Hello
I'm doing my own loft conversion following plans from a structural engineer and it’s Building Control approved.
For the new 22mm T&G chipboard floor I have to boost the 20 minute fire rating of the lath and plaster ceilings underneath by suspending 100mm depth of "mineral wool" on chicken wire between the new floor joists to provide an extra 10 minutes fire protection.
Apparently both glass and rock based wool are classified as "mineral wool" according to BS 3533. However, I'm getting conflicting answers from my Building Control office (depends which officer picks up the phone), structural engineer and Knauf help line about whether glass mineral wool is acceptable for this purpose or whether it has to be rock based. Web searches reveal the only official references are to mineral wool (without specifying glass or rock) for this purpose but there are lots of unofficial references to the Rockwool brand name.
I don't want to bin all my old mineral insulation (probably glass) and spend £150 on rock based insulation if I can reuse the glass to add the extra 10 minutes of fire protection. It's my understanding (from taking an average of opinions) that rock based wool is more fireproof and can stand much higher temperatures but that glass wool will suffice to supplement the lath and plaster and chipboard in this situation - is that correct please? Or do all loft conversion companies really bin the existing insulation and replace with Rockwool?
Thanks very much
I'm doing my own loft conversion following plans from a structural engineer and it’s Building Control approved.
For the new 22mm T&G chipboard floor I have to boost the 20 minute fire rating of the lath and plaster ceilings underneath by suspending 100mm depth of "mineral wool" on chicken wire between the new floor joists to provide an extra 10 minutes fire protection.
Apparently both glass and rock based wool are classified as "mineral wool" according to BS 3533. However, I'm getting conflicting answers from my Building Control office (depends which officer picks up the phone), structural engineer and Knauf help line about whether glass mineral wool is acceptable for this purpose or whether it has to be rock based. Web searches reveal the only official references are to mineral wool (without specifying glass or rock) for this purpose but there are lots of unofficial references to the Rockwool brand name.
I don't want to bin all my old mineral insulation (probably glass) and spend £150 on rock based insulation if I can reuse the glass to add the extra 10 minutes of fire protection. It's my understanding (from taking an average of opinions) that rock based wool is more fireproof and can stand much higher temperatures but that glass wool will suffice to supplement the lath and plaster and chipboard in this situation - is that correct please? Or do all loft conversion companies really bin the existing insulation and replace with Rockwool?
Thanks very much
