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Materials & Specificationsaka: fiberglass insulationaka: blanket insulationaka: batt and roll

Batt Insulation

In Plain English

Pre-cut blankets of fluffy insulation material installed between wall studs and ceiling joists.

Definition

Batt insulation consists of flexible blankets or rolls of insulating material, typically fiberglass or mineral wool, sized to fit between standard wall studs and floor joists. It is one of the most common insulation types used in residential and light commercial construction. R-value per inch varies by material, with fiberglass batts typically achieving R-3 to R-4 per inch.

Why It Matters in Bidding

Batt insulation is a square-footage takeoff tied directly to the assemblies and R-values called out in the energy and architectural specs, so reading the wall and ceiling schedules correctly prevents under- or over-pricing the package. The specified material and R-value, fiberglass versus mineral wool and faced versus unfaced, changes both unit cost and labor, and fire-rated or sound assemblies may require mineral wool that a default fiberglass price would miss. Friction-fit batts are labor-light compared with other insulation types, which makes accurate quantity and material matching the main pricing risk.

Example

On a light commercial bid the estimator checks the wall types and sees demising walls require mineral wool batts for fire and acoustic ratings while exterior walls use faced fiberglass, so he prices the two materials separately rather than applying one blended rate.

Related Terms

Rigid InsulationFoam InsulationSheathingDrywall

Frequently Asked Questions

Take off the square footage of each insulated wall, floor, and ceiling assembly, then match material and R-value to the spec for each location. Subtract large openings but add a modest waste factor for trimming around framing and penetrations. Separate any fire- or sound-rated assemblies that require a different material.
Mineral wool is typically specified where fire resistance, acoustic performance, or higher density is required, such as demising walls, rated assemblies, and sound-sensitive rooms. It costs more per square foot than fiberglass. Applying a single fiberglass rate across the whole project understates cost wherever the spec calls out mineral wool.
Yes. Faced batts include an integral vapor retarder and often a flange for fastening, while unfaced batts may require a separate vapor barrier line item in certain assemblies. The spec and climate zone dictate which is required, so confirm before pricing to avoid either over-buying faced product or missing a needed vapor barrier.

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