Frequently Asked Questions Fire, Smoke and Weather Sealing for Door Assemblies - Lorient Hong Kong

I need to buy a 30 minute fire seal - which product should I buy?

First of all, please remember that adding a fire seal to any door doesn't automatically make it a fire door. You must make sure that you have a properly tested fire door construction.

Also, please remember that not all fire doors are the same - so there's no single answer to this question! The first thing to check is the door manufacturer's test evidence for the door you have - whatever type and size (or sizes) of seal they have tested with is what you should buy.

Where door manufacturer's test evidence isn't available, the usual recommendation is to use a 15 x 4mm seal, fitted centrally at the head and both jambs of a single leaf, single acting door. (If you are in any doubt, or have a particular application you would like to discuss, please contact Chris Sin.

If it's a fire and smoke door, then do also remember that a fire seal alone will not be sufficient - you should purchase a combined smoke and fire seal, such as the Lorient DS. Don't forget to seal the threshold too - you may find our FAQ on threshold sealing helpful.

I have an existing fire rated door, but have been told it needs to provide smoke containment too. What do you recommend?

The first product we would always recommend you consider is our Batwing® seal. With proven performance for acoustic and smoke containment, a choice of sizes for different applications, and low frictional resistance for ease of door operation, it's a good all-round solution. As it fixes onto the doorstop with strong self-adhesive tape, it's easy to install and you won't need to remove your door to fit it.

Alternatively, our Integrity™ perimeter seals, face-fixed to the door stop provide a good option, and several have been designed to accommodate uneven doors.

If you have double leaf doors, remember you will need to fit a seal at the meeting stile too. We would suggest you consider our IS7061, as it incorporates a Lorient Batwing® seal.

And don't forget the threshold! - it's essential to seal it for effective smoke containment (please refer to our FAQ on threshold sealing for more information!). We have face-fixed options in both our Integrity™ 3000 and 8000 series that can be installed without removing the door.

What's the difference between a brush smoke seal and one with fins?

Brush seals were the first on the market (in fact, Lorient were the first to introduce them, back in 1979!), and hence they have popular appeal as the traditional smoke seal solution. Although they are still effective as smoke seals, they do not perform well as acoustic containment seals. They also create a lot of friction, so the doors become more difficult to open and close.

Fin-style seals provide a much more modern, comprehensive and
hygienic solution. They have better acoustic containment properties (particularly ones with dual fins) and much lower frictional resistance.

It's important though that the fin seal remains continuous around ironmongery for both acoustic and smoke containment - but this can be a challenge if the seal has centrally positioned fins. Offset fins make this much easier. This is why Lorient have introduced the DS and Finesse™ seals, with offset dual fins, for a complete acoustic, smoke, fire and low-friction solution.

The durability of some fin-style seals has been questioned in the market at times - but Lorient have extensively tested the DS, cycling it 1,000,000 times (10 times the usual industry level) on a full-size door assembly, without failure. As long as the seal is correctly installed, and the doors are suitably maintained, it will provide years of reliable service. The Finesse™ seal has been similarly tested too. It's unique in the industry, as its fins start at the base of the product and wrap around the sides of seal, both helping to hold it securely in place in the groove, and provide extra durability.

Please refer to the product pages highlighted for more information.

Do I need to fit a threshold seal - and if so, why?

BS5588 (an Approved Document to the Building Regulations for England & Wales - currently being superseded by BS9999) states that if a fire rated door has a gap of over 3mm at the threshold, then you do need to fit a threshold seal. It's very difficult to know before the door is installed whether the gap will be over or under 3mm, so we do always recommend fitting a threshold seal.

There are other reasons for this too. It is often assumed that the threshold is a low-risk area, but research has proven that this is not the case - an unsealed threshold presents a major cold smoke hazard. That is why undercutting the threshold of a door leaf to provide extra ventilation is extremely risky too. Threshold sealing is also essential for acoustic containment, as an acoustic sealing system will only be effective if it incorporates every gap around the door, and that includes the threshold. For more information on our threshold seals, please refer to our Integrity™ Architectural Seals 3000 series or 8000 series products.

If I fit a threshold seal, do I need to fit a threshold plate too?

A threshold plate is a good idea, for several reasons:

It will help to ensure a good seal is maintained at the threshold, by giving a firm surface for the threshold seal to rest against.
It can help to prevent weather ingress when used as part of a storm-guard system (such as our IS3100).
If you are sealing dissimilar surfaces (eg, carpet and vinyl), the threshold plate can cover the join to prevent both wear and tripping hazards. Our threshold ramps can also easily accommodate differences in floor heights, to make access easier for all.
If your floor surface is particularly liable to wear and tear in places below the door (eg, a high level of traffic, or over a carpet that may become compressed over time), then a threshold plate will help to prevent these uneven areas affecting the threshold sealing.

Please refer to our Integrity™ Architectural Seals 4000 series for details of the threshold seals and ramps we can offer.

Can you paint over fire and smoke seals?

Over-painting of fire seals should not affect fire performance. But do not paint over smoke seals as this will certainly stop them from working properly. If the smoke seal part of the seal has already been painted over, you will need to replace the smoke seal. Our seals are available in a range of colours, plus woodgrain and metallic finishes, so over-painting should not be necessary.

I need to fit a weather seal to an external door. What do you recommend?

Take a look at the IS3100 storm-proof seal, part of our Integrity™ Architectural Seals range.

Which of your products do you recommend for ease of door use and accessibility?

Many of our products have been designed with ease of access in mind, and the seals we recommend will provide very low frictional resistance to ensure the seal interferes as little as possible with the smooth operation of the doorset.

For a combined acoustic, smoke and fire sealing solution, we recommend you take a look at our DS or Finesse™ seal. Please remember that traditional brush-style fire & smoke seals provide very high levels of frictional resistance, so won't be suitable.
For acoustic and smoke containment only, either for new door assemblies or as a retrofit solution, our Batwing® seal is ideal - we've re-engineered the fins now into a unique curved design, so they provide even less resistance.
Alternatively, any of our Integrity™ perimeter seals mounted onto the doorstop (eg, our IS7025 si), will provide a compression seal that will provide minimal interference.
It's vital to have a seal at the threshold for effective acoustic and smoke containment, and our automatic threshold seals (eg, our IS8005 si) have been designed with high efficiency mechanisms, so doors can be opened with the minimum of effort.
We also offer a range of threshold ramps (IS4070, IS4075 and IS4077) for situations where different floor levels need to be accommodated.

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