You have a full basement
“We have a normal basement under the whole house.”
A full basement puts a large floor area in direct contact with the soil, which is why it is both the standard place to measure and usually the highest-reading level in a building.
It is also the easiest foundation to work with, which is why most published design guidance is written around it.
Why this matters
What it changes about the decision in front of you.
- The slab and the wall-floor joint are the largest contact area with the soil in most houses, so entry paths are concentrated there.
- Guidance asks for the lowest level lived in or reasonably occupiable, and a full basement is almost always that level.
What it could influence
Where the effect is likely to show, and in which direction where that is knowable.
- A basement figure is normally higher than the occupied floors above, sometimes considerably.
- Whether the space is finished changes both occupancy and the accessibility of the joint and any penetrations.
What this does not settle
What still stands. Noticing a problem is not the same as losing the evidence.
- A basement reading is not a worst-case exaggeration — it is the standard benchmark and the figure a buyer will ask for.
- The presence of a basement does not indicate elevated levels; plenty read low.
- It does not determine what design would suit the house, which depends on what is under the slab.
What a professional is likely to ask
Worth having answers ready. None of these is a test you can fail.
- Whether the slab is poured concrete throughout, and whether there are visible joints or penetrations.
- Whether the space is finished, and what the finish would have to be disturbed to reach.
- Where the sump, drain tile, and any floor drains are.
What you can check yourself
Things you can establish today, without anyone visiting.
- Visible cracks, the floor-to-wall joint, and any open penetrations around pipes.
- Whether there is a sump pit, and whether it has a sealed lid.
- How the space is used, and by whom.
What genuinely needs somebody on site
Where this platform stops. These are not questions a website can answer about your house.
- How well the material under the slab communicates, which determines whether one suction point will serve the whole floor.
- Whether the slab is continuous or has sections poured at different times.
Categories a next step could fall into
Unordered, and none of them is a recommendation. Which applies depends on things this page does not know about your situation.
Related reading
- Finished basements — A finished basement raises both the exposure and the cost of fixing it — which is why the timing question matters more than the technique.
- What makes a great system — Six design choices that decide whether a system performs for a decade.
Sources
- U.S. EPA — Consumer’s Guide to Radon Reduction
When you are ready to talk to somebody
Tell us about your home and what you are trying to work out. We will tell you honestly whether we can route it to a provider in your area today.