.

Air leakage through cracks, gaps, holes and improperly sealed elements such as doors and windows can cause a significant reduction in the performance of even thermally insulated envelopes.

Effective airtightness design

The two main ways to achieve airtightness in the building envelope are internally or externally, or in other terms, “inside of the services zone’ or ‘outside of the services zone’.

Traditional use of internal air barriers can be more complex and costly to install, due to the need to accommodate building services such as electrical, lighting, heating and drainage systems. An internal air barrier is only as good as it’s installation. If all the service penetrations are not adequately sealed, performance will be compromised.

For many years, external air barriers have been commonly specified in North American building design and construction. By moving the air barrier to the external side of the structural frame, external air barrier systems such as Wraptite® from A. Proctor Group allow for an almost penetration-free airtight layer, which can be installed faster and more robustly. This offers an effective but simple system comprising a self-adhesive vapour permeable air barrier membrane, plus vapour permeable sealing tape, Wraptite Corners and Wraptite Liquid Flashing, and provides effective secondary weather protection while preventing trapped moisture and air leakage. Far simpler than internal options an external air barrier system like Wraptite will maintain the envelope’s integrity, with less building services and structural penetrations to be sealed, and less room for error.

Fixing Options for Air & Vapour Control

The traditional forms of VCLs and airtightness membranes will often require mechanical fixing. In the case of timber structures using steel staples, and on concrete using a separate double-sided adhesive tape. The self-adhered nature of Wraptite allows for a simple and fast installation process, minimising the use of additional sealants and tapes, and requiring no specialist contractors to achieve a robust result. This one-step solution provides both a damage resistant air barrier layer and effective secondary weather protection in one installation process, allowing a wind and watertight envelope to be achieved more quickly than using traditional methods.

TopHat incorporates Wraptite into the design

One of the UK’s leading modular housing manufacturers TopHat has successfully incorporated Wraptite into the design of its high-quality timber-framed homes.  Wraptite is a patented external air barrier membrane system, which offers manufacturers and designers of modular and off-site buildings the ability to reliably and comfortably exceed current airtightness requirements. Wraptite is the only self-adhering vapour permeable air barrier certified by the BBA and combines the important properties of vapour permeability and airtightness in one self-adhering membrane.

The A. Proctor Group provides a range of high-performance membranes to address the requirements of heat, air, moisture management within the building element, and provides comprehensive guidance using modelling & analysis tools to ensure compliance and guide designers and manufacturers on best practice related to DfMA.

For more information please visit www.proctorgroup.com

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Deceuninck: the complete commercial package

Deceuninck Commercial Sales Manager John Duckworth explains how the company’s holistic approach to commercial projects benefits the specifier, contractor and end user.

Windows are a key part of the build process, providing natural light, protection from the elements and ventilation. They also have great architectural importance by helping to define the overall character of a building and create visual interest.

The latest innovations in window technology has given developers and specifiers a choice of materials, styles and designs to choose from. The very best of this technology also works seamlessly with modern construction methods to create the right aesthetics, reduce installation time and improve the building’s overall performance. Choosing the right supplier is critical in this process.

Deceuninck is a leading window systems company with strong ties in the commercial and housebuilding sector. We work with a number of large developers including Crest Nicholson, Catalyst Housing, Countryside Properties and Berkeley Group. Developers choose Deceuninck because our high performance window systems are engineered for aesthetics, with perfect symmetry and balanced sightlines, and they’re tried-and-tested for commercial applications. Linktrusion™ is our flagship window technology that combines pultruded glass-fibre with PVC-U in Deceuninck’s 5000 window for light and strong windows with slim sightlines and outstanding thermal efficiency. In terms of performance and benefits, Linktrusion™ combines the very best of PVC-U and aluminium, and developers love it, often choosing Deceuninck windows over aluminium, and in Deceuninck’s Grey Matt foil on grey substrate, it’s hard to tell them from aluminium.

Commercial partnership

Product is half the story and Deceuninck’s success comes down to our holistic approach to commercial projects. We work closely with developers, specifiers, fabricators and contractors to look at the full picture of how windows work within the build, be it timber frame, steel frame or modular, to get the best results for our clients.

