Solve backwards
How long a fire-rated wall will my Type X sheets board?
- 20 sheetsThe example worked below
- Multi-Layer Fire-Rated (Type X) Gypsum Sheet CalculatorEvery figure is its own
You have
How much Type X gypsum board?
Worked by the Multi-Layer Fire-Rated (Type X) Gypsum Sheet Calculator at the settings below.
The settings it uses
- Sheet Area
- 32 sq ft
- Layers per Side
- 1
What it will do
320 sq ft of rated wall
29.7 m²
One partition. Enough for a partition 32 ft long and 10 ft high.
Or several. About 1 partition of the size the Multi-Layer Fire-Rated (Type X) Gypsum Sheet Calculator opens on: a partition 22 ft long and 10 ft high.
Check it forwards
- Wall Area (One Side)
- 320 sq ft
- It asks for
- 20 sheets
- You have
- 20 sheets
The Multi-Layer Fire-Rated (Type X) Gypsum Sheet Calculator asks for 20 sheets at that size, and 22 sheets one step larger.
If you had more, or less
Around your amount
Each worked by the Multi-Layer Fire-Rated (Type X) Gypsum Sheet Calculator at the same settings.
Half
10 sheets
160 sq ft
a partition 16 ft long and 10 ft high
Yours
20 sheets
320 sq ft
a partition 32 ft long and 10 ft high
Half as much again
30 sheets
480 sq ft
a partition 48 ft long and 10 ft high
Double
40 sheets
640 sq ft
a partition 64 ft long and 10 ft high
Common amounts
What each amount of Type X gypsum board covers
The sizes it is usually sold in, each worked by the Multi-Layer Fire-Rated (Type X) Gypsum Sheet Calculator at the settings above.
| You have | It covers | As one partition | Average partitions |
|---|---|---|---|
| 10 sheets | 160 sq ft(14.9 m²) | a partition 16 ft long and 10 ft high | under 1 |
| 20 sheets | 320 sq ft(29.7 m²) | a partition 32 ft long and 10 ft high | 1 |
| 40 sheets | 640 sq ft(59.5 m²) | a partition 64 ft long and 10 ft high | 2 |
| 80 sheets | 1,280 sq ft(119 m²) | a partition 128 ft long and 10 ft high | 5 |
Two faces from every stack
The calculator counts one face, rounds up to whole sheets, then multiplies by the layers per side and by two sides. Read backwards, twenty 4 by 8 foot sheets board ten a side: 320 square feet of wall, 32 feet long at 10 feet tall. Twenty 1.2 by 2.4 m sheets board 28.8 m², 9.6 m of wall at 3 m. A second layer each side halves every one of those figures.
Full height, to the structure
Wall area means the full height of the rated wall, up to the underside of the floor or roof above. Measuring to a suspended ceiling is the classic way a rated partition ends up with an unrated gap over the tiles, and it drags the sheet count down with it. The number of layers comes from the tested UL or GA design for the rating you need — never assume one from a rule of thumb.
No waste, and the cheap half
The division carries no waste, which never happens on a rated wall: a multi-layer design offsets the face-layer joints from the base layer, so the face layer starts on a cut sheet in every run and the remainder is usually too narrow to reuse. And the board is the cheap half — stud gauge and spacing, screw type and spacing, joint treatment and the head-of-wall firestop are all set by the design and inspected.
How the answer is worked
Nothing here is a second formula. The Multi-Layer Fire-Rated (Type X) Gypsum Sheet Calculator runs forwards — a size in, a quantity out — and this page grows its own starting partition in proportion until the quantity it asks for is what you have. Where it rounds up to whole containers, the answer is the largest size before the next one would be needed.
Where the calculator adds an allowance for cuts or breakage when you order, the same allowance comes off here, because it is the same calculator: a stack you already own finishes less than its face value. Where it adds none, neither does this page — the settings beside the answer say which.
Multi-Layer Fire-Rated (Type X) Gypsum Sheet Calculator
runs it forwardsCalculate total Type X gypsum board sheets needed for a multi-layer, both-sides fire-rated wall assembly.
Work out what to buy insteadSolve backwards
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Solve backwards
Start from what is already in the yard
Paint, sheets, rolls, bags and pieces, each read the other way by the calculator that orders it.
The calculator's own figures
Nothing is estimated twice: the page runs the same calculator you would order with.
The largest size that fits
Where a calculator rounds up to whole containers, the answer stops before the next one.
Both unit systems
Gallons and litres, square feet and square metres, side by side.
Frequently asked questions
- How much rated wall does 20 sheets of Type X gypsum board cover?
- At the Multi-Layer Fire-Rated (Type X) Gypsum Sheet Calculator's own settings, 320 sq ft (29.7 m²) — a partition 32 ft long and 10 ft high. That is about 1 partition of the size the calculator opens on: a partition 22 ft long and 10 ft high. Every figure follows the settings, which you can change in the calculator.
- How many layers of Type X drywall for a one-hour wall?
- Take it from the tested UL or GA assembly for your construction; the calculator will not assume it. Many one-hour stud partitions use one layer of 5/8 inch (16 mm) Type X on each side and many two-hour designs use two layers a side, but the listed design fixes the layers, screws and joints.
- How many sheets for a 10 by 20 foot fire-rated wall?
- One face is 200 square feet (18.6 m²), 6.25 sheets of 4 by 8 feet, rounded up to 7 a side — 14 sheets for one layer on both faces, 28 for two layers a side. Add an allowance for the offset face-layer joints, which the division leaves out.
- Does fire-rated drywall go to the ceiling or to the deck?
- A rated partition normally runs to the underside of the structure above, not to a suspended ceiling, and its head is detailed with a deflection allowance and a listed firestop. Measure the wall to that full height; a wall measured to the ceiling tiles comes up short in both rating and sheets.