MDF?? Fire Doors.

[nearlythere]

During a recent survey of a 10 year old build I came across a door between an internal carpark and stairway which had all the trappings of being a fire door - about 45mm thick, 3 hinges. intumescent and smoke seals, georgeon wired glazed element and SC. However, a glazing slip a been removed and it could be seen that the door was made from what looked like MDF faced on each side with 3 or 6 mm ply. The absence of the slip also revealed that clear silicon had been used to seal in the glazing.

Has anyone ever come across a MDF fire door?

[CivvyFSO]

Seems 20 minutes is possible, but they seem to have a inner FR core to the door. The 30mins and above tend to have intumescent inner cores or timber inner cores with just a MDF facing. I can't find a FR door made purely out of MDF.

You can get fire rated silicon sealant that seems to be suitable for glazing in doors.

[Fishy]

Plenty of chipboard-core FD30 door leaves so don't see why MDF would be a problem, if properly framed internally.

The clear silicone probably wouldn't be fire-resisting as a glazing seal, though - the glass will get very hot and ignite it (even if it's sold as 'fire resistant', because I'd put money on it not being tested for this particular application).  Re-glazing using a proper intumescent glazing compound would be my recommendation.  Sealmaster do a mastic gun-applied product that's pretty fool-proof.

[CivvyFSO]

There are some silicone seals that are advertised as meeting BS476 and suitable for glazing in fire doors.

[Fishy]

I never believe the adverts unless I've seen the test reports - and I rarely regret it!!! 

Might be OK for insulating glass but not for GWPP - have a look on the Pilkington's website (they call Georgian Wired glass 'Pyroshield' these days) and you'll see that Silicone is not a recommended glazing medium.  As I said, under test the glass gets hot very quickly and can ignite the silicone (I've seen it happen in tests - even if the stuff is advertised as being fire-resisting).

Of course, if those 'advertising' that their product is suitable for this application can back it up with fire test evidence on non-insulating glass in timber doorsets, then that's fine; I've not made it a personal mission to review every product on the market, but I'll believe it when I see it.  There are loads of good fire-resisting glazing systems out there which are as easy or easier to apply than silicone mastic, and are able to give consistently good fire performance, so there's plenty of choice.