Our commercial team works with partners to ensure products not only meet technical specifications but are correctly installed and perform effectively in the finished project. We supply accurate data and test results on performance and acoustics, a growing and important point of specification. Working with Bluesky Certification and the University of Salford, we’re the first PVC-U systems company to commit to acoustic testing of our full range because it gives fabricator customers a big advantage in the tender process.

The Hinkley Point Worker Accommodation development is an example of a technically demanding project in which 80% of the 1,400 windows were installed into pre-fabricated modules off-site. Working in partnership with fabricator Dempsey Dyer, Deceuninck’s technical team ensured our Tilt and Turn windows met the highest energy and weather requirements both off-site and in installation. Once assembled, the windows passed the most stringent CWCT water testing, normally only used for curtain walling. Deceuninck’s technical team worked with Dempsey Dyer to successfully cut the windows’ decibel rating down by RW35db to RW40db and RW43db, helping to minimise the impact of noise on workers and make a quieter, healthier environment.

The Woodward Building at Imperial College London is another example of Deceuninck’s strong ties with developer, contractor and fabricator. Despite the complex requirements for aesthetics, weather performance, acoustics and safety, Deceuninck and fabricator Dempsey Dyer successfully broke the original specification for aluminium, bringing a 30% saving for the client. Our 2500 Tilt and Turn window impressed developer Berkeley Group with outstanding performance: Class 4 Air permeability; Class 8A Water tightness and Class A5 2000Pa exposure. The windows delivered U-Values of 1.5 and G-Values of 0.27 to prevent overheating in the building. Safety and durability were also important factors, and Deceuninck’s Tilt and Turn window is ideal for high-rise and student developments because it can be locked in the tilt mode for added safety and unlocked by maintenance teams when cleaning is required. The installation process included full EPDM shrouding and on-site water testing, and was completed on time and in full. Due to the success of this project, Berkeley Group has awarded Dempsey Dyer further contracts, and Deceuninck is now an approved supplier for the developer.

Call 01249 816 969 or visit the website to see more exciting commercial case studies and learn more about our commercial work. You can also download Deceuninck’s full product portfolio from the NBS National BIM Library at www.nationalbimlibrary.com/deceuninck-ltd.

For more information please visit www.deceuninck.co.uk
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Top three benefits of modular builds

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Whether you love or loath IKEA, there is no denying the thrill of picking out furniture and seeing it in your home on the same day. More and more house builders are now taking a leaf out of Ikea’s book with housing estates being constructed using modular build practices. Editor of buildingspecifier.com and MMC Magazine, Joe Bradbury hears the top three benefits of modular builds according to premium coil coated aluminium supplier Euromax:

While modular builds won’t mean new housing estates springing up in a matter of hours, it will considerably reduce the wait. However, that is just one of the benefits of a pre-fabricated approach, as Nick Cowley, managing director of uPVC windows and doors expert, Euramax, explains.

The flatpack phenomenon is still changing the way we live and work. In the last three decades, machinery and technology developments have meant that bigger, stronger and more efficient modular structures, including schools, business parks and medical facilities, are being built across the globe.

Modular buildings and homes are prefabricated away from the final building site in sections, or modules. These are then delivered to the intended site where installation occurs.

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The need for speed

As modular buildings are able to be constructed in highly controlled environments, it means that the build process can be completed up to 50 per cent faster than by using traditional construction methods.

This ability to be built and installed quicker, means that the return on investment (ROI) is potentially far greater than traditional building projects, as the construction phase is significantly shortened.

Show me the money

The overall cost of the build can be reduced by up to 30 per cent by using modular practices. Shorter build time saves money on reduced labour costs and on-site equipment hire costs.

The overall cost of construction materials will also be reduced as it means that the pre-fabricator can buy materials required in larger quantities for multiple projects, rather than just on an ad-hoc basis. These materials will all be delivered to one location, rather than multiple construction sites, so transportation and delivery costs are lower too.

Modular construction also means that any installed elements, like windows and doors, or practical elements such as kitchens or light fixtures, can be delivered and installed all at once. Expert suppliers, like uPVC window and door manufacturer, Euramax, can deliver equipment and materials either to the pre-fabrication facility, or directly on site.

The process of constructing a modular build off site means that any errors or issues with construction can be eliminated before arriving on site. This means that staff are less likely to need to spend large amounts of time and effort fixing things once installation is complete.

