Which BlastBlock grade: BB830, BB830FR or BB830LF

Two of them are the same sheet. The third is not

BB830 and BB830FR are the same sheet in every way that governs quantities and installation: nominally 5 kg/m² at about 3 mm according to the manufacturer’s datasheet, and the only difference between them is the independent fire classification that comes with FR. BB830LF is not the standard sheet in another formulation — it is a different sheet. Per the manufacturer it is nominally 10 kg/m² at about 5 mm: twice the mass and about five-thirds the thickness of the standard grade. That additional mass is what the LF premium buys. All three come as 1 m × 5 m rolls, are bonded with BA990, sealed with BA890 and ordered with the same 20% allowance — but an LF roll weighs about 50 kg against about 25 kg for the other two, so both the lift and the fixing have to be designed for twice the load.

Where LF wins, and where it loses

This is the whole case for paying the LF premium, and the same table is the case against buying it for every job. Figures are material sound reduction from each grade’s own manufacturer datasheet: BB830 from BB830/20/v2, BB830LF from BB830LF/DS/26/v2. Both are manufacturer data rather than independent third-party results, they come from two different documents, and BB830/20/v2 names no test standard — so read this as indicative, not as a controlled side-by-side test.

By situation

Three questions that settle it

1. Does the space carry a fire requirement, or will an inspector ask for evidence on the material? If yes, BB830FR, and the decision is made.
2. Is the complaint bass, machinery or a thump that carries no tune? If yes, BB830LF — and read the music-room page first, because no sheet does that job on its own.
3. If neither, BB830, and put the difference into sealant, the door and the penetrations, where it returns more than a grade change would.

Where the money goes wrong

• Buying LF for a speech problem. At 500 Hz, squarely in the speech range, the manufacturer gives the LF grade 26.5 dB against 34 dB for the standard grade — so the 57% premium buys a sheet that performs worse where the complaint actually is. Spend it on sealing, the door and the penetrations instead.
• Buying FR because it is assumed to be acoustically better. It is acoustically equivalent to the standard grade according to the manufacturer. The premium is for the fire evidence, not for decibels.
• Lining a hotel corridor with the standard grade and being asked for a fire report at inspection. The material then comes out, which costs far more than the 15% premium would have.
• Expecting LF alone to fix a subwoofer through a party wall. Mass is weakest at low frequency whatever the formulation; cavity depth, decoupling and mineral wool do the work and the sheet is one component.
• Mixing grades on one wall to save money. If a wall must be FR, all of it must be FR, because the fire evidence is asked of the whole assembly.

What is the same, and what is not

• Roll size is the same for all three: 1 m × 5 m, 5 m², sold whole.
• Roll weight is not. BB830 and BB830FR are about 25 kg a roll; BB830LF is about 50 kg. Plan an LF roll as a two-person lift and design the fixing for twice the load.
• Order about 20% over the measured area for overlaps and offcuts, rounded up to whole rolls — the same for all three.
• BA990 adhesive at roughly one cartridge per 3 m², BA890 sealant at roughly one per 3 m², BA650 putty pads per socket box. At the LF grade’s mass, do not rely on adhesive alone; add mechanical fixing.
• Heat tolerance 93 °C across all three grades, according to the manufacturer; not for surfaces hotter than that.
• All published figures are laboratory values. Field results are normally 5 to 10 dB lower, and sealing decides more than the grade does.