General SIPs questions

SIPs are Structural Insulated Panels. Made of two faces of OSB (Oriented Strand Board) with a sheet of Airpop/EPS foam sandwiched between them, they slot onto timber splines which join them together allowing a building to be cut into a kit of parts in a factory, then assembled on site quickly to produce a well-insulated and airtight building.

SIPs can be used in place of any traditional build method for walls or roofs allowing the building to be completed in less time and with a greater level of thermal insulation.

They are incredibly strong, robust and offer enormous flexibility in design. Made using sustainably-harvested timber with minimal waste, they are an environmentally-friendly building solution.

SIPs have great insulation properties with limited cold bridges – our 230mm SIPs have a low U-value of approximately 0.15 W/m²K. Because SIPs are pre-insulated, wall sections can be thinner to maximise on internal floorspace.

SIPs are quick and easy to install on-site and the OSB (Oriented Strand Board) skin provides a rigid surface for fixings. Once wrapped with a weather-tight breathable membrane, both external and internal follow-on trades can start work so SIPs building systems tend to be completed more quickly than traditionally-constructed houses.

With higher energy costs and increased performance required to meet building regulation requirements, SIPs provide a cost-effective solution. Thermally efficient, airtight, fast to erect and lightweight, SIPs are made offsite in a factory as a modern method of construction.

The SIPs system is an established method of construction and has been used as an alternative to brick cavity walls since the 1950s throughout the USA. Over the past decade, SIPs have become more commonly used here in the UK and are increasingly recognised as a superior alternative to traditional building systems. SIPs have full certification by the UK government and housing building regulations.

Historically, SIPs have been used for eco-housing due to their energy-saving properties which result in the highest sustainability and insulation rating levels. The large element SIP structure is a new product that’s superior to the conventional smaller SIP structure.

Yes. SIP houses are fully mortgageable. SIPs build systems are increasingly common in the UK construction industry and are recognised by major warranty providers and building control. Take a look at the STA guide to ensuring your SIPs timber build is mortgageable.

Project questions

Ecologic can provide a full structural shell; this typically includes SIP walls and roof, joist and deck system, internal stud walls and all structural elements required ie: Glulam/steel beams. We leave the structural shell wrapped in a weatherproof breathable membrane ready for follow-on trades.

It normally takes eight weeks from point of payment to delivery at site. We’ll keep you updated throughout the entire process.

SIPs are an accepted building technology and won’t cause problems with planning approval, just as a well-engineered SIPs design won’t raise difficulties with building control. We’re always available to give advice.

SIPs are manufactured efficiently and to a high quality with great accuracy in our factory workshop. Once manufactured, they are delivered to site in much larger sizes than other building materials. Erection is fast, easy and can continue in weather that would normally stop other construction methods. The building can soon be made weatherproof so that other sub-contractors can begin additional work.

SIP homes go up much faster than traditionally framed buildings. The nature of the panel system enables a fast-track building process which helps to reduce construction time. A typical two-storey 200m2 house takes approximately 10 days to fabricate in the factory and 15 days to erect on site.

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SAPs calcs (Standard Assesment Procedure) are worked out on the building as a whole including elements such as glazing, MVHR systems etc. You would need to employ an energy assesor to put together the SAPs package for your building but we are happy to assist by providing the U-values for our SIPs and any other information they might require as inputs.

Design questions

In most cases, it makes more sense to frame the internal walls with studwork. Using timber frame internally helps to keep costs down and allows for thinner internal walls that can also house plumbing and wiring.

External finishes include bricks, natural stone, brick tiles, polymer and cement renders, timber or metal cladding.

Please note, a brick outer skin will not be the most cost-efficient finish, self-coloured silicone render on a carrier board or cladding (timber or cement-based) is often far more cost-efficient.

Yes. Our SIPs kits are built with structural timbers for window frames and doors.

We work closely with local building authorities to arrange the necessary inspections and ensure building regulation compliance. We undertake this application for you and include detailed plans, engineering reports and calculations as part of the package.

On their own, SIPs can only be used to build up to three floors. However, there will be minimal build restrictions when combined with other commercial building systems or additional strengthening such as steel, timber and concrete frames.

Most architects and structural engineers are aware of this product. Although utilisation is relatively low in the UK compared to the rest of Europe and America, more construction professionals are realising the environmental and the long-term financial advantages of building in SIPs.

Flat roof SIPs will require a fall to be added to them using firring strips over-boarded with plywood or OSB onto which your final weathering finish. Your architect should detail how to cross ventilation can be provided between the firring strips.

Technical questions

Many different constructions can be used but the tolerance to level must be +/- 5mm to ensure the most efficient erection of the SIPs panels. The most common practice is to build up a dwarf wall in block from the poured foundations which the SIPs are fixed to.

Foundations for SIPs tend to be a strip foundation with a ground bearing slab. Block and beam foundations are also fine but only really work where there is an external brick skin being added to allow for snorkels to ventilate below the block and beam. SIPs are very light loading compared to traditional blockwork so foundation spec can be reduced and savings made on materials and labour although ultimately it comes down to what local building control are happy to sign-off on.

You can see this detail in our SIPs Details PDF here.