Customisable options

Modular builds open up huge potential in terms of design aesthetic and innovation. Traditional building designs are often restricted by the amount of space and planning regulations of how much work can be done to the local area and land. However, modular builds can be designed to a set of specifications that adapt to any restrictions that may be in place.

Nick Cowley - Managing Director

Nick Cowley – Managing Director

As each modular build is tailored to the individual users needs, the construction can be designed and made to the exact space, budget and design requirements. Modular buildings are also commonly constructed out of more durable and environmentally sustainable materials, making the properties a better investment for both the construction company and the buyer.

So, while the cheap and cheerful, cookie-cutter style furniture you buy and build from IKEA can be cost effective and an instantaneous moment of gratification, modular builds open up a much wider range of opportunity to reduce costs, speed up projects and create a unique look.

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Six Months in the UK’s First Energy-Positive Office

The UK’s first energy positive office, the Active Office, was opened in June last year at Swansea University. Designed by SPECIFIC Innovation and Knowledge Centre to be powered entirely by solar energy, the Active Office aims to generate more energy than it consumes over the course of a year.

The Active Office isn’t just meant to be a high performance building for its own sake, but also to demonstrate how well buildings can perform with technology available today. The building is packed full of cutting edge, commercially available technology to help generate, store and manage energy for the building.

One piece of technology provides both electricity and heat to the building; the photovoltaic thermal (PV-T) system by Naked Energy. Made up of a number of photovoltaic panels contained in vacuum sealed tubes, the system has been mounted onto the front elevation of the building and could potentially provide heat energy for the entire building through spring, summer and autumn.

More solar energy is collected through the roof which is covered in, or more accurately made up of, solar cells. The PV cells are bonded directly onto pre-painted steel to create a roofing system that can be installed using conventional methods. The Active Office features the first commercial installation of BIPVco’s technology on a curved profile, which aside from adding architectural flair, will also generate power throughout the year even in low light conditions.

The various systems are monitored by extensive metering installed throughout the building, enabling SPECIFIC to determine where energy is being generated and consumed. This is reflected in a real time display in the entrance foyer, allowing occupants and visitors to find out how the building is performing.

However, the building can’t reach its energy positive target if all the energy it generates is wasted. “We took a fabric-first approach to reducing energy consumption,” commented Joanna Clark, Building Integration Manager with SPECIFIC and Architect for the Active Office.

The Active Office was designed and conceived by SPECIFIC Innovation and Knowledge Centre and funded by Innovate UK with support from Swansea University and the European Regional Development Fund through the Welsh Government.

It was manufactured offsite by Wernick Buildings, in their factory in nearby Port Talbot. SPECIFIC knew that modular construction could deliver the levels of performance they needed against a challenging programme and budget.

Months later, the choice of modular is being borne out by data. On current performance, SPECIFIC predict an annual consumption of approximately 20MWh versus an annual generation of 24MWh.

The future looks bright for this new type of solar-powered building design. In September, the Chancellor of the Exchequer Philip Hammond annouced funding for the Active Building Centre through the Industrial Strategy Challenge Fund and UKRI. The new independent national centre will seek to remove barriers and accelerate market adoption of new Active Buildings.

It seems likely that modular construction will play an important part in progress towards a low carbon future.

For more information please visit www.wernick.co.uk or www.specific.eu.com.
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Cementing Compliance…

Over the past 100 years, through-wall construction has probably never seen such a period of significant change as what it has experienced in recent years. Traditional products that have become ingrained in building practices now require adapting because of changes to standards and performance requirements – most notably in relation to fire and thermal. John Taylor, Technical Director at Euroform, discusses the importance of continued product innovation to ensure that popular methods of modern construction – particularly facades in high rise buildings – can still be used.

Following changes to Part L of Building Regulations (England and Wales) surrounding the conservation of fuel and power and Approved Document B in relation to fire safety, there has been a renewed focus on the combustibility and thermal performance of building fabrics. Insurance companies have also tightened their approach and introduced new stipulations which dictate fire strategy. These changes have been welcomed by the industry in the best interest of safety and sustainability, but a new standard has been established for manufacturers and specifiers to comply with.

Building board specialist, Euroform, has responded to these market changes with the launch of A2 Versapanel®… a market-leading cement particle board which has been independently tested in accordance with BS EN 13501-1 and certified as a Euroclass A2 product.

