dimensionsLengths are sold in 1mtr sections and are 30mm thick (non-combustible materials), with a 6" internal diameter.
Installed in 1mtr lengths. When dropping the chimney liner down the stack, first secure the Rockwool to each 1mtr section of liner using high temperature aluminium tape (purchase separately) and install liner as normal.
Download Building Regulations Document J (effective October 2010) below
(Right click link, then select "save file as..")