Your building

Your home has more than one foundation type

“Part of the house is over a basement and part is a slab or crawl space.”

Houses that have been extended commonly end up with two or three foundation types under one roof, often separated by a wall that was once external.

Each section may need its own approach, and the junctions between them are frequently the least well sealed parts of the building.

Why this matters

What it changes about the decision in front of you.

A suction point serving one section may not extend under another, because the sections were poured separately and may not communicate.
The joint where an addition meets the original structure is a common entry path and is often concealed.

What it could influence

Where the effect is likely to show, and in which direction where that is knowable.

A design may need more than one suction point, or more than one method, which affects both scope and cost.
A measurement in one section may not represent another, particularly across a former exterior wall.

What this does not settle

What still stands. Noticing a problem is not the same as losing the evidence.

Multiple foundation types do not mean the house is difficult in a way that should discourage anyone — it means the design needs to reflect the building.
It does not follow that every section needs treatment; measurement and diagnostics determine that.
A single reading does not establish which section is contributing what.

What a professional is likely to ask

Worth having answers ready. None of these is a test you can fail.

Where the sections are, when the additions were built, and what separates them.
Whether measurements have been taken in more than one section.
Whether the sections share heating and ventilation or are on separate systems.

What you can check yourself

Things you can establish today, without anyone visiting.

Roughly where the original house ended, which is usually visible from outside.
Whether floor levels change between sections.
Where the boundary walls are internally.

What genuinely needs somebody on site

Where this platform stops. These are not questions a website can answer about your house.

Whether the sections communicate beneath the floor, which only a diagnostic can establish.
Whether one system can serve more than one section.

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.

Request a professional assessment

When it is considered. When the building itself is part of the question — foundation type, an existing system, access, or an unusual layout.

What it would establish. What the building is doing, which no amount of information typed into a website can establish.

Discuss another test

When it is considered. When the prior result is disputed, the conditions cannot be reconstructed, or a longer observation period would answer the question being asked.

What it would establish. A second reading under conditions someone can describe, which is what makes two numbers comparable rather than merely different.

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.

Start a request