A class of its own

Versapanel® is a widely specified product in building envelope applications and is long established in the market, proven to perform acoustically and deliver exceptional performance in the presence of moisture – cut edges do not require sealing to prevent degradation. In response to market demand for a simplified route to limited combustibility, Euroform has invested in the development of A2 Versapanel® to deliver enhanced fire performance.

The Euroclass A2 certification confirms the high mass and robust exterior lining of the boards is of limited combustibility when exposed to fire conditions.

As compared with standard Versapanel®, the new A2 Versapanel® delivers superior pull out resistance, with comparative tests demonstrating a marked improvement on an already very good performance. Offering superior mechanical performance as compared with exterior gypsum boards, A2 Versapanel® also helps to improve the air tightness of facades when sealed at joints. A wide range of finishes can be applied over A2 Versapanel®, including insulated render systems, terracotta cladding systems, high performance cladding systems and traditional brick coursework.
The launch of A2 Versapanel® is also timely for the construction industry. The simplified route to revised Approved Document B compliance is seeing many developments specify insulation materials which offer limited or non-combustibility – which place additional demands on the performance of the building boards in through-wall build-ups.

In the thick of it

The move to use materials of limited-combustibility in construction, particularly in high-rise buildings has resulted in the specification of heavier and thicker mineral-based external wall insulation. The industry has become accustomed to using light-weight building boards but building boards with a higher mass and robust exterior lining are often required to secure increased volumes of insulation.

A2 Versapanel® is an ideal solution as it offers enhanced mechanical performance and pull out resistance for help attaching insulation. In addition to mechanical strength, A2 Versapanel® also has excellent acoustic properties, which assists developers in constructing buildings which promote occupant comfort by minimising sound transfer from external noise sources.

From a handling perspective, A2 Versapanel® is supplied as standard in 2400mm x 1200mm boards in 10mm and 12mm thicknesses. The product can be cut to size on-site or provided in a pre-fabricated kit to simplify installation processes. CE marked according to BS EN 13986:2004+A1:2015, A2 Versapanel® has been independently tested as A2-s1,d0 reaction to fire according to BS EN 13501-1: 2007+A1:2009.

For further information on A2 Versapanel® or to learn more about specifying the product on buildings above 18m high, please visit www.euroform.co.uk or email info@euroform.co.uk.
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A guide to high-performance membranes for modular construction

The benefits of modular construction have been widely discussed with advocates including the government now recognising its potential to address the UK’s challenges in terms of both housing capacity and skills shortages. However, the growth and benefits of modular off-site construction are equally at home in student housing and commercial developments such as hotels and high-rise buildings.

The opportunities and benefits delivered by modular construction projects may range from significant reductions in programme length, waste and cost, whilst another major factor is the ability to achieve higher levels of quality control in the process.

From design through to construction and completion what is absolutely essential is that the selection of materials and products used within off-site projects is not compromised, ensuring performance is assured during the build process and throughout the lifetime of the building.

Helping to achieve this are some of the most technically advanced construction membranes available. The A. Proctor Group Ltd has been developing vapour permeable membranes and vapour control layers for over 25 years, and provides an extensive range of superior high-performance products suitable for modular and off-site construction.

The move to tighten building regulations

With the increased spotlight and focus on building regulations and the suitability of materials specified for use within external cladding, the correct selection and application of materials are at their most critical.

Following the Independent Review of Building Regulations and Fire Safety and subsequent Interim Report by Dame Judith Hackitt, the Government has introduced an amendment to the Approved Document B: Fire safety, which has a significant impact on the design and construction of buildings above 18 metres. Published in November 2018, the new regulations came into force on 21 December 2018. Guidance on how external walls can meet the Building Regulations requirement for resisting fire spread is set out in Approved Document B.

Changes to materials and workmanship

Regulation 7 of the Building Regulations relates to materials and workmanship and reads as follows:

7. (1) Building work shall be carried out-
(a) with adequate and proper materials which-
(i) are appropriate for the circumstances in which they are used,
(ii) are adequately mixed or prepared, and
(iii) are applied, used or fixed so as adequately to perform the functions for which they are
designed; and
(b) in a workmanlike manner.
(2) Subject to paragraph (3), building work shall be carried out so that materials which become part of an external wall, or specified attachment, of a relevant building, are of European Classification A2-s1, d0 or Class A1, classified in accordance with BS EN 13501-1:2007+A1:2009 entitled “Fire classification of construction products and building elements. Classification using test data from reaction to fire tests” (ISBN 978 0 580 59861 6) published by the British Standards Institution on 30th March 2007 and amended in November 2009.

