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Firestopping is an aspect of building construction that involves sealing openings or gaps in walls, floors, and ceilings to prevent the spread of fire, smoke, and toxic gases. A form of passive fire protection, firestopping is highly complex but crucially important, especially as buildings become more sophisticated. Despite this fact, firestopping is often overlooked or improperly installed during construction, leading to potentially catastrophic consequences in the event of a fire. Since most firestopping mistakes are borne from negligence, this article will highlight ways to avoid these wrong practices so that buildings and its occupants are kept safe and sound. 

firestopping and comparmentalisation


FS702 application in annular gapFire resistant sealant applied inside the annular gap.

1. Consider the Annular Gap

The annular gap refers to the space between the side of penetration opening and the penetrating material. To prevent spread of water, fire, smoke, and gas, this gap needs to be filled with a tested fire sealant system that allows for expansion, contraction, and movement, and is according to specific test approvals (ETA/BS-EN). Aside from sealants, other types of firestopping materials such as intumescent straps or collars must be installed at the correct depth. If the depth of the material is too shallow, it may not seal the annular gap completely, allowing fire and smoke to still pass through. The best practice is to always follow the instructions of the firestopping system manufacturer carefully.

2. Uncertified Products

Simply put, certified firestopping products provide a higher level of safety and reliability compared to non-certified products. This is because certified firestopping products have been tested and evaluated by independent third-party organizations to ensure that they meet specific standards for fire resistance and smoke control. These products have undergone rigorous testing and meet the requirements of building codes and standards. Unlike certified firestopping products which have been tested and approved for their intended use, using uncertified firestopping products can compromise the fire protection system of a building, potentially leading to loss of life, property damage, and legal liability (e.g., cannot claim for fire insurance).

3. Installation Shortcuts

Even the best products, when installed poorly or incorrectly, cannot perform as intended and thereby compromise the integrity of the whole system. The most common shortcuts include using the wrong density of rockwool, using lesser than the recommended thickness of sealant, using the wrong product in different applications, failing to clean the surfaces to be sealed, not using the proper adhesives, or using a "backer rod" that is too small.

All these shortcuts put the building’s structural integrity and its occupants’ safety at risk, not to mention it could lead to code violations and liability issues for building owners, contractors, and installers. Firestopping installation should always be done by trained and certified professionals who underwent the proper product, installation, and technical training by the product manufacturer.

4. Mixing Different Product Brands

Most firestopping products designed by a manufacturer can be used independently or as part of a system because they are compatible when tested together, thereby guaranteeing the most effective passive fire protection while also upholding a valid system warranty. However, if different brands of firestop products are used together, it could compromise the effectiveness of the overall performance of the firestop system because of different properties (e.g., expansion rates or adhesion qualities). 

In addition to the risk of decreased fire protection performance, mixing firestopping product brands may not meet building codes and standards, and it can also result in legal and regulatory implications.


More than anything, the best way to avoid any of the above mistakes is to include firestopping early in the building design process. By doing so, it will eliminate so many mistakes during the construction and installation phase, and even provide cost savings if there is no need for remedial work later on.

Nullifire Firestopping Group

Nullifire Presents: Firestopping Essentials

Substrate Type & Material
Wall (Concrete, Masonry, Dry Wall)
FB750 Intubatt Coated Batt
Floor (Concrete, Masonry)Non-load bearingFB750 Intubatt Coated Batt
Load bearingFR230 Intucompound Fire Mortar


Services Type & Material
Non-CombustibleMetal Pipe, Cables, Damper, DuctingFS702 Intumastic Fire Resistant Acrylic
CombustiblePlastic Pipes (up to 125mm),
Cables Conduit
FS709 HP Intumescent Sealant
Plastic Pipes (up to 160mm)FP302 Intustrap Intumescent Strap
Plastic Pipes (up to 400mm)FP170 Intucollar Intumescent Pipe Collar


Location & Size of Gap
Indoor5 - 200mm gap widthFS702 Intumastic Fire Resistant Acrylic
Outdoor10 - 220mm gap widthFS703 Fire Resistant Silicone Sealant

Nullifire manufactures a comprehensive range of fire stopping and fire-resistant products that cover an extremely wide range of construction applications. Moreover, Nullifire’s passive fire protection products undergo initial validation assessments at its in-house facilities prior to undergoing rigorous independent third-party testing with leading UKAS test houses, resulting in the following accreditations:

  • AS1530.4:2014
  • ETAG 026-2
  • AS4072.1-2005
  • CE Marking
  • BS476 Pt20, 21, 22, 25
  • Certifire
  • BSEN 1366-3/4
  • UL EU Classification
  • EN13501-2:2007

Nullifire speak to our expert banner

Nullifire is a brand of Tremco Construction Products Group, a global manufacturer and service provider of high-performance building materials. All of Nullifire’s systems, be they intumescent coating for structural steel, or the comprehensive fire stopping range, have been fully tested to relevant British, European and Australia test standards allowing them to be used in the whole of Asia Pacific.

Our expert team is on hand to help you in any current or upcoming project you may have, do get in touch with the team.

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Have a project that you need some assistance with? Send us a message.


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