What actually helps, at each risk band

Start with your risk band, not a generic checklist

AcoustaPLOT scores every property against the same seven-band risk scale used throughout this site (see the methodology page for the full definitions). What's actually worth doing about the result is different at each band — there's no single "best" fix that applies everywhere, and jumping straight to the most expensive option is often unnecessary.

That matters because most generic noise-mitigation advice online is written as a single checklist — secondary glazing, acoustic fencing, maybe a hedge — presented as though every noisy property needs the same response in the same order. In practice, the right response depends almost entirely on where a property actually sits on the risk scale, and treating a LOW-band garden the same way as a SEVERE-band one wastes money in one direction and leaves a real problem unaddressed in the other.

The band-by-band approach below reflects how AcoustaPLOT's own reports are structured: every paid report includes a mitigation section that is scaled to the property's actual result, not a fixed menu offered to everyone regardless of their score.

LOW / LOW-MODERATE: no mitigation needed

These bands sit at or near typical background noise levels, per AcoustaPLOT's own risk-band definitions. There's genuinely nothing to fix here — spending money on glazing or fencing at this level wouldn't produce a noticeable benefit, because the noise reaching the property is already close to what you'd experience in most residential settings away from a major road or railway.

This is worth saying plainly because it's easy to assume any traffic noise at all means something should be done about it. It shouldn't. A result in this band is the baseline the other bands are measured against, not a borderline case that's one bad day away from becoming a problem. If a report comes back LOW or LOW-MODERATE, the honest, useful advice is to spend nothing and move on with the rest of the purchase or tenancy decision.

MODERATE: check your existing windows first

Standard double glazing — already fitted on most modern homes — is usually sufficient at this level. Before considering any acoustic upgrade, it's worth checking window condition and seals; a draughty or poorly-sealed frame lets in far more noise than the glazing itself is responsible for.

In practice this means physically checking a few things that cost nothing to inspect: whether the rubber or brush seals around each opening sash have perished or compressed flat, whether trickle vents (the small slotted vents built into many UK window frames for background ventilation) are left permanently open and acting as a direct noise path, and whether the frame itself has gaps where it meets the wall. Any of these can undo a meaningful share of what the glazing unit is otherwise capable of, for the price of a tube of sealant or a replacement seal strip rather than a full glazing upgrade.

Only once those basics are confirmed sound is it worth asking whether the glazing itself needs upgrading at MODERATE — and for most properties in this band, after that check, the answer is no.

MODERATE-HIGH / HIGH: this is where secondary glazing starts to matter

Camden Council's own technical guidance states that secondary glazing with a 150mm cavity can reduce traffic noise from around 80dBA down to roughly 30–35dBA at the facade — a documented 30–50dB reduction range for typical busy-road noise levels of 70–80dBA.

That's a real, sourced figure, not a marketing estimate — worth knowing before you assume a full acoustic upgrade is needed, and worth using as a concrete benchmark when you do. The detail that drives this performance is the cavity, not the glass alone: a secondary pane sits well clear of the existing window, typically 100–200mm back from it, creating an air gap that decouples the two panes acoustically. A narrow gap under about 40–45mm gives up most of the benefit, which is why a cheap, close-fitted secondary panel can underperform badly compared to a properly specified one.

Glass specification adds a further, smaller improvement on top of the cavity effect: acoustic laminated glass, which sandwiches a soft interlayer between two panes specifically to damp vibration, outperforms plain float glass of the same thickness, particularly at the low-frequency end of the spectrum where road rumble and heavy vehicles concentrate most of their energy. For a MODERATE-HIGH or HIGH result, a secondary glazing system specified with both a generous cavity and an appropriate glass type is usually the single most cost-effective step available.

HIGH-SEVERE / SEVERE: glazing plus a barrier, where the boundary allows

At these levels, secondary glazing alone is unlikely to be enough on its own. Combining it with an acoustic barrier or fence — where the property boundary allows one — is the more realistic approach. This is exactly the scenario AcoustaPLOT's Acoustic Barrier Design report exists for: a full ISO 9613-2 barrier design with modelled height, length and position for your specific property.

ISO 9613-2 is the international standard for predicting how sound attenuates outdoors, including the effect of a solid barrier placed between a noise source and a receiver. A barrier works by diffraction — it doesn't block sound so much as force it to bend over the top edge, losing energy in the process, which is why height, length (how far the barrier extends past the direct line between source and garden), and exact siting all matter far more than material choice. A tall, badly positioned fence can underperform a shorter, correctly placed one by a wide margin, which is the whole reason a modelled design is worth having rather than guessing at a height from a DIY guide.

Not sure which AcoustaPLOT report matches your result? Use the two-question picker on the pricing page, or see the sample report walkthrough to understand what a report actually contains.

What doesn't help as much as people think

A few mitigation ideas come up constantly and deserve a direct, honest answer rather than being left unaddressed. A standard timber garden fence — the kind most gardens already have — does very little acoustically regardless of how tall it's built, because it's rarely solid, heavy, or continuous enough to meaningfully diffract sound; gaps at the base, between boards, and at gate openings leak far more noise through than the panel itself blocks over the top.

Dense planting and hedging are often sold as a "natural" noise solution, and they do help a little with the subjective sense of enclosure and privacy, but the measured acoustic benefit of a hedge is small — typically a decibel or two at most, even for a thick, mature evergreen screen — nowhere near enough to shift a property between risk bands on its own. It's a pleasant addition alongside a real fix, not a substitute for one.

Indoor white-noise machines and similar masking devices change how intrusive a noise feels without changing how much sound actually reaches the room — they work by adding a more constant, less jarring sound to cover an irregular one, which can genuinely help with sleep for some people, but it's a coping strategy, not mitigation in the sense this page means it, and it does nothing for time spent in the garden.

Getting the order of spend right

When more than one mitigation option is on the table, the sensible approach is to rank them by the value they actually deliver for the money, not simply by how many decibels each one is claimed to remove on a spec sheet. A window-seal fix that costs under £50 and recovers several decibels of otherwise-wasted glazing performance is worth doing before a £3,000 secondary glazing installation, every time — not instead of it, but before it, so the bigger spend isn't quietly undermined by a gap that was never fixed.

The same logic applies moving from glazing to an external barrier: glazing protects indoor noise exposure, which is where WHO's sleep-disturbance evidence concentrates, while a barrier protects the garden and other outdoor amenity space. If indoor exposure at night is the main concern, glazing is the higher-value spend even at a HIGH or SEVERE result; if the garden is unusable because of noise and indoor exposure is already reasonably controlled, a barrier becomes the priority instead. A report that's specific to the property — rather than a generic list — is what lets that ordering be based on the property's actual numbers rather than a guess.

One important caveat about the 30–50dB figure

Camden's figure is a documented range for typical secondary-glazing installations in general — it is not a guarantee for any specific property, and it isn't a modelled prediction the way an AcoustaPLOT report's own results are. Treat it as a real, useful benchmark for what's achievable, not as a number this site is claiming for your address specifically.

Real-world, whole-window performance is also usually lower than a glazing product's own lab-tested figure, for a straightforward reason: a lab test measures the glass and frame alone, under controlled conditions, while a real installation also has to deal with trickle vents left open for ventilation, gaps around the surrounding wall, and whatever the existing primary window was already letting through before the secondary pane went in. None of that makes secondary glazing a bad investment at HIGH or SEVERE bands — it remains the most effective widely available domestic option — but it's worth going in with a realistic expectation rather than assuming the top of a quoted range applies automatically to every room in every house.