It s important to add solid wood blocking as well if floor joists intersect a wall so that the fire can t go up a wall and then sideways in between floor or ceiling joists.
Fire stops in cavity walls.
If a fire starts within the wall the top block stops the fire from getting into the attic.
Cavity barriers also known as stop socks are blocks of fire resistant materials that seal cavities in the wall to prevent the spread of a fire.
It can also be used for the control of sound flanking at wall junctions.
Stopping the spread of fire in cavity walls.
The bottom block stops the fire from getting into the wall cavity to begin with.
The ultimate question being when do cavity closers need to have fire resistance.
What are cavity barriers and fire stops.
Cavity fire barrier are strips of low resin non combustible rock fibre mineral wool sleeved in 50 micron polythene for onsite protection.
Technical posted on 24 06 2019.
An issue that has been causing much confusion among developers at the moment is the requirement for the prevention of fire spreading within cavity walls.
One of the main challenges in these circumstances is ensuring that the breathability of the building is balanced with the ability to prevent the passage of smoke and fire through the channels.
Wherever there is a concealed cavity within a building whether that is a floor wall ceiling or external façade there is a risk of fire spreading.
Barriers used to close concealed spaces and prevent penetration of smoke or flame to restrict the movement of fire within a building.