There's a persistent belief that weeds push up through the membrane from the soil below. On a properly built drive that's rare. What actually happens is that airborne seed lands in a joint that's holding organic debris, and germinates in it.
Once you accept that, the solution becomes obvious: deal with the joint.
Why the usual approach fails
Spraying kills the visible plant and leaves the seed bed intact. The joint still contains the fine organic material that made it a viable place to grow, so a new seed germinates within weeks and you're back on the same treadmill.
What actually solves it
- Extract the old, contaminated joint material rather than just killing what's on top.
- Treat the surface and joints with a biocide to clear the biological layer.
- Refill joints fully with clean kiln-dried sand, settled and topped up until level.
- Consider polymeric sand where joints repeatedly wash out or weeds are relentless.
- Sweep the drive periodically so debris doesn't rebuild the growing medium.
Edges and gullies
Weeds almost always start at edges, along kerb lines and around gullies, because that's where debris collects and where water lingers. If your drive is otherwise fine but the edges are green, that's a maintenance clean rather than a full restoration.