Airtight Grommets & Cable Collars: How to Seal Cables and Pipes Through Airtight Membranes (New Build & Retrofit)

Airtight Grommets & Cable Collars: How to Seal Cables and Pipes Through Airtight Membranes (New Build & Retrofit)

How to Seal Cables and Pipes Through Airtight Membranes (New Build & Retrofit)

Why Airtightness Is Critical in Modern Buildings

Airtightness plays a decisive role in the performance of modern buildings. Whether the project is a low-energy home, a high-performance commercial building, a retrofit upgrade, or a Passivhaus-level development, uncontrolled air leakage leads to:

  • Increased heat loss and higher energy bills
  • Reduced thermal comfort and cold draughts
  • Moisture movement and condensation risk
  • Poor indoor air quality
  • Failed airtightness and blower door tests

While airtight membranes are now widely specified, one of the most common points of failure remains the same:
cables and pipes passing through the airtight layer.

This is where airtight grommets and airtight cable or pipe collars become essential.

Airtight Grommets, Cable Collars & Service Penetration Seals Explained

Airtight grommets - also known as airtight cable collars, airtight pipe collars, or service penetration seals, are purpose-designed components used to maintain airtightness where services pass through an airtight membrane.

In practical terms:

  • “Grommet” is commonly used by installers and contractors
  • “Collar” is often used by manufacturers, including DAFA

Both terms describe the same function:
  creating a durable, elastic, airtight seal around a cable or pipe penetration.

Using the correct airtight grommet or collar ensures the integrity of the airtight envelope is maintained for the lifetime of the building.

The Weakest Point in the Airtight Envelope: Service Penetrations

Even the best airtight membranes will fail if service penetrations are not sealed correctly.

Typical problem areas include:

  • Electrical power cables
  • Data, control and communication cables
  • Plumbing pipes
  • Heating and cooling pipework
  • MVHR and building services

Traditional site methods such as taping, foams, or mastics are often:

  • Highly installer-dependent
  • Difficult to apply consistently
  • Prone to shrinkage or cracking
  • Unsuitable for movement over time

The result is often air leakage at exactly the point where airtightness matters most.


Why Retrofit Airtight Grommets Are Increasingly Important

On real projects, services are not always installed in the ideal sequence.

Cables and pipes are frequently:

  • Installed before airtight detailing is complete
  • Added late in the build
  • Introduced during refurbishment or retrofit
  • Installed through existing membranes

Removing and reinstalling services to fit a traditional collar is rarely practical. This is why retrofit airtight grommets have become a key part of modern airtightness strategies.

DAFA Airtight Retrofit Grommets – A Patented Retrofit Solution

AC Cable Solutions is the UK & Ireland distributor for DAFA airtight grommets and cable collars, supplying proven airtightness solutions for new build and retrofit projects.

The DAFA Airtight Retrofit Grommet is the most widely used product in the range.

The Key Difference: Self-Amalgamating Rubber Technology

DAFA’s retrofit grommet incorporates a worldwide-patented self-amalgamating rubber sealing core that:

  • Moulds tightly around the cable or pipe
  • Bonds to itself to form a continuous airtight seal
  • Accommodates tolerances and irregular shapes
  • Maintains airtightness even with minor movement

Crucially, this allows the grommet to be installed after the cable or pipe is already in place, making it ideal for:

  • Retrofit and refurbishment
  • Late-stage service changes
  • Remedial airtightness works
  • On-site problem solving

 View product:
https://ductseal.com/products/dafa-airtight-retrofit-grommet 

Proven Airtightness Performance – Air Leakage Test Results

DAFA airtight retrofit grommets are independently tested and deliver exceptionally low air leakage, suitable for high-performance and Passivhaus-level airtightness targets.

Tested air leakage results:

  • 115mm retrofit grommet: ≤ 0.0003 l/s
  • 250mm retrofit grommet: ≤ 0.0001 l/s

These results demonstrate performance levels that are extremely difficult to achieve using tapes or site-applied sealants alone.

DAFA Airtight Universal Grommets – For Larger Pipes & Planned Installations

For larger pipes and ducts where service routes are known in advance, DAFA offers the Airtight Universal Grommet, also referred to as an airtight pipe or cable collar.

