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Further Information

Structural Insulated Panel Systems

  • Houses
  • Flats
  • Room in Roof
  • Dormers
  • Schools
  • Hotels & Leisure
  • Light Industrial

SIPFIT Limited is a leading provider of Structural Insulated Panels within the UK. The founders of SIPFIT have extensive experience of delivering Timber Engineered Solutions.

SIPFIT has invested in ‘state of the art’ computer controlled equipment to machine panels to exact shape and size. The sophisticated technology assures a consistent high quality product manufactured to a controlled tolerance. A fast response and controlled volumes are achievable and can help to reduce build programmes.

SIPFIT has built its reputation on customer care, high quality products with a market leading blend of guaranteed performance and competitive pricing. Continual innovations have resulted in reduced installation costs and improved performance.

SIPs in the UK
SIPs were first really introduced into the UK in the 1970’s but are still considered as a modern method of construction although it has been a long established form of house/ building construction in North America and Scandinavian Countries. The systems in the UK have adapted the construction and site practice from the European market. Accurate foundations, mechanical handling and good scaffolding are all key requirements to exploit the potential of SIPs construction.

Key advantages of SIPs

  • Environmentally friendly – CFC Free and ODP zero insulation core and OSB/3 faces made from sustainable forest resources • Excellent thermal performance – insulation U-value, lack of thermal bridging and airtightness helps reduce energy and heating costs

  • Save construction time and cost – large engineered components,

  • Space-maximising design flexibility – for housing the open habitable roof space is a winner. 3-bed houses can be 5-bed houses for little extra cost

  • Light-weight structural strength – saves on foundations. Pile and pad foundations are a real alternative. This can save time and cost. Also, if contaminated land is an issue the structure can be above ground level. Extra floors or mansard or replacement roof can be added to existing properties.

  • SIPs are a key enabler to achieving code level 4 and 5 sustainable construction.

One of the principal benefits of the panel is that it is very easy to apply finishes directly or indirectly to suit aesthetic requirements. For walls you can use cladding, brick slip and render systems that can offer a cost effective finish which is aesthetically pleasing and speeds construction. A conventional brick outer skin is also easy to use. For roofs various lightweight systems can be used as self-weight of the roof covering to resist wind uplift is generally not a consideration.

Structural performance

  • SIPs form a light and strong structure

  • Excellent for in-plane loads

  • SIPs buildings actually behave as thin shell structures, dispersing point loads throughout the entire surface area.


Working with SIPFIT

SIPFIT concentrates on developing and manufacturing the highest quality products. Through a number of partner companies, customers are offered a full service – from design, structural engineering to construction on site. This package of services can be tailored to meet the needs of each customer – from self-builder to large developer or housing association. At all times SIPFIT is available to give technical and design support.


What are SIPs?

SIPs is an acronym for Structural Insulated Panel Systems. Joining high performance rigid polyurethane foam insulation to oriented strand board, (OSB), produces these engineered building components.

The result is a building solution that is predictable, resource efficient and cost effective. SIPs are used as floors, walls and roofs on all types of buildings.

Why are SIPs so much better?
SIPs out perform other building methods in virtually every category because the insulation is a component of a system, rather than an addition. SIPs are a structural composite like an ‘I’-beam. The two faces act like the flanges and the rigid core is similar to the web. In short, the three components work together, rather than against one another. This composite assembly yields stiffness, strength and predictable responses. Not only do test results show panels are stronger, but real life natural disasters have proven it time and again.

Are SIPs new?
SIPs have been used and improved in the USA, Japan and Canada since the 1950’s, and are not a new untried method of building homes. Founders of SIPFIT have been manufacturing SIPs for several years and adapting and improving the technology to meet the needs of the stringent UK market.

Why are SIPs not more popular?
Simply a lack of awareness and the conservative nature of the UK building industry has held back the introduction of SIPs. However, higher insulation standards driven by the Building Regulations and the importance of sustainable building methods has made people look to SIPs as the most economical method of meeting new requirements. U-values as low as 0.14 W/m2K can be achieved in walls and roofs using SIPs which means the system can easily exceed the values within Building Regulations and the codes for sustainable construction.

Why are SIPs environmentally friendly?

  • SIPs buildings are more energy efficient, stronger, quieter and draft free than older technology systems, like timber framing. Less air movement or leakage translates into less drafts, fewer penetrations FAQ for noise, lower energy bills and a significantly more comfortable and controllable indoor environment. The result is lower energy consumption and CO2 emissions.

  • Factory made with minimal site wastage and less landfill use.

  • OSB is made from sustainable harvested spruce, thinning and managed plantations.

  • Up to 35% less raw timber use in SIPs buildings.

  • Combining SIPs and modern heating / ventilation systems dramatically reduces the carbon footprint.

How do SIPs react to fire?
SIPs have passed every Standard fire test that is required. A key element of fire safety is protection of the SIPs and any other underlying structure with thermal barriers like gypsum wallboard.

How do SIPs save so much labour?
SIPs are manufactured efficiently and to high quality and accuracy in SIPFIT’s factory. They are transported direct to site in much larger dimensional sizes than other building materials. Erection is fast and easy using SIPFIT’s spline jointing system that rigidly locks the panels together. The building is weather proof faster and other subcontractors can get a head start on the work that needs to be done.

What are the options for external finishes?
Almost total choice from bricks, natural stone, brick tiles, polymer and cement renders, timber cladding and metal cladding.

