A durable concrete driveway in Portland starts with soft soil dug out, a compacted subgrade and a crushed-rock base that drains, is commonly about four inches thick (more for heavy vehicles), uses an air-entrained mix and has planned control joints. In the City of Portland, installing or changing a driveway always requires a permit, and the contractor should hold an Oregon CCB license.
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A concrete driveway in the Portland area has a quieter enemy than heavy trucks: water. Months of rain soak the soil under the slab, downspouts and runoff wash fines out from the edges, and a slab sitting on soft, wet ground cracks and settles over time. A driveway built on a well-drained, compacted base can last for decades. One poured over mud and topsoil usually tells you within a few winters.
What goes into a durable driveway
- Tear-out and excavation. The old concrete or asphalt is broken out and hauled away, and the soil is dug down to make room for a base.
- Subgrade check. Soft, organic or saturated soil is removed and the subgrade is compacted. Around Portland, digging in the dry season makes this step easier to do well.
- Crushed-rock base. A compacted layer of crushed rock gives the slab even support and lets water move out from under it.
- Forms and slope. The driveway is shaped to shed water away from the garage and house, and toward a place that can take it.
- Reinforcement. Rebar, welded wire or fiber-reinforced mixes help hold cracks tight. They don't stop cracking.
- Placing, finishing and joints. Control joints are tooled or saw-cut at planned spacing so shrinkage cracks form along straight lines.
- Curing. The slab is kept moist or covered with a curing compound in its first days.
Thickness and mix
Residential driveways are commonly poured about four inches thick, with five inches or more often suggested where trucks, trailers or RVs will park. The Portland area gets freezing nights and the occasional ice storm most winters, so many contractors specify air-entrained concrete for exterior flatwork. The Portland Cement Association and the American Concrete Institute both explain how air entrainment helps concrete resist freeze-thaw damage.
Slopes and the West Hills
Steep driveways are common in the West Hills, around Lake Oswego and West Linn, and on the buttes in east Multnomah County. A steep slab needs a deliberate traction finish, careful forming and a plan for the water running down it. On hillside lots, ask whether the driveway work involves cutting into or filling the slope; Oregon's geology agency, DOGAMI, maps landslide-prone areas, and big cuts or fills on steep ground may call for an engineer's input and a city review.
The apron, the curb and the city
In the City of Portland, installing or changing a driveway always requires a permit, according to the Portland Bureau of Transportation (PBOT). The part in the public right-of-way, meaning the apron, curb cut and sidewalk crossing, needs a PBOT permit, and work on private property may need a separate permit from Portland Permitting & Development. PBOT also only authorizes curb cuts that serve legal parking. Suburbs such as Beaverton, Gresham and Hillsboro run their own right-of-way permits through public works or engineering. Ask the contractor who pulls each permit before work starts.
Licensing
Oregon's Construction Contractors Board (CCB) lists concrete among the kinds of work that require a contractor license. Look up any contractor's license on the CCB website before signing, and expect a written contract with the required consumer notices on larger residential jobs.
After the pour
- Stay off the slab on foot until your contractor says it's ready, and keep vehicles off longer, often about a week.
- Skip deicing salts on new concrete, especially in its first winter. Use sand for traction during an ice storm instead.
- Keep downspouts from dumping onto the edges.
- Ask about a penetrating sealer and when to apply it.
Questions to ask
- What's your CCB license number, and can you send a certificate of insurance?
- How thick is the slab, and what base and reinforcement are included?
- Where will water drain, and where will the joints go?
- Who handles the right-of-way permit, tear-out and disposal?
For a look at what moves the price, see our guide to concrete driveway cost in Portland. When you're ready, request a driveway contractor and include photos of the existing driveway.
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Frequently asked questions
Do I need a permit to replace my driveway in Portland?
According to PBOT, installing or changing a driveway in the City of Portland always requires a permit. The apron and curb cut in the right-of-way need a PBOT permit, and private-property work may need a separate permit from Portland Permitting & Development. Suburbs have their own permit offices.
Can a driveway be poured during Portland's rainy season?
It can, but it's harder. Wet ground makes base prep difficult, and rain during finishing damages the surface. Many contractors prefer the drier months and will reschedule around a wet forecast. A short delay is better than a slab poured on mud.
Does a concrete contractor need a license in Oregon?
Yes. Oregon's Construction Contractors Board lists concrete among the types of work that require a contractor license. You can look up a contractor's license, bond and insurance status on the CCB website.
Sources and further reading
- Oregon Construction Contractors Board: license requirements
- Oregon CCB: Guide to home improvement contracts
- Portland Bureau of Transportation: driveways
- Portland Bureau of Transportation: sidewalk repair notices
- Portland Permitting & Development: outside work permits
- Portland Bureau of Environmental Services: Clean River Rewards
- Portland Water Bureau
- City of Gresham Permit Services
- OSU Extension: clay soil challenges for Oregon gardeners
- DOGAMI: landslide hazard and risk study, Multnomah County (IMS-57)
- National Weather Service Portland
- Oregon 811: call before you dig
- American Concrete Institute (ACI)
- Portland Cement Association (PCA)