Should I fit intumescent lock wraps on fire doors?

We find that, whilst a lot of attention is given to the installation of intumescent hinge pads, fitters can sometimes be less aware of the intumescent requirements of mortice locks. However, when you consider the amount of timber that needs removing from a door to install a mortice lock, you realise how critical this is to fire integrity.

As always, we have to go by the fire test evidence, and it’s essential that the lock you are installing has been tested for use in a fire door.

Fire door test evidence

The most important thing is to check this and be guided by it.

Generally speaking, most fire door assessments will require an intumescent wrap that goes around the lock body, under the forend and also under the keep. For FD30 purposes, this will usually be required to be 1mm thick. For FD60 purposes, some or all of the wrap may have to be 2mm thick.

There are some exceptions, for instance the Flamebreak 30 door blank Certifire Certificate states that no intumescent is required assuming the lock falls within certain size and specification parameters.

Other things to check on the fire test assessment are;

  1. Maximum lock, forend and keep dimensions. Generally door cores will have been tested with all regular sized locks including DIN standard locks, but you should check this, especially if you have a large/unusually shaped lock body
  2. Lock positioning. There will usually be a maximum and/or minimum height that the lock can be installed at, make sure you are aware of this!
  3. Any forbidden door/design configurations, eg. rebated stiles.

Mortice lock test evidence

Where the fire door test evidence is not available, you should always go by the lock’s fire test evidence.

For example, we normally specify DIN Standard locks from our LZH600 range. These locks are Certifire, CE and UKCA Marked, and suitable for FD30 and FD60 fire doors.

Some details from the test evidence for these locks is listed below;

For FD30 timber doors, the Certifire fire test evidence requires that 1mm thick Mono Ammonium Phosphate or graphite-based intumescent sheet material is fitted aound the lock case and behind the forend and strike plate.

For FD60 timber doors, the same is required but the intumescent behind the forend and strike plate should be 2mm thick.

There is also an additional note for FD60 applications to say that the door/frame perimeter intumescent should bypass the strike plate or forend by a minimum of 7.5mm wide on each side (with the exception of the latchbolt lead where present).

In conclusion we can say that if you are fitting a lock into a fire door, it’s highly likely that you will need to fit an intumescent wrap with it. Consequently when quoting/specifying we will always allow for a 1mm thick intumescent wrap to FD30 doors and a 2mm thick intumescent wrap to FD60 doors.

Our wraps are made to fit the locks precisely and just need folding around the lock. There are also holes to match the spindle and lock positions, so fitting is really simple.

Please do get in touch if we can help you further with ironmongery fire requirements. We are trade only suppliers to commercial and refurbishment contractors, fire door manufacturers and installers, facilities management and maintenance companies.

Review of this page due May 2023. Please note that advice given is advisory only and to the best of our knowledge at time of writing. We cannot be held responsible for loss or damage incurred as a result of actions taken based on this article.

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