Fireline boards on top of floor?

[yar1950]

My plasterer told me that about 18 years ago he did some flats in London and building regs allowed them to fix two layers of fireline board on top of the floor and them went over it with a special thick hardboard.
Has anyone else come across this or done it as it would help me out no end to fireproof between my flat and the shop below.

 

[freddiemercurystwin]

Was probably done to improve sound insulation rather than fire resistance. Plasterboard thicknesses/specs would normally be increased on the ceiling to improve fire rating as heat tends to go up, to protect the joists and minimise the smoke entering the floor void as well as the rooms above.

 

[yar1950]

I pulled up a part of the floor in question today and found that the ceiling below has a layer of 12 mm fireboard. With this in mind do you think I may get away with putting another layer between the joists to give the two layers required?

many thanks all

 

[tony1851]

No, between a flat and a shop you need 60 mins. FR. I doubt putting any board between the joists will do.
There are some propreietory systems for upgrading the floor from above, but they are expensive.