Most concrete that fails early in this county fails from below. Water and soil do the damage, and the slab only shows it.
Do I need to worry about drainage?
Yes. Drainage is the first thing to plan here. Every outdoor slab needs a slope that moves water off it and a place for that water to go. The City of Vancouver requires driveway drainage to stay on site, so it cannot simply be sent to the neighbor or the street. Downspouts should be piped past the slab, not left to empty beside it.
My patio or driveway slopes toward the house. What can be done?
A slab that slopes toward the house has to be corrected, because it feeds water to the foundation or the crawl space all winter. If the slab is sound, it can sometimes be lifted on the house side. A channel drain cut in along the wall and piped away is another option. If neither works, the slab is replaced with the right fall. Clark County's building guidance calls for the ground to drop 6 inches in the first 10 feet away from a building.
Can tree roots crack or lift concrete?
Yes. Tree roots lift and crack walks and driveways all over the older parts of Vancouver, where big maples and firs stand close to the pavement. Roots grow under a slab because the soil there is moist, then thicken and push it up.
Can I fix the concrete and keep the tree?
Often you can keep the tree. Options are to curve the new walk away from the trunk, raise the slab over the roots on a rock bed, or use shorter panels that can be reset. Cutting big roots can kill a tree or make it unstable, so get an arborist's view first. A tree in the planting strip by the street may be regulated by the city, so ask before cutting.
My neighbor's new concrete sends runoff onto my property. What can I do?
Start by showing the neighbor during a rain. Most runoff problems come from a slab graded without thought, and a small drain or curb fixes them. If that fails, contact the city or county, since the City of Vancouver requires drainage from a driveway to remain on site. Water disputes between neighbors can also be a civil matter, so see a lawyer if the damage is serious. This is general information, not legal advice.
Does clay or soft soil change the job?
Yes. Much of the west and north of the county has silty and clay soils that hold water and go soft in winter. On that ground we dig out the soft layer and build up a thicker base of compacted crushed rock. The flat land around Orchards is gravelly and drains much better. The local building criteria assume a modest soil bearing value unless a soils report says otherwise, which tells you the ground here is not treated as strong.
My gravel driveway turns to mud every winter. Should I pave it?
Paving fixes a muddy gravel driveway for good, provided the water is dealt with too. Mud means water is sitting in the driveway, so the new slab needs a rock base and a ditch, drain or slope to move the water. Inside the City of Vancouver, gravel is not a permitted driveway surface for new or modified driveways. On rural lots, many owners pave only the slope and the parking area.
My patio was poured over an old trench and that strip settled. Why?
A trench settles because the soil put back into it was not compacted. Utility, drain and sewer trenches keep sinking for years, faster when rain runs into them. The patio above cracks along both sides of the trench and dips between. The repair is to cut out that strip, compact the fill in layers or replace it with rock, and pour it back with joints at the cut lines.
Can I build a raised patio or slab on a lot that can flood?
Possibly, but check the flood map first. Land along the Columbia River, Burnt Bridge Creek, Salmon Creek and the East Fork Lewis River includes mapped flood areas. Adding fill or a raised slab in a mapped floodplain is regulated and can need a permit. Ask the city or county floodplain staff before you plan it. Outside mapped areas, a raised patio still needs compacted fill and a retained edge.
Why does moss grow on my concrete, and does it hurt it?
Moss grows because the surface stays damp and shaded. It does not eat concrete, but it holds water against the surface and makes it very slippery. Brush or wash it off before winter, improve the sun and airflow where you can, and consider a penetrating sealer.
Text a photo of the problem area to (360) 995-1179 and we will tell you what we think is going on.