SIP House Building

The way we build houses is changing. With environmental issues likely to dominate our lives for the foreseeable future, the building industry is moving to adapt new technologies, which will lead to the building of a brand new type of environmentally friendly and energy-efficient housing.

Structural Insulated Panels (SIPs) are at the forefront of this radical change in building design and technology.

SIPs are one of the most ecologically friendly materials on the market and with their unique insulating properties, they dramatically reduce heating bills and significantly increase living spaces within the build.

SIPs technology is regarded by many influential figures in UK construction as the future of the industry in the UK and sometime soon all houses will be built like this.

JML Contracts Ltd is one of the only companies in Scotland with their own in-house SIP engineers, designers, installation team and SIP processing factory. We can offer a unique fully bespoke SIP design and build service for our clients.

We can offer the full package. This includes complete quality control over all aspects of the process, including design, groundworks and floor slab. We will process and panellise the kit, erect the kit and complete required finishing works right through to decoration.

SIPs Explained

  • History

    Construction using Structural Insulated Panels (SIPs) technology is regarded by many influential figures in the construction industry as the future of the industry in the UK.

    Structural Insulated Panel technology is not a new method of construction. It was invented in Canada in the 1960s and since then it has successfully been used domestically and commercially in Canada, North America and in Scandinavia for over fifty years.

    This method of construction was introduced into the UK in the 1970’s and more recently, SIPs have featured on Channel 4’s Grand Designs in many applications including use as complete houses, roofs, walls, floors, dormers, even bay window components.

    Due to their highly efficient thermal properties SIP panels are even used in Antarctica to construct expedition bases and monitoring stations for the National Science Foundations.

    There has been a rapid growth recently in the popularity of SIPs in the UK over the last 10 years mainly due to the following:

    • Revised code for sustainable homes
    • More stringent building regulations for increased insulation and lower U-Values
    • Increase in domestic fuel and heating costs
    • Increased public awareness for the care of the environment
    • New government reports calling for improvements in quality, efficiency and environmental awareness in the building industry
  • What are SIPs?

    Structural Insulated Panels (SIPs) are a high performance building system ideally suited to new builds, whether residential, commercial or industrial.  Structurally Insulated Panel systems (SIPs) are regarded by many as the future of the industry in the UK and are set to replace the traditional timber frame as the standard kit construction of the future.

    The Structural Insulated Panels are formed with a high thermal performance rigid Polyurethane (PUR) core of insulation sandwiched between two outer skins of oriented strand board (OSB/3).

    The polyurethane (PUR) core of insulation in Structural Insulated Panels is CFC/HCFC-free with zero Ozone Depletion Potential and has a low Global Warming Potential (GWP).

    SIPs are manufactured and processed under factory controlled conditions and can be fabricated to fit nearly any building design (including extension works to existing buildings). The result is a building system that is extremely strong, highly energy efficient and cost effective.

    Unparalleled thermal efficiency combined with high build-speed and low site wastage makes Structural Insulated Panels (SIPs) a very cost effective way of achieving and of exceeding the thermal requirement of the Building Regulations Standards.

    Building with Structural Insulated Panels (SIPs) can offer many advantages to you, your architect and your builder:

    Design Flexibility

    SIPs create new possibilities of design without the constraints of conventional building materials.

    Additional Floor Area

    SIPs create additional warm living space in the roof by eliminating conventional trusses. This can provide an additional 25% of floor space at no additional cost and makes use of all of the potential space in the building. A 3-bed house can become a 5-bed house for little extra cost.

    Thermal Performance

    SIPs can offer a thinner wall thickness than a conventional wall, but still offer improved insulation values, gaining greater internal space for the same size overall footprint. Unbeatable insulation value means energy costs can be reduced by up to 60% over conventional construction.

    Structural Advantages

    Structural superiority has been proven by independent testing. Point loads can be dispersed through the structure.

    Construction Benefits

    SIPs are a far quicker solution for the construction of your house. Pre-cut and fabricated panels reduce installation time by up to 60%.  The building can be erected and weather tight in a matter of days, allowing internal fit outs and first fix works to be started much sooner in the build timetable.

  • At JML Contracts we can offer the following SIP services:

    SIP Design and Build

    We offer a full Design and Build SIP package for both new-build houses and extensions. We can manage projects from the initial planning stages right through to completion. We work closely with architects and engineers and use our own tradesmen to deliver jobs to the highest standards.

