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

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.

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.

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.

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.

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.

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

In February, schoolchildren from around the globe went on strike to demand urgent action on climate change. It followed stark warnings within a report from the Intergovernmental Panel on Climate Change (IPCC) stating that unprecedented measures are required within the next 12 years to limit temperature rises to 1.5°C above pre-industrial times – avoiding potentially catastrophic global impacts.

With the built environment estimated to account for around 40% of total UK carbon emissions1, improving the energy efficiency of our buildings must be viewed as a priority.

The Passivhaus Standard offers a proven model for minimising the energy usage of buildings via a fabric-first approach. By applying its principals with the precise design, improved predictability and outstanding thermal performance of structural insulated panels (SIPs), developers are now achieving Passivhaus Certification on projects of increasing scale and complexity.

Getting Certified

At its core, the Passivhaus Standard aims to allow the creation of buildings which require very little energy to heat or cool, whilst also providing a high level of comfort for occupants. To achieve this, it sets clear energy performance targets which a building must meet:

  • Primary energy demand ≤ 120 kWh/m2/yr
  • Space heating/cooling demand ≤ 15 kWh/m2/yr
  • Specific cooling load ≤ 10 W/m2
  • Passivhaus performance targets for cooler climate buildings

To put these figures in context, the maximum space heating demand for a Passivhaus building is around 10% of that of an average home (estimated to be 140 kWh/m2/yr 2). As such, whilst these criteria do not specifically address a building’s carbon emissions, in practice they should significantly limit emissions when compared with a property built to current Building Regulations/Standards.

To meet these criteria, all areas of the external fabric of the property typically need to be insulated to a U-value of 0.15 W/m2.K, or lower. It is also a requirement of Passivhaus that the building be fundamentally ‘thermal bridge free’. To achieve this, close attention to detailing is crucial when designing the building and installing the insulation to ensure that potential thermal bridges around openings and at junctions (especially the wall / floor) are properly addressed. In addition, air leakage rates must be no higher than 0.6 ach@50 Pa. This is typically achieved by installing an airtight layer, such as oriented strand board (OSB), and airtight tape, which is applied to seal all junctions.

High levels of airtightness within Passivhaus buildings necessitates good ventilation via means of a mechanical ventilation with heat recovery (MVHR) system. MVHR systems extract the heat from outgoing stale air and transfer it to warm incoming fresh air, further reducing the heating demand and ensuring a fresh, comfortable environment within the home.

Whilst it is possible to attain Passivhaus certification with traditional construction methods, in many cases offsite construction approaches such as SIPs can provide a simpler, faster and more adaptable solution to meeting the demanding fabric requirements.

SIPs

A typical SIP comprises an insulated core sandwiched between two layers of oriented strand board (OSB), with a jointing system that ensures excellent insulation continuity throughout the envelope, limiting repeating thermal bridging. The panels are precision cut to each project’s particular specifications in a production facility, including spaces for openings, such as windows and doors. This ensures an accurate fit, significantly reducing the need for onsite adjustments and waste. It also gives architects considerable freedom in determining the design for the property.

The panels offer excellent ‘out-of-the-box’ fabric performance with whole wall and roof U-values of 0.20 – 0.17 W/m2.K, or better. By assessing all junctions and openings within the building envelope, and carefully installing additional insulation, thermal bridges can be eliminated, and the U-values of all elements reduced to the required level.

The jointing arrangements inherent in SIPs can also support extremely airtight structures. Once an airtight membrane is fitted internally and tape is applied to junctions, the air leakage rate can be reduced to the 0.6 ach @ 50 Pa required by the Passivhaus Standard.

SIPs also provide a number of practical benefits. Their offsite production process supports greater predictability in scheduling, allowing project teams to accurately plan for panel deliveries, avoiding trade overlaps and maximising site efficiency.

