What are falls and gradients?
Falls are the intentional slopes built into paved surfaces to direct rainwater away from structures and prevent standing water. Typical ratios range from 1:60 to 1:40 (1 mm drop per 60-40 mm of horizontal distance).
A fall is an intentional slope worked into a paved surface to shed rainwater away from buildings, walls, and other structures. Without adequate fall, water pools on driveways, patios, and paths, which accelerates surface deterioration, encourages algae growth, and risks water ingress into properties.
The gradient of a fall is expressed as a ratio. Standard practice for most domestic paving in Cheltenham involves a minimum fall of 1:60, meaning the surface drops 1 mm vertically for every 60 mm of horizontal distance. On steeper applications such as heavily trafficked areas or surfaces prone to standing water, falls of 1:40 (1 mm per 40 mm) are sometimes specified. These modest slopes remain imperceptible to the naked eye but are sufficient to move water effectively toward drainage points, soakaways, or surface channels.
Falls matter because they are built during installation, not added afterward. A patio or driveway laid flat or with an inadequate slope will shed water poorly from the outset, and correcting the problem later requires significant disruption. Paving contractors calculate and set falls as part of the base preparation and laying process, using screeds and levels to ensure the slope is consistent across the finished surface. The difference between correct fall and poor drainage often becomes apparent within the first heavy rainfall.