    SIP Kit Manufacture and Engineering

    If you already have your own architect and house design, we also offer a SIP kit manufacture and engineering service as a superior alternative to the traditional timber kit frames.

    There are a number of options available as shown below:

    • Structural Insulated Panel kit design and supply
    • Structural Insulated Panel kit design, supply and erect
    • Structural Insulated Panel kit design, supply and erect to wind and watertight (includes windows, external doors, etc)
    • A fully integrated package for the building of the whole house
    • A full turnkey solution from planning right through to completion

    With our SIP factory and joinery workshops in Central Perthshire, we are able to offer a comprehensive service of designing, manufacturing and erecting these highly insulated SIP houses.

    Utilising our extensive experience and expertise in this field, we are able to ensure maximum quality control throughout every step of the SIP building process. This is of primary importance to us and is a unique service that JML Contracts can offer.

    JML SIPs House Designs

    JML Contracts are currently developing a range of highly innovative self-build SIP kit house designs to offer as an attractive ‘off the peg’ solution to suit a varied range of house builders.  Please contact the office directly for more information.

    Garden Rooms

    Garden rooms are a popular and cost effective way of adding to a property’s square footage. Using our specialised SIP panels engineered and processed in our own workshops we can offer these highly insulated and modern structures in a variety of designs both bespoke and off the shelf. Add to your property by building a space outside for working, hobbies or extra living space.

    Please feel free to check out our new JML Garden Rooms website, by Clicking Here.

    Modular Buildings

    Using our SIP panel expertise and our LGSF (Light Gauge Steel Framework) designs we have been developing and engineering a range of modular and portable SIP structures including:

    • Biomass Plant Rooms to suit all sizes and styles of a Biomass heating systems and required chip/fuel stores
    • Portable toilet blocks
    • Sales suites and offices
    • Emergency shelters
    • Summer houses

    The benefit of this type of modular building system means all works can be done off site in a controlled environment at our factory premises. The completed building is then simply transported to site, lifted into place and connected up and commissioned.

    We have the ability to construct these buildings as a whole or in two halves depending on the size required.

    For any modular or portable building requirements please contact our office.

    Commercial Projects

    As well as individual self-builders, we are also able to supply to large-scale developers, social housing providers and hotel groups.

    Please contact our office for more information.

  • Building with Structural Insulated Panels (SIPs) can offer many advantages for you, your architect and your builder:

    Design Flexibility

    SIPs create new possibilities of design without the constraints of conventional building materials.

    Additional Floor Area

    SIPs create additional warm living space in the roof by eliminating conventional trusses. This can provide an additional 25% of floor space at no additional cost and makes use of all of the potential space in the building. A 3-bed house can become a 5-bed house for little extra cost.

    Thermal Performance

    SIPs can offer a thinner wall thickness than a conventional wall, but still offer improved insulation values, gaining greater internal space for the same size overall footprint.  Unbeatable insulation value means energy costs can be reduced by up to 60% over conventional construction.

    Structural Advantages

    Structural superiority has been proven by independent testing. Point loads can be dispersed through the structure.

    Construction Benefits

    SIPs are a far quicker solution for the construction of your house. Pre-cut and fabricated panels reduce installation time by up to 60%.  The building can be erected and weather tight in a matter of days, allowing internal fit outs and first fix works to be started much sooner in the build timetable.

  • The composite structure of Structural Insulated Panels (SIPs) offer many physical advantages:

    Strength

    Once completed, a SIPs structure forms a shell up to seven times stronger than a conventional timber frame structure and is a popular building method in areas subject to earthquakes, tornadoes and hurricanes. This provides a building with a very robust and solid feel which can be indistinguishable from a traditionally constructed building once complete.

    Air Tightness and Ventilation

    Poor air-tightness is a major cause of heat loss in traditional timber frame homes. The solid insulation core of a SIP house helps eliminate this.

    A SIP Home provides a controllable indoor environment due to the superior air tightness of the system. This is enhanced with the use of a Mechanical Ventilation with Heat Recovery (MVHR) system or similar.

    Excellent Thermal Performance

    Structural Insulated Panels provide superior thermal performance, which will last the life span of the building. The thermal conductivity of the polyurethane core is typically 0.14 W/m.ºK. Using SIPs panels can provide extremely low U-values for walls and roofs.

    The insulation is integral to a SIPs Building System and therefore eliminates the need and cost for cavity insulation.

    Fire Performance

    The SIPs panels meet with all the required Building Regulations regarding fire resistance when lined with plasterboard. These requirements are similar to those for timber frame construction. A single layer will provide 30 minutes rating and a double layer 60 minutes rating.