The panels can be quickly installed by a small team of trained operatives with a dry construction process that is less dependent on weather conditions than other traditional approaches. When SIPs are used for both the walls and roof, the outer shell of domestic properties can often be erected in just two to three weeks. With the addition of a breather membrane to the panel exteriors, the construction is made weathertight — allowing internal fit-out to begin. The outer timber facing also provides a suitable substrate for a variety of cladding options including brick slips, render and timber cladding.

In Practice

One project to take advantage of the benefits SIPs provide is the Norwich Regeneration Company’s Rayne Park estate. The development includes a mix of private and affordable housing, with 112 of the 172 properties, earmarked for full Passivhaus Certification.

The Kingspan TEK Building System was chosen to form the envelope of many of the dwellings based on its technical specification and value offered through its offsite production process. The first phase of the development completed this March, with the Passivhaus units expected to have a heating demand of just 11 kWh/m2/yr and a primary energy requirement of 77 kWh/m2/yr.

Scalable Solution

With over 65,000 buildings now certified Passivhaus around the globe, the Standard provides a clear route to dramatically reducing the energy performance, and consequently carbon emissions, from our buildings. Offsite approaches such as SIPs provide the ideal delivery method for this standard, allowing the cost-effective construction of entire estates.

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

Kerkstoel 2000+ manufacture so called twin walls and lattice slabs, these products combine the advantages of precast with insitu placed concrete.

Kerkstoel 2000+ is one of the most innovative concrete companies in Europe. It is part of the Kerkstoel Group and is based in Grobbendonk (Belgium).It specializes in the production of precast concrete walls and floors. Every precast element is made to measure in a highly automated factory. Based on the architect’s design (general arrangements and cross-sections), structural calculations, formwork and installation plans, Kerkstoel 2000+ develops an installation plan, with all the necessary details, so that everything runs smoothly and according to plan on site.

The floors, or lattice slabs, are used as a structural and aesthetic underside of a concrete floor. Basically permanent formwork they are the ideal substrate for concrete floors and can be made in all shapes, up to 7 cm thick. Wide plates are equipped with bottom reinforcement and on the underside they have a very smooth surface. After placing the lattice slabs and propping the top reinforcement is installed. Finally, the slabs are poured with concrete to the desired floor thickness. The result: a solid concrete floor where the load is perfectly distributed.

The reinforced twin walls of Kerkstoel consist of two shells of reinforced concrete that are connected to each other by lattice girders. All necessary built-in parts are provided in the walls during production (such as electrical boxes, power conduits, openings for windows and doors, wooden boxes, etc.).The wall elements are then assembled on site according to plan and then filled with concrete. The result is a solid construction as strong as a monolithic cast insitu concrete wall. These systems ensure high quality on site in a shorter construction time. The heavy skilled labour, such as steel-fixing and formwork, is limited to an absolute minimum. Thanks to the hybrid character, namely the combination between prefab concrete and in situ concrete, with the necessary water-bars the walls can also be used for underground structures.

In 2018 Kerkstoel 2000+ invested in a brand new automated production hall. With this production hall, Kerkstoel wants to further specialize in the concrete wall sector. Concrete walls with integrated insulation, sandwich panels, walls with prints, etc. will now also be be possible. Kerkstoel 2000+ has been active on the British market for more than 10 years, and has delivered walls and floor slabs to numerous contractors. Contact us and see what we can do for you!

For more information please visit www.kerkstoel.be/en

James Jones Timber Systems Division forms partnership with Ockwells to offer stairwell protection systems to UK housebuilders.

James Jones & Sons’ Timber Systems Division, the maker of the UK’s market-leading I-Joist system, JJI-Joists, has entered into a partnership with specialist building and protection materials manufacturer Ockwells, which will see it recommending Ockwells’ Stairwell Hatch System to all JJI-Joist customers in the future.

After months of research in to available stairwell protection systems, James Jones’ Timber Systems Division has opted to recommend the Ockwells temporary site protection system because of its superior build quality, flexibility in applications of use and the simplicity of installing the system to house building and construction sites without adaptation to existing build practices.
Independently tested and verified, the Ockwells Stairwell Hatch System is designed to provide full cover platforms over the stairwell openings in various combinations to suit all build sites and conditions. Once installed, the system prevents falls through large stairwell opening whilst giving access for operatives and materials.