 View product:
https://ductseal.com/products/dafa-airtight-universal-grommet

This version is not split, meaning it must be installed before or during the installation of the pipe or duct. It is particularly well suited to:

  • New build projects
  • Planned service penetrations
  • Larger diameter pipes

Retrofit vs Universal: Which Airtight Grommet Should You Use?

Feature

DAFA Airtight Retrofit Grommet

DAFA Airtight Universal Grommet

Also known as

Airtight grommet, retrofit cable collar

Airtight pipe collar, universal grommet

Installation stage

After cables or pipes are installed

Before or during installation

Split design

Yes

No

Sealing technology

Self-amalgamating rubber (patented)

Elastic airtight membrane seal

Best for retrofit

Excellent

Not suitable

Best for new build

Yes

Yes

Typical applications

Retrofit, refurbishment, late changes

Planned penetrations, larger pipes

Airtightness performance

≤ 0.0001–0.0003 l/s

Extremely airtight when correctly installed

Airtightness Failures: Why Penetrations Are Usually the Cause

On many projects that fail airtightness testing, the issue is not the membrane itself — it is poorly sealed service penetrations.

Common causes include:

  • Improvised sealing around cables
  • Inconsistent taping
  • Late service additions
  • Poor access for remedial work

Retrofit airtight grommets provide a reliable, repeatable solution where traditional methods fall short, allowing airtightness to be restored without re-running services.

Who Uses DAFA Airtight Grommets?

DAFA airtight grommets and cable collars are used across a wide range of projects, including:

  • Low-energy housing
  • Passivhaus and high-performance buildings
  • Retrofit and refurbishment
  • Timber frame construction
  • SIPs and modular buildings
  • Residential and commercial developments

They are specified wherever airtightness matters and performance must be proven.

About AC Cable Solutions & DAFA Airtight Grommets

AC Cable Solutions is the official distributor for DAFA airtight grommets and cable collars in the UK & Ireland, supplying high-performance airtight sealing solutions for cables and pipes through airtight membranes.

DAFA is a globally recognised manufacturer specialising in airtightness and building envelope solutions, with patented technologies used across residential and commercial construction worldwide.

By combining DAFA’s proven products with local stock, technical support, and fast UK & Ireland supply, AC Cable Solutions helps installers, contractors, and designers achieve reliable airtightness on site.

Frequently Asked Questions About Airtight Grommets & Cable Collars

What is an airtight grommet?

An airtight grommet is a purpose-designed sealing component used to maintain airtightness where a cable or pipe passes through an airtight membrane. Airtight grommets are also commonly referred to as airtight cable collars or airtight pipe collars.

What is the difference between an airtight grommet and an airtight collar?

There is no functional difference. Grommet and collar are interchangeable terms. Installers often say grommet, while manufacturers such as DAFA typically use the term collar.

Why are service penetrations such a problem for airtightness?

Service penetrations interrupt the airtight membrane and are often installed late or out of sequence. Without a purpose-designed airtight grommet or collar, small gaps around cables or pipes can significantly affect airtightness test results.

Can airtight grommets be installed in retrofit projects?

Yes. DAFA airtight retrofit grommets are designed specifically for retrofit and refurbishment. Their split design and patented self-amalgamating rubber seal allow installation after the cable or pipe is already in place.

How airtight are DAFA retrofit grommets?

Independent testing shows extremely low air leakage, with results as low as ≤ 0.0001 l/s, making them suitable for high-performance and Passivhaus-level airtightness requirements.

When should a universal airtight grommet be used?

A universal airtight grommet should be used when service routes are known in advance and pipes or ducts are installed during construction. As it is not split, it must be fitted before or during installation.

Are airtight grommets suitable for both cables and pipes?

Yes. DAFA airtight grommets and collars are suitable for sealing both cables and pipes through airtight membranes, provided the correct size and type is selected.

Who supplies DAFA airtight grommets in the UK and Ireland?

AC Cable Solutions is the official UK & Ireland distributor for DAFA airtight grommets and cable collars.

Small Components, Big Impact on Airtightness

Airtight grommets and cable collars may appear minor, but they have a major impact on building performance.

If your project requires:

  • Reliable airtightness
  • Low air leakage
  • Clean, repeatable installation
  • Effective retrofit solutions

then DAFA airtight grommets should be a core part of your airtightness strategy.

 Explore the full DAFA airtight grommet range:
https://ductseal.com/collections/dafa

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