Our standard panels are 2.4m x 1.2m. However, higher walls can be built by adding a short panel on top of a tall one, and so on.

Any conventional heating system can be used although SIPs are ideally suited to innovative and energy-efficient solutions. Your ventilation strategy will have a big impact on your heating decision, but we would generally advise installing a mechanical ventilation with heat recovery (MVHR) system to cut heat loss.

All new homes need a supply of fresh air not just for the health and comfort of the occupants, but also to control condensation, remove pollutants and to ensure efficient operation of various appliances. We do recommend the use of MVHR (mechanical ventilation with heat recovery) system but this will need to be discussed with main designer of the building.

The OSB (Oriented Strand Board) skins and the foam core materials do have some degree of resistance to the spread of fire but to ensure that construction fully complies with building regulations, internal walls are usually lined with a 12mm fire-resistant plasterboard which can then achieve a 60-minute fire rating.

No. The SIP panel is a thermally-efficient airtight product that works best without services running through. We recommend the use of a counter batten to create a service void for electrical wiring and fixtures to be installed.

If required on external walls, they can be surface mounted and then boarded over. Internal walls are timber stud and services follow a standard installation. Posi-Joists allow easy installation between floors.

Our standard wall panels can achieve U-values from 0.14 without additional insulation. Visit our technical section here for more details on specific panels.

Our standard panels have a core of modified Expanded Polystyrene (EPS). EPS foam provides lower U-values than other types of foam and does not contain chlorofluorocarbons (CFCs), which could deplete the Earth’s ozone layer. The U-value of our panels is extremely stable so values remain constant in both hot and cold temperatures. In field testing, EPS has been shown to retain virtually all of its original thermal and physical properties over a number of decades.

Our ambition is to develop our own environmentally-friendly insulation. We’re currently busy connecting with the sector’s most innovative suppliers, on a search for one that shares our vision for more sustainable building methods and materials. To learn more about this ambitious project, please check our news page.

An Ecologic SIP build system provides a vast improvement on air tightness as compared with more traditional construction methods, therefore careful attention needs to be considered to the ventilation method to create and maintain a healthy living environment. The average family of four produces up to 18 litres of water vapour everyday through normal activities such as bathing, cooking, and even breathing

Healthy buildings usually require a full change of air every two hours (m³/m²hr), as indoor air can be up to ten times more polluted than outside air. Mechanical ventilation with heat recovery (MVHR) offers the best solution to providing adequate ventilation for a SIP house. MVHR Systems are designed to quietly operate 24 hours a day, continuously circulating fresh air through the structure while removing unwanted moisture and pollutants.

MVHR systems, in combination with the excellent insulating properties of a SIP structure, greatly improve the energy efficiency and ultimately reduce your carbon footprint.

In a typical application, moist, stale air is extracted from wet rooms (kitchens, bathrooms, utility rooms). The air passes through a high efficiency heat exchanger which extracts the heat from the stale air and transfers it to incoming fresh air. Then the pre-warmed drier fresh air is delivered to other rooms. Most heat exchanger systems can recover up to 90% of the heat in the outgoing air, saving energy and money on heating costs.

We’ve teamed up with ADM Systems, they are experts at installing ventilation systems and have been working with clients across the private and public sectors for over a decade.

For more information on the benefits and features of MVHR systems and the optimum size required for your building please contact ADM Systems.

This is certainly common in smaller garden room type buildings in SIPs and technically possible in a full scale house build also. SIP floors should always have a minimum of 50mm airflow gap below. The ground beneath SIP floor buildings should be graded with a permeable membrane and/or Type 1 MOT/gravel cover or alike. We also recommend treating the underside face of SIP floor panels with a bituminous primer prior to assembly.

Whilst we can’t say there will be no movement in the structure it will be to an absolute minimum. The fact that the panels are one laminated entity with two sheets of structural sheathing to both the inner and outer face means shrinkage is reduced when compared to an equivalent typical timber frame construction.

That said, this is dependent on moisture content during the time of installation, and how dry the product is kept/allowed to dry once the sips system has been installed. We check the moisture content of both the OSB and timber at key points throughout the build to ensure they are within the parameters set by our accreditors (Structural Timber Association) and general timber construction standards.

We are also installing metal webbed engineered joists, one of the main advantages of these joists is their lack of shrinkage post-construction.

You get best thermal performance by centering the window within the SIP insulation. The two key things are:

  • To make sure the thermal resistance through the insulation around the frame is high enough to avoid a cold bridge (you will achieve this as long as the front face of the frame is no further forward than the front face of the insulation within the SIP or if it is then an insulated cavity closer is installed around the projecting window frame). If the window is positioned at the outer edge of the SIPs opening this will mean that there is less risk of water/weather exposure to the reveal of the SIPs.
  • To make sure windows designated as escape windows can open to the required angle.

Yes, the brickwork would form the outer leaf with a minimum 50mm cavity separating it from the internal SIP wall leaf. The brickwork should be tied to the SIPs with wall ties which can be fixed anywhere into the SIPs (see pages 76 and 77 of the STA SIPs pocket guide) and Simpson do a wall tie specifically suited to masonry>SIPs

If you have a question that we haven’t answered, please get in contact