CalcCalculatrice d'Isolation
Dernière mise à jour: 2026-05-07
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| Longueur du mur (m) | Largeur du rouleau (cm) | Longueur du rouleau (m) | Hauteur du mur (m) | |
|---|---|---|---|---|
| Small room | 4 m | 30 cm | 10 m | 2.7 m |
| Medium room | 6 m | 30 cm | 10 m | 2.7 m |
| Large room | 8 m | 40 cm | 10 m | 2.7 m |
| Office | 12 m | 55 cm | 10 m | 2.7 m |
| Warehouse | 16 m | 75 cm | 10 m | 2.7 m |
What is the Insulation Batt Calculator?
Proper insulation is one of the highest-ROI home improvements you can make — the right amount can cut heating and cooling bills by 20–30%. But calculating how many insulation rolls or batts you need for walls, floors, or ceilings requires knowing the stud spacing, roll dimensions, and the 10% waste factor that most guides forget to mention. This calculator handles all of it automatically.
You may also find the Drywall Calculator, Wallpaper Calculator, and Roofing Shingle Calculator useful.
Who Uses This Calculator?
This tool is used by homeowners insulating a new build or retrofit, builders specifying insulation for a project, and energy auditors calculating upgrade requirements.
How to Use the Insulation Batt Calculator
- Enter your Wall length.
- Enter your Wall height.
- Enter your Stud spacing.
- Enter your Roll width.
- Enter your Roll length.
- Click Calculate to see your results instantly.
Formula
The calculator uses the following formula:
Wall area = Length × Height; Rolls = ceil(area ÷ (roll_width × roll_length) × 1.1)
Worked Example
A 15 m × 2.4 m wall section with 600 mm stud spacing using rolls that are 600 mm wide × 2.4 m long requires 28 rolls including the 10% waste allowance.
Step-by-Step Calculation
- Wall area: 8 m × 2.7 m = 21.6 m²
- Coverage per roll: 0.38 m × 10 m = 3.8 m²
- Rolls needed: ceil(21.6 ÷ 3.8 × 1.1) = 7 rolls
Common Mistakes to Avoid
- Using stud spacing in metres instead of centimetres
- Forgetting to add 10% extra for cuts around windows and doors
- Not checking if the roll width matches your stud spacing
Frequently Asked Questions
R-value requirements depend on your climate zone and building element. As a guide: walls typically need R2.0–R2.5, ceilings R3.5–R6.0, and underfloor R1.5–R2.5 in temperate climates. Cold climates need higher values.
Batts are pre-cut to standard lengths (usually 1.2 m or 2.4 m) for easy installation between studs. Rolls are continuous and can be cut to length — better for irregular spaces and large open areas like attics.
Insulation must be cut around electrical outlets, pipes, and structural members. Off-cuts from windows and doors also generate waste. 10% is the industry standard; add 15% for complex layouts.
Yes — stacking two layers of R2.0 gives R4.0. In ceilings, you can lay a second layer perpendicular to the first to also eliminate thermal bridging at the joists.
Split the batt behind the box so it fills the wall cavity on both sides. Never compress insulation tightly behind a box — it creates a fire risk. Some codes require specific fire-rated insulation around recessed lights.