ROCKWOOL HARDROCK® Multi-Fix Recovery Board

An unusual approach to this month’s column Dear Reader; a focus on a single product from one of our manufacturing partners. But, before you accuse us of biased favouritism (and yes, we do stock ROCKWOOL HARDROCK® Multi-Fix Recovery Board) please let us explain the potential significance of this Euroclass A2-s1 ,d0 “non-combustible” to BS EN 123501-1 insulation board.

If you are a regular reader of this column, you will know that we have a bit of a focus on helping you achieve compliance with the fire performance requirements of the Building Regulations and understanding the nuances of Approved Document B/Scottish Technical Handbooks.

One common misconception is that these documents only relate to new build construction, which they do not. If you are carrying out a refurbishment project the Building Regulations still apply, which means if you are carrying out an over-roof to an existing flat roof build-up (i.e., not stripping to the structural deck) you still need to demonstrate compliance with boundary related fire performance requirements (BRooF{t4), CRooF(t4), DRooF(t4), ERooF(t4), FRooF(t4)).

Prior to the 2019 edition of Approved Document B, a bitumen felt flat roof that included any of the finishes contained in Table AS Part iii was deemed to achieve BRooF(t4). Of these the key finish of note was ‘bitumen bedded stone chippings cover the whole surface to a depth of at least 12.5mm’. Single Ply and Liquid Applied roof waterproofing never had this deemed to satisfy rule. In this post-2019 World this rule has been removed, so now to demonstrate fire performance compliance you need an actual test of the as built roof including any existing roof element left in place – not exactly simple and generally fairly impossible.

So how can you demonstrate fire compliance on an over-roof refurbishment project using RBM, Single Ply or Liquid Applied roof waterproofing?

This is a space where QI feel ROCKWOOL HARDROCK® Multi-Fix Recovery Board comes into its own – provided you have a fire test classification report with it included within the test assembly, and the client is not looking to thermally upgrade the existing roof significantly. A conversation will still need to be had with Building Control to get sign off, but if you have a fire test certificate for your choice of waterproofing over HARDROCK® Multi-Fix Recovery Board, the fact that the HARDROCK® Multi-Fix Recovery Board is non­combustible demonstrates that fire cannot penetrate the board and should satisfy Building Control that the new roof system is compliant with the requirements of the Building Regulations.

Next month: ROCKWOOL® Hardrock Multi-Fix Recovery Board