← ALL GUIDES

Plywood

What it's for

Counting sheets of sheathing for walls, a roof deck or a subfloor. You list the areas and walk away with a sheet count, a fastener count, ZIP tape and roof clips where they apply, and a layout drawing of the first area with the sheets on it. It is an order quantity, not a code check — the drawing tells you to verify nailing against APA and your code.

Step by step

The example is the screen as it opens: one 12' by 8' wall in 7/16" OSB, 4x8 sheets.

Plywood inputs at their defaults: APPLICATION Wall (Roof and Subfloor beside it), SHEATHING TYPE OSB (Plywood and ZIP System), SHEET SIZE 4x8 (4x10, 4x12), THICKNESS 7/16" (1/2", 5/8", 3/4"), then AREAS with AREA 1 and its trash button, LENGTH 12' 0", WIDTH 8' 0", ADD AREA, OPENING DEDUCTIONS 0 sq ft with a stepper, and WASTE FACTOR 10%. The answer bar under the title reads 4 sheets, with 264 nails under it. There is no JOIST SPACING row: it shows for a subfloor only. 1 2 3 4 6 7 8 9
Steps 1–4 and 6–9: what you are sheathing, what with, then the areas, the openings and the waste. Step 5, JOIST SPACING, is for a subfloor only and is not on this screen.
  1. APPLICATION — Wall, Roof or Subfloor. Leave it at Wall. Roof adds one more input, ROOF PITCH — see below.
  2. SHEATHING TYPE — OSB, Plywood or ZIP System. ZIP System adds seam tape to the results and the material list. Huber makes ZIP System panels 7/16" (4x8, 4x10, 4x12), 1/2" (4x8, 4x10) and 5/8" (4x8) only, for roofs and walls; pick another size or thickness, or a subfloor, and a note under THICKNESS says so. ZIP System is a trademark of Huber Engineered Woods LLC.
  3. SHEET SIZE — 4x8, 4x10 or 4x12. The count is by the area of one sheet.
  4. THICKNESS — 7/16", 1/2", 5/8" or 3/4". This names the panel on the material list. It does not change any quantity. On a subfloor it is also checked against the joists (below).
  5. Subfloor only: JOIST SPACING — 12", 16", 19.2" or 24" o.c., 16" to start — and 3/4 WOOD FLOOR ACROSS JOISTS, on when 3/4" wood finish flooring will be laid at right angles to the joists.
  6. Under AREAS, measure each rectangle: LENGTH (12' 0") and WIDTH (8' 0"). For a wall, that is the wall's length and its height, plate to plate. For a subfloor, the floor's length and width.
  7. Tap Add Area for each further wall, roof plane or floor. The trash can removes one.
  8. OPENING DEDUCTIONS — the total square feet of openings you want taken out, for all areas together. Tap the number to type it, or use − and + to move it 5 sq ft at a time. It opens at 0 sq ft.
  9. WASTE FACTOR — the extra for offcuts, in steps of 5%. It opens at 10%.
  10. Read RESULTS: 4 sheets, 264 nails, 96 sq ft net area.
  11. Check the layout drawing: two full sheets at 4' 0" and a closer at 3' 11-3/4", 12' 0" overall.
  12. Read MATERIALS — OSB 7/16, 4 sheets; Fasteners — 6d common (2" × 0.113") — IRC Table R602.3(1), 264 pcs. BASIS & WHAT WAS ASSUMED states the yields: the pitch factor on roof decking, fasteners per sheet and the nail the code names, ZIP tape per sheet and per roll, and on a roof that H-clips are optional.
  13. Save or share the job with the buttons at the foot of the screen.
Plywood scrolled to the layout. The bottom of the results card shows the BASIS & WHAT WAS ASSUMED row and the link Check before you cut · Measure twice. The WALL SHEATHING LAYOUT shows an 8' 0" by 12' 0" wall with sheets at 4' 0", 4' 0" and 3' 11-3/4", an EDGE NAILING detail headed 7/16" PANEL NAIL AT STUD, and the notes SHEETS VERTICAL — 8' 0" EDGE PLATE TO PLATE; 96 SF · 3 x 1 SHEETS · 1/8" GAP; JOB NET 96 SF · BUY 4 @ 32 SF +10%; and 264 NAILS @ 60/SHEET +10% — VERIFY PER APA/CODE, over the title strip WALL SHEATHING LAYOUT, 4X8 OSB, NOT TO SCALE. MATERIALS lists OSB 7/16, 4 sheets, and Fasteners — 6d common (2" × 0.113") — IRC Table R602.3(1), 264 pcs, above a dimmed SHARE PDF with a list icon at its right end, beside a lit SAVE. 10 11 12 13
The end of RESULTS (only its BASIS row shows here), the sheet layout, the order, and the save and share buttons.

