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The Dac-Hydro Alu system is designed to have 400% elasticity, and be vapour permeable. Reflective aluminium flakes in the coating film prevent warming of the roof covering. Dac-Hydro Alu builds an abrasion resistant, rubber-like coat without joints or seams. It keeps its aluminium finish even in strongly varying atmospheric conditions (UV rays, water, temperature fluctuations). Dac-Hydro Alu can be directly applied on metal roofing (except new galvanized steel), most bituminous products (more than 1 year old) and most waterbased products like Dakfill and Noxyde. It is not for use on Fillcoat or Fillcoat Fibres - in this case apply a primer coat of Dakfill. It cannot be applied on flexible PVC, EPDM, tar, polyisobutylene and smooth bitumen-polymers.


Clean substrate with water under high pressure (200 bars), and dry. Fill all joints with Elastofill, bridging active gaps with Dakfill Bridging Fleece or Overbridging Mesh.

Related literature

The following content references this product:

Standard product features

AFNOR Classification:

Group II, class 7b2.



Density (ASTM D1475, 20°C):

1.03–1.06 g/cm³.

Drying time at 20°C:

  • Dust free: 4 hours.
  • Rain resistant: 6–7 hours.
  • Re-coatable: 24 hours.
  • Full cure: 1 week.

Actual drying times are dependent on relative humidity, temperature and composition of the material.

Flashpoint (DIN 53213):


Solids content (ASTM D1644/a):

In volume 47–49%. In weight 50–52%.



Very porous substrates: Primer 44 diluted with 30% Thinner 22.


Dakfill Fleece (polyester fibres woven in hexagonal meshes) embedded in the first coat of Dakfill New is recommended on roofs with pitches between 1° and 5° or where movement of the substrate is to be expected.

Coating - rate of application:

  • Decorative: 0.3–0.5 litres/m².
  • Waterproofing: 1–1.5 litres/m² depending on type of roof.
  • Where standing stagnating water is possible: 2 litres/m² with Dakfill-mesh reinforcement.

NBS Specification

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This product is associated with the following NBS Create clause:
45-35-50/315 Acrylic based waterproof coatings

NBS Specification

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This product is associated with the following NBS clauses:

Product specification

An important note about specifying



Rust-Oleum UK Ltd


+44 (0)24 7671 7329

Product reference

Dac-Hydro Alu


[Not required]
[Primer No 44 diluted with 30% Thinner No 22]

Coating application

Dac-Hydro-Alu, brush or roller applied

Rate of application

[0.3–0.5 litres/m²]
[1–1.5 litres/m²]
[2 litres/m²]


[Not required]

Minimum dry film thickness

480 micrometres

Manufacturer details

PO Box 261,
Chester Le Street, DH3 9EH
Tel +44 (0)24 7671 7329
Fax +44 (0)24 7671 8930
NBS Plus