Is an aluminum downspout an approved material to vent vapor mitigation systems? Will VOCs being vented compromise the aluminum or caulk?
Yes, aluminum downspout material is permitted to be used for the exhaust stack from the fan for a sub-slab depressurization system (SSDS) per USEPA Radon Guidance (Radon Reduction Techniques for Existing Detached Houses: Technical Guidance (Third Edition) for Active Soil Depressurization Systems; EPA/625/R-93/011). The connections between lengths of the material are sealed with caulking and secured with sheet metal screws. To seal the connection a bead of silicone caulk is placed along the inside of the female end, then the connecting end is inserted. Another bead of caulk is placed on the outside of the seam of these pieces, making the assembly air-tight. Sheet metal screws are then installed through both pieces to prevent the piping from separating. The seam is checked for leakage with various methods depending upon ambient conditions. During routine O&M system inspections, fitting seams are checked where caulk was used in the assembly. The VOCs being vented from the sub-surface thro
