Bake-outs are a frequent topic of discussion on Toxic Free Q&A. Many people have reported success reducing odors from off-gassing building materials and household items using the bake-out method. After reviewing available research, I believe the risks outweigh the potential benefits.
A bake-out is a method of heating rooms to make chemicals from paints, finishes, and other building materials offgas more quickly.
The bake-out method was designed to accelerate the curing process of certain building materials that have some toxicity during application, but cure to a nontoxic finish. In these materials the sources of off-gassing are solvents used to keep the material pliable (as in the case of caulks, paints, and other finishes) or residual chemicals used in manufacturing that have not completely dissipated (such as adhesives used to hold together wood floor tiles). Once these chemicals offgas, however, the resulting product is non-toxic.
Unfortunately, research shows that the method does not routinely lower VOC levels.
Bake-Outs Can Increase VOC Levels
Researchers have found that bake-outs do not lower, and can sometimes increase, VOC levels (1,2,3). One explanation for an increase in levels is that the high concentration of VOCs generated by high temperature can become reabsorbed by porous material.
According to the Healthy House Institute, bake-outs seem to have little effect on formaldehyde levels, probably because formaldehyde-containing materials, such as particle board, are thick enough to have a substantial reservoir of formaldehyde in them.
There are additional risks to conducting a bake-out:
- Studies show that some chemicals are released into the air that are not released at room temperatures.
- All materials in the heated room can potentially emit VOCs. The mix of chemicals could form new, harmful compounds.
- Some materials will heat faster than others which can cause building materials to warp or crack.
Flush-Outs Recommended for New Construction
A flush-out is a technique that forces large amounts of air through a building before occupancy to lower VOCs. This is the method recommended by the U.S. Green Building Council for LEED credit prior to occupancy. The method requires very specific levels of ventilation, humidity and temperature.
Tips to Reduce VOCs in Your Home
- Purchase building materials and home furnishings with low or no VOCs.
- Improve ventilation. Open windows frequently and use fans to bring outdoor air inside. Consider mechanical ventilation for new construction.
- Seal building materials and wood furniture that are known to have high levels of VOCs with a product designed to seal in toxins, such as AFM Safecoat.
- Use a high quality air purifier designed to remove VOCs.
- Work with an indoor air quality professional if you are considering a flush-out for new construction.