What is a mineral-bound nonwoven sheet?

A nonwoven fibre carrier holds a mineral matrix together. The thin sheet forms an additional layer between insulation or an existing roof and new waterproofing. BarrierSheet data sheet AB4478 2026-04 states 2.5 mm and 3.0 kg/m², both ±10%, and a new mechanically fixed membrane. These are manufacturer values for that reference product, not guaranteed properties of a VlamShield sheet. This layer replaces neither the structural deck nor the waterproofing. [2]

Magnesium phosphate: the chemical principle

EP4060105B1 describes, among other options, magnesium compounds combined with acidic phosphates within a nonwoven. For magnesium potassium phosphate cement, an example of struvite-K formation is: MgO + KH₂PO₄ + 5 H₂O → MgKPO₄ · 6 H₂O. The matrix forms through a chemical reaction with water; no ceramic kiln is required. The patent also describes a silica-fume and alkali-silicate alternative. It documents these technologies but does not identify the complete current commercial formulation of BarrierSheet. [1, 6]

Manufacturing: what is published and what is missing?

The patented route applies mineral binder powder during or after nonwoven production; water then activates curing. For the phosphate route, the description gives magnesium-to-phosphate component molar ratios from 1:1 to 6:1 and binder quantities of 1–5 kg/m². These ranges are not a ready-to-use mixing instruction. An exact reproducible commercial recipe would require identified raw-material grades, additives, water dosage, process settings and quality limits. A factory-cured commercial sheet must also not be treated as identical to the water-activated supply form described in the patent. [1]

Where the approach has advantages

Low build-up height and surface mass can help where load reserves are limited. A factory-made layer avoids mixing and curing on site. Beneath a new membrane it is protected from direct rain and UV exposure. The substrate still needs to be flat and fully supporting; joints, fixing and wind uplift remain design tasks. Thin and flexible does not automatically mean the same load distribution as a stiffer cover board. [2]

Containing fire does not mean avoiding all damage

ZAG P448/25-560-1 describes four investigated configurations. In the scenarios considered, fire spread remained largely within the PV array area. The report also documents local thermal damage to PIR and melted EPS; in AS-1 the full 100 mm EPS layer was locally affected. Remaining small flames were extinguished after 30 minutes in that test. This does not prove general product failure, but neither does it guarantee undamaged insulation or remove the need for the fire service. The results apply to the stated test conditions. [3]

Compare the complete tested roof assembly

Efectis report R000982 includes BarrierSheet both above and below 140 mm PIR insulation. Testing was at 15°; the document refers formal classification to a separate assessment. Omitting a layer while assuming the same evidence is therefore unsupported. Section 9.2 of FM PR472014 names RoofNav 568563-0-0 with specific Sarnafil membranes, fixing and PV components. Such a system assessment does not provide blanket approval for every membrane and insulation. [4, 5]

Water, frost and service life

The protected position beneath waterproofing reduces weather exposure but does not eliminate construction moisture, condensation or leaks. In MPC research, water curing impairs strength development in certain formulations; other investigated MKPC mortars show good frost performance within their particular comparison. Neither universal roof unsuitability nor a 30- or 50-year life for a thin commercial sheet follows from this. Ageing and composite-performance data for the specific product version are needed. [2, 6, 7]

What a concrete selection needs

Identify the manufacturer and product version, layer construction, moisture and mechanical data, complete relevant test reports and a traceable supply chain. The EPO register records unitary effect for EP4060105 in Germany and the Netherlands, among other states. A different brand or colour does not establish technical patent clearance. A comparable private-label sheet therefore needs established supply rights or a substantiated product-and-claims review. This article explains a material family and documented reference tests; it does not declare a private-label product patent-free or certified. [1, 8]

A thin mineral layer can limit fire spread. Its exact chemistry, scope of protection and suitability depend on the specific product and the complete roof assembly.