When you’re comparing timber specifications, not all ‘superficial mass’ values are created equal. What looks like a thick, heavy acoustic barrier may, in fact, be weaker than it appears to be, depending on how that mass has been calculated.
Superficial mass vs. weight and density
The most critical specification for acoustic performance is the superficial mass of the solid, imperforate surface. Weight is only relevant for structural requirements and lifting requirements during installation, not for acoustic performance.
Likewise, you should never confuse weight or average density figures with superficial mass. They are quite simply, not the same thing. It’s absolutely vital that when you’re making a product comparison that you understand how superficial mass has been calculated.
The importance of superficial mass
Superficial mass is the mass per unit area of a panel (kg/m²), based on the solid wood section’s thickness, multiplied by the density of that wood. It reflects both how thick and how dense the material is, offering a way to compare real strength and durability, not just appearance.
Different suppliers may measure superficial mass based on nominal thickness (including air gaps or profiles), so mass looks higher, even if the thickness of solid wood is less. Without knowing both thickness (solid section) and density, you can’t trust a product is equivalent on quality even if its quoted superficial mass appears (superficially) to be similar or better.
Watch out for misleading calculations
Over the years, it’s become apparent that not all suppliers are clear about how they calculate superficial mass. Some quote weight in kg/m² and call it density, which is incorrect. Others use inflated assumptions on timber density to present higher figures than are realistic for softwood. And sometimes the figure may be given with no explanation at all – leaving specifiers at risk of comparing numbers that don’t represent the same thing.
Why it matters
It matters because if you want reliable acoustic performance and compliance with standards, you need to know how the figure was reached. Products with a higher superficial mass (properly calculated) will offer better resistance to weather, wear and sound making them better suited to noise barriers and highways timber.
If two barriers cost a similar amount but one has higher true superficial mass, you get better performance, and of course, better value for money. And importantly, when your project needs to comply with minimum standards, using misleading figures could leave you exposed.
Superficial mass isn’t just a technicality; it’s a key measure of product quality. When you compare the numbers, it’s essential you’re comparing like with like, so you can make a truly informed decision about strength, durability and performance.
Pioneers in acoustic fencing
As one of the pioneers of this environmentally sound solution to noise pollution, Ransfords are one of just a handful of companies who can manufacture factory-built Environmental Noise Barriers compliant with the exacting standards required for ‘highway works’ specified in drawings HCD, H1 to H48 band NC2504.
And that means you can rely on Ransfords to give you honest, accurate data. We calculate superficial mass correctly, using the thinnest solid timber section multiplied by the real density of the stated species – so you get dependable data and panels that deliver the high-quality performance you need, time after time.
If you’d like help making sense of a product specification or want to check whether you’re comparing like with like, give our team a call on 01588 638 331 – we’ll be happy to talk you through it.