Waterproofing consumption per m² for a brush-on membrane is a rate for the full cycle of two solid coats: about 3 kg/m² for Aqua Block and 4.3 kg/m² for Water Block. Multiply the area by this rate, add a margin of at least 10 % and divide by the bucket weight; there is no need to multiply by the number of coats. The waterproofing consumption calculator does all of this.
Where the rate comes from
Both membranes go on in two solid coats. The calculator treats them as a layer of given thickness multiplied by the material's density:
- Aqua Block acrylic waterproofing: two coats, 1 mm in total, density 1520 kg/m³, so ≈ 3.04 kg/m²;
- Water Block acrylic waterproofing: two coats, 1.5 mm in total, density 1420 kg/m³, so ≈ 4.3 kg/m².
Formula: waterproofing, kg = area, m² × two-coat consumption, kg/m² × (1 + margin / 100). Packages = result / bucket weight, rounded up.
Using the calculator
In the "Pick a product" tab choose the membrane; the calculator takes its density and package sizes from the manufacturer's data and picks the best-value combination of buckets. In the "Enter manually" tab the field is "Two-coat consumption per m², kg", with defaults of 3 kg/m², a 10 % margin and a 7 kg bucket. You can enter the area directly or by dimensions.
Example 1: a bathroom floor before tiling
A 2 × 1.7 m bathroom, with the waterproofing turned up the walls by 20 cm all round.
- Floor: 2 × 1.7 = 3.4 m².
- Upstand: (2 + 1.7) × 2 × 0.2 = 1.48 m².
- Total 4.88 m² × 3.04 kg/m² = 14.8 kg of Aqua Block, 16.3 kg with a 10 % margin.
- Buy: two 7 kg buckets (6.9 kg net) and one 3 kg, 16.8 kg in total.
Aqua Block's blue colour acts as a check here: every missed spot shows on grey screed, especially in corners.
Example 2: a 3 × 1 m balcony
A balcony above a living room, using elastic Water Block.
- 3 m² × 4.3 kg/m² = 12.9 kg.
- With a 10 % margin: 14.2 kg.
- Buy: a 12 kg and a 3 kg bucket.
Example 3: a foundation
Strip foundation walls in contact with soil: 30 m perimeter, 0.8 m coating height, Aqua Block.
- Area: 30 × 0.8 = 24 m².
- 24 × 3.04 = 73 kg, 80.3 kg with a 10 % margin.
- Buy: twelve 7 kg buckets, or eleven 7 kg plus two 3 kg. The product-page calculator shows the cheaper option.
The membrane protects against moisture pressing on the wall, not against pressurised groundwater. If a basement floods under pressure, a different solution is needed.
POLIFARB waterproofing rates
Membrane | Two coats | Consumption | Packs | Largest bucket covers | Application |
|---|---|---|---|---|---|
Aqua Block | 1 mm | ≈ 3.04 kg/m² | 3 and 7 kg | ≈ 2.3 m² | +5…+35 °C |
Water Block | 1.5 mm | ≈ 4.3 kg/m² | 1.2, 3, 6 and 12 kg | ≈ 2.8 m² | +10…+35 °C |
Aqua Block is blue, UV-resistant and can stay exposed on roofs and foundations. Water Block is white, can be tinted, stretches by 400 % and works as a membrane under electric underfloor heating; its stated service life is 15 years.
What affects consumption
- Substrate. Porous or unprimed screed takes more membrane, so allow at least 10 %. PROFI GRUNT primer evens out absorption and reduces the consumption of materials applied on top.
- Junctions and corners. Wall-to-floor joints and corners are taped, and that strip should be included in the area too.
- Substrate moisture. Acrylic membrane will not bond to damp screed: dry it first, then apply.
Common mistakes
- Multiplying the rate by two coats. It already covers the full cycle.
- Applying the second coat over a wet first one. The second coat goes on after the first has fully dried, at right angles to it.
- Forgetting the wall upstand: in the bathroom example it is a third of the area.
- Using the membrane for drinking-water pools or against pressurised water.
For preparing bathroom walls for paint, see how to paint a bathroom wall, and for why mould appears in wet areas, why mould appears in the home.
What to buy
Under tiles in bathrooms and kitchens, Aqua Block is handy: the blue colour shows gaps and the 3 kg/m² rate makes it more economical. For balconies, terraces and roofs where the substrate keeps moving, Water Block with 400 % elasticity. After tiling, the bath-to-wall joint is closed with sanitary silicone sealant. Check the area and the number of buckets in the waterproofing calculator.
FAQ
How much waterproofing does a 4 m² bathroom need?
At about 3 kg/m² for two coats, 4 m² takes roughly 12 kg plus margin, i.e. two 7 kg buckets.
Do I multiply the consumption by the number of coats?
No. The calculator's rate already covers two solid coats.
When can I tile over the waterproofing?
After the second coat has fully dried. Aqua Block takes 24–72 hours to cure fully, depending on thickness, temperature and humidity. Choose a tile adhesive compatible with acrylic waterproofing.
How does Aqua Block differ from Water Block?
Aqua Block is thinner (1 mm for two coats, ≈ 3 kg/m²), blue and applied from +5 °C. Water Block is thicker (1.5 mm, ≈ 4.3 kg/m²), white, 400 % elastic and applied from +10 °C.
