Yes. A newly built home can have elevated radon just like an older home. Modern construction and a builder-installed radon rough-in do not tell you the radon level inside the finished house.
Radon comes from the soil and can enter anywhere the home contacts the ground. Foundation joints, sump pits, service penetrations, floor drains, and cracks can exist in both new and older homes. Building features can influence how radon enters and accumulates, but testing is the only way to know the level in a specific home.
Health Canada recommends testing a newly built home during the first heating season after occupancy and testing it again two years after the year of construction.
Why can a new home still have high radon?
New construction does not remove the source of radon beneath the home. The soil, foundation design, sub-slab material, sump, ventilation, weather, and occupant habits can all affect the indoor level.
Newer homes are often built with tighter windows, more continuous air barriers, and less uncontrolled air leakage than older homes. Reduced natural ventilation can influence how an indoor contaminant accumulates. However, that does not mean every new home will have more radon than every older home. It simply means that age and apparent construction quality cannot predict the result.
Two nearly identical homes on the same street can have very different radon levels. One may remain below the Canadian guideline while the other requires mitigation.
What is a radon rough-in?
In many newer Calgary homes, the visible part of a radon rough-in is a capped pipe extending from the basement floor, often in or near the mechanical room. The pipe may be white, black, or grey and may have a coloured cap or label identifying it for radon or soil gas.
The visible pipe connects to the area beneath the basement slab. Its purpose is to make it easier to add a radon-reduction system if testing later shows that one is needed.
The appearance varies between builders and code generations. If you are unsure whether a pipe is a radon rough-in, do not cut, open, or connect equipment to it without having it identified and evaluated.
A capped rough-in is not an operating mitigation system
This distinction matters:
- A capped rough-in is preparation for a future system. While it remains capped, it does not draw radon from beneath the home or exhaust it outdoors.
- A passive soil depressurization system connects the sub-slab pipe to an exhaust above the roof and relies on natural airflow rather than a fan.
- An active soil depressurization system adds a continuously operating fan that actively draws soil gas from beneath the foundation and releases it outdoors.
Health Canada describes passive and active systems as different levels of radon control. A passive stack may reduce radon, but the home still must be tested. If the passive system does not produce enough reduction, it can be converted to an active system by adding an appropriately selected fan.
A capped pipe in the basement should not be described as a working passive system. It is only a rough-in until it is connected to a complete exhaust pathway.
Why must the rough-in be tested before adding a fan?
The pipe has to communicate with the material beneath the slab. If its lower end is blocked, poorly located, or surrounded by material through which air cannot move adequately, attaching a fan may produce poor airflow and fail to depressurize the foundation.
ATMOS evaluates an existing rough-in using diagnostic suction and pressure measurements. This tells us whether the pipe is clear enough to use, whether suction reaches the required areas beneath the slab, and what fan performance the home requires.
What problems can occur with builder rough-ins?
ATMOS has encountered many rough-ins that could not be used effectively. Common problems include:
- A blocked or obstructed sub-slab opening
- A pipe surrounded by material that restricts airflow
- Insufficient communication across the basement footprint
- A location that creates a difficult or unnecessarily intrusive pipe route
- Foundation sections or slab levels that the rough-in cannot adequately reach
An unusable rough-in does not prevent the home from being mitigated. It normally means creating a new suction point in a location supported by diagnostic testing.
When should a newly built home be tested?
The best time to begin thinking about radon is now, but the measurement used for a final decision should follow current testing guidance.
Health Canada recommends:
- Test during the first heating season after occupancy. The long-term measurement should include at least 91 days during the heating season.
- Retest two years after the year of construction. New construction can continue to dry, settle, and change after occupancy.
- Retest after major changes. Basement development, a new furnace or ventilation system, energy-efficiency upgrades, excavation near the foundation, or structural cracking can change the conditions affecting radon.
A homeowner can start monitoring at any time of year. A high summer result should be taken seriously, but it does not prove that winter will be higher. Conversely, a low test that does not contain enough heating-season days may underestimate the annual average and should be repeated according to Health Canada guidance.
Does a new home’s HRV solve radon?
Not necessarily. A properly balanced heat-recovery ventilator can sometimes reduce radon by increasing controlled ventilation, but it is not a substitute for testing. Its performance depends on the home, airflow balance, operating settings, and the amount of reduction required.
If a home has significantly elevated radon, active soil depressurization is generally the most effective and reliable solution. Testing tells the homeowner whether the existing construction and ventilation are keeping the level acceptably low.
What happens when the rough-in works?
When diagnostic testing confirms that the rough-in is clear, properly located, and capable of depressurizing the required area, ATMOS can use it as the system’s suction connection.
We then install the appropriate fan and piping, route the system to a compliant exterior discharge, seal accessible radon entry points, and verify the system’s operation. Using the rough-in avoids creating a new opening through the basement floor and saves some installation time.
An ATMOS installation using a suitable existing rough-in currently starts at approximately $2,350 plus GST. A standard installation requiring a new suction point is typically around $2,500 plus GST.
What if the rough-in does not work?
The solution is usually straightforward: ATMOS selects a more suitable location, creates a new suction point, and installs the active system independently of the blocked rough-in.
The new suction point is not a lesser alternative. When it is chosen through diagnostic testing, it can be as effective as—or more effective than—an existing builder rough-in.
ATMOS guarantees that systems we install will reduce the home’s radon level below 75 Bq/m³.
New home or old home, the answer is the same
Radon does not care whether a home is new or old, north or south, expensive or modest. Every ground-contact home in Alberta is capable of having an elevated level.
A rough-in makes future mitigation easier only when it is usable. It does not replace the need to test, and a capped rough-in does not reduce radon by itself.
Testing is affordable, straightforward, and the only reliable way to understand your home.
Sources
- Health Canada: Guide for Radon Measurements in Homes
- Health Canada: Reduce Radon in Your Home
- City of Calgary: Radon Information