Whitehall and Reynoldsburg ranch radon: slab, crawl, basement

You live in a one-story ranch in Whitehall or Reynoldsburg, and a radon test just came back at or above 4 pCi/L. Before comparing proposals, find out what the house sits on, because a ranch can rest on a slab, a crawl space or a basement, and each one gets a different system.

The postwar neighborhoods of Whitehall and Reynoldsburg include slab ranches, crawl space ranches and some built over basements. Here are the three side by side.

Slab-on-grade: the floor is the foundation

A slab ranch has its living-room floor poured directly on the ground. Soil gas enters through cracks, the joint at the slab edge, and gaps around plumbing and utility lines. Every room is in ground contact, so nothing stands between the soil and the bedrooms.

The fix is sub-slab suction: a hole through the slab, a small pit dug into the fill beneath it, and a pipe that pulls soil gas from under the floor before it can come inside. The suction point usually goes in a closet or utility area where the pipe can rise straight into the attic, or near an outside wall so it can exit to an exterior fan. Where nobody knows what fill lies under the slab, the Ohio Radon Mitigation Standards (ORMS) require a communication test first to show how far suction spreads.

EPA's Consumer's Guide to Radon Reduction puts active sub-slab suction at 50 to 99 percent reduction. Passive suction, the same pipe without a fan, is listed at 30 to 70 percent; it runs on natural draft, and a one-story house gives the pipe less height to build draft. For a slab ranch, plan around the active version; the passive range is too wide to count on.

A typical active sub-slab system on our price list runs $1,200-$2,400.

Crawl space: the house sits over open soil

A crawl space ranch has its floor framing raised above a shallow space with dirt at the bottom. Soil gas collects there and rises through the subfloor, around pipes and wires, and through any ductwork that runs below the house. Bare earth or torn plastic gives it an easy start.

The fix is sub-membrane depressurization. ORMS sets the sheet at a minimum of 6 mil polyethylene, or 3 mil cross-laminated, and calls for heavier material where the crawl is used for storage or entered often. Seams overlap by a foot or more and are sealed, and the sheet is fastened mechanically to the walls and piers. A suction point under the sheet pulls gas out through a pipe that leaves the crawl. EPA lists sub-membrane suction at 50 to 99 percent reduction, the same range as sub-slab suction.

Natural crawl ventilation, meaning open vents and moving air, is listed at 0 to 50 percent. Opening the crawl vents is not a radon system; EPA's own range for it starts at zero.

The fan never goes in the crawl, under the house, or in any conditioned room. ORMS allows only an attic, a garage with no living space above it, or the exterior. If the fan goes outside, it is hard-wired, with a disconnect outdoors within sight of the fan and within 4 feet of it. A plug-in fan's cord can be no longer than 6 feet and can never pass through a wall.

A crawl space system sits in the higher tier on our price list, $1,800-$3,500, because the membrane adds material and labor a slab job does not have. See crawl space radon mitigation for what that work includes.

Full or partial basement: the ranch with a lower level

Some postwar ranches were built over a full basement, and others over a partial one with a crawl or slab under the rest. Soil gas enters a basement through the slab, the floor-wall joint, cracks, floor drains and the sump. If the walls are concrete block, the hollow cores can carry gas from the soil into the space as well.

A full basement gets sub-slab suction, the same method as a slab ranch, except the pipe starts lower and has to leave the basement before it reaches the fan. The floor-wall joint is sealed with urethane caulk, with backer rod where the gap tops half an inch, in a way that keeps any perimeter channel drain working. A sump pit with a working pump is not the main suction point; it gets an airtight, labeled cover with a view port so the pump can still be serviced.

A partial basement usually means a combination system: suction under the basement slab plus a membrane over whatever crawl sits beside it. Diagnostics decide whether both legs share one fan. A full basement typically prices in the $1,200-$2,400 tier; a partial basement with a crawl moves into the crawl tier.

Testing each foundation type

The Ohio measurement protocol tests the lowest structural area suitable for occupancy, in a room that can be regularly used. Bathrooms, kitchens, laundry rooms, closets, crawl spaces and sumps do not count. That plays out differently under each ranch:

• Slab: the main floor is the lowest level, so the device goes in a bedroom, living room or den.
• Crawl: the crawl is never a test location, so the device goes in a regularly used room above it.
• Basement: the basement is the test level when it is suitable for occupancy.
• Mixed: Ohio's protocol asks for each foundation type to be tested in a split-level, and the same logic fits a ranch that combines a partial basement with a crawl or slab. Results from separate locations are never averaged.

The crawl space and the sump are never where the test goes, no matter which ranch you own. After a system is installed, the follow-up test goes in the same spot as the first one, at least 24 hours after the fan starts and within 30 days.

Which one is yours

A quick way to tell from the yard and the hallway:

• No stairs down, no foundation vents, and a floor that sits close to ground level outside: slab.
• Small vents or an access door in the foundation wall, or a hatch in a closet floor, and floors that sound hollow underfoot: crawl space.
• A stairway down: basement. If it runs under only part of the house, look for a knee wall or an opening into a crawl at its edge.
• A later addition may sit on a different foundation than the original house, so treat it as its own foundation type for testing and design.

Knowing the foundation before anyone visits makes every proposal easier to compare. Our pricing by foundation type shows how the tiers line up. Then call or text us with the foundation type and your result, or run a first estimate with the calculator.