Slab foundation building in Kirkland WA - a level floor that drains and holds up

Most people who call me about a slab already have plans in hand, often for a detached garage, a shop or an addition, and want to know what their ground and the city will mean for the job. The price moves with the slab's size and thickness, how much digging and base the site needs, how much steel goes in and how close a concrete truck can get, plus any extra steps the city asks for on your lot. The schedule mostly turns on what the city says about your lot and the weather in the weeks you want to pour, and if your plans need concrete footings under the walls, those go in first. You'll get the figure for your own job at the estimate, once I've walked the site.

I start by walking the lot and checking what the city's maps show for it, because that can change the plan and the schedule before we dig anything. Then our crew digs out the topsoil and soft ground down to the subgrade, the firm ground the slab will sit on, and brings in gravel that we pack down in layers so the slab doesn't settle with the dirt under it. We set the forms, make sure the finished grade sends water away from the building, and set the rebar, the steel that ties the slab together, up on supports at the height it's drawn for so it ends up inside the concrete instead of pressed into the dirt. We pour early in the day to stay out of the afternoon heat, which can leave a weak, dusty top. Then we finish the surface and cut control joints, shallow grooves that give the concrete a place to crack where we choose. After that we keep the slab covered and protected while it cures and gains strength. The base is the part nobody sees once the concrete is down and the first thing people want to trim from a budget, and I won't trim it, because a slab is only as flat as what's under it.

A slab is often one piece of a bigger build. When the plans call for footings and walls with a crawl space under the floor, that's foundation installation, and we can handle both parts on the same project. For small property owners putting up a shop or a rental, we can also take on concrete parking lot building for the ground around it, so the base work and the drainage get planned together.

In Kirkland, work within a geologically hazardous area needs a critical area permit from the city, and those areas include land prone to landslides or severe erosion. The city's interactive maps give you a general idea of where critical areas are, but only the city can say what applies to your property, and it asks owners to contact it early to confirm whether that permit is needed. Its guidance also says a lot within 125 feet of a stream or 300 feet of a wetland should be looked at by a qualified professional. Fees and review times depend on the project's size and the type of critical area, so that early check is what sets a realistic budget and start date. When your job needs a permit, I'll tell you at the estimate and either take care of the application with the city or county or walk you through it, so you know where it stands. The city's Development Services Center takes permit questions at 425-587-3600.

A lot of the slabs we pour around here go on sloped or tight lots where the truck can't pull right up, and our wet months put rain into every plan, so we work out the pour route and where the water will run before the forms go up. We're based in Kirkland and work across the cities around it, inside city limits and out in the county areas, and we plan slabs the same way on jobs in Bellevue and Redmond.