Sourcing mineral wool and expanded clay

0% duty

Read from the UK Trade Tariff on 26 September 2026, slag wool, rock wool and similar mineral wools, expanded clays, other expanded mineral materials, and mixtures and articles of heat- or sound-insulating mineral materials carried 0% duty on goods from China, with no anti-dumping measure. Glass wool is classified with glass fibres in heading 7019; see the glass fibre and glass wool guide and confirm the commodity code.

Construction product rules and fibre safety

Mineral wool insulation for buildings is covered by the designated standard BS EN 13162 under the retained Construction Products Regulation 305/2011, so the manufacturer declares thermal conductivity, thickness tolerance, reaction to fire classified under BS EN 13501-1 and other characteristics in a declaration of performance, with UKCA or CE marking. Specifiers compare products on the declared thermal conductivity and fire class, so the test reports must match the exact product.

Man-made mineral fibres are exempt from carcinogen classification under GB CLP only when they meet the note Q conditions on bio-solubility, so ask for the evidence, commonly a certification scheme for the fibres, and the safety data sheet. Expanded clay for horticulture is sold on grain size, bulk density and pH. See UK REACH for importers.

Worked duty example

Suppose, purely for illustration, you import a container of rock wool insulation slabs under 6806 10 00 00. At £12,000 free on board and £4,000 to ship and insure, the customs value is £16,000. With 0% duty on mineral wool, the only charge is import VAT: 20% of £16,000, or £3,200. VAT-registered businesses usually recover that in their next return. Insulation is bulky and light, so freight is a quarter of the customs value here. The method is set out in how UK import duty and VAT work.

What goes wrong

Insulation fails on density, performance and the paperwork. Slabs are lighter than the declared density so thermal performance falls short, rolls compressed for shipping do not recover their thickness, and a declared thermal conductivity has no test report for the product supplied. Binder content is uneven so boards crumble or smell, product arrives wet and loses performance, and a fire class is claimed without a classification report.

Measure thickness to BS EN 823 and density to BS EN 1602 on samples from each lot, ask for thermal conductivity tests to BS EN 12667 and the reaction to fire classification report for the exact product, check recovery of compressed rolls after unpacking, check moisture and packaging, and collect the declaration of performance and the fibre bio-solubility evidence before shipment.

Cambridge China Bridge sources rock wool, slag wool and expanded clay for builders' merchants, contractors and horticulture, with density, thermal and fire evidence checked before shipment. See our insulation sourcing service.