Roof decking

With APPLICATION on Roof, ROOF PITCH appears, in inches of rise per 12. Enter each roof plane by its plan size — the footprint measured level, not up the slope. The calculator uses the pitch to work out the sloped area. The material list adds H-clips for the panel edges, marked optional: every panel offered spans 24" without edge support under IRC Table R503.2.1.1(1). If you use them it counts one per rafter bay along each panel's long edge at 24" on center — 4 on a 4x8, 6 on a 4x12.

A subfloor adds Subfloor adhesive (28-oz), the glue the layout's detail calls for: a 1/4" bead on each joist the sheet crosses and in the tongue-and-groove edge. A 28-oz tube runs about 86' of that bead, so a 4x8 at 16" on center (7 joists × 4' plus the 8' groove, 36') takes a tube for every two sheets and a bit.

Reading the results

The headline is sheets to buy: net area plus waste, divided by the area of one sheet and rounded up. The drawing note shows the sum — JOB NET 96 SF · BUY 4 @ 32 SF +10%. It also shows in a strip under the title whenever the results card is scrolled off screen.

Nails is a fastener allowance per sheet with your waste factor added, and the material row names the nail IRC Table R602.3(1) gives for the panel: 6d common (2" × 0.113") for 7/16" and 1/2" on a wall or subfloor, 8d common (2-1/2" × 0.131") for 5/8" and 3/4", and on a roof 8d common or an RSRS-01 ring-shank nail. The drawing note reads 264 NAILS @ 60/SHEET +10% — VERIFY PER APA/CODE. It is a quantity to buy. It is not a nailing schedule, so take edge and field spacing from your plans or the code.

Net area is your areas added up, sloped for a roof, less OPENING DEDUCTIONS, before waste.

Tape appears only with ZIP System: rolls of seam tape and the lineal feet behind them. The count follows Huber's own figure: one 90' roll tapes about seven 4x8 panels, close to 12' 10" a sheet; a 4x10 or 4x12 takes more in proportion to its edges. Roof Rafter orders ZIP roof sheathing tape the same way.

The subfloor check appears only for a subfloor. It holds the panel to IRC 2021 Table R503.2.1.1(1), which limits a subfloor by its span rating: 7/16" (24/16) and 1/2" (32/16) to 16" o.c., 5/8" (40/20) to 20" and 3/4" (48/24) to 24". Note h of the table lets 1/2" and 5/8" go to 24" when 3/4" wood flooring runs across the joists, which is what the toggle is for; 7/16" gets no such exception. Green reads, for example, 7/16" (24/16) subfloor on joists at 16" o.c.: within 16" o.c. (IRC Table R503.2.1.1(1)). Past the table it turns red — 7/16" (24/16) SUBFLOOR SPANS 16" O.C. MAX — JOISTS AT 24" O.C. FAIL IRC TABLE R503.2.1.1(1) — and the drawing carries the same flag. Pick a thicker panel or close up the joists. Wall and roof sheathing are not checked: there is no pass or fail for them.

The drawing is area 1 with the sheets laid on it, the way the notes describe — for the wall, SHEETS VERTICAL — 8' 0" EDGE PLATE TO PLATE with a 1/8" GAP between panels. A sheet longer than the wall reads VERTICAL · 12' 0" SHEET CUT TO 8' 0" PLATES, and one shorter than the wall reads … SHEET + FILL TO … PLATES. An area under 1' is drawn as a schematic, not dimensioned. That gap is why the last sheet in the example is 3' 11-3/4" and not 4' 0". The shaded sheet is the one you cut. The corner detail shows edge nailing where two panels meet on a stud. Pinch to zoom, or tap the expand button at the top right to open it full screen. See Reading the drawing.

SHARE PDF sends a sheet with the drawing, your inputs and the material list. The list icon at the right end of the same button sends the material list alone. SAVE puts the job in History. SHARE PDF and the list icon in it stay dim until you change at least one input. SAVE stays lit, but while every input is still a default a tap only answers Enter your job's numbers first and saves nothing.

Plywood is a Pro calculator, and sharing a PDF and saving to History are part of Pro too. This help is free. See Free and Pro.

Common mistakes