Fire-Rated Drywall Layer Calculator

Estimate how many layers and sheets of Type X drywall a fire-rated wall assembly needs.

Wall Area (sq ft)

Total wall area to be covered, one face.

Fire Rating (hours)

Required fire-resistance rating for the assembly — 1 or 2 hours are the common residential/commercial targets.

Sheet Size (sq ft)

Standard 4x8 sheet = 32 sq ft.

Sides to Cover (sides)

Use 2 for a wall covered on both faces, 1 for a single-face assembly.

Fire-rated assemblies are built around layers of 5/8" Type X gypsum board rather than the framing itself — a typical 1-hour rated wall uses a single layer of Type X per side, while a 2-hour rating generally requires two layers of Type X per side. This calculator estimates sheet counts from that rule of thumb, but the exact layer count, screw pattern, and joint treatment for a given assembly must always be verified against the specific UL or GA fire-rated assembly listing your local code official requires — this tool is for material estimating, not code compliance sign-off.

Frequently Asked Questions

How many layers of drywall does a 1-hour fire rating need?

Most 1-hour fire-rated wall assemblies use a single layer of 5/8" Type X gypsum board on each side of the framing, though the exact assembly must match a tested UL or GA design listing.

Does a 2-hour fire rating just mean double the drywall?

Generally yes — a common way to achieve a 2-hour rating is two layers of 5/8" Type X per side instead of one, though staggered joints and specific fastening patterns from a tested assembly are also required, not just the extra layer alone.