One-component foam joint sealant is widely used to seal air leaks by homeowners. Various chemicals can be emitted from a foam joint sealant. The goal of this study was to develop a glass chamber method to examine the emissions of 4,4′-methylenediphenyl diisocyanate (4,4′-MDI) and tris(2-chloroisopropyl)phosphate (TCPP) from foam joint sealants. The concentrations of 4,4′-MDI and TCPP were measured during a 24-h chamber test that involved a 3-L chamber operated at 40°C, 20 % relative humidity (RH), 22.2 air changes per hour, and 2 sampling media (glass filter coated with 9-methylaminomethyl anthracene for 4,4′-MDI and sorbent tube filled with Tenax^® TA for TCPP). The 4,4′-MDI concentration peaked within 11 min and decayed to below the lowest limit of quantification within 1 h. The TCPP concentration reached a maximum value at approximately 4 h and decayed relatively slowly or stayed almost constant afterward. The 4,4′-MDI concentration after applying foam joint sealant to all the windows of a small house was predicted to be much lower than the reference value of 0.6 μg/m³ by the U.S. Environmental Protection Agency. Conversely, the higher predicted concentrations of TCPP than the measured indoor levels may imply the potential of foam joint sealants as an important source of TCPP in homes. In addition, the test with 4,4′-MDI for method optimization showed that the effect of environmental factors (temperature and RH) as well as the sink effect by interior surfaces could be significant. When a test method is standardized for 4,4′-MDI emissions, these influential factors should be investigated.