U-VALUE CALCULATOR
SuperFOIL product applied to a flat rood under-joist

UNDER JOIST
(INTERNAL)

While insulating under the joists, an additional VCL is preferred below the insulation to keep warm, moist air from moving into the build-up. SuperFOIL’s internal solutions ensure a built-in vapour resistance of 1200MNs/g, better functionality, improved space optimisation, and the ability to install up to twice as fast compared to traditional insulation types; with much less material.

Application

Apply SuperFOIL directly from the roll on the internal joist face, starting horizontally at the external wall. Staple the start of the roll onto your joist and continue rolling the product across the joists. While fitting SuperFOIL, hold the product taut and staple it into place at approximately 50mm-100mm intervals using the correct size staples.

Once you finish a length, cut it to the correct size and continue fixing the next layer with a minimum of a 50mm overlap. Ensure secure fixing by stapling the insulation onto the joists where the joint crosses. Seal all joints, tears, and cuts with SuperFOIL 100mm tape, paying special attention to any penetrations through the insulation to ensure an airtight finish.

Complete your installation by fixing counter battens on top of the insulation horizontally (maximum of 600mm centers) to allow adequate air space. Attach your internal finish to battens following the manufacturer’s guidelines. SuperFOIL should be stored indoors until used and covered within 48 hours after fitting.

SuperFOIL’s flexibility extends to its application; you can use it on its own, in single/duet configurations, or in combination with traditional insulation types like mineral wool or PIR boards.

Best Products for Internal Application

Choose Your Solution

Use the charts below to find the ideal combination of insulations for your project

Construction Thickness R-Value
External Surface 0.040
Single Ply Membrane 1mm
OSB 9mm 0.138
Firrings / Cavity 0-75mm 0.476
SuperFOIL 40-100mm See Table
Joist Cavity 25mm 0.476
Additional Insulation 40-100mm See Table
Joist Cavity 25-63mm 0.184
Plasterboard 12.5mm 0.066
Internal Surface 0.1
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Technical Information

Technical Information

SELECT VARIABLE

THERMAL PERFORMANCE
PRODUCT DIMENSIONS
FIRE PERFORMANCE
ADDITIONAL INFO
PRODUCT COMPOSIITON
SF19+ SF40 SF60
Core performance 1.63 R Value 2.57 R Value 3.58 R Value
Roof Performance* 2.27 R Value 3.47 R Value 4.42 R Value
Wall Performance* 2.73 R Value 3.91 R Value 4.88 R Value
Floor Performance* 4.37 R Value 5.22 R Value 6.53 R Value
Emittance 0.05 0.05 0.05

*Core value + 2 air spaces / EN 16012

SF19+ SF40 SF60
Thickness (Nominal) 45mm 65mm 100mm
Length 10m 10m 8m
Width 1.2m/1.5m 1.5m 1.5m
Coverage 12m²/15m² 15sqm 12m²
Weight 10kg/13kg 15kg 17.75kg

*Core value + 2 air spaces / EN 16012

SF19+ SF40 SF60
Reaction To Fire (Euroclass) Class E Class E Class E

*Core value + 2 air spaces / EN 16012

SF19+ SF40 SF60
Water Vapour Resistance 2,500MNs/g 2,500MNs/g 2,500MNs/g
Resistance To Water Penetration W1 W1 W1
Tensile Properties (Length) 757/ 784 N/50mm 757 N/50mm 757/ 784 N/50mm
Tensile Properties (Width) 726 / 757 N/50mm 726 N/50mm 726 / 757 N/50mm
Resistance to Tearing (Length) 450N 450N 450N
Resistance to Tearing (Width) 491N 491N 491N
Elongation (Length) 15% / 17% 15% / 17% 15% / 17%
Elongation (Width) 14% / 16%
Flexibility at Low Temp. -40°C -40°C -40°C

*Core value + 2 air spaces / EN 16012

SF19+ SF40 SF60
Reinforced Heavy Duty Double Foil Laminated Outer Layers 2 2 2
Mesh Reinforced Foil Laminated Outer Layers 0 0 0
Aluminium Coated Reflective Foil PET Layers 4 8 11
Thermo Foam Separation Layers 0 0 0
Loft Quilt 80g/sqm Layers 5 9 12
Total Layers 11 19 25

*Core value + 2 air spaces / EN 16012

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