Slurry Seal

Updated: July 2024

What’s happening now?

SDOT will begin applying a slurry seal treatment to the streets highlighted below in Northeast Seattle. This work will begin, weather permitting, in early August 2024.

Map showing streets that will receive the Slurry Seal treatment. Click this link to download the full map.

Here’s what to know if your streets are being slurried:

  • Everyone who lives on or operates a business on the blocks to be slurry sealed will receive a flyer about three weeks prior to the actual work. The notice will include information on the expected schedule and details about what to expect on the day the slurry seal treatment is applied.
  • A second notice will be delivered three to five days prior to the actual slurry sealing of your street.
  • Up to three days prior to any work, you will see “No Park” signs go up along the impacted street. On-street parking will not be permitted on the selected blocks on the day of the slurry seal treatment. The street will also need to be closed for up to 10 hours after completion to provide the best result. During this time, residents, businesses and workers will need to park vehicles on a nearby street that is not being slurry sealed that day.
  • Pedestrians and pets should keep off the slurry seal material until the street is reopened for traffic because the emulsion that has not cured is difficult to remove from clothing, shoes or paws.
  • If you have any private construction work that will involve utility cuts in the street pavement, please have the pavement cuts completed and restored permanently prior to the slurry seal work.
  • If your street is scheduled to be slurried on your garbage or recycling pick up day you will be notified to make sure your bins are put out the night prior for an early morning pick up before our work begins. Questions about garbage and recycling pick-up, or if your garbage was not picked up and it should have been, can be directed

Questions about the slurry seal process should be directed to or (206) 775-8742.

What We Do

Slurry seal is a protective seal coat which extends the life of pavement. It is a thin, tough layer of asphalt emulsion blended with finely crushed stone for traction.

This is a cost-effective method to renew the road surface and seal minor cracks and other irregularities. This preventive maintenance process protects the pavement from moisture penetration and oxidation.

Similar to painting a house, slurry seal creates a protective layer which preserves the underlying structure and prevents the need for more expensive repairs in the future.


The Slurry Sealing Process

The process of slurry sealing is very similar to microsealing. A mixture of asphalt emulsion and aggregate (crushed stone, gravel and sand) is applied to the road. As shown in this short video, as the slurry seal equipment moves along the street, the mixture is fed into a spreader box. The material is spread across the full width of a traffic lane and then smoothed by a squeegee. The equipment also feathers the edges for a smooth transition. All this happens in one step.

After the seal coat cures (hardens), the street can be reopened and used normally. However, there may be parking restrictions and road closures for the entire day the work is scheduled.


  • Slurry sealing is an efficient surface treatment particularly where traffic volumes are low and the street is not regularly used by heavy trucks or buses.
  • City crews will complete all of the preparatory work for the slurry seal project. A contractor will then come in to complete the actual slurry seal process.

How does SDOT select the streets for treatment?

In the 1950's and 1960's, the City of Seattle annexed several parts of King County. Most of these streets had a dirt or gravel surface. The City paved these streets with a minimal amount of asphalt and began a regular preventive maintenance cycle to keep these streets in serviceable condition. SDOT typically sealed the streets on a 10-year cycle. For many years these streets were sealed using a process called chip seal. In 2013, SDOT tested microsurfacing in place of chip sealing, and then used microsurfacing through 2017. In 2018, SDOT began using slurry seal. Each method has its advantages, but they all seal the surface and extend the life of the pavement.

Because these streets are mostly low volume non-arterial streets and have received preventive maintenance in the past, they continue to be the best candidates to receive preventive maintenance. Such blocks resurfaced in a slurry seal project are selected based on the age of the current pavement and an on-site inspection by SDOT staff.

A second category of streets which the City has identified for preventative maintenance are streets which are part of a neighborhood greenway.

Our street looks fine. Why resurface it?

Flexible pavements (typically asphalt) need periodic resealing to protect them from the deteriorating effects of water (rain) and sun. If left untreated, the surface becomes brittle and may crack and ravel. Periodic resealing prevents more extensive and costly repairs. Regular preventive maintenance is the most cost-effective way to maintain streets.

Preparing the street: fixing potholes, cracks, etc.

It is essential that structural damage is repaired prior to the slurry seal process. SDOT crews will begin to patch deteriorated areas of the selected roads well in advance of the slurry seal operation. In addition, low hanging branches and overgrowth may need to be trimmed to allow for the slurry seal equipment to navigate the roads. On the day of slurry sealing, crews will sweep the street before applying the slurry seal material.

Project Library 


Greg Spotts, Director
Address: 700 5th Ave, Suite 3800, Seattle, WA, 98104
Mailing Address: PO Box 34996, Seattle, WA, 98124-4996
Phone: (206) 684-7623

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The Seattle Department of Transportation (SDOT) is on a mission to deliver a transportation system that provides safe and affordable access to places and opportunities for everyone as we work to achieve our vision of Seattle as a thriving, equitable community powered by dependable transportation.