Fixed Bid vs Time & Materials for Welding

Choose the contract shape before you argue about operating factor

The Weld Cost Calculator and Cost Estimation Guide tell you what a job should cost. This page decides whether that number becomes a firm fixed price, an open T&M ticket, or a hybrid with a cap. If a fixed bid already lost money, diagnose inputs on Weld Cost Troubleshooting.

Decision Quick Answer

Use a fixed bid when scope, access, and joint details are locked and you can defend OF + deposition with history. Use time & materials when the customer owns the unknowns (discovery repair, undefined fit-up, live plant access). Use a hybrid (T&M with NTE cap, or fixed labor + materials at cost+) when you need a ceiling without eating infinite risk.

Situation	Prefer	Why	Watch-out
Print complete, shop access, repeat joint family	Fixed bid	You can model inches, size, OF	Change orders must be written
Cut out / repair / “see what’s inside”	T&M	Scope expands with every cut	Agree rate card before striking arc
Field access uncertain, customer delays likely	T&M or hybrid NTE	OF collapses on waits you don’t control	Define wait/standby billing
New customer, thin trust, wants a number	Hybrid: estimate + T&M actuals	Gives a planning number without free risk transfer	Put the estimate label in writing
Code / CWI / hold points unknown count	T&M or fixed + inspection allowance	Inspection cycles are not weld inches	Exclude third-party fees or bill through

1. When Fixed Bid Is the Right Tool

Fixed price transfers estimate risk to you. That is fine when you control the variables the calculator models: weld length, size, process, access, and a realistic operating factor. It is the wrong tool when the customer still owns discovery.

Do this before you lock a number: run the cost calculator with conservative OF; cross-check filler with deposition/consumption tools; write inclusions/exclusions (blast, paint, CWI, standby, customer-furnished material delays).

Good fixed-bid signal: You have completed 2+ similar jobs and your actual OF / lbs matched the model within ~15%.

2. When Time & Materials Protects Both Sides

T&M bills clock time + materials (+ agreed markup) as the work reveals itself. It is not “no estimate” — it is “no free transfer of unknown scope.” Customers still deserve a planning range; you still deserve a signed rate card.

Rate card minimums: shop vs field hourly, overtime/weekend, helper rate, standby/wait, mileage or portal-to-portal, consumable markup %, cylinder/gas handling, minimum call-out. Build the hourly from the guide’s true rate math — don’t invent a round number under pressure.

Field example A plant asked for a “quick quote” to repair a cracked base. Fixed bid would have assumed one crack. Opening the joint found three more. T&M with a written NTE kept the relationship; a fixed bid would have forced a fight or a loss.

3. Hybrid Structures That Actually Work

T&M with not-to-exceed (NTE): You stop or renegotiate at the cap. Price the NTE with conservative OF — it is still a risk ceiling.
Fixed labor / materials at cost+: Useful when labor is predictable but alloy filler or rental gear floats.
Phased fixed: Fixed price for known Phase 1; Phase 2 re-bid after teardown. Common on repair and retrofit.

Labor-only vs full-service packaging (who buys wire/gas) is covered in the estimation guide — choose that packaging inside whichever contract shape you pick here.

4. Build the Rate Card Before the Argument

Arguments happen when billing rules are verbal. Print a one-page rate card and attach it to every T&M or hybrid PO. Include how you handle: failed customer fit-up, missing prints, hold for inspection, and “while you’re here” extras.

Field vs shop uplift reasons (travel, staging, power, weather) stay in the guide’s field rates section. This page only decides whether those rates are billed open or wrapped into a fixed number.

5. Change Orders — The Fixed-Bid Survival Skill

Fixed bids die from unsigned scope creep. Any change to joint size, length, process, access, or inspection triggers a written change order with hours + materials from a fresh calculator run — not a handshake “we’ll catch up later.”

Trap: Absorbing small extras “to keep the customer happy” trains them that the fixed price was never fixed. Price the small ones; the large ones get easier.

6. When to Walk Away

Walk when the customer demands a fixed bid on undefined scope, refuses standby language, or wants your fully loaded rate with zero margin “because it’s easy.” A calculator cannot save a bad contract. Prefer T&M or decline.

Chart Skipped

No separate chart page: contract choice is a decision matrix (above), not a numeric lookup table. Cost numbers stay on the calculator; rate building stays on the guide.

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