Concrete repair · Based in Eau Claire
Concrete Curb and Gutter Replacement for Parking Lots
The curb takes the plow and the gutter takes the salt, so the curb line is where a lot starts failing. Sections come out joint to joint, formed to the radius, doweled into the curb on either side, and the asphalt tied back in.
What Curb and Gutter Is
Curb and gutter is one piece of concrete doing two jobs. The curb is the vertical face that keeps traffic off the island or the landscaping. The gutter is the flat strip at the bottom of it, and it is the channel the lot drains along on its way to a catch basin.
A curb is a drainage structure as much as it is an edge. Water comes off the asphalt, runs to the gutter, and follows the gutter to the grate. When a length of that gutter is broken, tipped, or sitting at the wrong height, water stops going where the lot was built to send it and starts standing somewhere it was not.
The Wisconsin Asphalt Pavement Association's 2018 parking lot design guide puts a number on the fall a curbed lot needs: at least 2.0 percent, with 1.0 percent the minimum, and it says lots with grades flatter than 2 percent are subject to surface ponding and birdbaths. That is the association's guidance rather than a code, and it is a useful thing to hold a lot against when the water is not moving.
The two parts
- The curb face, which keeps traffic off
- The gutter, which carries the water
- The joint at the back, where the asphalt meets it
The gutter carries water to the structure in the lot, and a basin that has sunk will still pond after new curb goes in. See catch basin installation.
What Winter Does to a Curb
Four things, and all four are winter.
The plow blade rides up the gutter and catches the curb face. It takes the nose off in chunks, usually in the same few places year after year, and the broken face is open concrete from then on.
The gutter holds the salt. Everything on the lot drains to it, so the slush that sits in the gutter sits there longest and with the most de-icer in it. The gutter scales before any other concrete on the property.
Meltwater that cannot get to the basin ends up behind the curb instead. It freezes there, frost lifts the back of the section, and the face tips out of plumb.
Once the face has tipped, the joint between the curb and the asphalt is open. Water goes down that joint into the base under the asphalt, and the lot fails in a strip along the curb line while the middle of it still looks fine.
What we look at
- Where the plow has taken the face off
- Whether the gutter is scaled or still tight
- Whether the face is plumb or leaning out
- Whether the joint at the back is open
- Where the gutter is trying to send the water
- What the asphalt along the curb line is doing
A curb that has been hit and a curb that has moved are different jobs. The second one has a base problem behind it, and new concrete on the same ground tips again.
What the Code Says About Curb Work
Two of these are Chippewa Falls' ordinance and the third is an association's design guide. Each is attributed to where it comes from, because they are not the same kind of thing.
| What | The rule | Whose rule it is |
|---|---|---|
| A drive opening cut into existing curb | The entire curb and gutter is removed and reconstructed of concrete to form a standard drive opening | Chippewa Falls 8.04(9)(a) |
| Curb removed for that work | Restored within 30 days of the removal beginning | Chippewa Falls 8.04(9)(d) |
| Grade on curbed pavement | At least 2.0 percent, 1.0 percent minimum; flatter than 2 percent is subject to ponding and birdbaths | Wisconsin Asphalt Pavement Association, 2018 Parking Lot Design Guide |
The first two rows are Chippewa Falls' code and apply to a property in Chippewa Falls. In Eau Claire, work in a street, alley or public place goes through the Engineering department under 13.10.020, and what a curb cut has to become there is on the driveway approach page.
How We Replace a Curb and Gutter Section
Measured joint to joint, cut out, based, formed to the radius, poured and tied back into the asphalt.
Measure the section that comes out
Curb and gutter goes back joint to joint, so what comes out runs past where the nose has broken or the face has tipped, to the joints on either side of the damage.
Saw cut at the joints
Cut at the joint lines, so the new section starts against a straight vertical face rather than against a broken one.
Break out the curb and haul it off
Broken curb and gutter out and hauled away, down to whatever the new pour needs to sit on, including the ground behind the face where frost lifted it.
Prepare and compact the base
Graded and compacted. Concrete poured on soft ground cracks on a schedule set by the ground, not by the concrete, and a curb on soft ground tips before it cracks.
Build the radius forms and set the dowels
Radius forms built to the curve rather than faceted out of straight boards, staked off, with rebar dowels set into the ends of the existing curb so the sections stay in one plane.
Pour and finish the gutter to grade
Placed, screeded and floated, with the gutter finished to the fall it needs so water leaves along it instead of standing in it. Control joints cut where the section is going to crack.
Tie the asphalt back in at the curb line
Asphalt cut tight to the new edge, compacted, joint sealed. An open joint at the back of a curb is a straight path into the base, which is what took the last one out.
What Usually Comes With It
The curb line is where the water runs, so what fails around it is usually connected.
This page is the curb line. For what curb and gutter costs by the linear foot, and for dock aprons, pads, sidewalks and the rest of the flatwork, see concrete.
Questions We Get
The plow took the nose off our curb. Does the whole section have to come out?
Why does the gutter wear out before the rest of the lot?
The curb is leaning out and there is a gap behind it. What causes that?
Our asphalt is failing along the curb before anywhere else. Are the two connected?
What holds a new section to the curb on either side of it?
We are cutting a new drive opening through the curb. What happens to the curb?
Send a Photo of the Curb
One down the curb line from one end, and one straight at the worst section showing the gutter and the asphalt beside it. Whether the face is still plumb is most of the answer.
(715) 450-9897