{"id":17121,"date":"2023-02-09T23:04:13","date_gmt":"2023-02-10T07:04:13","guid":{"rendered":"https:\/\/essential.construction\/academy\/?post_type=glossary&p=17121"},"modified":"2026-11-03T10:09:33","modified_gmt":"2026-11-03T17:09:33","slug":"critical-path","status":"publish","type":"glossary","link":"https:\/\/essential.construction\/academy\/glossary\/critical-path\/","title":{"rendered":"Critical Path"},"content":{"rendered":"

The critical path<\/strong> in construction is the longest sequence of dependent activities in the project schedule. It sets the shortest possible time to finish the job, and the activities on it have no float, so any delay to a critical activity delays project completion unless the time is recovered elsewhere.<\/p>\n

On a Gantt chart<\/a> the critical path is usually shown as red bars. As work progresses and activities finish early or late, the critical path can move to a different chain of activities, so it needs to be checked at every schedule update.<\/p>\n

How the critical path works<\/h2>\n

Every activity has a duration and logic links to other activities (see schedule relationships<\/a>). Scheduling software runs a forward pass<\/strong> to find each activity’s early start and finish, and a backward pass<\/strong> from the finish date to find its late start and finish. The difference is total float<\/strong>: how long an activity can slip without moving the end date. Activities with zero total float are critical.<\/p>\n

Critical path example<\/h2>\n

A simple slab-on-grade building has these activities:<\/p>\n\n\n\n\n\n\n\n\n\n
Activity<\/th>\nDuration<\/th>\nFollows<\/th>\n<\/tr>\n<\/thead>\n
A. Excavation<\/td>\n5 days<\/td>\nStart<\/td>\n<\/tr>\n
B. Footings and foundation walls<\/td>\n4 days<\/td>\nA<\/td>\n<\/tr>\n
C. Underground plumbing<\/td>\n3 days<\/td>\nA<\/td>\n<\/tr>\n
D. Slab on grade<\/td>\n2 days<\/td>\nB and C<\/td>\n<\/tr>\n
E. Framing<\/td>\n10 days<\/td>\nD<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Path A-B-D-E takes 21 days. Path A-C-D-E takes 20 days. The longest path, A-B-D-E, is the critical path, and the project cannot finish in less than 21 days. Underground plumbing has 1 day of float: it can slip one day without delaying the job (it would then become critical), but a two-day slip would delay completion by a day.<\/p>\n

How to manage the critical path on site<\/h2>\n