DIY radon mitigation

Start with the saving, not the project

Most DIY guides open with a parts list. It is more useful to open with what you are saving, because that is the number that decides whether the weekend is worth it.

A full sub-slab system installed by a York County contractor averaged 1,279 dollars across 834 jobs in the state record. Materials for that job, a fan, PVC pipe, fittings, a manometer and sealant, are a substantial part of the total; the rest is labour, the core drill, and knowing where to put the hole. Doing it yourself is therefore a saving of several hundred dollars rather than of a thousand.

Against that saving, weigh three things you give up. A contractor's post-mitigation test proves the work succeeded. A warranty covers the fan. And a DEP certified installer has usually placed hundreds of suction points, which is the single judgement call that determines whether the system works.

Are you allowed to do it yourself?

Pennsylvania runs a certification programme covering radon testing, mitigation and laboratory analysis, for individuals and firms alike. That programme governs people performing these services, and whether it reaches an owner working on their own house is a question for the department rather than for a guide.

Ask them before you start. The DEP Radon Division answers on 800-237-2366, and a call costs nothing compared with discovering afterwards that a system cannot be documented when you sell. Two related points are not in doubt: work on a property you rent out, or on anyone else's house, sits squarely inside the certification requirement, and any system you install will be looked at by an inspector when the house changes hands.

How a sub-slab system goes in

1. Choose the suction point. Usually one, in the basement, ideally near the sump pit. This is the decision the whole system rests on, and the one hardest to judge without experience.
2. Test the draw before committing. Drill a small test hole, and check whether the material under the slab is gravel or compacted clay. Gravel spreads the suction across the footprint. Clay does not, and a house on clay may need two or three points.
3. Cut the suction hole. Four to six inches through the slab, then clear a void underneath so the fan draws from a space rather than a hole.
4. Run the pipe. Three or four inch PVC from the suction point out through the rim joist and up the exterior wall, or internally to the roofline. It must discharge above the roof and away from windows.
5. Mount the fan outside the living space. Attic or exterior wall, never inside a room you occupy. Downstream of the fan the pipe is under positive pressure, so a leak indoors would discharge radon into the house.
6. Wire it properly. The fan runs continuously on its own circuit. If you are not comfortable with that, this is the step to hire out.
7. Seal the openings. Sump lid with a gasket, visible slab cracks, and the slab to wall joint.
8. Test afterwards. Wait for the system to draw down, then run a fresh test. Without this the job is unfinished, whatever the manometer says.

Steps one and five are where DIY installations go wrong. A suction point in the wrong place leaves half the slab unserved, and a fan mounted in the basement turns the pipe into an indoor radon source if it ever cracks.

When doing it yourself does add up

There is one case where the arithmetic clearly favours you, and one where it clearly does not, and they are easy to tell apart.

If your house already has a passive pipe running from under the slab to the roof, fitted during construction, then the expensive part is in the ground. Adding a fan is a smaller job, and a competent DIY installer can do it. Note that this is also the cheapest professional job in the county, averaging 770 dollars across 143 installations, so the saving is modest and the professional route comes with a test and a warranty.

If there is no pipe, you are cutting a slab, judging a suction point, running pipe through a wall and wiring a fan. That is the 1,279 dollar job, and it is the one where the experience is worth what it costs. A house with a crawl space, a stone foundation or an addition raises the difficulty further.

Whichever route you take, do not skip the post-mitigation test. The state record shows what professional work achieves, and the only way to know your own system reached the same place is to measure it. The page on radon testing in York County covers how, and when.

What the job needs

The tool that stops most DIY attempts is the core drill. Cutting a clean four inch hole through a concrete slab needs a rotary hammer with a core bit, and hiring one for a day is the usual answer.

Beyond that: PVC pipe and fittings, an inline radon fan rated for the job, a U-tube manometer, a sealed sump lid, polyurethane sealant for the slab joint, and the electrical materials for a dedicated circuit. Fan sizing is not guesswork; a fan matched to gravel under the slab behaves very differently from one matched to compacted soil, and getting it wrong means either poor suction or a needlessly noisy system that costs more to run.

Common questions about DIY radon mitigation