Field

What is a blanket purchase order in construction?

A blanket purchase order is one PO that covers many deliveries from the same supplier over a period of time, with agreed prices and a not-to-exceed amount, instead of writing a new PO for each order.

Two construction professionals review paper plans beside a tablet at a jobsite workbench.
Plan reviews connect field conditions, drawings, and the next decisions on a job. AI-generated illustration.

A blanket purchase order (blanket PO) is a standing agreement with a supplier to buy recurring items over a set period, up to a maximum dollar amount, at agreed prices. Each time the field needs material, they place a release (sometimes called a call-off) against the blanket instead of starting a new purchase order from scratch.

Contractors use blankets for things they buy over and over: ready-mix, aggregate, fasteners, consumables, rental equipment, fuel, and dumpster service. The federal government uses a similar tool. FAR 13.303-1 describes a blanket purchase agreement as a simplified method of filling anticipated repetitive needs for supplies or services by establishing charge accounts with qualified sources.

How a blanket PO works on a real job

Say a GC is building a 120-unit apartment complex with concrete work spread over seven months. Instead of a new PO for every pour, purchasing issues one blanket PO to the ready-mix supplier:

  • Job and cost code: concrete material.
  • Term: through the end of the concrete scope.
  • Pricing: per cubic yard for each mix design, plus listed extras like hot water, fiber, or short-load fees.
  • Not-to-exceed: the budgeted concrete material amount.
  • Who may place releases: the superintendent and the concrete foreman.

Each pour is a release. The supplier's delivery tickets reference the blanket PO number. The AP clerk matches each invoice to the tickets and the blanket pricing, and the system shows how much of the cap is used.

Example blanket PO tracking
ReleaseDescriptionCubic yardsAmountRemaining on cap
1Footings, 3,000 psi84$13,440$226,560
2Foundation walls, 4,000 psi112$19,040$207,520
3Slab on grade, Bldg A146$24,820$182,700

The example assumes a $240,000 cap and made-up unit prices. The point is that anyone can see the balance on the blanket after every pour.

Why use a blanket purchase order

  • Locks pricing for the period, which helps when material escalation is a risk.
  • Less paperwork for the office and faster ordering for the field.
  • Shows committed cost for the whole scope up front.
  • Gives a clear audit trail when invoices are matched to releases.

Common mistakes

  1. No not-to-exceed amount, so spending runs past budget without anyone noticing.
  2. Letting anyone on site call in releases. Limit it to named people.
  3. Invoices that do not reference the blanket PO, which breaks the match and slows payment.
  4. Forgetting that a blanket does not commit the supplier to stock or the contractor to buy the full amount unless the terms say so.
  5. Leaving blankets open after the scope is done, which invites stray charges.

Related terms

See procurement, supplier, encumbrance, and invoice approval. The guide how to manage construction purchase orders covers PO controls in detail. Smart Business Automator ties purchase orders and supplier invoices to each job and cost code, so blanket balances stay visible in job cost views. See job costing and WIP automation.

Frequently asked questions

What is the difference between a blanket PO and a standard PO?

A standard PO covers one defined purchase. A blanket PO covers repeated purchases from one supplier over a period, up to a cap, with releases placed as needed.

Does a blanket purchase order commit the contractor to buy the full amount?

Not necessarily. It depends on the terms. Many blankets set a maximum, not a minimum, so the contractor pays only for what is released and delivered.

Is a blanket purchase order the same as a blanket purchase agreement?

They work similarly. Blanket purchase agreement is the term used in federal acquisition (FAR 13.303), where it is described as a simplified method for filling anticipated repetitive needs through charge accounts with qualified sources.

What items are good for blanket POs on construction jobs?

Recurring purchases with steady pricing: ready-mix, aggregate, rebar, fasteners, consumables, rentals, fuel, and waste hauling.

Sources

  1. Acquisition.gov: FAR 13.303-1, General (blanket purchase agreements)
Written and edited by

Maurice Francois writes and edits construction operations guides for Smart Business Automator. More from Maurice on the Scaling Legends podcast.

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