Worked decision · Original example reviewed 2026-10-12 · Worksheet checked 2026-10-29
A short second area can use the first area’s offcut
With a 5 in face and zero side gap, two 5×60 in areas need two 60 in pieces. A 10×36 in area needs two 36 in pieces. At zero kerf, two 96 in stock boards each yield 60+36 exactly: 2 new boards, not four. Cutting both areas in a single plan makes the reusable offcuts visible.
The reuse result assumes both 48-inch offcuts are sound and usable; measure their cuttable length and saw kerf before ordering boards.
Load this decision in the calculatorPrimary sources & calculation review
Original example reviewed 2026-10-12 by TwoCut Tools using Codex; worksheet arithmetic checked 2026-10-29. The cited decking instructions provide product context; TwoCut modeled the offcut allocation, without a customer installation or manufacturer endorsement.
- Trex, How to Easily Space Deck Boards
https://www.trex.com/deck-ideas/how-to-space-deck-boards/ - Trex product-specific installation guide directory
https://www.trex.com/customer-support/trex-owners/downloads/
Inputs and alternative plans
One 40-inch-wide by 48-inch-long surface; actual board face 5.5 in, zero side gap, zero kerf; 96-inch stock and two existing 48-inch offcuts.
| Plan | Rows | Existing offcut pieces | New 96-in stock |
|---|---|---|---|
| Without offcuts | ceil(40/5.5) = 8 | 0 | 8 / 2 = 4 boards |
| Reuse two 48-in offcuts | 8 | 2 | 6 / 2 = 3 boards |
What changes the order?
Each 96-inch board provides two 48-inch cuts only when kerf is zero. The final row is 1.5 inches wide because 40−7×5.5=1.5. Offcut reuse changes stock purchasing, not the number of finished rows.
Before using this result
This is a zero-kerf arithmetic comparison, not a saw setup. Enter real kerf before buying; with positive kerf, two 48-inch pieces no longer fit exactly into 96 inches.
Worksheet: account for every reusable length
Set a rectangular surface to 40 inches across the boards and 48 inches along each board. Use a 5.5-inch actual face width, zero side gap for this arithmetic comparison, 96-inch new stock, one board per bundle and two existing full-width offcuts of 48 inches each. Enter the offcuts as two separate lengths, not as one imaginary 96-inch board: each finished row must be continuous in this model.
| Input or calculation | No saved offcuts | Two eligible 48-inch offcuts |
|---|---|---|
| Row count | ceil(40/5.5) = 8 | 8 continuous 48-inch rows |
| Last row width | 40 − 7×5.5 = 1.5 in | 1.5 in; reuse does not change coverage |
| Rows from existing pieces | 0 | 2 |
| Rows requiring purchased stock | 8 | 8 − 2 = 6 |
| Zero-kerf 96-inch stock | 2×48 = 96; 4 boards | 3 boards yield 6 rows |
| Purchase with pack size one | 4 boards | 3 boards, plus 2 existing offcuts |
For the reuse plan, mark existing pieces E1 and E2 as rows one and two. Cut rows three and four from new board N1, five and six from N2, and seven and eight from N3. This is a concrete allocation, not simply an area divided by board area. Check that the two saved pieces really have at least 48 inches of usable length after damage and any end cleanup, match the purchased profile, and retain full face width. A 47.9-inch remnant is not an eligible 48-inch row under the continuous-row rule.
The zero-kerf comparison is a mathematical boundary, not a saw setting. With 0.125-inch kerf and exactly 96-inch stock, the first 48-inch cut leaves 47.875 inches; the second 48-inch row cannot fit. Keeping the two exact-length existing offcuts would then require six new 96-inch boards under this planner. If a supplier offers 97-inch usable stock, two 48-inch cuts plus two charged kerfs consume 96.25 inches, so three such boards can again supply the six new rows. Confirm the actual usable stock length and blade loss before comparing those alternatives.
Side gaps were intentionally zero to expose the cut arithmetic. With a real side gap, row count and the ripped final width can change. Existing pieces also need an appropriate support and fastening arrangement, which length alone cannot validate. See the deck offcut guide for a broader purchase checklist, then enter the current material and cut lengths in the deck planner.