How purchase orders work in construction
A purchase order is a request to buy products or services from a supplier or subcontractor. It states what is being ordered, how much of it, and the agreed price. On most sites it is still sent as an email.
Project costs come from several places: overheads, contracts and material purchases. A large share also comes from one-off purchases that different people on site request from vendors. Each of them is focused on getting the parts in on time, and the project manager has limited sight of what has been committed.
Why one system for every order matters
Sending orders by email is quick, but the orders end up scattered across several inboxes. The project manager cannot see when an order was issued, who issued it or what it will cost until the invoice arrives. At that point it is hard to check whether the company actually bought what it is being asked to pay for.
Issuing the order through purchase order software takes the same effort. You create the order, enter the items and send it to the supplier’s email. The difference is that the order is now visible to the project manager the moment it is sent, with the date, the person who raised it and the expected cost. Payments due in the coming weeks can be predicted from the orders already placed.
Set a threshold for when an order is required
Running every small purchase through a formal process is not worth the effort, because small items barely move the total cost. The usual rule is a value limit: every purchase above a set amount, for example $1,000, must go through a purchase order.
Once the limit is agreed, decide where the orders will live. That can be a shared Excel file or, for easier use, purchase order software. Then introduce the rule to everyone who buys for the project and make clear that it applies to them.
Match invoices to purchase orders
When a supplier’s invoice arrives, it is checked against the order it belongs to. The project manager compares the items and amounts on the invoice with what was ordered. If the invoice asks for more than was agreed, it shows up before the invoice reaches accounting. Nothing has to be typed in again, since the order already holds the planned quantities and prices.