    Integral Insulation

    The solid core of rigid PUR foam insulation in the panels cannot slump over time and the minimal thermal bridging ensures that the building is heated evenly, free from cold spots and condensation. The building will benefit from reduced heating costs for its entire lifetime. This is a very important consideration at a time of spiralling energy costs.

    Rigid Surface for Fixings

    The OSB skin of a SIPs structure provides a continuous surface for easy fixing of services, lights, radiators and kitchen units without having to build in additional support.

    Lightweight

    Structural insulated panels are relatively lightweight (approximately 20Kg/m2 for a 150mm panel) and can allow a reduced foundation specification.

    Structural Performance

    • SIPs form a light and strong structure
    • Excellent for in-plane loads
    • SIPs buildings behave as thin shell structures, dispersing point loads to the entire surface area

    Uniformly Distributed Load

    Tests have shown that the panels have a very high ultimate bending strength. Deflection, calculated as described in the Design Guide, is the governing criterion in design. This increases user confidence knowing that safe working loads are well in excess of standard deflection limits.

    Axial Load

    Axial loading tests on panels 100m thick, 2.4m in height and 2.4m in width were seen to fail at a load of 440kN/m. Using a factor of safety of 2.0 it is seen that panels will comfortably support a vertical load of 90 kN/m. These loads are well in excess of the average foundation loading from a typical two-storey house of traditional construction.

    Resistant to Rodents, Mould and Microbes

    The PUR (Polyurethane) core and the OSB facings used in the manufacture of Structural Insulated Panels do not provide any food value to vermin and are resistant to attack by mould and microbes.

    Choice of Finish

    A SIPs structure will form the hidden shell of the building. The external walls can then be finished in many ways. These can include traditional cavity and facing brickwork, timber cladding, brick slips and render systems. Internal walls are normally finished with fire resistant plasterboard. Roofs are finished as normal with battens and slates, although the inherent strength of a SIPs roof does not require the same weight of finish as a conventional vented roof void. This can allow the use of a lightweight roof finish if desired.

    The Code for Sustainable Homes

    Structural Insulated Panels contribute to The Code for Sustainable Homes through excellent thermal performance, air tightness and limited cold bridging.

    British Board of Agrément (BBA)

    The Structural Insulated Panels that we use at JML Contracts is a certified product of the British Board of Agrément (BBA). BBA Certificate

  • Cost comparisons have shown that building with SIPs is no more expensive than traditional Timber Frame Technology when the following factors are taken into consideration:

    Reduced Cost of Foundations

    A SIPs structure is a lightweight shell and therefore does not require a heavy foundation design.

    Increased m2 Floor Area

    A SIPs roof structure does not require roof trusses and will provide an open habitable warm room in the roof, allowing a three bedroom house to be turned into a five bedroom house on the same size plot.

    Reduced Cost of Labour

    A SIPs structure simplifies the process of construction and can reduce construction time by up to 60%. Once the foundations have been completed, our team can arrive on site with a pre-engineered structure and within 2 to 4 weeks will have erected a weather-tight structural shell ready for windows, doors, services and internal and external finishes. The nature of SIPs provides a square, smooth structure which helps follow-on trades and so reduces the eventual cost of snagging.

    Reduced Cost of Waste Disposal

    A SIPs structure is pre-engineered off-site to avoid both the additional labour and the ever increasing cost of the safe disposal of waste materials.

    Reduced Site Costs

    A faster build programme will reduce the overall cost of project management, and in turn will also reduce the cost of hiring scaffolding, plant, safety and security equipment and temporary accommodation.

    Reduced Heating Costs

    The unbeatable insulating qualities of SIPs allow a much smaller heating system, combined with a mechanical ventilation system, to be installed. This will permanently reduce heating bills by up to 60% over the lifetime of the building when compared with traditional methods of construction.

  • Another clear advantage of building with SIPs is a stronger, more advanced construction product with fewer impacts on the environment.

    Environmentally Friendly Materials

    The outer skins of SIPs panels are manufactured from Orientated Strand Board (OSB). This is made from young fast growing trees which are deliberately grown in plantations accredited by the Forest Stewardship Council (FSC). Young trees produce oxygen and remove more carbon dioxide from our atmosphere than mature trees and are renewable, recyclable, bio-degradable and non-toxic. The core insulation is polyurethane foam (PUR) which is CFC and HCFC free and has an ozone depletion potential of zero.

