Fire-stopping webinar questions and answers

Your questions answered.

How do you find out what the ratings for different elements of building construction are? Especially in Domestic

Obtaining fire ratings of particular building elements can be a tricky process. For England and Wales, Appendix B of Approved Document B for Fire Safety provides useful information on minimum periods of fire resistance for different types of building and building elements. However, if any doubt exists you should contact the Local Authority Building Control (LABC) for further guidance.

Should a mastic type of fire stopping that adheres to cables be used? As it makes further cable installation difficult.

The type of product required depends on many different factors, the use of a sealant type product would probably not be the best solution for the situation which you describe. 

Regarding the 527... regulation, does fire stopping have to be done between any, for example, wall or ceiling, or only where the hole penetrates fire separating walls and ceilings?

Regulation 527 of BS 7671:2018+A1:2020 states that the remaining opening ‘shall be sealed according to the degree of fire-resistance (if any) prescribed for the respective element of building construction before penetration. However, sealing holes is considered to be good practice to prevent spread of smoke or transmission of heat and sound.

If the electrician fits fire bags on a trunking penetration, should this be documented?

Any works to the fire stopping system, even something simple, such as installing bean bags should be documented. This could be used to provide evidence that the works have been carried out, should an incident occur.

Do fire pillows in trunking need to be installed by a certified person or can an electrician do this?

There is no requirement for a person to be ‘certified’ but the law requires persons installing fire stopping products to be competent. Competence is a combination of knowledge, skills and experience. 

Where work is undertaken in an occupied private residence it could be difficult to determine what the status of a wall is - what is common practice in these cases?

Obtaining ratings of fire ratings of particular building elements can be a tricky process. For England and Wales, Appendix B of Approved Document B for Fire Safety provides useful information on minimum periods of fire resistance for different types of building and building elements. However, if any doubt exists you should contact the Local Authority Building Control (LABC) for guidance.

If a 10mm hole will allow a room to fill with smoke in a short time how can intumescent pillows guarantee sealing of penetration, are pressure tests carried out between spaces by approved companies?

Intumescent pillows are usually installed within the trunking, and the main purpose is to prevent the spread of fire. The fact they are installed within the trunking, and the trunking system itself will have an IP rating which will minimise the spread of smoke to a certain extent. It should be ascertained if there are any particular requirements to prevent the spread of smoke.

Ideally, a person must be competent to fit fire stopping. From an enforcing authority, we see many questionable installations of fire stopping. What training is needed, or can anyone fit fire stopping?

There is no requirement for a person to be ‘certified’ but the law requires persons installing fire stopping products to be competent. Competence is a combination of knowledge, skills and experience. 

You mentioned that fire stopping is recommended for rooms with electrical & electronic equipment as per BS 6266. Is it only recommended or mandatory?

From an insurance aspect, we would look to the building standards for construction. We cannot enforce but recommend compliance.

If modification/upgrade works are being carried out, which require a fire seal(s) to be dismantled to allow running of replacement cables, are there any concessions that might be allowed for the duration of the works? i.e. between removal of redundant cables and running of replacements. If not, what process should be followed to ensure compliance?

The type of temporary arrangements required will depend on several factors, such as the type of building and overall fire risk. A risk assessment carried out by a competent person would be required to determine if temporary fire stopping would be required during modification works.

I've seen approved fire stopping details for cables that involve covering cables either side of a wall with an intumescent coating. Do the IET have a view on this e.g. sheath deterioration, derating of cable?

Cable Manufacturers are the best source of information, regarding the derating factors and suitability of products in direct contact with the cables.

At what point during a construction project should one start using fire compartmentation, albeit temporary?

The type of temporary arrangements required will depend on several factors, such as the type of building and overall fire risk. A risk assessment carried out by a competent person would be required to determine if temporary fire stopping would be required during modification works. The CDM regulations cover fire safety for a construction project from start through to completion.

We are constantly coming up against sub-standard fire stopping works, that should have been signed off by Approved Inspectors, the building gets occupied and the fire service then finds countless issues. Is there no way this process can be fine-tuned and basically insurers not providing insurance if the works are substandard and not signed off correctly?

The insurance companies don’t always physically visit the construction, they will take the sign off by the inspector as work completed correctly. For industrial constructions, the insurance companies will send a surveyor to the site before commissioning, but even then things can get overlooked.

