This common question can often cause confusion!

Generally, our customers are dealing with either FD30 or FD60 doors (30 minute fire resistance or 60 minute fire resistance). FD30 doors will normally be 44mm thick, and FD60 doors will be 54mm thick.

You need to make sure firstly that you are using a suitable fire tested hinge (more about that on our separate post ‘What should I consider when fitting hinges to fire doors’) with CE and EN 1935 markings stamped on it.

It’s important to know the fire test data for the hinge because generally when they are put through their fire test they will have been fitted with an intumescent pad behind both hinge leaves (on the door side and the frame side).

For example, our HFR014 Ball bearing butt hinge CE Certificate of Approval states that, for FD30 doors; All hinges must be bedded onto a 1mm thickness of mono ammonium phosphate intumescent material behind both blades. For FD60 applications; All hinges must be bedded onto a 2mm thickness of mono ammonium phosphate intumescent material behind both blades.

These intumescent hinge pads can be purchased separately (our code HAF014), ready cut to size to suit the hinge blade. To achieve the 2mm thickness required for FD60, 2no 1mm pads can be stacked on top of each other.

Simple, right? Well no, not really…!

The other important thing to consider is the fire test assessment for the door that you are using.

In many cases (but not all), the fire test assessment for the door states that for standard sized FD30 doors, intumescent hinge pads are not required.

For instance the BM Trada Field of Application Report for the Strebord 44mm FD30 door core states that hinge pads are not required for doors of height 2670mm and under. Doors of height 2671mm and over need 1mm intumescent pads under both hinge leaves.

Likewise, BM Trada’s Field of Application Report for the Halspan Optima 30 door core, simply says; hinge intumescent protection not required.

And a third example is Jeld-Wen’s Tubeboard FD30 door core, where the Certifire Certificate of Approval also says; none required.

When we get to FD60 door tests however, we start to see fire test assessments requiring intumescent behind the hinge pads, as you would imagine for a door that has to resist fire for an extra 30 minutes.

IFC’s Field of Application Report for the Optima 60 door core states ‘hinge blades must be bedded on graphite based or non-pressure forming intumescent material at least 1mm thick.’

Jeld-Wen’s Certifire Certificate of Approval for their FD60 Flush Timber Door Assemblies says ‘1mm Interdens or Graphite intumescent sheet material under all hinge blades’

So what do you do when the hinge fire test and the door fire assessment give different requirements? Well, the door test evidence takes precedence over the hinge’s test evidence – as long as the hinge specification falls within the parameters specified in the door fire fire assessment (size, material etc).

Therefore if you are fitting, for example, approved hinges to a Strebord 44mm FD30 door core, (assuming the door is less than 2671mm high and has a timber frame) you don’t need to fit hinge pads.

However, if you are not sure which door core you are dealing with, you should go by the hinge test data and fit them! As you can see from the above examples, generally the hinge intumescent requirements are in excess of the door requirements so this is the safe option.

Note that all of the scenarios that we discuss are assuming that standard timber frames are being used. If you have frames such as pvc encapsulated, metal etc., advice may well differ; please check the detail of the relevant fire test reports, or get in touch with us for further advice.

Review of this page due December 2022. 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.

Architects and clients often request ‘hidden’ doors on higher specification projects. This generally involves concealed door hinges which are invisible when the door is shut. 

Traditionally ‘Soss’ hinges were the main type used to fulfil the ‘hidden door’ brief, and we still sell many of these. They are available in a wide range of sizes and can be used for everything from small cupboard doors right up to FD30 and FD60 doors.

However, they do have the disadvantage of not having any adjustment, so that once morticed out there is no easy way of adjusting the position of the door within the frame.

This is where other, more recent, types of concealed hinges come into play – most notably the ‘Tectus’ brand. These have the added benefit of 3 dimensions of adjustment within the hinge body, so that the door can be precisely positioned. They also come in larger sizes and can cope with doors of up to 300kg in weight!

Obviously installing concealed hinges involves quite a lot of morticing into the door leaf and frame – more so than a conventional butt hinge. This consequently has a greater impact on the fire integrity of the door. What aspects therefore do I need to consider when fitting such hinges to fire doors?

Firstly, it’s critical that any concealed hinge you are considering has been through a successful fire test in an accredited test house to the level you are requiring (FD30/FD60).

Secondly, and very importantly, you must check the fire test data for the door you are using. Because of the specialist nature of concealed hinges, the fire assessment is normally quite specific on what models of hinge can be used.

For instance, the Warrington Fire Field of Application report (Chilt/AO2066 Revision 0) for the standard Strebord 44mm door core specifies the following hinges that may be used;

Simonswerk Tectus TE340 3D FR, TE540 3D FR, TE540 3D A8 FR, TE640 3D FR and TE640 3D A80 FR

Various other stipulations are made re the installation, including;

Hinges must be fitted according to the manufacturers instructions including using the supplied hinge fixings.

The mortice for concealed hinges must be no closer than 50mm to any aperture or other mortice or recessed area within the door leaf.

The hinges must be used in conjunction with a twin strip perimeter intumescent arrangement where one of the seals remains continuous past the hinge blade in the frame reveal or leaf edge.

The timber based frames must be hardwood of minimum density 640kg/m3.

For doors of leaf height 1201 – 2400mm, the top hinge should be 150-200mm from head of leaf to top of hinge. Second hinge should be Minimum 200mm from top hinge and maximum centrally between top and bottom hinge. The Bottom hinge should be 150-300mm from the foot of the leaf to bottom of hinge.

It is not permitted to fit more than 3 hinges unless the door is over 2400mm high – different hinge spacing pertains in this circumstance!

I have included all the above detail to illustrate the importance of carefully studying the door’s fire test assessment. It’s not enough to simply fit one of the hinges specified – their positioning, fixings and the frame details are also critical.

It’s worth noting that many of the Tectus fire rated hinges come with intumescent pre-installed within the hinge which makes fitting them simple.

We keep a Tectus jig which we rent out if you are needing it to make installation simpler – just get in touch to discuss!

If you are wanting to fit another brand of concealed hinge, it would be worth checking to see if another fire assessment would cover this.

In conclusion, concealed hinges are aesthetically beautiful but need a lot of care installing in a fire door situation!