Who can design SIPs?
Professionals are increasingly aware of SIPs and there should be no problem designing a building from scratch to use SIPs or modifying an existing design. SIPFIT and its partner companies will be happy to provide technical advice and support to professionals and self-builders.

Is planning a problem with SIPs?
SIPs is an accepted building technology and will not cause problems with planning approval. In the same way a well detailed and engineered SIPs design will not raise difficulties with building control. SIPFIT is always available to give advice.

Are SIPs houses covered by warranty schemes?
All the companies offering warranty schemes accept SIPs construction. A well-designed and constructed SIPs house should have a life expectancy equal to present types of construction. Most lenders are able to offer mortgages on SIPs houses.

What foundation should be used?
Any construction can be used but the tolerance to level must be +/- 5mm to ensure the most efficient erection of the SIPs panels.

What is the best heating system for a SIPs house?
Any conventional heating system can be used although SIPS are also ideally suited for more innovative and energy efficient solutions such as air source heat pumps, solar, photovoltaic and mechanical vented heat recovery systems.

SIPFIT have strategic partners who can provide bespoke solutions such as smart metering / control on community or social housing schemes.

Where can SIPs be used?
SIPs can be incorporated into all forms of construction. They can be used as structural elements or for in fill roof or wall panels within masonry or steel frame structures.



The SIPs panels consists of two facings of 11mm OSB [oriented strand board] bonded by pressure injection to CFC free/ODP zero polyurethane closed cell foam. The option of 15mm OSB is also available. The facings and core act as a composite structure.

OSB/3 board comprises softwood flakes/strands bonded together with MUPF (melamine urea-phenolic) resin, MDI (diisocyanate diphenylmethane) binder and waxes. The board is manufactured to the specification detailed in BS EN 300 : 1997 for OSB/3, loadbearing oriented strand boards for use in humid conditions.

All OSB/3 used by SIPFIT is from sustainable timber sources.

Overall thickness 75mm, 100mm, 125mm, 142mm and 150mm.

Individual panel widths up to 1220mm. Individual panel lengths up to 6250mm.

Wall and roof panels made up of multiple sections are also available.

Other widths and thicknesses are available on request.

The thermal conductivity of the SIPFIT polyurethane core is typically 0.024 w/mk. The SIPFIT panel can provide extremely low U-values for walls. Depending on the detail of construction this can be in the range 0.26 to 0.12.

SIPFIT are happy to give advice on specific fabric solutions with both U Value calculations and Condensation risk analysis.

Fire performance
The SIPs panel will meet all the requirements in the Building Regulations with regard to 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.

SIPFIT can provide standard construction details and results from independent fire tests.

Acoustic insulation between rooms and externally is improved by the plasterboard lining. SIPFIT can advise on constructions to achieve levels of sound reduction required by the Building Regulations.

A building constructed with SIPs panels will have durability comparable to other forms of construction. As long as the design follows best practice and the building is maintained and weathertight, a life of at least 60 years may be expected.

The durability of SIPFIT system has been independently assessed and approved by the BBA. Contact SIPFIT for a full copy of the BBA certificate.

Air tightness and ventilation
Use of the SIPs panel and jointing system can create an airtight structure that meets requirements in the new Building Regulations. Such is the effectiveness of the system that positive ventilation methods should be considered. At the same time positive ventilation systems can be linked to heat recovery that can save energy costs. SIPFIT will be pleased to advise.

Structural performance

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

SIPFIT has invested in an extensive structural testing program. These include loading the panels with a uniformly distributed load, axial loads centrally and eccentrically placed, racking loads, long-term creep, fixing pullout and shear and bending loads on the panel joints. All tests have been done by independent UKAS approved laboratories. For more information on the test results please contact SIPFIT. The strength of the joints between the individual panels is such that panels can be used to span over openings and be supported by the panels each side. Its easy to incorporate additional timber to support localised concentration of loading. Routinely this is done at the joints in the panels. However, with careful detailing, much of this can be avoided.

Structural strength

Axial load
The maximum permissible design values(1) that can be used when evaluating the vertical resistance of 100 mm thick wall panels with 11 mm OSB/3 skins, up to 3 m high are:

  • 64(2) kNm–1 when axially loaded
  • 53(2) kNm–1 when eccentrically loaded by not more than 25 mm from centre line of the panel.

(1) The values given as above are for medium-term loads and are based on two sets of tests to failure of six panels using the methods of BS 5268- 2 : 2002, Section 8. Data for other panel configurations is available on request. The engineer must take into account the reduction in axial load capacity that will occur when the panel is also subject to transverse loading such as wind. The values also assume a serviceability deflection limit of span/333 and any limitations that may be imposed due to fire resistance.

Permissible transverse load values to be used when evaluating the design resistance of the panels are given in the below Table (1). The values are based on test results carried out on a 150 mm thick SIP with 11 mm OSB/3 skins and analysis carried out in accordance with BS 5268-2 : 2002.


Advantages of SIPs

  • Environmentally friendly – ODP zero insulation core and OSB from sustainable forest resources

  • Excellent thermal performance – insulation U-value, lack of thermal bridging and airtightness

  • Platform to achieve Code Level 4 and 5 for Sustainable Homes

  • Save construction time and cost – large engineered components,

  • Space-maximising design flexibility – for housing the open habitable roof space is a winner. 3-bed houses can be 5-bed houses for little extra cost

  • Light-weight structural strength – saves on foundations. Pile and pad foundations are a real alternative


For more information on this system please contact us