Arched fire door

[buffster]

We have an arch on a hallway under a staircase, and, while it looks nice, we need to fit a fire door there somehow. The top of the arch is a touch less than a standard door, so we can't square off the arch with a door below it or only very short people would be able to get through. I'm sure a custom fire door would extortionately expensive, but is it possible to modify an existing fire door somehow? I suspect that simply cutting it to shape would not be viable, but would it be an option to remove the faces of the door, cut the door to pretty much the right shape but create a top arch of say 2 bits of (say) MDF )(or another sheet material) bonded together and shaped to an arch and dovetail this into the vertical timbers of the door before reattaching the faces of the door?

Would this even be possible, and would it be possible for such a door to be suitable for use as a fire door?

Many thanks in advance.

 

[gregers]

iirc any major cutting on a fire door needs to be completed by the manufacturer.
so that the guarantee is still valid.

 

[Deleted member 174758]

Not only the guarantee, but also that the door is still classed as a fire door by the insurers