How to Calculate Facade Area, ETICS Materials and Quantities

How do you calculate facade area? Multiply the house perimeter by the wall height, add the gables (base × height ÷ 2) and subtract windows and doors; then multiply the net area by the consumption of each ETICS layer and round up to whole packs. Here are the steps, a table per m² and a worked example.

Step 1: Calculate the facade area

Area = walls (perimeter × height) + gables (base × height ÷ 2) − windows and doors. Example: a house with a 36 m perimeter and 5.5 m wall height gives 36 × 5.5 = 198 m². Two gables of 8 m × 2.5 m ÷ 2 = 10 m² each add 20 m². Openings of 18 m² are subtracted: 198 + 20 − 18 = 200 m². The facade calculator in detailed mode for these four elevations (two walls 10 × 5.5 m, two 8 m gable walls with a 2.5 m high gable, 6 windows 2 × 1.5 m) gives the same: gross 218 m², openings 18 m², net 200 m².

Step 2: Material consumption per m²

These are the facade calculator's default values for an ETICS system with EPS boards. The calculator adds a 5% reserve to consumption and rounds up to whole packages. Profiles are not calculated per m² but per linear metre of edges: starter profiles along the plinth, corner profiles on external corners, window profiles along finished reveals and drip profiles above windows. The values are indicative, so follow your system manufacturer's data sheets.

Material	Per m²	For 100 m²
EPS adhesive	4.5 kg	450 kg
EPS insulation	1.05 m²	105 m²
Insulation anchors	6 pcs	600 pcs
Reinforcement mesh	1.1 m²	110 m²
Mesh adhesive	4.2 kg	420 kg
Quartz primer	0.25 kg	25 kg
Finish plaster (1.5 mm grain)	2.5 kg	250 kg

Step 3: Worked example for 200 m²

In the quick calculation for 200 m², the calculator gives: EPS boards 210 m² (70 packs of 3 m²). Board adhesive 4.5 × 200 × 1.05 = 945 kg = 38 bags of 25 kg. Anchors 6 × 200 = 1200 pcs = 12 boxes of 100. Mesh 200 × 1.1 × 1.05 = 231 m² = 5 rolls of 50 m². Mesh adhesive 4.2 × 200 × 1.05 = 882 kg = 36 bags. Primer 0.25 × 200 × 1.05 = 52.5 kg = 3 buckets of 25 kg. Finish plaster 2.5 × 200 × 1.05 = 525 kg = 21 buckets of 25 kg.

How many m² does a 25 kg bag of finishing render cover

Short answer: 25 kg of thin-coat finishing (decorative) render covers about 10–12.5 m² with a 1.5 mm grain and about 7.4–8.9 m² with a 2 mm grain. Coverage = 25 kg ÷ consumption (kg/m²); consumption depends mainly on the grain size (the coat is about as thick as the grain) and texture, then on the substrate and application. The table shows typical ranges for acrylic, silicone, silicate and mineral full-grain renders and the facade calculator’s defaults; the figure on the pack of the product you buy applies.

A grooved (ribbed) texture uses slightly less than a full-grain render of the same grain size. A dry mineral render applied on a rough lime-cement base or with a coarse grain (about 4 mm) can use 4–6 kg/m², so a 25 kg bag covers only about 4–6 m². For ordering, multiply the area by the consumption on the pack and add a 5 % reserve.

Grain	Typical kg/m²	25 kg covers	Calculator (kg/m²)	25 kg (calculator)	100 m² + 5 %
1 mm	1.7–2.0	12.5–14.7 m²	1.9	13.2 m²	8 buckets
1.5 mm	2.0–2.5	10–12.5 m²	2.5	10 m²	11 buckets
2 mm	2.8–3.4	7.4–8.9 m²	2.9	8.6 m²	13 buckets
2.5–3 mm	3.5–4.0	6.3–7.1 m²	3.9 (3 mm)	6.4 m²	17 buckets

What the price depends on

Multiply each quantity by your supplier's price, then add scaffolding and labour. The calculator does not estimate a price, because it depends on the product, the region and the workers.

What changes the quantities

Uneven walls need more adhesive and produce more cutting waste.
Many windows, corners and edges need more profiles and anchors.
Wind load and building height can require more anchors.
The manufacturer's system sets the exact consumption and build-up.

Common mistakes

Forgetting the gables when measuring the area.
Subtracting the openings but forgetting the profiles around them.
Skipping profiles at corners, windows and the base.
Applying the finish plaster without primer on the base coat.
Buying exactly the calculated quantity with no reserve for cutting.

Frequently asked questions

How do you calculate facade area?

Multiply the length of each wall by its height, add the gables (base × height ÷ 2) and subtract windows and doors.

How much adhesive for 100 m² of EPS boards?

About 450 kg (4.5 kg/m²), and with a 5% reserve 472.5 kg, which is 19 bags of 25 kg. The reinforced layer with mesh needs about another 441 kg (18 bags).

How much does a facade cost?

Multiply the calculated quantities by your supplier's prices and add scaffolding and labour. The calculator only calculates quantities.

How many m² does 25 kg of finishing render cover?

With a 1.5 mm grain about 10–12.5 m², with 2 mm about 7.4–8.9 m², with 3 mm about 6.3–7.1 m². These are typical values; the consumption on the pack is what counts.

Open the calculator: Facade (ETICS)