thermabate cavity closers vs weatherbate cavity closers
 

Hi all I am building a double block wall on my extension.To get the u value
up the cavity is 50% filled with rigid insulation board.The architect has
specified Thermawall cavity closers around the window openings.The builders
merchant has supplied weathershield cavity closers-the BC dept queried the
fire retardant properties of the thermawall.
Could I install the weathershield.
Is it not covered in completely anyway.