How Much Plywood for an 8x10 Shed Floor?
Sheets to buy
3 sheets
An 8 by 10 ft floor, 80 square feet, joists 16 in on center, ten percent waste.
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How that number is worked out
These are the figures this page was built with and every line the calculator produces from them. Change anything above and all of it moves.
- Length of the area10 ft
- Width or height8 ft
- What it is forSubfloor
- Framing spacing16 in on center
- Openings to deduct0 sq ft
- Waste allowance10 %
Sheets to buy3 sheets
| Gross area | 80 sq ft |
|---|---|
| Openings deducted | 0 sq ft |
| Net area | 80 sq ft |
| One sheet covers | 32 sq ft4 by 8 |
| Sheets before waste | 2.5 |
| Squares | 0.83.125 sheets per square |
| Nails per sheet | 646 in edges, 12 in field at 16 in spacing |
| Nails in total | 1921.9 lb of 8d common |
| Joist under the sheets | 60 ft |
| Subfloor adhesive | 1 tubes28 oz, about 84 ft of quarter inch bead each |
| Screws instead of nails | 3 lbsame count, number eight at about 95 to the pound |
The material list this produces
| Sheathing, 4x8 sheets | 3 |
|---|---|
| Subfloor screws, lb | 3 |
| Or 8d ring shank nails, lb | 2 |
| Subfloor adhesive, 28 oz tubes | 1 |
Floor size compared
The common eight foot wide shed floors. The middle column is what the area divides into before the waste allowance, and the gap between it and the sheet count is what you pay for and cut off.
| Floor size | Sheets to buy | Sheets before waste | Joist under the sheets |
|---|---|---|---|
| 8 by 8 ft | 3 sheets | 2 | 48 ft |
| 8 by 10 ft | 3 sheets | 2.5 | 60 ft |
| 8 by 12 ft | 4 sheets | 3 | 72 ft |
| 8 by 16 ft | 5 sheets | 4 | 96 ft |
What else matters here
Three sheets, and the interesting part is that the area divides into 2.5 of them. You cannot buy half a sheet, so the third is bought whole and most of it gets cut off.
It is worth thinking about the layout rather than the area, because at this size the two are not the same question. A 4x8 sheet is four feet one way and eight the other. Laid with the eight foot length running down the ten foot side, two sheets cover 8 ft of the 10 and leave a 2 ft strip across the whole width. That strip is cut from the third sheet, and what is left of the third sheet is 6 ft of it.
Turn the sheets the other way and the same thing happens in a different place. There is no orientation that avoids the offcut, because neither 8 nor 10 is divisible by 4 and 8 together without a remainder. What the orientation does decide is where the joints land, and they should land on a joist, which is the constraint that usually settles it.
What this calculator assumes
- A sheet is 4 by 8, which is 32 square feet, so three and an eighth sheets cover a square.
- Openings come off in full here, not at half. A window hole in a sheathed wall is a real hole and the offcut around it is what the waste line is for.
- The nail count is the fastener schedule rather than a rule of thumb: six inches around every edge and twelve inches into the framing in the field, so a sheet at 16 inch spacing takes 64 nails and one at 24 inch spacing takes 56. Eight penny common runs about 100 nails to the pound.
- Subfloor adhesive is figured on the linear feet of joist under the sheets, at about 84 feet of quarter inch bead from a 28 ounce tube, which is the size subfloor adhesive actually comes in.
- Roof sheathing wants H clips in each bay along the unsupported joint between rafters, which is four per sheet at 24 inches on center. At 16 inches most panel thicknesses do not need them, so the list leaves them off below 19.2 inch spacing.
- A subfloor gets screwed rather than nailed on most jobs, so the list carries the same fastener count in number eight screws at about ninety five to the pound and leaves the nail line under it as the alternative. Only one of those two lines gets bought.
- Thickness does not change the count, only the price and the span rating. Check the panel span rating against your framing spacing before you buy the thin one.
Questions people ask
How many sheets of plywood for an 8x10 shed floor?
3 sheets of 4x8 plywood. The 80 square feet divides into 2.5 sheets, and you cannot buy half a sheet.
How much joist is under an 8x10 floor?
About 60 ft at 16 in on center, which is what the calculator returns. That is the running length of joist, not the number of pieces.
Which way should plywood run on a shed floor?
Whichever way puts the end joints on a joist. Neither 8 nor 10 divides cleanly by a 4 by 8 sheet, so there is an offcut either way, and the joint position is the thing worth choosing.
The plywood calculator takes any dimensions you like and hands back the same list.