Chapter 7 Case Study - Panelised Construction: SIPs
(Kingspan TEK Building System illustrated with kind permission of Kingspan Insulation Ltd.)
Rigid insulation is sandwiched between skins of oriented strand board to create a structural insulated panel. The panels are craned into pre-determined positions to create a thermally efficient external enclosure. Here we can see the temporary bracing that allows window and door openings to be formed in the panels at the factory, whilst maintaining structural rigidity in transit and assembly. Similarly to traditional timber frame construction the scaffolding is erected prior to assembly of the panels to aid with ensuring structural stability during the construction process.
The incorporation of interlocking edge details for the panel assembly minimises thermal bridging through interlocking profiles. Note the pre-positioned sole plate on to which the SIP sits and is secured. The panels may be stabilised using timber or steel column sections for some SIP systems. The panels are uniquely referenced at the factory to ensure that they are placed in the correct position during assembly and the high levels of manufacturing accuracy ensure tight tolerances and good levels of air-tightness in the finished building envelope. The logistics of managing crane access must be considered at the design stage to allow for ease of construction.
Individual panels are manufactured to create the bespoke design solution required. Individual panels are referenced with unique identifier labels to ensure accurate location and ease of assembly on site. As well as the walling units it is possible to utilise SIPs for intermediate floors and roof sections by combining with I section beams, roof cassette details and structural timber members.
Sips are assembled to create the cellular structural form of the building with internal and external walls and suspended floors. Door openings etc are pre-formed with closure sections in place to allow stability to be maintained whilst placing the panels. These are removed after fixing the panel to form the complete opening. The structural role of the scaffolding may be important is some design solutions although the SIP construction process is such that there is considerable structural integrity in the construction and assembly phase. The accurate design and manufacture results in readily assembled sections which have strong structural connections at the time of initial placement. Intermediate timber beams, often in the form of I section beams or laminated beams are utilised to provide intermediate support for floor and roof panels as required.
SIPs are craned in to position based on pre-designed panel layout. Door and window openings are partially formed to maintain rigidity of the panels during transit and assembly. The temporary closure pieces that ensure structural rigidity can be removed or cut out once the panels are placed and secured to the surrounding panels that create a robust cellular structure.
SIPs allow for the creation of well insulated pitched and flat roof forms which can span the roof extent with the use of intermediate purlins or beams to provide additional structural support.
Roof SIPs are placed with integrated openings for dormers and roof windows prior to over cladding of the entire building to complete the external enclosure. The completed SIP construction provide excellent thermal performance and air-tightness. The adoption of SIPs provides a cost effective solution to individual or one-off designs as well as for multiple, repetitive design options. Transporting of panelised buildings to site is less logistically difficult than volumetric forms and the inherently rigid nature of SIPs makes them easy to transport, store and assemble with minimum risk of distortion or damage in transit.
The cladding of the finished structure can utilise a variety of design solutions including brick cladding, panel based cladding or tiling. The connection detailing to the SIP panel is largely the same as that utilised for traditional timber frame housing.