Paul J S Green writes
Meant to put on original post; my "fire door" says "Lightweight Firecheck
Doorblanks" on it.

I'm sure you know these are interior doors that will *need* the
protection of your ply - I usually use 12mm WBP - and, if in an exposed
location, edging strip round the whole door.

And the advice to use lay-on bead is spot-on. If you expose the
original door ply, it won't last a year in most locations.
--
roger
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