01-06-2023
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Rockwool Duct Insulation/Lagging (Duct Slab)
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Rockwool Duct Insulation/Lagging (Duct Slab)
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Description
Description
ROCKWOOL | HVAC Duct Insulation
ROCKWOOL DuctSlab – Foil-Faced Duct Insulation
ROCKWOOL DuctSlab is a semi-rigid, non-combustible stone wool insulation slab with a factory-applied reinforced aluminium foil facing. Specifically designed for the thermal insulation of square and rectangular ventilation ductwork.
Suitable for air-conditioning, warm-air and extract duct systems, DuctSlab helps limit heat transfer and can help prevent condensation on chilled ductwork when correctly specified and installed.
Available in 40mm and 50mm thicknesses, with slab dimensions of 1000 x 600mm. Select your required thickness from the product options above.
40 / 50mm
Thickness Options
0.035
W/mK at 10°C
A1
Non-Combustible
230°C
Max. Service Temp.
Applications & Benefits
Where Can ROCKWOOL DuctSlab Be Used?
Rectangular HVAC Ductwork
Designed for square and rectangular ventilation ducts, including warm-air, air-conditioning and mechanical extract duct systems.
Thermal Insulation
Helps reduce heat transfer through ductwork, with declared thermal conductivity of 0.035 W/mK at a mean temperature of 10°C.
Condensation Control
Can help prevent surface condensation on chilled ductwork when the correct insulation thickness is specified and a continuous vapour barrier is maintained.
Foil-Faced, Non-Combustible Insulation
Semi-rigid stone wool with reinforced aluminium foil facing and Euroclass A1 reaction-to-fire classification. Suitable for service temperatures up to 230°C.
Thickness & Pack Sizes
Choose Your DuctSlab Thickness
Both thicknesses are supplied as 1000 x 600mm foil-faced slabs. Pack quantities and coverage differ between the two options.
| Specification | 40mm | 50mm |
|---|---|---|
| Thickness | 40mm | 50mm |
| Slab Size | 1000 x 600mm | 1000 x 600mm |
| Slabs Per Pack | 10 | 8 |
| Coverage Per Pack | 6m² | 4.8m² |
| Packs Per Pallet | 15 | 15 |
Pack and pallet quantities are based on the Insulation & More product listing. Choose thickness according to the duct operating temperature, surrounding conditions and project specification.
Technical Specifications
ROCKWOOL DuctSlab Product Information
| Manufacturer | ROCKWOOL |
|---|---|
| Product | DuctSlab |
| Insulation Material | Semi-rigid stone wool |
| Facing | Reinforced aluminium foil |
| Available Thicknesses | 40mm / 50mm |
| Slab Dimensions | 1000 x 600mm |
| Thermal Conductivity | 0.035 W/mK at 10°C |
| Reaction to Fire | Euroclass A1 |
| Max. Service Temperature | 230°C |
| Max. Outer Foil Temperature | 80°C |
| Product Standard | EN 14303:2009+A1:2013 |
| Declaration of Performance | RWUK-CE-0108-06 |
Technical information from ROCKWOOL's DuctWrap & DuctSlab datasheet, Version 3.03, March 2026. Thermal conductivity varies with mean operating temperature. The insulation must be specified to keep the outer foil surface at or below 80°C.
Buying Guide
How Many Packs of DuctSlab Do You Need?
Each slab covers 0.6m² before cutting. However, duct insulation quantities depend on the duct dimensions, insulation thickness and installation details, not just the flat duct surface area.
ROCKWOOL's rectangular duct formula:
L = 2a + 2b + 8t
Where a and b are the duct side dimensions and t is insulation thickness, all in metres. L gives the approximate developed insulation length for one metre of rectangular duct.
Multiply the developed length by the insulated duct run length to estimate the required area, then divide by 6m² for 40mm packs or 4.8m² for 50mm packs.
This is a material estimating guide. Allow for bends, branches, cut-outs, joints, wastage and the installation arrangement specified for your project.
Installation Considerations
Installing ROCKWOOL DuctSlab
Fixing the Insulation
ROCKWOOL identifies suitable adhesives and/or insulation stick pins for applicable installations. Fixing arrangements must account for the duct dimensions and insulation weight.
Sealing Foil Joints
Manufacturer guidance specifies 75mm-wide soft aluminium self-adhesive tape for suitable joints to maintain a continuous vapour barrier.
Cold Ductwork
For below-ambient operation, maintain vapour barrier continuity at joints, edges and penetrations. Tape over any fixing points that puncture the foil facing.
External Ductwork
Outside installations require appropriate weather protection. The reinforced foil facing alone should not be treated as a complete external weatherproof cladding system.
Related Products
Complete Your Duct Insulation Project
Looking for a more flexible insulation format, installation accessories or protective cladding? Explore the related product ranges below.
Technical Resources
Official ROCKWOOL Product Information
ROCKWOOL provides technical properties, specification information and installation instructions for DuctSlab. Refer to the manufacturer's guidance and the product datasheet before specifying your insulation system.
Frequently Asked Questions
ROCKWOOL DuctSlab FAQs
What is ROCKWOOL DuctSlab used for?
ROCKWOOL DuctSlab is used for thermal insulation of square and rectangular ventilation ductwork, including warm-air, air-conditioning and extract duct systems.
What is the difference between DuctSlab and DuctWrap?
DuctSlab is a semi-rigid foil-faced stone wool slab designed for square and rectangular ducts. DuctWrap is a flexible foil-faced stone wool roll primarily designed for circular ductwork.
How many slabs are in a pack?
The 40mm option contains 10 slabs covering 6m². The 50mm option contains 8 slabs covering 4.8m². Each slab measures 1000 x 600mm.
Should I choose 40mm or 50mm DuctSlab?
The correct thickness depends on duct air temperature, ambient conditions, heat-loss requirements and any condensation-control specification. Check the relevant BS 5422 guidance and project requirements.
Does DuctSlab prevent condensation?
It can help prevent condensation on chilled ductwork when correctly specified and installed. The foil-facing joints, edges and penetrations must be sealed appropriately to maintain vapour barrier continuity.
Is ROCKWOOL DuctSlab non-combustible?
Yes. ROCKWOOL identifies DuctSlab as Euroclass A1 in accordance with BS EN 13501-1. This is a reaction-to-fire classification and does not establish a fire-resistance period for a complete ductwork assembly.
Can ROCKWOOL DuctSlab be used outside?
External applications are possible when designed with suitable weather protection, fixings and joint sealing. Follow ROCKWOOL's specification guidance for external ductwork.
What temperatures can DuctSlab withstand?
ROCKWOOL specifies a maximum service temperature of 230°C. The insulation thickness must be selected to ensure the outer aluminium foil surface does not exceed 80°C.
Insulation & More | Trade Supply
Need Duct Insulation for a Trade Project?
We supply ROCKWOOL, PAROC and specialist duct insulation materials for HVAC installers, M&E contractors, mechanical insulation specialists and commercial projects.
Need help selecting insulation or sourcing materials for a larger installation? Contact our team for product and quantity enquiries.
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