Dac-Hydro Alu

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.

General information

Uniclass 2015

Pr_35_31_68_01 Acrylic-based waterproof coatingsPrimary


J31/5 Cold deck roof coating

M60/195 Special coating

M60/18 Special coating

J31/110 Cold deck roof coating

Specification data - Acrylic-based waterproof coatings

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

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%.

Product Options


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.

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