Almost every home in Central Florida with a lawn has an irrigation system, and almost every irrigation system has at least one head that sprays the driveway. It seems harmless. It is water, and the driveway gets rained on anyway. But rain falls a few times a week and dries. A sprinkler hits the same strip of pavement every morning before sunrise, and the difference shows up within a couple of years.
What constant wetting does
Asphalt is designed to shed water, not to sit in it. A sprinkler that wets the same edge daily keeps that section damp for hours each morning, which does several things at once. It softens the ground beside the pavement so the edge loses its support. It keeps the surface wet long enough for algae and mildew to grow, which then holds more moisture. And it carries fine sand and soil onto the pavement, which abrades the surface and clogs any sealcoat.
The most visible result is edge failure along the sprinkler line: crumbling, ravelling and a soft shoulder where the tire drops off. Our post on crumbling asphalt edges covers the repair. The second result is a dark or green stain in the spray pattern that no amount of sweeping removes.
Reclaimed water and well water
- Many Central Florida communities irrigate with reclaimed water, which carries nutrients that feed algae and biofilm on pavement.
- Well water in parts of Orange, Seminole and Lake counties is high in iron, which leaves rust-coloured staining on any surface it hits repeatedly. That staining is very hard to remove from asphalt and shows through sealcoat.
- Both are more damaging than municipal water for the same spray pattern, and both make adjusting the heads more important.
Rain falls on the whole driveway and dries. A sprinkler hits the same foot of edge every morning of the year.
The fixes are cheap
Most of the damage is prevented by adjusting the heads. Rotor and spray heads along the driveway should be set so their arc stops at the pavement edge, or swapped for heads with a narrower pattern. Where a head sits right at the edge, moving it back a foot or two often solves the problem. A short strip of gravel or a mulched border between the lawn and the pavement also gives the spray somewhere to land other than the asphalt. Running the system less often but longer, which is better for the lawn in any case, reduces the number of daily wettings.
If the edge has already failed, the repair needs the irrigation corrected first. Rebuilding an edge that is still going to be sprayed every morning is a short-term fix.
On commercial property
The same problem occurs at larger scale on commercial lots in Orlando, Lake Mary and Altamonte Springs, where landscaped islands and perimeter beds are irrigated by systems that were set up when the plants were small. Heads that once watered a bed now overshoot onto the drive aisle, and the edge of the asphalt along every island softens and breaks. Walking the lot early in the morning while the system is running shows exactly where it is happening. It is worth adding to any maintenance program, because it is one of the few pavement problems that can be fixed with a screwdriver.
Sealcoating and irrigation
Sealcoat should not go on a surface that is being wetted daily, and it should not be wetted for a period after application while it cures. Turning the irrigation off for the sealcoating window is part of the job. Once cured, sealcoat gives the surface some protection from staining, but it does not stop the edge problem if the ground beside it is kept saturated. Our sealcoating page covers what the process involves.
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Iron Ridge Pavement LLC repairs irrigation-damaged edges and staining on driveways and lots across Orlando, Winter Park, Lake Mary and Central Florida. Request an estimate and we will point out which heads to move.
