BB850

BB850 BlastLag is an acoustic lagging for pipes and ductwork. Its job is to control noise break-out — the sound that radiates outward through the wall of a pipe or duct into the room it passes through.

The problem is a modern one. Cast iron soil stacks were heavy and well damped, and the pipe itself did much of the acoustic work. PVC and HDPE replaced them because they are cheaper, lighter and faster to install, but those same properties make them efficient radiators of the noise travelling inside them. In a hotel corridor or an apartment service riser, a PVC stack can be clearly audible in the adjacent room every time a cistern discharges.

BB850 addresses this with two layers working together. A limp mass barrier at 5 kg/m² provides the mass needed to block airborne sound. A layer of open-cell polyether polyurethane foam sits between that barrier and the pipe, breaking the vibration path so the barrier is not driven directly by the pipe wall. Without the foam, the barrier is simply coupled to the pipe and adds far less than its mass would suggest. The outer reinforced foil facing protects the assembly and gives a surface that can be taped at the joints.

The foam is hydrolysis resistant, which matters in a service riser or a plant room where humidity is high and the material has to survive for the life of the building. The construction is fibre free, so unlike mineral wool lagging there is nothing to release into the air during installation, and nothing that will compress and settle over time, leaving an acoustically weak section at the top of the wrap.

Where BB850 performs: the manufacturer’s test on a 100 mm PVC pipe shows insertion loss rising steadily with frequency — modest in the lowest bands, around 10 dB at 500 Hz, above 20 dB at 1 kHz, and above 30 dB at 2.5 kHz and beyond. The overall A-weighted figure from that test is up to 25 dB(A). It is worth being clear about the other end of the spectrum: between 100 Hz and 315 Hz the measured insertion loss is only about 2 to 9 dB. That is normal for any lagging of this mass and thickness, and it is why a lagging specification for a low-frequency source such as a pump or a compressor should be checked against the actual spectrum rather than assumed from a single headline figure.

These figures are the manufacturer’s declared data. The supporting test report is available on request. BlastBlock has not commissioned independent testing of BB850 under its own name, and we would rather state that plainly than imply a certification that does not exist.