--- title: Questions to Ask Your Builder About Radon canonical: "https://radonmitigationyorkpa.net/radon-guide/questions-to-ask-builder-about-radon/" pubDate: "2026-10-01T00:00:00.000Z" updatedDate: "2026-10-03T00:18:00.000Z" author: Radon Mitigation York PA description: "A short checklist for new-home buyers: what radon features to ask about, where the vent stack goes, the attic outlet, testing and who pays to add a fan." --- # Questions to Ask Your Builder About Radon Ask your builder whether the house will be [built to resist radon](/services/new-construction-radon/), with these features: gravel or a mat under the slab, a vapor retarder and sealed openings. Then ask where the vent stack will run, whether there is an attic outlet for a fan, who tests after move-in and who pays to activate the system if the test is high. ## Why ask before you build Radon control is cheap and easy to include before the slab is poured, and harder to add later. EPA notes the cost to the builder of including radon-resistant features is typically less than mitigating the home after construction. Once the concrete is down, you cannot add a gravel layer or plastic sheeting under it. Pennsylvania's building code does not require radon-resistant construction statewide, so it is up to you to ask. Get the answers in writing, ideally in your purchase agreement or spec sheet. ## The checklist ### Under the slab 1. **Will there be a gas-permeable layer under the slab?** Look for about 4 inches of clean, coarse gravel or a soil gas collection mat. 2. **Will plastic sheeting go over that layer?** EPA cites 6 mil polyethylene, with seams overlapped and taped. 3. **Is there a suction pipe or T-fitting in the gravel?** It connects the sub-slab layer to the vent stack. ### Sealing 4. **Will slab cracks, joints and pipe penetrations be sealed?** Ask about the floor and wall joint in particular. 5. **If there is a sump pit, will it have a sealed, gasketed lid?** An open pit lets soil gas skip the whole system. ### The vent stack 6. **Where will the vent stack run?** It should go up through the inside of the house, often in a closet or chase, not up an outside wall. 7. **What size is the pipe?** EPA's guidance calls for 3 or 4 inch Schedule 40 PVC. 8. **Will the pipe be labeled on every floor?** Labels keep future trades from cutting into it. ### Ready for a fan 9. **Will there be an electrical outlet in the attic near the stack?** That makes adding a fan a quick job. 10. **Is there room in the attic to install a fan?** The pipe should not be buried under insulation or boxed in. ### Testing and activation 11. **Will the home be tested for radon, and when?** A test after occupancy, under normal living conditions, gives a real result. 12. **Who pays to add a fan if the test is 4.0 pCi/L or higher?** Some builders cover activation. Others leave it to the buyer. 13. **Will a PA DEP certified mitigator do the test and activation?** Pennsylvania requires certification for anyone who tests or mitigates for others. ## What good answers sound like A builder who takes radon seriously can point to each feature on the plans. They can tell you where the stack runs and show you the attic outlet location. They know the difference between a passive and an active system. Our guide to [radon-resistant new construction explained](/radon-guide/radon-resistant-new-construction/) walks through each part, so you know what you are looking at. EPA's [radon-resistant construction basics](https://www.epa.gov/radon/radon-resistant-construction-basics-and-techniques) page is another good reference to share with your builder. ## Red flags Be cautious if you hear: - "Radon isn't a problem around here." York County is in [EPA Radon Zone 1](https://www.epa.gov/radon/epa-map-radon-zones-and-supplemental-information), the highest potential category. - "The plastic under the slab takes care of it." A vapor retarder alone is not a radon system. - "We can always add a pipe later." You can, but it usually means a retrofit with a pipe on the outside of the house. - "There's no need to test a new house." EPA recommends testing every new home after occupancy. ## If the house is already built If you are buying a spec home or a home that is already framed, you can still ask most of these questions. Look in the basement or utility room for a labeled PVC pipe coming out of the slab, and check the attic for the pipe and an outlet. If there is no stack, plan to test after move-in. A retrofit system is still an effective fix. ## Key takeaways - Ask about radon before the slab is poured, when it is cheapest to add. - Check for gravel or a mat, plastic sheeting, sealing, a labeled interior stack and an attic outlet. - Settle who tests and who pays for a fan, in writing. - Pennsylvania does not require RRNC statewide, so you have to ask. ## Frequently Asked Questions ### Can I ask my builder to add RRNC if it is not in the spec? Usually, yes, if you ask before the slab is poured. Expect it to be a change order. ### Should the system be active from day one? It is your choice. Many buyers test first and add a fan only if needed. Others activate right away. ### Who can do the radon test on a new home? In Pennsylvania, anyone testing for someone else must be certified by PA DEP. ## Get a second set of eyes on your build We work with York builders and buyers to plan, check and activate radon systems. Call [(717) 356-3035](tel:+17173563035) any time for a same-day callback.