Is 20mm adequate for a fire door lining?

[9namjam9]

I just had a couple of fire door linings replaced as they were not deep enough after I overboarded the stud wall they are set in. The original linings were made with 30mm thick timber, and I only realised this evening that the new linings are made of 20mm thick timber. One of the doors was also replaced with a heavier fire door , about 45kg. The frames seem sturdy and the doors close fine, but I’m concerned 20mm isn’t thick enough long term for such heavy doors. Also there is now a 4cm gap on one side of the doors filled with foam which doesn’t seem very fire safe…. What do you think?

 

Edited December 10, 2021 by 9namjam9

[carlb40]

This might help. https://www.forza-doors.com/performance-guides/general-guidance/fd30-fd60-timber-frame-minimum-dimensions-and-specification.aspx