The system is designed to be lightweight for handling and ease of use on site and it allows safe and fixed access to a ladder prior to a staircase being fitted. The system comprises three parts – hinged and framed glass reinforced plastic (GRP), a steel ladder plate for securing a ladder and a steel box sections adjustable telescopic joist, which allows openings next to party walls to be accommodated by the system.

Speaking of the joint venture Mark Tilston, Systems Development Manager for James Jones’ Timber Systems Division, said “Stairwell protection systems is something that our business has been investigating and researching for a while now and we are delighted to have found in Ockwells a partner that provides a robust and safe solution for all JJI-Joist distributors and end users.
“The Stairwell Hatch System is well designed, solidly manufactured and above all, it works. They have also produced a simple step by step installation guide which gives you clear advice on many applications. The system allows you to continue using crash deck systems and bird cage platforms which is unique. Their product has been independently tested to give you confidence.”

John Gray, Sales Director at Ockwells, said “Ockwells are delighted to be partnering with James Jones’ in this new and exciting development. Having spent a great deal of time developing the Stairwell Hatch System it’s great to see that our customers are seeing the benefits from our safety system.

“As well as providing a safe working platform over stairwell openings, the Stairwell Hatch System is also very cost-effective, being reusable means that the initial investment is quickly recouped when compared to the cost of using sacrificial joists, which can run into hundreds of pounds per plot. We believe that the combined expertise of James Jones’ and Ockwells will result in significant health and safety, and cost benefits to James Jones’ customers.”

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

FLI Carlow are the premier total service provider of engineered structural solutions to the Water, Energy, Storm Attenuation and Bespoke markets. Our capacity to design not just the precast units, but the structure into which they integrate and the manufacturing tools used to make them has kept us at the forefront of innovation in our industry.

Semi-precast is the core of our business, a hybrid between traditional in-situ concrete and traditional precast. Although sometimes seen as an under-developed off-site manufactured solution, the semi-precast design philosophy brings enormous improvement to cost and construction efficiency.

The semi-precast approach aims to deliver solutions fully compliant with the operational design requirement. The ideal configuration is not adapted to prefabrication. Whereas we will identify cost and time saving opportunities during the design development phase, we can adapt to the most precise configurations for operational accuracy. In principle, any structure imagined in in-situ concrete can be delivered in semi-precast. Approving Authority confidence is engendered by implementing designs which cannot be disproved by failure to comply in any respect with the specified codes and standards, whether national, international or customer specific. We place wet concrete against hard concrete, the way it’s always been done. The difference is that some of the concrete was manufactured elsewhere and the location of joints and interfaces are unconventional. Regardless, the integrity of joints and interfaces remains uncompromised and verified by design.

The Benefit of Prefabrication

We complete the difficult parts of construction in our factory, under ideal conditions and under quality supervision. Features including pipe-fittings, nibs, corbels, launder-channels, formwork attachments and stability-footings (among others) are eliminated from the site works. Products are delivered to site on a just-in-time basis then taken from the delivery vehicle to their service position in one simple operation without fuss or temporary propping. Small crews achieve amazing productivity by following simple steps and using well designed components and delivery systems.

Tolerance

Precast concrete units can weight in excess of 20 tonnes. Under normal manufacturing tolerances, it could be very difficult to ensure the precision required to maintain accurate alignment and watertight fit. The in-situ joint provides a transition between elements which ensures a complete and perfect fit (in it’s liquid phase) and a completely ‘relaxed’ structure at introduction to service. We don’t stress pieces into alignment or position. The design assumptions are fully realised.

