Home Renovation Brazil — Cheat Sheet¶

Area to tile (m²) = length (m) × width (m)

Tiles needed = Area ÷ tile area × (1 + waste factor)

Standard waste factor: 10% for simple layouts (0.10)
                       15% for diagonal or complex layouts (0.15)

Example:
  Room: 4.0 m × 3.5 m = 14.0 m²
  Tile: 60×60 cm (0.36 m² per tile)
  Tiles needed = 14.0 ÷ 0.36 × 1.10 = 42.8 → round up to 43 boxes if 1 tile/box
  (Most tiles come in boxes covering 1.5–2.5 m²; divide area by box coverage)

Consumption = tile area (m²) × consumption rate (kg/m²)

Standard consumption rates:
  AC-I (dry areas, smooth substrate): 4–6 kg/m²
  AC-II (wet areas, standard use):    5–7 kg/m²
  AC-III (heavy-duty, large tiles):   6–9 kg/m²

Example:
  14.0 m² floor, using AC-II mortar at 6 kg/m²
  Mortar needed = 14.0 × 6 = 84 kg
  Bags needed = 84 ÷ 20 (standard bag size) = 4.2 → buy 5 bags

Consumption (kg/m²) = (tile width + tile height) × joint width × tile thickness × grout density
                       ───────────────────────────────────────────────────────────────────────
                                    tile width × tile height × 1000

Simplified approximation for standard joints (3 mm):
  30×30 cm tile: ~0.5 kg/m²
  45×45 cm tile: ~0.4 kg/m²
  60×60 cm tile: ~0.3 kg/m²

Example:
  14.0 m² floor, 60×60 cm tiles, 3 mm joints
  Rejunte = 14.0 × 0.3 = 4.2 kg → buy 5 kg bag

Wall/ceiling area (m²) = perimeter × height (for walls)
                        = length × width (for ceiling)
Subtract door area: 2.1 × 0.9 = ~1.9 m² per door
Subtract window area: measured per window

Paint needed (litres) = area ÷ yield per litre × number of coats

Standard yields (manufacturer datasheets vary — always verify):
  PVA primer: 8–10 m²/litre
  PVA latex (interior): 10–12 m²/litre, 2 coats recommended
  Acrylic latex (interior): 10–12 m²/litre, 2 coats
  Acrylic (exterior): 8–10 m²/litre, 2 coats minimum

Example:
  Room: 4.0 × 3.5 m, ceiling height 2.7 m
  Wall area = (2 × 4.0 + 2 × 3.5) × 2.7 = 40.5 m²
  Subtract 1 door (1.9 m²) + 1 window (1.2 m²) = 37.4 m²
  Ceiling area = 14.0 m²
  Total = 51.4 m²
  Primer: 51.4 ÷ 9 = 5.7 L → buy 6 L
  PVA (2 coats): 51.4 ÷ 11 × 2 = 9.3 L → buy 10 L (standard 18 L bucket may be more economical)

Wall area (m²) = length × height (subtract openings)

Mortar consumption for 9 cm ceramic block walls: ~18–22 kg/m² of wall

Blocks needed (9×19×19 cm nominal):
  Blocks per m² ≈ 25 blocks (for 9 cm wall)
  Blocks per m² ≈ 13 blocks (for 14 cm wall)
  Add 5% waste factor

Example:
  5.0 m × 2.7 m wall = 13.5 m², subtract 1 door (1.9 m²) = 11.6 m²
  Blocks (9 cm): 11.6 × 25 × 1.05 = 304 blocks → buy 310 blocks
  Mortar: 11.6 × 20 = 232 kg → ~12 bags of 20 kg pre-mixed argamassa

Chapisco: 4–6 kg/m² (thin coat, rough texture)
Emboço:   25–30 kg/m² for 20 mm thickness
Reboco:   10–15 kg/m² for 8 mm thickness

Cement content in a 1:3 traço emboço (cement:sand):
  1 bag cement (50 kg) + 3 × 50 kg sand = covers ~2.5 m² at 20 mm

Total load (W) = sum of all connected appliance wattages

Minimum circuit current (A) = total load (W) ÷ voltage (V)
  At 127 V: I = W ÷ 127
  At 220 V: I = W ÷ 220

Select breaker at next standard size above calculated minimum:
  Standard breaker sizes in Brazil: 6, 10, 16, 20, 25, 32, 40, 50, 63 A

Example:
  Kitchen circuit at 220 V: refrigerator (150W) + microwave (1200W) + blender (400W)
  Total = 1750 W
  I = 1750 ÷ 220 = 7.95 A → use 16 A breaker, 2.5 mm² conductor

What are you doing?
│
├── Bonding masonry units (blocks, bricks)?
│   └── Use argamassa de assentamento (1:2:8 with lime)
│
├── Applying a wall plaster base coat?
│   └── Use emboço mortar (1:2:9 or industrializado tipo A)
│
├── Applying a finish plaster coat?
│   └── Use reboco mortar (1:2:8 fine sand or gesso)
│
├── Setting floor or wall tiles?
│   ├── Dry area, smooth substrate → AC-I mortar
│   ├── Wet area (bathroom, kitchen) → AC-II mortar
│   └── Large format tiles (>60 cm) or swimming pool → AC-III mortar
│
└── Waterproofing before tiling?
    ├── Bathroom floor/walls → liquid impermeabilizante (2 coats)
    ├── Flat roof (laje) → asphalt sheet membrane or elastomeric coating
    └── Underground/water tank → crystalline or cementitious waterproofing

Interior or exterior?
│
├── Interior — dry areas (living room, bedroom)
│   └── PVA latex (econômico) or acrylic latex (better washability)
│
├── Interior — wet areas (bathroom, kitchen walls)
│   └── Semi-gloss or gloss enamel (esmalte) or acrylic with anti-fungal additive
│
├── Exterior — walls
│   └── Acrylic exterior (tinta acrílica para fachadas) — minimum 2 coats
│   └── Apply elastomeric (borracha acrílica) for crack-prone facades
│
└── Metal surfaces (gates, grilles, gutters)
    └── Metal primer + oil-based enamel (esmalte sintético)