Two of the most extensively used types of frames used in construction are open panel and closed panel timber frames.
Here, we explore two key points that should factor into your decision-making when it comes to open panel vs closed panel timber frames.
Open panel and closed panel timber frames differ fundamentally by the increased factory value added to the closed panel. The value added is usually to the ‘room side’ of the panel and as a result impacts the manufacturing process given both sides of the panel need to be accessed. Both systems are manufactured offsite according to your specifications.
As a minimum closed panels arrive ready-insulated and tested for consistent quality of thermal insulation, while open panels aren’t pre-insulated. At the extreme end of a closed panel, windows, services, plasterboard and even cladding can be factory installed. The level of factory value added has been referred to as PMV.
Pre-manufactured value (PMV)
Pre-manufactured value is the measure of the extent of the project’s offsite construction. Structures built using modern methods of construction (such as closed panel timber frames) have a higher PMV percentage than more traditional building methods.
A higher PMV means that a project is less labour intensive with less risk to its workforce as there are less dangerous tasks to perform on-site. It also reduces the overall carbon cost of a finished structure, in terms of materials and energy used to construct it, energy used to dispose of the waste it created, and the ongoing operational costs (of running the house etc.). Of course, build times are also significantly reduced proportionate to the level of PMV.
Homes England and the Government incentivises a higher PMV through grant funding in its Affordable Homes Programme. Funding is granted to strategic partners who build houses using modern methods of construction.
Houses with PMV scores of 55% and above attract a higher grant rate. Because the Government is promoting the use of offsite manufacture in the construction industry, we’re likely to see policy development in this area further encouraging the use of closed panel timber frames.
Using closed panel timber frames on your project is one of the best ways to ensure a high PMV return. Timber is renewable, a natural insulator, and stores carbon dioxide for the duration of its lifetime, reducing the carbon cost of a new-build property with less embodied carbon and more carbon capture. And houses built using timber frames are generally completed eight weeks faster because the frame is ready to go as soon as it arrives on site.
It is not though all straight forward, and there are a range of advantages and disadvantages to consider. A challenge to increased levels of PMV is the cost efficiency of the manufacturing process versus the equivalent on site process. Product repetition and standardisation in a factory environment drives efficiency and as we know, the designs of many developments are anything but standard. The need then to ‘design for manufacture’ must start at the very beginning of a project and early engagement with the closed panel supplier is essential for successful project execution.
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Submit an enquiry or call us now on 01767 651218 to discuss your timber frame requirements. We’ll ensure you make an informed decision and get precisely the timber frame solution your project needs.