Do I need Intumescent seals on a 20 minute fire rated door set?
A 20 minute fire doorset had previously comprised a 25mm doorstop, no requirement for intumescent seals and a 1/2 hour blank, can I continue to use this format?
Before 1972 the British Standards defined how to construct a fire doorset that included 25mm doorstops, in subsequent changes the standards have been altered regarding proving performance by controlled independent testing.
Due to reasons of economy manufacturers generally test to a 30 minute rating and market those same products for 20 minute applications.
In general the safe approach is to assume that 20 minute fire doorsets should have intumescent strips fitted that have been tested to a 30 minute rating.
Specifiers and purchasers should confirm that acceptable evidence exists, rather than assuming that old or out of date prescribed solutions will be acceptable, so the quick answer is no, why bother trying to find and use a 20 minute rated door when they have in the main been tested to 30 minute ratings.
Chippy for DirectDoors.com