What is Overbanding?

Overbanding is a band of hot applied bituminous material laid over a crack or joint after it has been treated, wider than the crack itself, bonded to the surface either side. It does two jobs: it keeps water out of the crack, and it takes the traffic wear that would otherwise fall on the sealant underneath.

Overbanding is the closing operation, not the repair. The crack is chased to a clean reservoir, cleaned, dried and sealed, and the overband goes over the top. Laid straight onto an unprepared crack it is cosmetic: it will bridge the gap for a while, then debond and peel, and the crack underneath will be exactly as it was.

Overbanding compounds are supplied in blocks and melted in a boiler to application temperature, then applied hot and squeegeed or shoed to width and thickness. OBS 45 is the industry standard general purpose material. OBS 60 and Ultra-Band are in the same family with different performance characteristics. Where heat is not permitted, cold applied overbanding does the same job chemically.

This is where overbanding gets a bad reputation, and it is worth understanding before specifying it. A band laid too thick becomes a raised strip, and a raised strip of bitumen is slippery when wet and can be a hazard to motorcyclists in particular. Highway specifications limit overband thickness and width for exactly that reason, and good practice is to dress the surface with grit or use a material with an aggregate content to restore skid resistance.

An overband applied to specification is a legitimate, long-lived treatment. An overband applied thick and wide because it was quicker is a liability. The difference is entirely in the workmanship.

Overbanding treats a crack. It does not treat a failing slab. Where a bay has broken up, lost support or become an isolation point that could lift under load, no amount of surface sealing will hold it, and the work is structural surface repair instead. A contractor who overbands a slab that needs replacing has sold you a delay, not a repair.

We are based at Little Westerhill Farm near Maidstone in Kent. Kent, London, Sussex, Essex and the wider South East are covered from our own yard, and longer programmes are mobilised UK wide. For the service itself see overbanding.