Insulation Batt Calculator

Enter wall/ceiling area — get R-19 fiberglass batt roll count. Reference Korean Energy Code Annex 1 for R-value.

Result

Enter material and area.

What this tool does

The insulation batt calculator gives roll/batt count and total weight from wall or ceiling area plus a waste factor. The reference spec is R-19 fiberglass batt at 600×2400mm (1.44㎡/batt, 5kg/batt), sized for 2×6 stud walls at 600mm spacing. The default 10% waste covers cutting around pipes, wiring, and openings. Mineral wool (rock wool) is dimensionally compatible but heavier — note that this calculator uses fiberglass weight.

Who uses this

R-19 batt count for 2×6 timber-frame exterior walls
Ceiling and attic insulation batt quantity and weight planning
Retrofit insulation replacement quantity for renovation projects
Checking area requirements for Korean Energy Code Annex 1 R-value compliance
Pre-ordering insulation to plan truck delivery by total weight

How to use (3 steps)

1Enter the installation area (m²) — full stud-bay wall area including stud framing is acceptable.
2Set the waste factor (%). The default 10% covers pipe and wire penetrations and openings. Use 15% in conduit-heavy zones.
3Click Calculate to get batt count (rounded up) and total weight with step-by-step workings.

Formula & reference

Batt spec: 600mm × 2400mm = 1.44㎡/batt, R-19, 5 kg/batt (Optimised for 2×6 stud walls at 600mm spacing) Adjusted area = installation area × (1 + waste% / 100) Batt count = ceil(adjusted area ÷ 1.44) Total weight = batt count × 5 kg R-19 thermal performance: RSI ≈ 3.35 m²·K/W (1 R-unit = 0.176 m²·K/W) Check against Korean Energy Code (별표1) for your climate zone Recommended waste: straight walls 10% / high pipe/wire density 15% / irregular shapes 20%

Real examples

Example 1: Single-storey timber house exterior walls (90㎡, 10% waste)

Adjusted area = 90 × 1.10 = 99㎡. Batts = ceil(99 ÷ 1.44) = 69 batts. Weight = 69 × 5 = 345kg. Fits on a small truck.

Example 2: Ceiling with attic (60㎡, 15% waste)

Higher waste for recessed lighting and wiring penetrations. Adjusted area = 69㎡. Batts = ceil(69 ÷ 1.44) = 48 batts. Weight 240kg.

Example 3: Two-storey house all exterior walls (160㎡, 10% waste)

Adjusted area = 176㎡. Batts = ceil(176 ÷ 1.44) = 123 batts. Weight 615kg — single small truck delivery.

Frequently asked questions

What thermal performance does R-19 represent?

R-19 equals approximately RSI 3.35 (m²·K/W). Korea's Energy Code Annex 1 sets wall U-values by climate zone (e.g., 0.210 W/m²K for central zone 2 exterior walls). Whether R-19 batts alone meet the requirement depends on the full wall assembly — confirm with your designer.

Can 600mm-wide batts be used in 400mm stud spacing walls?

R-19 batts at 600mm width are designed for 600mm stud spacing. For 400mm stud bays you need 400mm-wide batts (a separate product). Forcing a 600mm batt into a 400mm bay creates significant cutting waste, so raise the waste factor accordingly.

What is the difference between fiberglass and mineral wool (rock wool)?

Fiberglass (glasswool) is lighter and easier to handle — this is the spec used here. Mineral wool (rock wool) has superior fire resistance and sound absorption but is 1.5-2× heavier. If you switch to mineral wool, the batt count stays the same but the weight figure will understate actual delivery weight.

What does the 10% waste factor cover?

Cutting around pipe and cable penetrations, fitting around window and door openings, imperfect fill at joist ends, and breakage allowance. In zones with dense conduit runs or complex ceiling framing, use 15%.

Is the vapour barrier (vapour retarder) included?

No. Vapour barrier (poly sheet) on the warm side of the insulation is a separate installation step and separate material. This calculator covers batts only. Vapour control is essential for condensation prevention in cold climates.

What is the difference between a batt and a roll?

A batt is a pre-cut panel of fixed width and length — this calculator's reference format (600×2400mm). A roll is continuous insulation wound on a spool, commonly used for horizontal attic coverage. The calculator uses the batt (panel) format.

Cautions

•Based on R-19 600×2400mm fiberglass batt spec. Other R-values or sizes need separate calculations.
•Compliance with Korean Energy Code Annex 1 requires full wall assembly assessment by a qualified designer.
•Always wear safety glasses, dust mask, and gloves when handling fiberglass insulation — fine fibres are irritants.
•Vapour barrier installation is not covered by this calculator and must be planned separately.
•Ensure insulation fills stud bays without gaps to prevent thermal bridging.