Changes on the use of membranes within external wall construction

It is important to note that with specific reference to membranes the Regulation provides a critical exemption and further clarification is found within Regulation 7, as stated below:

12.14 Particular attention is drawn to the following points.

a. Membranes used as part of the external wall construction should achieve a minimum classification of European Class B-s3, d0.

In summary, the amendment stipulates significant changes to which membranes can now be used and limits these to a rating of Class B,s3,d0.

It is crucial that all those involved in the construction of highrise modular construction fully understand the implications of this amendment in the wider context of building safety and protection. Critically designers should note that some European membrane products whilst quoting A2 ratings do not breathe sufficiently to comply with BS5250, meaning the use of these membranes in the UK climate could make the building unhealthy and result in a much greater risk of condensation issues and mould growth.

The complexity of manufacturing a non-combustible membrane which is still breathable to BS5250 standard is extremely difficult to achieve. In selecting a membrane it is important that performance is not compromised and that compliance meets the requirements of both Approved Document B: Fire Safety and BS5250 the Code of Practice for Condensation Control.

High-performance membranes – air tightness:

Wraptite

An example of a high-performance membrane in practice is the Wraptite air barrier system. Wraptite offers a safer and simplified membrane system, conforms with the required Class B rating, and it provides a fully self-adhered vapour permeable air barrier certified by the BBA and combines the important properties of vapour permeability and airtightness in one self-adhering membrane. The membrane bonds back to the substrate, ensuring a simplified design to airtightness and simple installation method.

System benefits

• Complies with use on buildings of high rise and over 18m under Part B amendments made in November 2018, Membranes need to be Class B,s3,d0 or better, with Wraptite classified as Class B,s1,d0 when used over a Class A1 or A2 substrate.
• Included within BS8414 testing with cladding manufacturers.
• EPDM not needed to the frame of the building as the self-adhesive membrane continues across the whole envelope of the building against the sheathing board and the frame of the building.
• Less EPDM around window details due to the membrane lapping into the building at junctions.
• Corner detailing for opening and movement joint interfaces are easily treated.
• Improved airtightness and may negate the use of a VCL totally from the design internally, meaning easier a quicker install of dry lining package.
• Hygrothermal Modelling will identify whether the construction requires a VCL or not. In some instances, the use of this self-adhesive without a VCL may be the most efficient option.
• Improving airtightness may allow you to change thickness or type of insulation used when modelled through SAP or SBEM.
• No need to tape sheathing boards as the membrane is positioned across the whole board.
• By using this membrane on the external may show improvement on making the building watertight, allowing the cladding package to come off the critical path and internal works to start earlier, and also internal works may not be installing a VCL so the site program is potentially quicker.

High-performance membranes – fire protection: Fireshield

The culmination of years of research into membranes has led to the development of a vapour permeable membrane with a fireproof surface, which has a unique intumescent composition that actively reacts to prevent fire taking hold and that also significantly reduces the formation of droplets and smoke.

Crucially the new membrane fully complies with BS5250, BS4016 and NHBC requirements for vapour permeable walling underlays. Having succeeded in overcoming the complexity of creating a non-combustible, yet vapour permeable membrane, Fireshield has also been able to meet long term 5000hr UV ageing. This allows the membrane to be used in open jointed rainscreen and cladding applications.

The installation procedure is the same as for standard breather membranes, with the membrane fixed to the substrate using mechanical fixings. Applications include both commercial and residential buildings including apartments and student accommodation, as well as Rainscreen cladding and applications over 18m high.

System benefits

• Fireproof surface – unique intumescent composition actively reacts to prevent fire taking hold
• Vapour permeable walling underlay for use either directly onto sheathing or insulation
• Class B, s1-d0 but performs differently to other similar class products
• Complies with BS5250, BS4016 & NHBC requirements for vapour permeable walling underlays
• Ideal for use in rainscreen/façade construction
• Suitable for applications over 18m high
• Long term UV exposure suitable for open joint facades
• Airtight

Spacetherm A2

Spacetherm A2 is a flexible, high-performance, silica aerogel-based insulation material of limited combustibility suitable for use in exterior and interior applications. Supplied in a variety of finishes, the substantial layers of Spacetherm A2 meet the requirements for A2 classification (insulation, MgO and plasterboard).

