The Structural Timber Association talks through timber-based offsite technology and how it can provide self-builders with the ultimate solution in terms of accuracy, control and cost-effectiveness

Any structural method created in a factory away from the building site comes under the bracket of offsite manufacture. It is a broad term covering a number of options, namely, timber frame, SIPs (structural insulated panel systems) and oak frame, all benefiting from enhanced energy efficiency, short construction timescales and guaranteed build quality. Along with vastly reduced running costs, it is clear that there are compelling reasons to specify one of these systems for your self-build project.

Offsite manufacture explained

Intelligent, integrated construction systems such as closed panel timber frame, SIPs and volumetric modular options are now driving innovation in the timber industry, thus giving you more choice than the classic kit systems and panelised solutions.

Fundamentally, offsite construction describes structural systems that are factory-manufactured to an advanced level to allow for onsite assembly (as opposed to construction) via controlled installation processes. Exact levels of prefabrication can vary, from factory-fitted insulation and pre-cut service channels through to panels that come complete with windows and doors already installed. Even internal finishes and external cladding can be pre-applied – especially where volumetric modular construction techniques are used.

Six reasons to choose offsite construction

1. Speed of construction

The high degree of factory prefabrication enables a rapid build process, which will not be adversely affected by inclement weather and buildings can easily be watertight in around seven to 10 days.

2. Build cost and programme certainty

Scheduling and costing are more predictable with offsite construction as the design and planning are all carried out with precision before any systems reach site. Onsite installation of panels is a prepared process making it more timely than with traditional building methods. 

3. Quality assurance

Manufacturing sites have stringent quality control processes and procedures in place which ensures the precision manufacture of the structural elements, making sure you get a modern, high-performance structural envelope for your new home.

4. Energy usage

Offsite manufactured systems offer a thermally efficient, highly airtight structure which can vastly reduce energy consumption during the life of the building. Some systems come with the insulation pre-installed in the panel as with SIPs, and U-values below regulations can easily be reached, as well as Passivhaus standards.

5. Design flexibility

Just because your home is effectively built in a factory, doesn’t mean that design is inhibited. Most designs will be able to be accommodated by your timber system manufacturer – but it is really important to engage early with your architect and preferred supplier to ensure your expectations can be met. Plus with a wide range of innovative products and cladding solutions, structural timber systems can meet the aspirations of both architects and self-builders.

6. Sustainability

Timber is the only truly sustainable building material. All Structural Timber Association members use timber from Programme for the Endorsement of Forest Certification (PEFC) or Forest Stewardship Council (FSC) certified sources, ensuring responsible forest management – with five trees planted for every one removed.

Utilising an offsite manufactured timber system for your project does not hinder your design aspirations, as although systems are designed and engineered to exacting specifications, the design itself can still be innovative and striking. Not to mention the performance assurance you will have when backed by the STA’s Quality Assurance Scheme, STA Assure. 

Providing confidence in the use of structural timber and determining member competency and compliance, the scheme is recognised by warranty providers, as well as other key stakeholders. By using an STA member to deliver your self-build project you will be assured that they meet or even exceed current standards and regulatory requirements. We have members who focus solely on the self build market and will support you through the whole design and build process. 

Timber-based offsite technology is not necessarily perfect for every project, of course and you will need to ascertain this with your architect and system provider. However, when you look at all the benefits and measure value, offsite manufactured structural timber systems are a cost-effective option.