Caulk would be better due to expansion & contraction - as for "soiling," was the system tested for leakage. You are in California & it should have been but was it sealed adequately. The biggest reason for dust coming through is leakage especially in the return ducts located in the attic & crawls For More: http://thehtrc.com/2011/air-sealing-duct-system
Is there a green product I can use to prevent ventilation soiling of my wool carpet?
Is there a green product I can use to prevent ventilation soiling of my wool carpet?Asked by Deborah
Is there an expanding foam that's green and safe to use around wool carpet? We have a new HVAC system, regularly change the filters, keep interior doors open, vacuum weekly, installed wool carpeting upstairs.