A growing number of newer Dublin driveways are not solid paving with drains around the edge — they are built to let rainwater pass straight through the surface into the ground underneath. That is a different structure, not just a different look, and cleaning it like an ordinary driveway can undo the entire reason it was built that way.
Why permeable paving exists at all
Paving over a garden removes ground that used to soak up rain, and enough of that happening across a city raises the amount of water reaching drains and watercourses all at once, which is a real contributor to localised flooding. Irish planning rules address this by treating hard surfacing over a certain area differently depending on whether it lets water through — permeable surfacing generally avoids triggering requirements that a purely solid equivalent would. The exact area thresholds and how they are applied is a matter for each local authority and changes from time to time, so this guide will not quote a figure that might be wrong for a specific site by the time it is read.
What to check before assuming either way
Not every block-paved driveway that looks ordinary is solid, and not every one built for drainage looks obviously different. Two things to look for: the joints between blocks on permeable paving are usually noticeably wider than standard block paving and filled with a coarse, open-graded stone rather than fine sand — it looks gritty rather than sandy up close. And water genuinely disappearing into the surface within a minute or two of a hose running on it, rather than sheeting off toward a drain, is the clearest practical test.
How the structure differs underneath
Ordinary block paving sits on a compacted base with the joints filled with kiln-dried sand, and the whole point is that water is shed off the top and directed to a drain. Permeable paving sits on a much deeper sub-base of open-graded stone that itself stores and slowly releases water into the ground, and the surface joints are deliberately left open, filled with a coarse aggregate rather than sand, so water can pass straight through rather than run off. The system only works if that open structure — both the joints and the sub-base underneath — stays clear.
What that means for cleaning it
The joint-sand problem covered in power washing driveways and patios is the opposite problem here. On ordinary block paving, pressure washes sand out of the joints and the fix is re-sanding with kiln-dried sand. On permeable paving, kiln-dried sand is exactly the wrong material to reintroduce — it is fine enough to clog the open structure the whole system depends on, which quietly turns a driveway built to drain into one that does not.
- Lower pressure and wider coverage, rather than concentrated passes, reduces how much jointing material gets disturbed in the first place.
- Debris and silt need lifting out, not just rinsing. Fine material washed off the surface and down into the joints is what clogs the sub-base over time, so a proper clean removes it rather than moving it one layer down.
- If jointing needs topping up, it is a specific permeable jointing compound — a coarse, free-draining aggregate designed for the purpose — never standard kiln-dried sand.
- Periodic suction sweeping to lift compacted fines out of the joints is the maintenance permeable paving actually needs and ordinary paving does not, and it is worth asking whether a contractor offers it as its own service rather than assuming a standard driveway clean covers it.
Signs it has stopped draining as designed
Puddling that lingers on the surface after rain has stopped, rather than disappearing within a few minutes, is the main warning sign — it means the joints or the sub-base beneath them have clogged with fine sediment and the system is behaving like ordinary paving with nowhere for the water to go. Moss establishing in the joints is a related signal: it needs the same standing moisture that a clogged permeable surface is now holding.
Where that has already happened, the fix is proper decompaction and clearing of the jointing material rather than a standard driveway wash — a job worth getting quoted specifically as permeable paving rather than as a generic driveway clean, since the two are not the same work.