Does fire stop labelling have to be third party accredited?

The labelling is part of the installation process, whilst there is no legal requirement for fire stopping to be carried out by a third party, it is a good way to reduce liability.

Is the NFPA a US system? if so is there a UK equivalent?

Yes NFPA is a USA system, it is used for the insurance market as we cover the world. Sorry, I don’t know if there is a UK equivalent. 

How often should fire compartmentation be inspected?

The inspection frequency for fire stopping will be specified by the designer, it will depend on risk and the use of the building. For existing buildings, a fire risk assessment will be required to determine the frequency for inspection of the fire compartmentation.

I was taught that the original manufacture material to be used on a compartment to a building should be used on any other intrusions through fire breaks installed. Should they always use products the same as used on the compartment, for the building?

The type of material required will depend on several factors including the building fabric type, fire rating and the service type passing through. Specialist third party fire-stopping contractors are best placed to provide guidance on this.

If you install fire pillows in trunking etc would this derate the current carrying capacity of the cables i.e. would you have to use (ci)?

Cable Manufacturers are the best source of information, regarding the derating factors and suitability of products in direct contact with the cables.

Who is responsible to ensure each contractor on-site completes his fire stopping?

The responsibility for fire-stopping should be determined at an early stage of a project. Whilst the main contractor is likely to be responsible for ensuring fire stopping works are completed overall, this does not negate responsibilities on each contractor, for example, an electrical contractor needs to identify that the electrical installation works have been completed.

Are you then saying that the electrician needs to attend a course on fire stopping?

The law requires operatives to be competent to carry out works. Competence is a combination of knowledge, skills, experience and training. It would be difficult to see how competence could be justified without receiving training.

In older industrial buildings, if the design specification is not available, or incomplete, how would we determine what walls/rooms are for fire compartmentation? Is it best to recommend fire-stopping as part of the test and inspection?

A fire risk assessment would be required to determine the overall fire strategy, part of which would include determining the appropriate fire ratings for compartmentation.

If you install, say, a 25mm/32mm pvc conduit through a fire compartment walls, is this acceptable, as you cannot fire stop this, like trunking?

As described in Regulation 527.2.3 below, providing a conduit is made from metal and less than 710mm2, which is 30mm diameter, it does not require fire stopping. However, your question mentions PVC conduit, which would not be deemed suitable in terms of the spread of fire.

In a bundle of, say, data cables, do the gaps between the individual cables need to be sealed or are small gaps allowable?

I think the situation you are describing is using a sealant for multiple cables, which is probably not the best solution as you say will leave gaps for fire to spread easily. Whilst the material expands it also needs to have suitable mechanical strength, this would be difficult to achieve with several ‘gaps’ in the material.

With reference to fire ratings, does the same comment apply to all products such as back boxes as downlights i.e. 30, 60 or 90-minute rating?

There are so many different types of intumescent electrical accessory boxes, it is important to check with the manufacturers, but most usually have a 120-minute fire rating.

When trunking, for example, passes through a wall there is always a gap between the trunking and the building structure. I assume that this gap is then the responsibility of a specialist fire sealing company - not the electrician?

The responsibility for fire-stopping will need to be determined with the main contractor for the project. It is important not to assume that it will be done by others as it could be in the contract, or in some cases, it can be forgotten from the tender completely, in which case someone will have to foot the bill.

Where cables run through a raised floor, do the cables need to be fire stopped when they penetrate the raised floor?

Requirements for fire-stopping a suspended flooring system depends on if the floor has a designated fire rating or not, which all depends on the fire strategy for the building. It is important to check this with the responsible person.

Grade B1 PU foam is not flammable. B2 and above are. So "pink" PU foam may be unsuitable but are you stating that PU foam generally should not be used as it is only the installer who knows if it is B1 or not?

Generally speaking, foam is not suitable for the fire-stopping of cables. It is difficult to get assurance from manufacturers that this will not affect the cable and it makes future installation of cables difficult.

Is the PU foam mentioned in the example of the fire, fire rated or standard?

The foam mention was fire-rated foam. Generally speaking, foam is not suitable for fire-stopping of cables. It is difficult to get assurance from manufacturers that this will not affect the cable and it makes future installation of cables difficult.