The product optimises both the thermal performance and fire properties of façade systems, enhancing the thermal performance of the ventilated façade and addressing thermal bridging in the façade. It is also useful in minimising thermal bridges around windows in areas such as window reveals.

With a thermal conductivity of 0.019 W/mK, Spacetherm A2’s performance credentials qualify it as one of the best Class A2 insulations materials available worldwide. Engineered for space-critical applications, the product offers low thermal conductivity, superior compression strength, plus breathability allied to hydrophobic characteristics.

System benefits

• Class leading fire performance from an Aerogel insulation
• Superior thermal performance
• Limited combustibility
• Water vapour diffusion open
• Permeable
• Flexible
• Thinnest Aerogel insulation available

For more information please visit www.proctorgroup.com.

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Cross Laminated Timber (CLT) & its use in structures

Premier Guarantee Technical Standards Manager, John Gilbert, provides technical guidance on the treatment of Cross Laminated Timber. The recent interest in ‘modular buildings’ as a solution to the housing crisis and current skills shortage, has brought forward the potential use of ‘CLT’ (Cross Laminated Timber) as a structural panel to produce wall panels or indeed modular pods.

A number of CLT products have third party product approval for the use as a structural plank for construction uses. However, it is also important that manufacturers have a quality management process to ensure consistent quality. Usually these approvals and manufacturing processes are for the solid plank and therefore full designs of the construction including its external cladding. are required on a site by site basis. CLT as a structural timber product isn’t preservative treated. It is also difficult to ‘post treat’ the panels due to the compact layers of softwood timber making penetration of the preservative across the full cross section difficult to achieve. So, it is important that the design keeps the CLT panel completely dry, particularly at ground level and around critical junctions.

Where structural timber, such as these wall panels are to be used in an external wall construction consideration should be given whether timber treatment is necessary if the species of the timber isn’t sufficiently naturally durable.

The vulnerability of timber in external walls is particularly critical where the timber is positioned in certain areas including at the horizontal damp proof course without the inclusion of a treated sole plate. Whilst the use of CLT panels in external walls is a relatively new occurrence in the UK, wall panels incorporating CLT have been successfully used in Europe.
Premier Guarantee are actively involved with the Structural Timber Association and have recently supported and endorsed technical guidance produced by the STA. The recently reviewed CLT guidance is available via The Structural Timber Association and BM Trada.

For our warranty purposes

Where projects are proposed that incorporate CLT wall panels; they must not be used with a render or other cladding system that is directly bonded to the wall panel. A drained and vented cavity must be provided. The CLT panel must be suitably protected as follows:

At DPC level

The CLT wall panels can be positioned directly onto the horizontal dpc (over the substructure walls) without a treated timber sole plate providing that:

  • The DPC extends at least 50mm past the face of the CLT and in the case of on the cavity wall side- extends down 50mm below the horizontal DPC without bridging the cavity.
  • The lowest level of the CLT panel where it sits onto the horizontal dpc must be not less than 150mm above the finished ground level. The residual cavity must extend 225mm below the lowest horizontal DPC level.
  • Open brick perpends / Weeps should be sited under the external horizontal DPC in the cladding at 1200mm centres.
  • Measures to prevent cold bridging at the substructure wall / ground floor / CLT wall panel junctions must be in place.
  • Ground levels immediately in front of the external wall should slope away from the building cladding.
  • CLT panels must not be constructed into ‘troughs or pockets’ e.g. for an internal wall panel on a structural slab. The risk of hidden damage from accidental water leaks could lead to moisture collecting around the panel.

Above horizontal DPC level

  • All exposed end grain to the wall panel must be suitably treated (e.g. end grain edges of the panel or where holes are cut through the panel to form openings – windows, doors, flues etc.) The end grain sealant should extend 50mm onto the panel sides.
  • There must be a drained and vented cavity with a minimum 50mm residual cavity retained.
  • The external wall insulation must be a ‘breathable’ type insulation and directly fixed to the CLT wall panel.
  • An approved breathable membrane must be installed to protect the insulation on the cavity side.
  • Suitable approved wall ties must be used which are secured to the CLT panel.
  • The CLT panels should be protected on the ‘Warm side’ by a suitable vapour control layer (vcl) unless interstitial condensation risk analysis calculations prove that the risk of interstitial condensation will not occur within the construction.
  • The structural engineer must provide details of suitable mechanical fixings to secure the CLT panels to the substructure.

