A shell package

package for an extension

The Shell Package refers to a bundle of services provided by a timber frame manufacturer.

The shell is the timber-framed superstructure that sits on the foundations. A factory-fabricated shell is delivered to site and then assembled within a matter of days. Very often, the manufacturer will provide a package that includes design, planning, fabrication, delivery and assembly of the structure.

This is just one version of a Shell Package; there are many other versions. The pre-fabricated kit house market is relatively new and timber technology is constantly improving. New types of shell packages include the following:

Basic Shell
A shell is factory-fabricated and delivered to your site. Design and planning services are optional.

Weathertight Shell
As Basic Shell, plus assembly to a weathertight condition.

Externally-clad Shell
As Weathertight shell, plus wall and roof cladding.
Rainwater goods are optional.

First Fix
As above, plus first-fix of services.

Second Fix
As above, plus second-fix of services. Plus customised list of internal work (excluding eco-works).

Eco Engineering
As above, plus all eco-works.

Turnkey Contract
As above, plus decoration. The house is ready for you to move in.

It’s not enough to identify the type of package you require and then decide on which supplier seemingly offers the best deal. This is because a shell can mean different things to different suppliers. To one supplier, a shell-only service is the provision of groundworks, drainage, foundations and the fabrication and erection of the main structure. However, another supplier might not include the foundations for a shell-only service. And another might not include the assembly of the structure.

To make an effective comparison, you must compare the package specifications provided by the suppliers. This is the only way that you will be able to identify the quality or functionality of the quoted base package.

Comparing the specifications
The price quoted by a supplier for a shell package will, in the absence of instructions to the contrary, assume a base specification for each element of the package. For example, for external wall panels, the price quoted will assume base specifications for timber quality, the type of insulation installed, breather membrane specification etc. These base specifications are not always provided in the detail required; some suppliers will provide highly-detailed specifications while others provide the minimum of information.

The provision of detailed specifications is very useful for self builders who understand the technicalities of construction. However, a self builder without this knowledge is unlikely to make a meaningful comparison of competing packages. See article on Specification

The lack of standardisation on specifications makes it very difficult to compare prices. There appears to be 3 main approaches to pricing from the package suppliers:

  • Price per square metre (or square foot)
  • Fixed price for a catalogue model
  • Custom-pricing, by reference to house plans

These different pricing approaches do not present too much of a problem. It is fairly straightforward to convert, say, a fixed price to a price per square metre. The difficulty lies in knowing exactly what the price includes as you review the content of each package.

Ideally, an online review of suppliers and their packages should be possible so that you can short-list a few suppliers. However, the shortage of pricing information online means that it is very difficult to get any idea of price points, value-for-money and chargeable extras.