    Reduced Timber Usage

    To make a product with the same strength, timber uses 20% of the energy needed for concrete. Timber is naturally low in thermal conductivity and an excellent insulator. It is 15 times better as an insulator than concrete; 400 times better than steel and 1770 times better than aluminium. A 25mm timber board has better thermal resistance than a 114mm brick wall. When compared with traditional timber frame buildings, SIPs construction uses approximately 50% less wood, which all adds to the positive environmental impact of this form of construction.

    High Insulation Value

    Structural Insulated Panels provide an extremely high thermal performance and U-values can be as low as 0.14W/m²K.  There is minimal thermal bridging compared to conventional construction and the insulation will not sag or slump over time.  The construction is inherently airtight, warm in the winter and cool in the summer. This drastically reduces energy consumption which leads to a corresponding reduction of up to 60% in carbon dioxide emissions from the burning of fossil fuels for the lifetime of the building.

    Minimal Wastage

    Building with SIPs produces less waste than other forms of construction.  The panels are engineered in a controlled environment, reducing the amount of waste produced on the building site and allowing unused materials to be recycled.

  • Thermal Performance

    The Core

    The core of Structural Insulated Panels is a high performance CFC/HCFC-free rigid urethane insulant of a typical density 33kg/m3.

    CFC/HCFC-Free

    JML Structural Insulated Panels are manufactured without the use of CFC/HCFCs and have zero Ozone Depletion Potential (ODP).

    Thermal Conductivity

    Calculations of the thermal transmittance of specific constructions should be based on the thermal conductivity values (Wm-1 K-1) of their materials. These are:

    SIP Panels: Thermal Conductivity Values
    Material Thermal conductivity values (Wm-1 K-1)
    Polyurethane insulation core 0.025 (Wm-1 K-1)
    OSB/3 0.13 (Wm-1 K-1)

    Typical U-values

    A U-value is a measure of heat loss. It is expressed in (W/m2k), and shows the amount of heat lost in watts (W) per square metre of material, when the temperature (k) is one degree lower outside. The lower the U-value, the better the insulation provided by the material.

    SIP panels: typical U-values
    Panel Thickness U-value (W/m2k)
    100mm 0.27
    125mm 0.21
    150mm 0.17
    175mm 0.14

    Subject to the composition of the wall or roof section, extremely low U-values can be achieved with SIP panels, between 0.1 (W/m2k) and 0.23 (W/m2k).

    These U-values are much lower than those of standard timber frame construction techniques, and demonstrating that SIP panels will insulate your property more efficiently to reduce heat loss.

    Fire Performance of SIPs

    Structural Insulated Panels meet the building regulations requirements with regard to fire resistance when lined with plasterboard. These requirements are similar to those for timber frame construction.

    A single layer will provide a 30 minute fire resistance rating, and with a double layer a 60 minute fire resistance rating.

    Structural Insulated Panel solid-core construction eliminates the ‘chimney effect’ that causes fires to spread rapidly through hollow conventional-built walls.

    When tested to BS 476-21: 1987, the panel system achieved the results shown below.

    SIPS Fire performance
    Performance Axial load (kNm-1) Construction
    FR30 8.33 12.5mm fire-resistant plasterboard fixed directly to OSB or via 38mm x 25mm battens
    FR60 13 One layer of 19mm fire-resistant plasterboard, plus one layer of 12.5mm plasterboard fixed directly to OSB

    Assessment of test results and design details show that panels are suitable for use in external walls (with service loads up to the stated values in the above table), not less than one metre from a relevant boundary, and in separating walls that require fire resistance periods not less than the following:

    SIPS fire resistance periods for separating walls
    External Walls 30or 60minutes (from inside)
    Separating Walls 60 minutes (from either side)

    Structural Performance

    The Panels consist of two 12mm OSB boards which are bonded by pressure injection to CFC-free polyurethane closed cell foam. The two boards and foam core act as a composite structure, similar to an I-beam, and are very strong.

    The wall and roof panels have been extensively tested to calculate maximum permissible design values. These tests were carried out using the methods of BS 5268-2:2002, and were axially and eccentrically loaded until the point of failure.

    Panels that are 100mm thick, up to 3m high, can take:

    • 64 kNm-1 when Axially loaded
    • 53 kNm-1 when eccentrically loaded

    These calculations also take into account the reduction in axial load capacity due to transverse loading such as wind.

