Why it is there
A number you cannot trace is a number you cannot defend. The Source tab is the trail from the takeoff back to the documents.
What it shows
- Spec items. Each requirement it found in your section.
- Sheet references. The sheets it used for the count.
- Cover notes. The facts it read from the front of the packet.
- Scope. What it took your scope of work to be.
When to open it
Open it when a line surprises you. Check what the spec said and which sheet the count came from.
Reading your takeoff · Updated 11 Nov 2026