MICORE 300 Mineral Fiber Boards – 48" x 24" x 1/2" (4-Pack)

Premium Fireproof Underlayment for Stoves & Fireplaces

Fire-rated MICORE® 300 boards provide reliable underlayment protection beneath wood stoves, pellet stoves, and fireplaces.

Key Features:

• High thermal resistance for NFPA-compliant hearth pad builds

• Ideal insulating layer beneath hearth pads, tile, and stone

• Sold as a 4-pack (32 sq. ft. total coverage)

• Easy to cut, shape, and install on-site

• Must be layered under cement board before tile or stone

Product Features

UL-Listed Fireproof Insulation Board

MICORE 300 is a non-combustible, UL-listed mineral fiber board designed for use as a fire barrier beneath freestanding stoves and fireplaces. Commonly used to construct code-compliant hearth pads and floor protection systems.

High Thermal Resistance (R-Value)

With an R-value of approx. 1.03 per 1/2" sheet, MICORE 300 helps reduce heat transfer through combustible floors. Meets or exceeds many stove manufacturers’ hearth insulation requirements.

Designed for Hearth Pad Use

Use MICORE 300 as the bottom insulating layer in a hearth pad assembly. Always overlay with a structurally supportive, non-combustible surface such as cement board, followed by tile or stone.

Not a Final Tiling Surface

While its mineral fiber surface bonds well with mortar or thinset, MICORE 300 is not designed to support tile or stone directly. A top layer of cement board is required for structural integrity under flooring or stove load.

Lightweight & Easy to Work With

Each board is lightweight yet rigid enough for simple, precise cutting with standard tools. Perfect for fitting into corners, alcoves, or custom pad designs.

DIY & Pro Friendly

Ideal for contractors or DIYers building custom hearth pads, floor protectors, or heat shields for freestanding appliances.

Product Specifications