Deck budget spreadsheet: material upgrades and impact on contingency

In this example one decision moves the numbers: the decking material. The composite upgrade is only Proposed, and the sheet shows the contingency left now and the contingency left if every pending change order were approved.

General information only, not financial, construction or legal advice. Contingency, holdback and payment-split percentages are your own inputs, and payment and deposit rules vary by contract and by state or province; check yours. Names and numbers in the example are invented.

What changes for this kind of project

In this example one company, Northfield Decks, holds three lines: footings and framing, decking and hardware. The railing, stain, trim boards and permit have no contractor, so the Contractors tab lists one company and the other lines sit in its separate row for lines with no contractor, as owner purchases and fees.

The pressure-treated quote is the Committed amount on the decking line. The composite upgrade is a Proposed change order, so it counts as pending exposure only. Approved, it would push that line far enough over its budget that Contingency left if all pending approved drops below zero in this example. The railing posts change is already Approved and has used part of the pool.

A worked example: Deck, 14 x 16 ft

Invented numbers, to show the shape. Settings on Start Here: contingency 12% (an example value you set), total project budget $19,100.

The contingency pool is $2,292 ($19,100 x 12%). That leaves $16,808 to share out as line budgets. The lines below add up to $16,750, so $58 is unallocated.

Change orders on the Change Orders tab. Only Approved rows move into Committed:

What the summary shows

• Committed: $14,990. Paid: $5,010. Unpaid commitment: $9,980.
• Contingency used: $520, what each line's committed total goes above its line budget, added up. Contingency left now: $1,772.
• Pending exposure (Proposed change orders): $3,200. Contingency left if every proposed change order were approved: -$1,228.

Where each piece goes in the workbook

1. Start Here: Type the total project budget, which includes the contingency pool, the contingency percentage and Northfield Decks as the one contractor. The percentage is an example value you overtype, not a recommendation.
2. Budget: Seven rows: footings and framing, decking, railing, stain, hardware, skirt and trim boards, and the permit. The decking row carries the pressure-treated quote. Stain has no accepted quote yet, so it reads Not committed.
3. Change Orders: Enter the composite upgrade against the decking line as the price difference you were quoted, status Proposed. Approved raises Committed on that line; Rejected counts nowhere. The railing posts change is the Approved row.
4. Rooms & Summary: Every line uses the Backyard room, so type it once in the Start Here room list and one room row fills in. In the contingency summary, read Contingency left now, then Contingency left if all pending approved: the second number is the one to check before you say yes to composite.

Two formulas worth a cell of their own

• Committed for one room: =SUMIFS(Budget!$K$6:$K$65,Budget!$B$6:$B$65,"Backyard") returns $14,990 on this example.
• Contingency used, the sum of the Overrun now column: =SUM(Budget!$S$6:$S$65) returns $520.

Four tracking tips

1. Keep the decking line at the pressure-treated quote and enter composite only as a change order. The base quote stays visible, and if you reject the upgrade the line stays exactly as it was.
2. The railing line has no contractor, yet it already carries an Approved change order for the posts. Approved rows raise Committed whether or not a contractor is named, so that line is over its budget and has used part of the pool.
3. Northfield Decks has three lines, so a payment goes on L01, L02 or L05 depending on what it covers. The Contractors tab adds the three together for paid and balance due, while the Budget tab keeps each line's Unpaid commitment.
4. Stain and sealer has no accepted quote, so it reads Not committed and counts as zero in Committed. Its line budget still sits in the Forecast column until you type a quote, so the plan keeps room for it.

Questions

How do I log a footing surprise once the crew starts digging?

Add a change order on the footings and framing line with the extra amount, reason Unforeseen and status Proposed. Proposed is pending exposure only; once you agree, mark it Approved and it raises Committed on that line, and Overrun now once the line passes its budget.

What if I choose composite and the contingency pool is not enough?

Approving it raises Committed on the decking line, so Overrun now rises and Contingency left now can go below zero. Savings on other lines do not refill the pool. Two ways to cover it are a higher total budget on Start Here or keeping the pressure-treated boards.

Related renovation guides

• Renovation change order tracker: a spreadsheet for homeowners
• Renovation contingency tracker: how much contingency is left
• Renovation budget by room spreadsheet: SUMIFS per room, with an overrun flag

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