Fire Resistance
Fire Resistance
All Thomas Armstrong lightweight, dense and Airtec aertaed blocks and achieve the very best possible resistance to fire rating of "Class A1" (BS EN 13501-1:2002). This European Standard supercedes and exceeds the former British Standard BS 6073 "Class 0" spread of flame rating.
FIRE RESISTANCE PERIODS
|
SOLID LIGHTWEIGHT, DENSE or AIRTEC BLOCK (In single leaf or inner leaf of cavity wall) "Class 1" = Airtec, Masonry & Lightweight blocks "Class 2" = Dense Concrete Blocks | ||||||||
|
Block Thickness |
Loadbearing Wall |
Non-Loadbearing Wall | ||||||
|
No Finish |
VG Finish |
No Finish |
VG Finish | |||||
|
Class 1 |
Class 2 |
Class 1 |
Class 2 |
Class 1 |
Class 2 |
Class 1 |
Class 2 | |
|
75mm |
- |
- |
- |
- |
2 |
- |
4 |
2 |
|
90mm |
1 |
- |
2 |
2 |
2 |
1.5 |
4 |
3 |
|
100mm |
2 |
2 |
4 |
4 |
2 |
2 |
6 |
4 |
|
140mm |
3 |
2 |
4 |
4 |
4 |
3 |
6 |
6 |
|
190mm |
6 |
2 |
6 |
4 |
6 |
4 |
6 |
6 |
|
215mm |
6 |
2 |
6 |
4 |
6 |
4 |
6 |
6 |
VG finish = vermiculite/gypsum plaster or pearlite/gypsum plaster 13mm minimum thickness applied to both faces of single leaf walls and inner leaf of external cavity walls.
|
CELLULAR / HOLLOW LIGHTWEIGHT or DENSE BLOCK (In single leaf or inner leaf of cavity wall) "Class 1" = Airtec, Masonry & Lightweight blocks "Class 2" = Dense Concrete Blocks | ||||||||
|
Block Thickness |
Loadbearing Wall |
Non-Loadbearing Wall | ||||||
|
No Finish |
VG Finish |
No Finish |
VG Finish | |||||
|
Class 1 |
Class 2 |
Class 1 |
Class 2 |
Class 1 |
Class 2 |
Class 1 |
Class 2 | |
|
90mm |
0.5 |
- |
1.5 |
- |
0.5 |
0.5 |
3 |
1.5 |
|
100mm |
2 |
- |
2 |
- |
2 |
1.5 |
4 |
2 |
|
140mm |
2 |
- |
2 |
- |
3 |
3 |
4 |
4 |
|
190mm |
2 |
0.5 |
2 |
1 |
4 |
4 |
6 |
6 |
|
215mm |
2 |
0.5 |
2 |
1 |
6 |
6 |
6 |
6 |
VG finish = vermiculite/gypsum plaster or pearlite/gypsum plaster 13mm minimum thickness applied to both faces of single leaf walls and inner leaf of external cavity walls.
CAVITY BARRIERS
Cavity Barriers and Cavity Barrier closures are required to be installed in and around cavities to resist the spread of smoke and flame.
In general no continuous void should exceed eight metres in a single dimension measured in one plane, or 20 metres if the exposed surfaces within the cavity have Class 0 ratings. A selection of barrier materials are available:
i) asbestos-free board which would give similar protection to that given by 9mm thick asbestos building board or asbestos insulating board (but not asbestos cement),
or
ii) plastered board at least 12.5mm thick,
or
iii) steel at least 3mm thick,
or
iv) timber at least 38mm thick,
or
v) wire-reinforced mineral wool blanket at least 50mm thick,
or
vi) polythene sleeved mineral wool, or mineral wool slab, in either case under compression when installed in the cavity.
Useful information is given in Building Research Establishment Digest 214 and 215, Cavity Barriers and Fire Stops, Part 1 and 2.