Waterproofing Integrity

At every interface a scabbled surface is prepared. In addition, a smooth dense slot is preserved for the application of hydrophilic strip. This provides ongoing self-healing capability in service. We use only one hydrophilic product; Denso Hydrotite. Hydrotite is resilient to inflation prior to encasement in concrete. It can compress against the surrounding concrete with a pressure of up to 3MPa on contact with water and has been approved by Tokyo Underground for design life up to 100 years. It is also DWI and Materials in Contact approved for potable water applications in the UK. That’s 100 years to first significant maintenance of the structure – no compromise. Sealants used at the mechanical interfaces of traditional precast concrete tanking structures rarely have a service life in excess of 20 years. These features are particularly relevant to storm attenuation, storage, treatment and basement applications,

Structural Continuity

Although relatively short, the in-situ joint is used to enable two-way bending of the structure. This capacity is not available using any other precast approach. Reinforcement lap lengths are designed on a bond-stress basis to ensure full capacity in smaller spaces. Even the interface between the in-situ concrete stitch and the precast unit is designed for the same crack-width control as the body of the structure. This ensures that all elements of the structure provide the minimum standard of waterproofing integrity and full compliance with concrete structures design standards.

By bending in both orthogonal directions, structures are thinner, lighter, economical, require less transport, less craneage and have a lower carbon cost.

Carbon

Our particular concrete mix design delivers very high early strength for efficient production, typically, 25 Newtons at 16 hours. This ensures maximum safety and maximum value by extracting products daily. We use very high concentrations of GGBS (66%) which in conjunction with other energy and carbon saving measures has reduced our carbon cost from 278kg/tonne of concrete manufactured to 182kg/tonne. To ensure the high early strengths despite the use of GGBS we use thermal activation. By adding mixing water at up to 80°C the disadvantage of slow strength development of GGBS is eliminated.

Sulphate Resistance

High levels of GGBS when used in conjunction with limestone cement and limestone powders (for self-compacting behaviour) produce a design chemical resistance class DC4. That’s sulphate resistant concrete at no additional cost.

Value

The precast unit is delivered to site with projecting reinforcement often from five of it’s six faces. All components are 3D modelled prior to manufacture and assembled in model-space prior to fabrication. This eliminates the risk of clashing reinforcement and disruption to programme. Projecting reinforcement leaves very few bars to be placed on site.

Typically the vertical in-situ stitches represent 30% of the volume of the perimeter and internal walls. While precast concrete products are relatively expensive (although value-adding), the concrete used in the joints is locally sourced readymix at approximately £40 per tonne.

The formwork required is very light. Shuttering ply facing with vertical stiffeners is locked against the structure using steel braces and MKK cone anchors. The advantage in this low cost approach is that the formwork is torsionally flexible adapting easily to the surfaces on which they bear. Smooth transitions and tight interfaces are achieved. Through-ties are completely eliminated. These are often a problematic feature of conventional in-situ works.

Length of Joints

The number and length of joints in our solutions are often questioned. Our industry sees joints as the most problematic elements of waterproof concrete construction – more joints, more risk. The rebuttal is that it’s not the number of joints you fear, but the distance between them. Traditional construction methods utilise joints at 6m – 10m centres. Thermal and drying shrinkage accumulate over these lengths and are concentrated at a single interface. The precast unit has long completed its shrinkage when placed on site therefore the shrinkage to be addressed is that occurring over only 500mm. In addition, each interface has the benefit of a factory prepared scabble, reinforcement continuity designed to the higher standards for crack-width control and a self-healing strip at each end. The semi-precast interface is subject to only between 5% and 10% of the movement occurring at conventional joint. As a result, it is significantly better preforming than conventional concrete in this respect.

Rate of Construction

Semi-precast structures are typically completed in 60% to 40% of the time taken to deliver conventional structures. This is where the value lies, both in terms of reduced preliminaries and hugely increased productivity. During the conventionally difficult construction of vertical and suspended works, equivalent productivity per person on site is ten times greater.

For more information please call +44 (0) 1279 423303, email enquiries@flicarlow.com or visit www.flicarlow.com