Talk all you like about sustainability and the whole life costing of a building, the bottom line for most housebuilders is cost. If designers are to choose offsite construction methods, such as Structural Insulated Panels (SIPs), over traditional building methods, they have to prove their worth. TiC hears from Tom Jones, of SIPS Design about how to measure up the cost of SIPs.
THIS is the most common question posed by prospective self builders ~ how much will building a house from Structutal Insulated Panel Systems (SIPs) cost?
When deciphered this usually means ~ how will the construction of a SIPs house or building relate in its cost against the same house or building that is being built by the traditional brick, slate and mortar methods. In order to provide a meaningful answer to this question it has been necessary to enter into discussions with several of the SIPs Panel manufacturers and also with the Panel Engineers (those who cut, shape and machine the panels ready for assemble use on site). From these conversations, and after posing this same question to each, the following approximations have been provided as a guide to help in the costing of the SIPs build.
Before relating to these costs however it should be borne in mind that many of these designs are varied in all sorts of ways, some dwellings are single storey while others are three storey. Some buildings have flat roofs while others have multi-facetted roofs with dormers, for example.
It soon became evident that a direct proportional comparison between a SIPs construction and traditional build is not so easily provided and in order to do this effectively it would need to take in all types of brick, tile and all variety of surface finishes. In these terms, the task was becoming quite extensive.
So, in the light of this, it has been decided just to provide the main costings which relate to the SIPs build only to simply provide the basic costs expected for the required and typical parts of a usual SIPs construction. The approximate costs include the panel and the engineering content, the cost of to creating its shape and profile complete with all necessary fixings, timbers and splines. Where the roof is concerned, the cost takes into account the basic support structure.
All costs are expressed as being directly related to the surface area of SIPs used as part of the construction and are not related to the area of the building footprint.
For the external walls, SIPs build costs between £50 and £60 a square metre, whereas it costs between £40 and £50 a square metre for the internal walls. For the roof and beam support structure SIPs build costs between £70 and £80 a square metre
Onsite assembly for SIPs build costs between £15 and £20 a square metre.
For providing internal floors using Eco-joists and overlaid with flooring would be approximately £25 to £30 a square metre.
These are representative charges only, which one may expect to pay, but they could vary from house design to house design depending on factors such as maximum panel length, room widths or the type of roof.