Fire, Smoke and Weather Sealing for Door Assemblies
I need to buy a 30 minute fire seal - which product should I buy?
First of all, please do remember that adding a fire seal to any door doesn't automatically make it a fire door. Do 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 our Technical Services team on +65 6270 1279 for details.
If it's a fire and smoke door (which will be denoted FD30S), 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 ultra-low frictional resistance for ease of door operation, it's an exceptional 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 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.
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 door bottom seals and drop seals 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, the Building Regulations have moved on since they were introduced, most notably with new requirements in the last few years for doors to provide acoustic containment, and also be easy to operate to allow access for all. With so many doors now needing to conform to these new requirements, the brush-style smoke seal is simply not up to the challenge any more. Brushes are particularly poor at providing acoustic containment, as the brush fibres allow air to pass straight though, and therefore sound too. They also provide plenty of friction, which makes doors more difficult to operate.
Fin-style seals provide a much more modern, comprehensive and indeed 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?
BS9999 (an Approved Document to the Building Regulations for England & Wales) 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 extensive research has proven that this is definitely 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, both in practice and principle. Threshold sealing is also essential for acoustic containment, as an acoustic sealing system will only truly 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 door bottom seals or drop seals.
If I drop seal, do I need to fit a threshold plate too?
A threshold seal 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 drop seal to rest against.
- It can help to prevent weather ingress when used as part of a storm-guard system (such as our LAS3008).
- 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 threshold seals 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 compromise performance in a fire situation - however, do not paint over smoke seals as this will certainly compromise smoke containment performance. 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 LAS3008 storm-proof seal, part of our Lorient Architectural Seals range.
I'm working on a hospital project that needs a sealing system that will stand up to rigorous cleaning. What do you recommend?
We'd recommend you consider using a stainless steel sealing system from our range. There are perimeter and threshold sealing products included, and both the carriers and gaskets are impervious to most strong cleaning chemicals, making them ideal for hospitals. Please click to link to the following pages:
- LAS4050, LAS4055, LAS4060 and LAS4065 threshold plates
- LAS3050 door bottom seal
- LAS8060 or LAS8070 drop seals.
Please note that while these seals will provide a comprehensive smoke sealing solution, if you have a fire rated door then an appropriate fire seal should be fitted in addition.
Approved Document M says that doors need to be easy for everyone to use. Which of your products do you suggest?
Many of our products have been designed with ease of access in mind, and the seals we recommend will provide exceptionally 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 perimeter seals mounted onto the doorstop (eg, our LAS7001), 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 drop seals (eg, our LAS8005) 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 for situations where different floor levels need to be accommodated.
What standards and regulations relate to fire & smoke containment for doors?