How Do You Keep Radon and Chemical Off-Gassing Out of a New ADU?

By Buz Artiano, BuildX | October 2026

Watch: Designing Concepts & Tools for Net Zero Homes w/ Gwendolen St. Sauveur | BuildX Podcast #18

A brand new ADU has a smell of fresh lumber, fresh glue, and fresh paint. Most families think that smell means that the place is clean. If someone in your family has a health condition, is sensitive to chemicals or lungs that are sensitive to everything then that smell brings up a question. What might be coming off the walls, or up through the floor? You're building a home for someone you love, and you really don't want it to come with a bunch of problems.

My name is Buz Artiano, and I am the founder of BuildX. We've built dozens of ADU projects across Massachusetts, mostly around the South Shore and Plymouth County areas. We are the only team you need: we do the design, permitting, and construction. So we see every phase of a project from the first site visit up until you move in. We evaluate septic constraints, zoning issues, utility connections and the requirement to get a permit from the city. The quality of the air has to go through those same regulations.

Over the last few years, we've had a lot of clients come to us with some sort of environmental issue, and they want to know that when we build them a new home, it's not going to aggravate the problems they're already having. So we've had lots of conversations about radon, and about how much glue is used during framing. Our position is this: the time to deal with this stuff is before the floor is poured and before the walls are closed up, because that's when you can make some meaningful changes.

What Does It Take to Lower Radon and Off-Gassing in My New ADU?

It takes different steps for different sources that are put into the plans before construction starts. Radon comes from below. Off-gassing comes from the materials used. Dust and pollen will be tracked in on your boots. Each one of these needs its own control, and no single thing will take care of all three.

• Radon control gives the gas a way to go up and out of the house so it doesn't get into your living area.
• Lower-emission materials will reduce how much off gassing there is from new products.
• Ventilation and filtration help clean the inside air and trap small particles.

Rough-in is the part of construction when pipes, wires, and ducts are installed before insulation and sheetrock go up. The timing is the whole solution. Each one of these steps are easy to do at the rough-in stage, but become very difficult to add later.

Isn't Indoor Air Quality Only an Old-House Problem?

It's actually the exact opposite. Older houses will lose air through every gap around windows, sills, and outlets. And yes, that wastes energy, but it also brings outside fresh air into the house. A new ADU that's built to current energy standards is air tight on purpose. Whatever gets released inside stays inside unless a ventilation system gets rid of it.

A new ADU begins by releasing more than an old house. Off-gassing is the slow release of volatile organic compounds, or VOCs. Those are the chemicals that evaporate off of building materials, adhesives, and finishes when at room temperature. An old house has already released most of its VOCs a long time ago. A new ADU is releasing them from the first day.

And of course there's the issues that every house has, which is pollen, dirt, and dust are brought in on your shoes every day, and if you have pets, add more dirt and pet hair on top of that. That's why our clients with health concerns ask us about air quality before they ask about any of the finishes or other details.

Why Do We Put a Radon Pipe in Every Structure at Rough-In?

When rock in the ground decays it makes Radon and starts to give off radioactive gas that goes up through the ground and whatever is on the top of it. The Massachusetts Department of Public Health says radon causes cancer and says that all houses should be tested for it. The guidelines from the state are at mass.gov.

We put a radon pipe in all our structures now ahead of time. The pipe is put into the floor and then goes straight up through the house by using what's called the chimney effect which means that warm air goes up. Air with gas from the soil in it from under the floor will go through a pipe and up out of the living area. Every time the pipe bends it slows that down so we make a straight path in the framing plan.

The pipe is just one part of a system. Radon-resistant construction puts the vent pipe together with a gas-permeable layer underneath the foundation. That allows the gas from the soil to collect and reach the pipe, the slab that lets soil gas collect and reach the pipe, a sheet barrier over that layer, and sealed cracks and openings in the floor. A passive system can be activated by adding a fan to the pipe if testing shows elevated levels. Massachusetts requires a passive radon system in new one- and two-family homes in Worcester, Essex, and Middlesex Counties, with details at mass.gov. If you don't live in one of these counties, ask your builder which components are in the specifications.

We're not going to tell you that this was always the standard for us. We built quite a few of houses that didn't have a radon pipe. It's a requirement for us now, because so many of our discussions with clients recently have involved radon. A pipe doesn't prove that a house is protected because levels of radon vary from property to property. The only way to know what your ADU has is to test it after you move in.

Where Do Adhesives Hide in an Ordinary ADU Framing Package?

Most homeowners think that glue is used at the end of the construction, under the floor or behind a backsplash. But the truth is that glue is actually built into the structure of the ADU itself. There's a lot of adhesive in a standard framing package:

• OSB, which stands for oriented strand board, are sheathing panels made of wood strands pressed together with resin.
• Microlams are engineered beams made of thin wood veneers glued into a solid header or beam.
• I-joists are the floor joists built from a thin web glued between a top and bottom flange.
• Construction adhesive are beads of glue that hold framing members and sheathing together.
• Spray foam and spray foam glue include an adhesive that goes under the subfloor to hold it to the joists.
• Acrylic window wrap is the adhesive-backed flashing tape that seals the framing around each of the window openings.

Everything on this list is there for a reason. Engineered lumber goes across longer distances with straighter, more consistent material, and subfloor adhesive helps keep the floor from squeaking. Your exposure from these glued products depends on their emissions. Two products that use the same amount of adhesive might release very different amounts of VOCs, so the question that's most useful for each one is if there is a lower-emission version and what the manufacturer says about emissions.

We have a client working on that question right now, trying to find the most cost-effective way to limit the adhesives in their house. The list above is where to begin, because you can't evaluate what you haven't listed. Each item becomes a decision point in the specifications, and should be made before the lumber order is placed.

What Does Ventilation Handle That Material Choices Cannot?

There is no materials list that has no emissions, and pollen and dust never came from the materials. When a client asks how to protect someone with some type of sensitivity, our answer is always the same: be smart about what we can eliminate, and then make sure that the whole house has an energy recovery ventilation system that works with an indoor air quality sensor.

An energy recovery ventilator, or ERV, gets rid of the stale inside air and brings in fresh outdoor air all the time, moving the heat and moisture between the two, so that you can keep most of the heat that you paid for. Ventilation dilutes indoor gases like VOCs. But particles like pollen and dust have to go through a filter in the ventilation or the system that handles air. Radon has its own system, not the ERV. The sensor will respond so when it sees that the indoor air quality has gone down, it will tell the system to come on and run air changes, meaning it replaces indoor air with outdoor air. A sensor works with only what it's built for, so make sure you pick one that matches the issues in your household. A good reading on one sensor doesn't mean that all the air in the house is safe.

Does Every ADU Need the Full Healthy-Air Spec?

Since we put all of this into our construction process, you'd expect us to tell you that every family needs this. But that's not the case. The radon pipe does go into every structure we build, and testing after move-in is done for every family. Ventilation works for every tight new home.

However, the deep product-by-product emissions work is a choice. If someone in your family suffers from reactions from chemicals or has an environmental condition, that extra time and cost is worth it. For other families, choosing lower-emission finishes on the things they'll touch the most is a good compromise. We are builders, we are certainly not doctors. If someone in your family has been diagnosed with a sensitivity, the advice of your doctor should be part of the design plan, we can build around that.

When Should You Lock These Air Quality Choices Into Your ADU Plans?

Make a decision on them before the rough-in. The radon system, the decisions about materials, and the ventilation design all need to be in the plans before construction starts, while each is just a simple choice instead of an expensive retrofit. The radon test will be done after you move in.