Skip to content
Submit a quotation form and a member of our team will be in touch to assist you with your order
Submit a quotation form and a member of our team will be in touch to assist you with your order
How to Seal a Cable Duct using Duct Seal LG

How to Seal a Cable Duct using Duct Seal LG

A Step-by-Step Guide

To achieve optimal results when sealing your cable ducts using Duct Seal LG, follow these detailed installation steps:

Duct Seal LG comes complete with our unique daisy-chained breathable circular foam tubes that easily wrap and separates cables to ensure limited movement while applying our NEW flexible intumescent, zero halogens, & zero Meko adhesive and sealing compound, GreyStuff.

Tools Required for Installation:

  • High Ratio Skeleton Gun (Not Included)
  • Cellulose Sponge (Included)
  • Cleaning Wipe (Included)
  • Long Nose Pliers (Not Included)
  • Nitrile Protective Gloves (Included)
  • Tape Measure (Not Included)
  • Water (Not Included)
  • Sandpaper (Included)

Essential Installation Requirements

  • All cables, pipes, ducts, & penetrations must be clean, dry and free of any loose debris
  • No running water (water blocking kit sold separately, please contact AC Cable Solutions)
  • All dirt, grease & debris must be removed from the cables & duct
  • Curing is between 8 to 14 days to cure fully. This depends on humidity & temperature. The more humidity, the faster GreyStuff cures.
  • Cables or pipes must be separated a minimum of 5mm from cable to cable and from cable to duct.
  • All Penetrations must have a minimum supporting space of 80mm (Please contact AC Cable Solutions if you have less)
  • Cable or pipes must not be moved until GreyStuff is fully cured

Providing Duct Seal LG is installed correctly:

  • Up to 1.0 bar Gas & Water Resistance
  • Resists Hydrocarbons
  • Resists Hazardous Gases
  • Resists Rodents
  • Flame retardent: Tested to UL94

Kit Sizes

  • 1 x Kit will seal ducts from 50mm to 125mm
  • 2 x Kits will seal ducts from 150 to 200mm



1. Thoroughly Clean the Duct and Cables:

  • Ensure the removal of all debris, grease, and dirt from both the duct and cables. A clean surface is crucial for effective sealing.

2. Abrade (Key) the First 20mm of the Duct and Cables:
  • Use sandpaper to roughen 20mm of both the duct and cables. This process enhances adhesion, promoting a stronger seal.

3. Apply Foam Circular Tubes:

  • Take the strip of foam circular tubes and wrap them around the duct and in between the cables, maintaining separation between cables and the inner duct.
  • Pack the Foam Tightly: Ensure a snug fit by packing the foam tightly around the cables.
  • Customisable for Gaps: Single tubes can be easily ripped off, and their centres can be pulled out to fill smaller gaps effectively.
  • Maintain 5mm Gap Separation: Ensure a minimum gap of 5mm between each cable and the inner surface of the duct
  • Leave a 20mm Gap for GreyStuff Sealant: Reserve a 20mm gap at the front of the duct for the application of the GreyStuff sealant.

4.  Adjust Foam Placement with Precision:

  • In case the foam is inadvertently pushed too far back during installation, use long nose pliers to carefully pull it forward. Maintain a minimum 20mm gap at the front to accommodate the GreyStuff Sealant application.
  • Orientation Matters: Ensure the black side of the foam is facing you during the installation process.
  • Centers for Versatility: If necessary, use pliers to remove the centers of the foam, allowing for filling smaller gaps or wrapping around cables to ensure adequate separation.

5. Application of GreyStuff Sealant:

  • Begin applying the GreyStuff Sealant by encircling the cables and gradually working from the bottom up, ensuring comprehensive coverage.
  • Custom Nozzles for Tight Spaces: Larger nozzles can be provided if space restrictions are a concern during installation, facilitating a more adaptable application process.
  • Slight Overfill: Optimal results are achieved with a slight overfill of the GreyStuff Sealant
  • Sealant Gun Technique: Keep the nozzle in the sealant while applying with the gun to create a smooth, even paste.

6. Finishing Touch with Wet Cellulose Sponge:
  • Wet the provided cellulose sponge and gently squeeze out excess water. Use the damp sponge to dab the GreyStuff Sealant, ensuring it adheres to both the cables and the duct. 
  • Anti-Stick: Because the sponge is wet, it prevents sticking to the GreyStuff Sealant, allowing for easy installation.
  • Optional Glove Technique: For an added touch of finesse, consider wetting nitrile gloves and using them to smooth and finish the sealant. This technique imparts a smooth and shiny finish to the sealed surface, elevating the overall aesthetics of the duct sealing.


Written by Carl Pike - The Duct Sealing Man 

    Previous article The Best Duct Sealing Systems for Trefoil Cables
    Next article What Duct Sealing System Should I Use?