Timber - Structural Insulated Panels (SIPs) Construction Methods
Structural Insulated Panels (SIPs) are high-performance building panels used in floors, walls, and roofs. The panels are typically made by sandwiching a core of rigid foam plastic insulation between two structural skins of OSB (oriented strand board), but other skin material can be used for specific purposes.
They are manufactured under factory-controlled conditions and can be custom designed for each home.
Tests show that SIPs panels can be up to five times stronger than a timber-frame structure, and SIPs uses about 60 per cent less timber than conventional timber-frame construction. The vertical posts and horizontal beams carry the building’s loads, while diagonal braces are required for lateral restraint. As the beams also support the roof, there’s no need for large numbers of load bearing interior walls, which facilitates the creation of open-plan spaces within the structure.
SIPs have thermal and sound-insulation properties that comply with, or often significantly exceed, current Building Regulations and some incorporate a vapour-controlling membrane.
What forms do SIPs come in?
SIPs come as individual panels for walls, floors and roofs, or in kit form, ready to be joined together to make a whole house.
They can come with windows and doors already installed, plasterboard lining and first-fit electrics. A finished house built with SIPs can be clad with bricks, timber, render or stone.
What are the advantages and disadvantages of building walls with SIPS?
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SIPs have a high U-Value (measure of thermal transmittance) relative to their thickness, so maximising available room space;
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SIPs are similar to panelised timber frame in that they are prefabricated off site in a factory;
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The use of Computer Aided Design (CAD) technology ensures that every panel is precision cut, so they are always straight and true. This means little to no construction waste is created and work needed on site is considerably reduced;
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Although SIPs can be used as part of a conventional build, this is not as efficient in terms of time and materials, or as economical, as building a whole house from SIPs.
SIPs Panel Construction
Although it might look as though it is an expensive way to build, there are savings. What are the advantages of building a whole house with SIPs?
Fast Construction
As the house can go up in a matter of days – construction is made simpler as window and door openings can be pre-cut, and the inside is battened to accept plasterboard while leaving gaps for the electrics – fewer tradespeople are needed and for a much shorter time than with a conventional build.
A four-bedroom house, for instance, can be erected and weatherproof in a minimum of five days.
Design Flexibility
The lightweight nature of the panels can lead to a reduction in foundation loadings, giving the structural engineer flexibility of design, and often meaning a reduction in groundwork costs.
This makes SIPs ideal for adding to existing structures, such as converting bungalows into two storey houses. Other applications include building a structure inside an existing shell for conversion projects, as infill panels for timber frame, or to create liveable roofspace.
Once the shell is complete, the external walls can then be finished in a huge variety of ways to create a traditional, contemporary or fusion aesthetic. Common finishings include traditional cavity and facing brickwork, timber cladding, brick slips and render systems.
Lower Energy Bills
Because a whole SIP house will be very airtight and thermally efficient, heating costs will be lower than homes built with other systems.
The method’s superior insulation levels offer a huge benefit in terms of space heating – SIPs homes require very little – which means that the system lends itself perfectly to eco-heating systems that have low output temperature.
Standard heating system choices for SIPs homes include heat recovery and air ventilation systems.
Indeed, SIPs lends itself well to the Passivhaus building standard.
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Timber - SIP Construction Guide - PDF Download
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