    The permissible transverse loads to be used when evaluating the resistance of the panels are given below:

    Permissible transverse load for 150mm thick roof panels
    Span condition Load at span/333
    (kNm-2)
    Admissible load with FOS of 2.25 aplied
    (kNm-2)
    3m double span 4.1 9.0
    4m double span 2.1 8.0

    Notes: Load limit assuming a serviceability deflection limit of span/333. The figures are the result of short-term loading tests. When assessing deflections, the engineer must take into account simple bending, shear deflection and creep effects. The Certificate holder is able to provide further design advice on request.

    Sound Insulation & Durability

    Sound Insulation

    Our construction method and precise manufacture means that the panels create an airtight structural shell. The air tight construction process leads to a product with good resistance to airborne sound.

    Our panels have been tested against their resistance to airborne sound, in accordance with BS EN ISO 140-3:1995

    Durability

    The panels will have comparable durability to that of OSB/3 to BS EN 300 : 1997 therefore, provided the installation remains weather tight, a life of at least 60 years may be expected.

    Timber used in areas that could be at risk, e.g. sole plates, should be preservative treated in accordance with the recommendations given in BS 1282 : 1999.

    Interior Finishes, Plumbing & Wiring

    Interior Finishes

    When you first walk into a SIP building after the shell has been erected, the first thing you notice is the continuous surface of the oriented strand board (OSB) facing.

    Unfortunately, you cannot just paint the OSB surface because all buildings require a fire-resistant surface on interior walls.

    The standard finish for interior walls is to have fire-resistant plasterboard fixed to the inside face of the SIP wall, followed by dry lining or a plaster finish.

    How do you install the wiring?

    A service wiring void on a SIP can be achieved using one of the following two options.

    Option 1: Plasterboard & Battens

    Single Layer of Plasterboard & Battens. Fix timber battens or similar and run the wiring between them along with an IEE approved guard. Affix plasterboard with drywall screw to battens.

    Option 2: Double Plasterboard Layer

    Fix first layer of plasterboard with a suitable void for wiring, run the wiring in the void using an IEE approved guard. Affix the second layer of plasterboard over the first layer using plasterboard screw fixings.

    As well as increased acoustic and thermal qualities the further benefit of the double layered plaster board is a 60 minute fire rating which can be achieved when using a fire resistant board.

    How do you install plumbing?

    Plumbing can be installed in a similar way to the wiring in Option 1 (plasterboard & battens).

    The installation of plumbing where possible can be integrated into the open side of internal stud partition wall.

    The joist systems can accommodate plumbing within the floor joist in accordance with each of the manufactures technical service guides.

    When using Option 2 (double layer of plasterboard), radiators and other similar items can be surface fixed to the plasterboard/OSB without the need to facilitate timber noggins to establish a fixing.

    Exterior Finishes

    With many exterior wall finishes available, a SIP house looks no different from the outside to its surrounding neighbours.

    The variety of available wall finishes is vast and will be dictated as much by the style of the building as the customer’s budget.

    Exterior wall finishes start after the SIP shell has been erected and the waterproof breather membrane is fitted.

    Brick/Natural Stone Finish

    Stone and brick are excellent wall finishes for a SIP building. The inert nature of the SIP panels prevents the building from suffering any shrinkage that could distort walls and cause joint cracks in the masonry.

    For all masonry construction, foundation support needs to be included in the sub structure design.

    Block & Render 

    A traditional block and cavity construction is achieved with the use of stainless steel brick ties.

    The ties are fixed to the outer face of the SIP panel with a stainless steel screw.

    Timber Cladding

    Weather boarding is available in a variety of types and has been used on many SIP buildings.

    Two of the most compatible boarding materials used with SIPs in Scotland is Larch and Cedar. It is fixed to treated softwood counter battens that are attached to the SIP walls.

    As an alternative to timber cladding, a light weight cement fibre weather board is also available. This is a man-made product, designed to replicate the visual appeal of the original. Weatherboard can be supplied in a natural finish or in a variety of factory applied colours.

    Slates, Tiles and Profile Sheet Roofing

    Similarly to traditional roof finishes roof battens and counter battens are fixed to the outside face of the SIP roof panel, followed by your chosen finish.

    Roof pitches below 12.5 degrees require a specialised membrane.

    Single Ply Roof Membranes can also be used on a SIP roof panel, applications typically include flat or mono pitched roofs.

JML Contracts Ltd, The Arns, Auchterarder, Perthshire PH3 1EJ.
Tel: 01764 663 271 Email: info@jmlcontracts.co.uk