Longview slabs and the Kelso-Longview weather record
Before a crew sets a single form board in Longview, it helps to know what the published weather record says. NOAA keeps engineering weather data for Kelso-Longview, a station at an elevation of 16 feet. For that station it lists:
- a 50-year basic wind speed of 85 mph, measured as a 3-second gust at 33 feet;
- a 100-year rainfall rate of 1.0 inches per hour;
- about 27 freeze-thaw cycles in an average year;
- a 99% winter design temperature of 26°F;
- a 1% summer design temperature of 82°F, with a mean coincident wet-bulb temperature of 65°F;
- about 1 hour a year with the wet-bulb temperature above 73°F, and about 72 hours above 67°F.
Those are the station's numbers. Your driveway, patio or walk sits on its own patch of ground, with its own shade, slope and soil, so treat the list as background and let the contractor who walks your lot tell you how they plan for it.
Deciding what you are asking for
A clear request gets clear answers. Before calling anyone, write down:
- each surface you want poured or replaced, with rough measurements;
- what it will carry: foot traffic, a car, a pickup with a trailer, a hot tub;
- the finish you have in mind, from plain broom texture to stamped or exposed aggregate;
- whether old concrete, asphalt or pavers have to come out first;
- any spot where water already puddles or runs toward the house.
Give that same page to every company. Bids written against one scope are far easier to compare than bids written against three different guesses.
Soil, base and the first day on site
Concrete is only as steady as what lies under it. Topsoil, roots and loose fill settle over the years, and a slab resting on them settles too. Questions for each bidder:
- How deep will you dig, and what happens if the crew finds soft, wet or organic soil?
- What base material goes in, how thick, and is it compacted in lifts?
- Who arranges the utility locate, and how long do you wait for the marks?
- Where does the truck park, and will a pump or chute cross a neighbor's yard or the sidewalk?
- Where does the broken-out material go, and is haul-off in the price?
What goes into the truck
Ask what compressive strength the mix is designed for and whether exterior concrete will be air-entrained. Tiny entrained air bubbles give freezing water room to expand inside the paste, which is why outdoor flatwork in places with freezing winters commonly gets it. Ask what slump the crew wants at placement and what their rule is about adding water at the chute, since extra water makes the paste easier to spread and weaker once it sets.
Reinforcement comes next. Rebar, welded wire and fibers each do a different job, and steel lying on the dirt does very little. Ask what your slab gets and how the steel is held up in the middle of the thickness during the pour.
Planned cracks and an isolation gap
Concrete shrinks as it dries, so a crack somewhere is normal. Control joints decide where it shows up. Request a drawn joint plan with spacing and depth, and ask whether joints will be tooled while wet or sawn soon after. Where new concrete meets the foundation, a step or an existing slab, ask whether an isolation joint goes in so each piece can move independently.
Where the water goes
A slab sheds every drop that lands on it. Ask how much fall each section gets per foot, which way it runs, and where the runoff ends up. Ask whether downspouts should be extended or piped before the pour, and how the soil at the slab edge will be shaped so water moves away rather than under. A walk that tips toward the house is far cheaper to fix on the drawing than after it cures.
Pour day and the weeks after
Ask what forecast would make the contractor reschedule, in heat, cold or rain. Ask how the slab will be protected if a frost is predicted in the first days, and how it will be kept from drying too fast on a warm afternoon: wet curing, plastic sheeting, a curing compound, or a mix of them. Ask how long before you can walk on it, and how long before a car can park on it. Ask which sealer they recommend, when the first coat should go on, and which deicers to keep off the new surface.
Registration, permits and coverage
Paperwork questions belong in the first meeting, not the last:
- What state registration or license, if any, covers this work, and what is the number?
- Which city permits does the job need, and who pulls them?
- Will an inspection be part of the job, and at what stage?
- Can you show proof of liability coverage and workers' compensation?
Write down the answers next to each company's name.
Weighing the bids
Line the written bids up and check each for:
- square footage, thickness and finish by area;
- demolition and disposal;
- excavation depth, base and compaction;
- mix strength, air entrainment and reinforcement;
- the joint plan and the slope plan, including downspout changes;
- curing method and any sealer;
- permits, locates and cleanup;
- the written warranty and its exclusions.
When one number sits far below the rest, look for the line it skipped, and ask about it before you sign.