Over Joists (External) Insulation Solutions

INSULATING A FLAT ROOF OVER JOISTS.

Insulating a flat roof over the joists is the most common method chosen for extensions, new builds and re-roofing existing buildings as it provides superior thermal performance for the building without affecting the internal finish of the property. Insulating the roof above the joists is known as warm roof insulation, as the joists are brought into the insulated envelope of the building.

This over-joist insulation method also reduces thermal bridging, giving an airtight continuous layer of high-performance insulation and results in a well-insulated space. The need for ventilation is also removed*

The recommended insulation for this method of warm roof construction shown below.

SuperQuilt & Traditional Insulation Over Joists

Our over joist solution is perfect for any type of application where there is access to the external side of the roof.

SuperQuilt can be pulled taut over the joists, followed by a minimum 25mm timber batten, this option is good for projects where there is limited space between the joists, or the profile height of the roof has no restrictions.

For applications where there are large joists with no restrictions, SuperQuilt can be recessed down between the joists. This detail also keeps the overall roof profile height down to a minimum, by allowing the SuperQuilt to expand between the joists.

Multiple layers of SuperQuilt can be used to achieve your desired U-Value, for more information speak to our technical support team on 01909 726 025

Once SuperQuilt has been taped and sealed on all overlaps and perimeter, it also works as a high performing VCL (vapour control layer).

Description (rafters at 400mm centres)U-Value
SuperQuilt (Recessed)0.38
SuperQuilt (Recessed) and 60mm PIR (0.022 W/mK)0.18
SuperQuilt (Recessed) and 110mm PIR (0.022 W/mK)0.13
In accordance with BDA Kiwa Agrèment certification(W/m²K)
Description (rafters at 600mm centres)U-Value
SuperQuilt (Recessed)0.37
SuperQuilt (Recessed) and 60mm PIR (0.022 W/mK)0.18
SuperQuilt (Recessed) and 110mm PIR (0.022 W/mK)0.13
In accordance with BDA Kiwa Agrèment certification(W/m²K)

* It is always recommended that you speak with one of our technical support team on 01909 726 025, if you are unsure about the ventilation requirements of your application.

2 layers of SuperQuilt & traditional insulation over joists

Our 2 layer over joist solution is perfect for any type of application where there is access to the external side of the roof or there is limited space between the joists.

SuperQuilt can be recessed down between the joists. This detail also keeps the overall roof profile height down to a minimum, by allowing the SuperQuilt to expand between the joists.

SuperQuilt is then pulled taut over the first layer of SuperQuilt, followed by a minimum 25mm timber batten, this option is good for projects where there is limited space between the joists, or the profile height of the roof has no restrictions.

Multiple layers of SuperQuilt can be used to achieve your desired U-Value.

Once SuperQuilt has been taped and sealed on all overlaps and perimeter, it also works as a high performing VCL (vapour control layer).

Description (rafters at 400mm centres)U-Value
SuperQuilt (2 layers) 0.22
SuperQuilt (2 layers) and 20mm PIR (0.022 W/mK)0.18
SuperQuilt (2 layers) and 65mm PIR (0.022 W/mK)0.13
In accordance with BDA Kiwa Agrèment certification(W/m²K)
Description (rafters at 600mm centres)U-Value
SuperQuilt (2 layers) 0.22
SuperQuilt (2 layers) and 20mm PIR (0.022 W/mK)0.18
SuperQuilt (2 layers) and 65mm PIR (0.022 W/mK)0.13
In accordance with BDA Kiwa Agrèment certification(W/m²K)

* It is always recommended that you speak with one of our technical support team on 01909 726 025, if you are unsure about the ventilation requirements of your application.

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YBS Insulation products are manufactured to the highest quality and certified to industry standards.

YBS Insulation Product Information

Product - SuperQuilt - See more

SuperQuilt is one of the UK’s leading multifoil insulations. This flexible, easy to install, multilayer insulation offers tremendous thermal benefits. The benefit of multifoil insulation is that it is suitable for a range of applications from roof insulation, floor insulation and wall insulation and due to the slim depth, you can save valuable space on your installation. The unique composition of the product effectively deals with all forms of energy transfer.

This product is suitable for roofs, walls, floors and offers the following major benefits –

  • Cost saving Solution
  • Effective 2 in 1 insulation and vapour control membrane
  • Reduces Construction Depth
  • Reduces Risk of Condensation
  • Non degradable maintaining thermal performance and product integrity

SuperQuilt has been independently tested and certified to the latest Industry Standards, including BDA Kiwa certificate of Agrément, Building Control Compliance (LABC registered detail) and NHBC Acceptance.

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