The easy-to-use kit to assemble your subframe.

Since the launch of DuoSpan and DuoLift, Millboard has looked at how to make installation of our new subframe system as easy as possible. DuoKit gives you peace of mind that you’ll have everything to hand that you need to assemble your subframe. DuoKit is designed to be used on residential applications due to the joist centres and spans. For commercial applications, you should follow the guidance in our DuoSpan and DuoLift installation guide below.

DuoKit is designed to work with the width of our Enhanced Grain decking boards and all colours are available. You can order the boards as an additional purchase and they will be supplied in full lengths with the correct number of fixings needed to use in conjunction with DuoKit.

Available add-ons to work with DuoKit are DuoLift™, Millboard Enhanced Grain decking and Edging and Fascia.


DuoKit is available for the following deck sizes:

  • 1.2m x 3.6m (KK1236), exact size with boards – 1200 x 3614mm
  • 1.8m x 3.6m (KK1836), exact size with boards – 1804 x 3600mm
  • 2.4m x 2.4m (KK2424), exact size with boards – 2347 x 2400mm
  • 3.6m x 3.6m (KK3636), exact size with boards – 3614 x 3600mm
  • 3.6m x 5.4m (KK5436), exact size with boards – 3614 x 5400mm

For larger sized decks, two kits can be put together.

DuoKit contains the following items:

1. DuoSpan 51mm Joists
2. DuoSpan Joist Inserts
3. DuoSpan 51 90° Angle Brackets (boxes of 10)

DuoKit layout for 1.2m x 3.6m:
DuoKit layout for 1.8m x 3.6m, 2.4m x 2.4m, 3.6m x 3.6m and 3.6m x 5.4m:

DuoKit™ Gallery