Generally

  • The project using CLT panels must be supported by full structural design specifications.
  • General construction should follow the guidance contained within Timber frame section of the Technical Manual.
  • Detailing for Gas membranes must be considered on a project by project basis and you should consult with our Warranty Surveyor for further advice.
For more information please visit www.premierguarantee.com.
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The Flint Walls of Dover

Milbank Concrete Products recently worked alongside RG Group on the design, manufacture and installation of over 90 specialist precast concrete flint embossed retaining walls at the St James Retail Leisure Park development in Dover, with an estimated contract sum of circa £24m.

The St James development has transformed the retail and leisure offer in the heart of Dover and south Kent and is located on the A20, the main road leading to the Port of Dover, making it highly visible and accessible to visitors, tourists and those travelling to and from the port.

The development comprises a range of outlets including an M&S store, a six-screen multiplex Cineworld cinema, a 108-bed Travelodge hotel and five national chain restaurants, along with a further 12 retail units ranging in size from 2730 to 16,000ft2 (254 to 1486m2). With over 450 car parking spaces and 156,915ft2 (14,578m2) of new retail and leisure space in total, the development is well equipped to cater for a large number of visitors on a daily basis.

Design and construction

Milbank produced 97 precast concrete walls in total, ranging from 6 to 11 tonnes, using four separate timber moulds. The complex moulds were handcrafted by skilled, in-house carpenters and specific requirements were agreed with regard to the flint layout by Dover District Council, Dover Planning Departments and the site contractors in co-ordination with Historic England, using examples of local existing flint walls.

The flexibility of having four individual moulds allowed the production team to hand-lay the flint into two moulds, while the remaining two moulds were poured. The panels were cast over a ten-week period at Milbank’s precast concrete factory in Earls Colne. During the casting process, sand was used as a bed within the timber moulds to assist with the placement and spacing of individual flint stones, which were hand laid face down in the agreed style. Dover District Council visited the factory during the production period to assess the flint arrangement and to ensure it met its needs and gave the best possible match to existing flint walls and buildings in the vicinity.

To create the desired finish, the production team hand-picked the stones to ensure they all interlocked together neatly. Once this extremely time-consuming process was complete, steel cages, lifters and pipes were located and installed and the concrete carefully poured over the top of the flint stones to form the wall structures. The following day, once the concrete curing process was complete, the excess sand was washed off and the units were turned using the in-house gantry crane to present the finished article.

Milbank’s modern Sipe batching plant is capable of producing 35m3 of concrete per hour. For this particular project, a standard C40/50 strength-class concrete comprising of 460kg/3 of Portland cement, 1800kg/m3 of mixed aggregates and 40kg/m3 calcium carbonate fines were selected to create the desired finish and achieve the level of structural integrity required.

Installation and completion

Due to the size and weight of the wall units, with some weighing up to 11 tonnes and sitting at over 5m tall, a complex installation procedure was required involving the use of both 100-tonne and 80-tonne mobile cranes (lifting up to a radius of 17m) in combination with the specialist precast installation team. Due to the access restrictions on-site, short trailers were arranged for delivery ahead of schedule following on from an initial site consultation and the delivery vehicles arrived on a ‘just-in-time’ basis, allowing for the walls to be offloaded directly into position.

Each individual wall was located over projecting steel dowels and cast into the foundations on-site by the main contractor RG Group, a specialist in the retail, student accommodation and commercial sectors of the construction industry. Lined and levelled on shims and bedding, the walls dowel connections were fully grouted using specialist pipes cast into the rear of the structures during the manufacturing phase. The walls were designed with male-to-female connections to act as a shear key, which allowed the walls to act in unison and to reduce individual movement once installation was complete.

Due to the walls being manufactured and installed as individual units, it was required that the joining sections be hand-filled on-site by the main contractor with matching flint stones to consolidate all units into one flowing piece. Finally, end columns and caps were also manufactured on-site by the main contractor to provide finishing touches to the wall structure. The flint walls now act as a screen to the service area for the main retail block from the roadside, which includes M&S and Next at the Dover St James development.

For more information please visit www.milbank.co.uk
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